diff --git a/.ccignore b/.ccignore new file mode 100644 index 000000000..14561791f --- /dev/null +++ b/.ccignore @@ -0,0 +1,7 @@ +.pre-commit-config.yaml +.github/ +docs/changelog.mdx +docs/python-sdk/ +examples/ +src/fastmcp/contrib/ +tests/contrib/ diff --git a/.claude/hooks/session-init.sh b/.claude/hooks/session-init.sh new file mode 100755 index 000000000..3c767fc54 --- /dev/null +++ b/.claude/hooks/session-init.sh @@ -0,0 +1,26 @@ +#!/bin/bash +set -e + +# Only run in remote/cloud environments +if [ "$CLAUDE_CODE_REMOTE" != "true" ]; then + exit 0 +fi + +command -v gh &> /dev/null && exit 0 + +LOCAL_BIN="$HOME/.local/bin" +mkdir -p "$LOCAL_BIN" + +ARCH=$(uname -m | sed 's/x86_64/amd64/;s/aarch64/arm64/') +VERSION=$(curl -fsSL https://api.github.com/repos/cli/cli/releases/latest | grep '"tag_name"' | cut -d'"' -f4) +TARBALL="gh_${VERSION#v}_linux_${ARCH}.tar.gz" + +echo "Installing gh ${VERSION}..." +TEMP=$(mktemp -d) +trap 'rm -rf "$TEMP"' EXIT +curl -fsSL "https://github.com/cli/cli/releases/download/${VERSION}/${TARBALL}" | tar -xz -C "$TEMP" +cp "$TEMP"/gh_*/bin/gh "$LOCAL_BIN/gh" +chmod 755 "$LOCAL_BIN/gh" + +[ -n "$CLAUDE_ENV_FILE" ] && echo "export PATH=\"$LOCAL_BIN:\$PATH\"" >> "$CLAUDE_ENV_FILE" +echo "gh installed: $("$LOCAL_BIN/gh" --version | head -1)" diff --git a/.claude/settings.json b/.claude/settings.json new file mode 100644 index 000000000..afc82c2ea --- /dev/null +++ b/.claude/settings.json @@ -0,0 +1,15 @@ +{ + "hooks": { + "SessionStart": [ + { + "hooks": [ + { + "type": "command", + "command": "bash \"$CLAUDE_PROJECT_DIR\"/.claude/hooks/session-init.sh", + "timeout": 120 + } + ] + } + ] + } +} diff --git a/.claude/skills/code-review/SKILL.md b/.claude/skills/code-review/SKILL.md new file mode 100644 index 000000000..2542ee68f --- /dev/null +++ b/.claude/skills/code-review/SKILL.md @@ -0,0 +1,94 @@ +--- +name: reviewing-code +description: Review code for quality, maintainability, and correctness. Use when reviewing pull requests, evaluating code changes, or providing feedback on implementations. Focuses on API design, patterns, and actionable feedback. +--- + +# Code Review + +## Philosophy + +Code review maintains a healthy codebase while helping contributors succeed. The burden of proof is on the PR to demonstrate it adds value. Your job is to help it get there through actionable feedback. + +**Critical**: A perfectly written PR that adds unwanted functionality must still be rejected. The code must advance the codebase in the intended direction. When rejecting, provide clear guidance on how to align with project goals. + +Be friendly and welcoming while maintaining high standards. Call out what works well. When code needs improvement, be specific about why and how to fix it. + +## What to Focus On + +### Does this advance the codebase correctly? + +Even perfect code for unwanted features should be rejected. + +### API design and naming + +Identify confusing patterns or non-idiomatic code: +- Parameter values that contradict defaults +- Mutable default arguments +- Unclear naming that will confuse future readers +- Inconsistent patterns with the rest of the codebase + +### Specific improvements + +Provide actionable feedback, not generic observations. + +### User ergonomics + +Think about the API from a user's perspective. Is it intuitive? What's the learning curve? + +## For Agent Reviewers + +1. **Read the full context**: Examine related files, tests, and documentation before reviewing +2. **Check against established patterns**: Look for consistency with codebase conventions +3. **Verify functionality claims**: Understand what the code actually does, not just what it claims +4. **Consider edge cases**: Think through error conditions and boundary scenarios + +## What to Avoid + +- Generic feedback without specifics +- Hypothetical problems unlikely to occur +- Nitpicking organizational choices without strong reason +- Summarizing what the PR already describes +- Star ratings or excessive emojis +- Bikeshedding style preferences when functionality is correct +- Requesting changes without suggesting solutions +- Focusing on personal coding style over project conventions + +## Tone + +- Acknowledge good decisions: "This API design is clean" +- Be direct but respectful +- Explain impact: "This will confuse users because..." +- Remember: Someone else maintains this code forever + +## Decision Framework + +Before approving, ask: + +1. Does this PR achieve its stated purpose? +2. Is that purpose aligned with where the codebase should go? +3. Would I be comfortable maintaining this code? +4. Have I actually understood what it does, not just what it claims? +5. Does this change introduce technical debt? + +If something needs work, your review should help it get there through specific, actionable feedback. If it's solving the wrong problem, say so clearly. + +## Comment Examples + +**Good comments:** + +| Instead of | Write | +|------------|-------| +| "Add more tests" | "The `handle_timeout` method needs tests for the edge case where timeout=0" | +| "This API is confusing" | "The parameter name `data` is ambiguous - consider `message_content` to match the MCP specification" | +| "This could be better" | "This approach works but creates a circular dependency. Consider moving the validation to `utils/validators.py`" | + +## Checklist + +Before approving, verify: + +- [ ] All required development workflow steps completed (uv sync, prek, pytest) +- [ ] Changes align with repository patterns and conventions +- [ ] API changes are documented and backwards-compatible where possible +- [ ] Error handling follows project patterns (specific exception types) +- [ ] Tests cover new functionality and edge cases +- [ ] The change advances the codebase in the intended direction diff --git a/.claude/skills/python-tests/SKILL.md b/.claude/skills/python-tests/SKILL.md new file mode 100644 index 000000000..4193f6144 --- /dev/null +++ b/.claude/skills/python-tests/SKILL.md @@ -0,0 +1,220 @@ +--- +name: testing-python +description: Write and evaluate effective Python tests using pytest. Use when writing tests, reviewing test code, debugging test failures, or improving test coverage. Covers test design, fixtures, parameterization, mocking, and async testing. +--- + +# Writing Effective Python Tests + +## Core Principles + +Every test should be **atomic**, **self-contained**, and test **single functionality**. A test that tests multiple things is harder to debug and maintain. + +## Test Structure + +### Atomic unit tests + +Each test should verify a single behavior. The test name should tell you what's broken when it fails. Multiple assertions are fine when they all verify the same behavior. + +```python +# Good: Name tells you what's broken +def test_user_creation_sets_defaults(): + user = User(name="Alice") + assert user.role == "member" + assert user.id is not None + assert user.created_at is not None + +# Bad: If this fails, what behavior is broken? +def test_user(): + user = User(name="Alice") + assert user.role == "member" + user.promote() + assert user.role == "admin" + assert user.can_delete_others() +``` + +### Use parameterization for variations of the same concept + +```python +import pytest + +@pytest.mark.parametrize("input,expected", [ + ("hello", "HELLO"), + ("World", "WORLD"), + ("", ""), + ("123", "123"), +]) +def test_uppercase_conversion(input, expected): + assert input.upper() == expected +``` + +### Use separate tests for different functionality + +Don't parameterize unrelated behaviors. If the test logic differs, write separate tests. + +## Project-Specific Rules + +### No async markers needed + +This project uses `asyncio_mode = "auto"` globally. Write async tests without decorators: + +```python +# Correct +async def test_async_operation(): + result = await some_async_function() + assert result == expected + +# Wrong - don't add this +@pytest.mark.asyncio +async def test_async_operation(): + ... +``` + +### Imports at module level + +Put ALL imports at the top of the file: + +```python +# Correct +import pytest +from fastmcp import FastMCP +from fastmcp.client import Client + +async def test_something(): + mcp = FastMCP("test") + ... + +# Wrong - no local imports +async def test_something(): + from fastmcp import FastMCP # Don't do this + ... +``` + +### Use in-memory transport for testing + +Pass FastMCP servers directly to clients: + +```python +from fastmcp import FastMCP +from fastmcp.client import Client + +mcp = FastMCP("TestServer") + +@mcp.tool +def greet(name: str) -> str: + return f"Hello, {name}!" + +async def test_greet_tool(): + async with Client(mcp) as client: + result = await client.call_tool("greet", {"name": "World"}) + assert result[0].text == "Hello, World!" +``` + +Only use HTTP transport when explicitly testing network features. + +### Inline snapshots for complex data + +Use `inline-snapshot` for testing JSON schemas and complex structures: + +```python +from inline_snapshot import snapshot + +def test_schema_generation(): + schema = generate_schema(MyModel) + assert schema == snapshot() # Will auto-populate on first run +``` + +Commands: +- `pytest --inline-snapshot=create` - populate empty snapshots +- `pytest --inline-snapshot=fix` - update after intentional changes + +## Fixtures + +### Prefer function-scoped fixtures + +```python +@pytest.fixture +def client(): + return Client() + +async def test_with_client(client): + result = await client.ping() + assert result is not None +``` + +### Use `tmp_path` for file operations + +```python +def test_file_writing(tmp_path): + file = tmp_path / "test.txt" + file.write_text("content") + assert file.read_text() == "content" +``` + +## Mocking + +### Mock at the boundary + +```python +from unittest.mock import patch, AsyncMock + +async def test_external_api_call(): + with patch("mymodule.external_client.fetch", new_callable=AsyncMock) as mock: + mock.return_value = {"data": "test"} + result = await my_function() + assert result == {"data": "test"} +``` + +### Don't mock what you own + +Test your code with real implementations when possible. Mock external services, not internal classes. + +## Test Naming + +Use descriptive names that explain the scenario: + +```python +# Good +def test_login_fails_with_invalid_password(): +def test_user_can_update_own_profile(): +def test_admin_can_delete_any_user(): + +# Bad +def test_login(): +def test_update(): +def test_delete(): +``` + +## Error Testing + +```python +import pytest + +def test_raises_on_invalid_input(): + with pytest.raises(ValueError, match="must be positive"): + calculate(-1) + +async def test_async_raises(): + with pytest.raises(ConnectionError): + await connect_to_invalid_host() +``` + +## Running Tests + +```bash +uv run pytest -n auto # Run all tests in parallel +uv run pytest -n auto -x # Stop on first failure +uv run pytest path/to/test.py # Run specific file +uv run pytest -k "test_name" # Run tests matching pattern +uv run pytest -m "not integration" # Exclude integration tests +``` + +## Checklist + +Before submitting tests: +- [ ] Each test tests one thing +- [ ] No `@pytest.mark.asyncio` decorators +- [ ] Imports at module level +- [ ] Descriptive test names +- [ ] Using in-memory transport (not HTTP) unless testing networking +- [ ] Parameterization for variations of same behavior +- [ ] Separate tests for different behaviors diff --git a/.coderabbit.yaml b/.coderabbit.yaml new file mode 100644 index 000000000..b7937d760 --- /dev/null +++ b/.coderabbit.yaml @@ -0,0 +1,3 @@ +reviews: + path_filters: + - "!docs/python-sdk/**" diff --git a/.cursor/rules/core-mcp-objects.mdc b/.cursor/rules/core-mcp-objects.mdc new file mode 100644 index 000000000..ccbc829ec --- /dev/null +++ b/.cursor/rules/core-mcp-objects.mdc @@ -0,0 +1,13 @@ +--- +description: +globs: +alwaysApply: true +--- +There are four major MCP object types: + +- Tools (src/tools/) +- Resources (src/resources/) +- Resource Templates (src/resources/) +- Prompts (src/prompts) + +While these have slightly different semantics and implementations, in general changes that affect interactions with any one (like adding tags, importing, etc.) will need to be adopted, applied, and tested on all others. Note that while resources and resource templates are different objects, they are both in `src/resources/`. \ No newline at end of file diff --git a/.github/ISSUE_TEMPLATE/bug.yml b/.github/ISSUE_TEMPLATE/bug.yml new file mode 100644 index 000000000..267df6812 --- /dev/null +++ b/.github/ISSUE_TEMPLATE/bug.yml @@ -0,0 +1,73 @@ +name: 🐛 Bug Report +description: Report a bug or unexpected behavior in FastMCP +labels: [bug, pending] + +body: + - type: markdown + attributes: + value: Thanks for contributing to FastMCP! 🙏 + + - type: markdown + attributes: + value: | + ### Before you submit + + To help us help you, please: + + - 🔄 **Make sure you're testing on the latest version of FastMCP** - many issues are already fixed in newer versions + - 🔍 **Check if someone else has already reported this issue** or if it's been fixed on the main branch + - 📋 **You MUST include a copy/pasteable and properly formatted MRE** (minimal reproducible example) below or your issue may be closed without response + - 💡 **The ideal issue is a clear problem description and an MRE — that's it.** If you've done a genuine investigation and have a non-obvious insight into the root cause, include it. But please don't speculate or ask an LLM to generate a diagnosis or proposed fix. We have LLMs too, and an incorrect analysis is harder to work with than none at all. + - ✂️ **Keep it short.** A one-paragraph description and a working MRE is the ideal bug report. Issues that are difficult to parse — due to length, speculation, or generated content — may be closed without response. + + Thanks for helping to make FastMCP better! 🚀 + + - type: textarea + id: description + attributes: + label: Description + description: | + Please explain what you're experiencing and what you would expect to happen instead. + + Provide as much detail as possible to help us understand and solve your problem quickly. + validations: + required: true + + - type: textarea + id: example + attributes: + label: Example Code + description: > + If applicable, please provide a self-contained, + [minimal, reproducible example](https://stackoverflow.com/help/minimal-reproducible-example) + demonstrating the bug. If possible, your example should be a single-file script. + + placeholder: | + import asyncio + from fastmcp import FastMCP, Client + + mcp = FastMCP() + + async def demo(): + async with Client(mcp) as client: + ... # show the bug here + + if __name__ == "__main__": + asyncio.run(demo()) + render: Python + + - type: textarea + id: version + attributes: + label: Version Information + description: | + Please tell us about your FastMCP version, MCP version, Python version, and OS, as well as any other relevant details about your environment. + + To get the basic information, run the following command in your terminal and paste the output below: + + ```bash + fastmcp version --copy + ``` + render: Text + validations: + required: true diff --git a/.github/ISSUE_TEMPLATE/config.yml b/.github/ISSUE_TEMPLATE/config.yml new file mode 100644 index 000000000..7c4bef52e --- /dev/null +++ b/.github/ISSUE_TEMPLATE/config.yml @@ -0,0 +1,8 @@ +blank_issues_enabled: false +contact_links: + - name: FastMCP Documentation + url: https://gofastmcp.com + about: Please review the documentation before opening an issue. + - name: MCP Python SDK + url: https://github.com/modelcontextprotocol/python-sdk/issues + about: Issues related to the low-level MCP Python SDK, including the FastMCP 1.0 module that is included in the `mcp` package, should be filed on the official MCP repository. diff --git a/.github/ISSUE_TEMPLATE/enhancement.yml b/.github/ISSUE_TEMPLATE/enhancement.yml new file mode 100644 index 000000000..a803ec399 --- /dev/null +++ b/.github/ISSUE_TEMPLATE/enhancement.yml @@ -0,0 +1,35 @@ +name: 💡 Enhancement Request +description: Suggest an idea or improvement for FastMCP +labels: [enhancement, pending] + +body: + - type: markdown + attributes: + value: Thanks for contributing to FastMCP! 🙏 + + - type: markdown + attributes: + value: | + ### Before you submit + + To help us evaluate your enhancement request: + + - 🔍 **Check if this has already been requested** - search existing issues first + - 💭 **Think about the broader impact** - how would this affect other users? + - 📋 **Consider implementation complexity** - is this a small change or a major feature? + - ✂️ **Keep it short.** Describe the problem you're trying to solve and why existing behavior falls short. Skip proposed implementations unless you have a specific, well-considered suggestion — we don't need LLM-generated API designs. Requests that are difficult to parse may be closed without response. + + Thanks for helping to make FastMCP better! 🚀 + + - type: textarea + id: description + attributes: + label: Enhancement + description: | + Please describe the enhancement: + + - What problem or use case would it solve? + - How would it improve your workflow or experience with FastMCP? + - Are there any alternative solutions you've considered? + validations: + required: true diff --git a/.github/actions/run-claude/action.yml b/.github/actions/run-claude/action.yml new file mode 100644 index 000000000..fff6788a6 --- /dev/null +++ b/.github/actions/run-claude/action.yml @@ -0,0 +1,95 @@ +# Composite Action for running Claude Code Action +# +# Wraps anthropics/claude-code-action with MCP server configuration. +# Template based on elastic/ai-github-actions base action. +# +# Usage: +# - uses: ./.github/actions/run-claude +# with: +# prompt: "Your prompt here" +# claude-oauth-token: ${{ secrets.CLAUDE_CODE_OAUTH_TOKEN }} +# github-token: ${{ steps.marvin-token.outputs.token }} +# allowed-tools: "Edit,Read,Write,Bash(*),mcp__github__add_issue_comment" +# +name: "Run Claude" +description: "Run Claude Code with MCP servers" +author: "FastMCP" + +branding: + icon: "cpu" + color: "orange" + +inputs: + prompt: + description: "Prompt to pass to Claude" + required: true + + claude-oauth-token: + description: "Claude Code OAuth token for authentication" + required: true + + github-token: + description: "GitHub token for Claude to operate with" + required: true + + allowed-tools: + description: "Comma-separated list of allowed tools (e.g. Edit,Write,Bash(npm test))" + required: false + default: "" + + model: + description: "Model to use for Claude" + required: false + default: "claude-opus-4-6" + + allowed-bots: + description: "Allowed bot usernames, or '*' for all bots" + required: false + default: "" + + track-progress: + description: "Whether Claude should track progress" + required: false + default: "true" + + mcp-servers: + description: "MCP server configuration JSON" + required: false + default: '{"mcpServers":{"agents-md-generator":{"type":"http","url":"https://agents-md-generator.fastmcp.app/mcp"},"public-code-search":{"type":"http","url":"https://public-code-search.fastmcp.app/mcp"}}}' + + trigger-phrase: + description: "Trigger phrase (for mention workflows)" + required: false + default: "/marvin" + +outputs: + conclusion: + description: "The conclusion of the Claude Code run" + value: ${{ steps.claude.outputs.conclusion }} + +runs: + using: "composite" + steps: + - name: Clean up stale Claude locks + shell: bash + run: rm -rf ~/.claude/.locks ~/.local/state/claude/locks || true + + - name: Run Claude Code + id: claude + env: + GITHUB_TOKEN: ${{ inputs.github-token }} + uses: anthropics/claude-code-action@v1 + with: + github_token: ${{ inputs.github-token }} + claude_code_oauth_token: ${{ inputs.claude-oauth-token }} + bot_name: "Marvin Context Protocol" + trigger_phrase: ${{ inputs.trigger-phrase }} + allowed_bots: ${{ inputs.allowed-bots }} + track_progress: ${{ inputs.track-progress }} + prompt: ${{ inputs.prompt }} + claude_args: | + ${{ (inputs.allowed-tools != '' || inputs.extra-allowed-tools != '') && format('--allowedTools {0}{1}', inputs.allowed-tools, inputs.extra-allowed-tools != '' && format(',{0}', inputs.extra-allowed-tools) || '') || '' }} + ${{ inputs.mcp-servers != '' && format('--mcp-config ''{0}''', inputs.mcp-servers) || '' }} + --model ${{ inputs.model }} + settings: | + {"model": "${{ inputs.model }}"} diff --git a/.github/actions/run-pytest/action.yml b/.github/actions/run-pytest/action.yml new file mode 100644 index 000000000..ff429a4cc --- /dev/null +++ b/.github/actions/run-pytest/action.yml @@ -0,0 +1,44 @@ +name: "Run Pytest" +description: "Run pytest with appropriate flags for the test type and platform" + +inputs: + test-type: + description: "Type of tests to run: unit, integration, or client_process" + required: false + default: "unit" + +runs: + using: "composite" + steps: + - name: Run pytest + shell: bash + run: | + if [ "${{ inputs.test-type }}" == "integration" ]; then + MARKER="integration" + TIMEOUT="30" + MAX_PROCS="2" + EXTRA_FLAGS="" + elif [ "${{ inputs.test-type }}" == "client_process" ]; then + MARKER="client_process" + TIMEOUT="5" + MAX_PROCS="0" + EXTRA_FLAGS="-x" + else + MARKER="not integration and not client_process" + TIMEOUT="5" + MAX_PROCS="4" + EXTRA_FLAGS="" + fi + + PARALLEL_FLAGS="" + if [ "$MAX_PROCS" != "0" ] && [ "${{ runner.os }}" != "Windows" ]; then + PARALLEL_FLAGS="--numprocesses auto --maxprocesses $MAX_PROCS --dist worksteal" + fi + + uv run --no-sync pytest \ + --inline-snapshot=disable \ + --timeout=$TIMEOUT \ + -m "$MARKER" \ + $PARALLEL_FLAGS \ + $EXTRA_FLAGS \ + tests diff --git a/.github/actions/setup-uv/action.yml b/.github/actions/setup-uv/action.yml new file mode 100644 index 000000000..0becaffad --- /dev/null +++ b/.github/actions/setup-uv/action.yml @@ -0,0 +1,33 @@ +name: "Setup UV Environment" +description: "Install uv and dependencies (requires checkout first)" + +inputs: + python-version: + description: "Python version to use" + required: false + default: "3.10" + resolution: + description: "Dependency resolution: locked, upgrade, or lowest-direct" + required: false + default: "locked" + +runs: + using: "composite" + steps: + - name: Install uv + uses: astral-sh/setup-uv@v7 + with: + enable-cache: true + cache-dependency-glob: "uv.lock" + python-version: ${{ inputs.python-version }} + + - name: Install dependencies + shell: bash + run: | + if [ "${{ inputs.resolution }}" == "locked" ]; then + uv sync --locked + elif [ "${{ inputs.resolution }}" == "upgrade" ]; then + uv sync --upgrade + else + uv sync --resolution ${{ inputs.resolution }} + fi diff --git a/.github/ai-labeler.yml b/.github/ai-labeler.yml deleted file mode 100644 index 23a7dc1d3..000000000 --- a/.github/ai-labeler.yml +++ /dev/null @@ -1,2 +0,0 @@ -context-files: - - README.md diff --git a/.github/copilot-instructions.md b/.github/copilot-instructions.md new file mode 120000 index 000000000..be77ac83a --- /dev/null +++ b/.github/copilot-instructions.md @@ -0,0 +1 @@ +../AGENTS.md \ No newline at end of file diff --git a/.github/dependabot.yml b/.github/dependabot.yml new file mode 100644 index 000000000..20d3ccecf --- /dev/null +++ b/.github/dependabot.yml @@ -0,0 +1,14 @@ +version: 2 +updates: + - package-ecosystem: "pip" + directory: "/" + schedule: + interval: "daily" + labels: + - "dependencies" + - package-ecosystem: "github-actions" + directory: "/" + schedule: + interval: "weekly" + labels: + - "dependencies" diff --git a/.github/pull_request_template.md b/.github/pull_request_template.md new file mode 100644 index 000000000..68212c72f --- /dev/null +++ b/.github/pull_request_template.md @@ -0,0 +1,28 @@ +## Description + + +**Contributors Checklist** + + +- [ ] My change closes #(issue number) +- [ ] I have followed the repository's development workflow +- [ ] I have tested my changes manually and by adding relevant tests +- [ ] I have performed all required documentation updates + +**Review Checklist** + + +- [ ] I have self-reviewed my changes +- [ ] My Pull Request is ready for review + +--- diff --git a/.github/release.yml b/.github/release.yml new file mode 100644 index 000000000..5ff95aace --- /dev/null +++ b/.github/release.yml @@ -0,0 +1,47 @@ +changelog: + exclude: + labels: + - ignore in release notes + + categories: + - title: New Features 🎉 + labels: + - feature + + - title: Enhancements 🔧 + labels: + - enhancement + exclude: + labels: + - breaking change + + - title: Fixes 🐞 + labels: + - bug + exclude: + labels: + - contrib + + - title: Breaking Changes 🛫 + labels: + - breaking change + exclude: + labels: + - contrib + + - title: Docs 📚 + labels: + - documentation + + - title: Examples & Contrib 💡 + labels: + - example + - contrib + + - title: Dependencies 📦 + labels: + - dependencies + + - title: Other Changes 🦾 + labels: + - "*" diff --git a/.github/scripts/mention/gh-get-review-threads.sh b/.github/scripts/mention/gh-get-review-threads.sh new file mode 100755 index 000000000..2e1f4b35d --- /dev/null +++ b/.github/scripts/mention/gh-get-review-threads.sh @@ -0,0 +1,62 @@ +#!/usr/bin/env bash +set -euo pipefail + +# Get PR review threads with comments via GitHub GraphQL API +# +# Usage: +# gh-get-review-threads.sh [FILTER] +# +# Arguments: +# FILTER - Optional: filter for unresolved threads from specific author +# +# Environment (set by composite action): +# MENTION_REPO - Repository (owner/repo format) +# MENTION_PR_NUMBER - Pull request number +# GITHUB_TOKEN - GitHub API token +# +# Output: +# JSON array of review threads with nested comments + +# Parse OWNER and REPO from MENTION_REPO +REPO_FULL="${MENTION_REPO:?MENTION_REPO environment variable is required}" +OWNER="${REPO_FULL%/*}" +REPO="${REPO_FULL#*/}" +PR_NUMBER="${MENTION_PR_NUMBER:?MENTION_PR_NUMBER environment variable is required}" +FILTER="${1:-}" + +gh api graphql -f query=' + query($owner: String!, $repo: String!, $prNumber: Int!) { + repository(owner: $owner, name: $repo) { + pullRequest(number: $prNumber) { + reviewThreads(first: 100) { + nodes { + id + isResolved + isOutdated + path + line + comments(first: 50) { + nodes { + id + body + author { login } + createdAt + } + } + } + } + } + } + }' -F owner="$OWNER" \ + -F repo="$REPO" \ + -F prNumber="$PR_NUMBER" \ + --jq '.data.repository.pullRequest.reviewThreads.nodes' | \ +if [ -n "$FILTER" ]; then + jq --arg author "$FILTER" ' + map(select( + .isResolved == false and + .comments.nodes | any(.author.login == $author) + ))' +else + cat +fi diff --git a/.github/scripts/mention/gh-resolve-review-thread.sh b/.github/scripts/mention/gh-resolve-review-thread.sh new file mode 100755 index 000000000..5dc08c239 --- /dev/null +++ b/.github/scripts/mention/gh-resolve-review-thread.sh @@ -0,0 +1,61 @@ +#!/usr/bin/env bash +set -euo pipefail + +# Resolve a GitHub PR review thread, optionally posting a comment first +# +# Usage: +# gh-resolve-review-thread.sh THREAD_ID [COMMENT] +# +# Arguments: +# THREAD_ID - The GraphQL node ID of the review thread to resolve +# COMMENT - Optional: Comment body to post before resolving +# +# Environment (set by composite action): +# MENTION_REPO - Repository (owner/repo format) +# MENTION_PR_NUMBER - Pull request number +# GITHUB_TOKEN - GitHub API token +# +# Behavior: +# 1. If COMMENT is provided, posts it as a reply to the thread +# 2. Resolves the thread + +# Validate required environment variables +: "${MENTION_REPO:?MENTION_REPO environment variable is required}" +: "${MENTION_PR_NUMBER:?MENTION_PR_NUMBER environment variable is required}" +THREAD_ID="${1:?Thread ID required}" +COMMENT="${2:-}" + +# Step 1: Post comment if provided +if [ -n "$COMMENT" ]; then + echo "Posting comment to thread..." >&2 + COMMENT_RESULT=$(gh api graphql -f query=' + mutation($threadId: ID!, $body: String!) { + addPullRequestReviewThreadReply(input: { + pullRequestReviewThreadId: $threadId, + body: $body + }) { + comment { + id + } + } + }' -f threadId="$THREAD_ID" -f body="$COMMENT") + if echo "$COMMENT_RESULT" | jq -e '.errors' > /dev/null 2>&1; then + echo "Error posting comment: $COMMENT_RESULT" >&2 + exit 1 + fi +fi + +# Step 2: Resolve the thread +echo "Resolving thread..." >&2 +RESOLVE_RESULT=$(gh api graphql -f query=' + mutation($threadId: ID!) { + resolveReviewThread(input: {threadId: $threadId}) { + thread { + id + isResolved + } + } + }' -f threadId="$THREAD_ID" --jq '.data.resolveReviewThread.thread') + +echo "$RESOLVE_RESULT" +echo "✓ Thread resolved" >&2 diff --git a/.github/scripts/pr-review/pr-comment.sh b/.github/scripts/pr-review/pr-comment.sh new file mode 100755 index 000000000..d571f6757 --- /dev/null +++ b/.github/scripts/pr-review/pr-comment.sh @@ -0,0 +1,251 @@ +#!/bin/bash +# pr-comment.sh - Queue a structured inline review comment for the PR review +# +# Usage: +# pr-comment.sh --severity --title --why [suggestion via stdin] +# pr-comment.sh --severity --title --why --no-suggestion +# +# Arguments: +# file File path (required) +# line Line number (required) +# --severity Severity level: critical, high, medium, low, nitpick (required) +# --title Brief description for comment heading (required) +# --why One sentence explaining the risk/impact (required) +# --no-suggestion Explicitly skip suggestion (use for architectural issues) +# +# The suggestion code is read from stdin (use heredoc). If no stdin and no --no-suggestion, errors. +# +# Examples: +# # With suggestion (preferred) +# pr-comment.sh src/main.go 42 --severity high --title "Missing error check" --why "Errors are silently ignored" <<'EOF' +# if err != nil { +# return fmt.Errorf("operation failed: %w", err) +# } +# EOF +# +# # Without suggestion (for issues requiring broader changes) +# pr-comment.sh src/main.go 42 --severity medium --title "Consider extracting to function" \ +# --why "This logic is duplicated in 3 places" --no-suggestion +# +# Environment variables (set by the composite action): +# PR_REVIEW_REPO - Repository (owner/repo) +# PR_REVIEW_PR_NUMBER - Pull request number +# PR_REVIEW_COMMENTS_DIR - Directory to cache comments (default: /tmp/pr-review-comments) + +set -e + +# Configuration from environment +REPO="${PR_REVIEW_REPO:?PR_REVIEW_REPO environment variable is required}" +PR_NUMBER="${PR_REVIEW_PR_NUMBER:?PR_REVIEW_PR_NUMBER environment variable is required}" +COMMENTS_DIR="${PR_REVIEW_COMMENTS_DIR:-/tmp/pr-review-comments}" + +# Severity emoji mapping +declare -A SEVERITY_EMOJI=( + [critical]="🔴 CRITICAL" + [high]="🟠 HIGH" + [medium]="🟡 MEDIUM" + [low]="⚪ LOW" + [nitpick]="💬 NITPICK" +) + +# Parse arguments +FILE="" +LINE="" +SEVERITY="" +TITLE="" +WHY="" +NO_SUGGESTION=false + +# First two positional args are file and line +if [ $# -lt 2 ]; then + echo "Error: file and line are required" + echo "Usage: pr-comment.sh --severity --title --why [<<'EOF' ... EOF]" + exit 1 +fi + +FILE="$1" +LINE="$2" +shift 2 + +# Parse named arguments +while [ $# -gt 0 ]; do + case "$1" in + --severity) + SEVERITY="$2" + shift 2 + ;; + --title) + TITLE="$2" + shift 2 + ;; + --why) + WHY="$2" + shift 2 + ;; + --no-suggestion) + NO_SUGGESTION=true + shift + ;; + *) + echo "Error: Unknown argument: $1" + exit 1 + ;; + esac +done + +# Read suggestion from stdin if available +SUGGESTION="" +if [ ! -t 0 ]; then + SUGGESTION=$(cat) +fi + +# Validate required arguments +if [ -z "$SEVERITY" ]; then + echo "Error: --severity is required (critical, high, medium, low, nitpick)" + exit 1 +fi + +if [ -z "$TITLE" ]; then + echo "Error: --title is required" + exit 1 +fi + +if [ -z "$WHY" ]; then + echo "Error: --why is required" + exit 1 +fi + +# Validate severity level +if [ -z "${SEVERITY_EMOJI[$SEVERITY]}" ]; then + echo "Error: Invalid severity '$SEVERITY'. Must be one of: critical, high, medium, low, nitpick" + exit 1 +fi + +# Require either suggestion or explicit --no-suggestion +if [ -z "$SUGGESTION" ] && [ "$NO_SUGGESTION" = false ]; then + echo "Error: Suggestion required. Provide code via stdin (heredoc) or use --no-suggestion" + echo "" + echo "Example with suggestion:" + echo " pr-comment.sh file.go 42 --severity high --title \"desc\" --why \"reason\" <<'EOF'" + echo " fixed code here" + echo " EOF" + echo "" + echo "Example without suggestion:" + echo " pr-comment.sh file.go 42 --severity medium --title \"desc\" --why \"reason\" --no-suggestion" + exit 1 +fi + +# Validate line is a positive integer (>= 1) +if ! [[ "$LINE" =~ ^[1-9][0-9]*$ ]]; then + echo "Error: Line number must be a positive integer (>= 1), got: $LINE" + exit 1 +fi + +# Get the diff for this file to validate the comment location +DIFF_DATA=$(gh api "repos/${REPO}/pulls/${PR_NUMBER}/files" --paginate | jq --arg f "$FILE" '.[] | select(.filename==$f)') + +if [ -z "$DIFF_DATA" ]; then + echo "Error: File '${FILE}' not found in PR diff" + echo "" + echo "Files changed in this PR:" + gh api "repos/${REPO}/pulls/${PR_NUMBER}/files" --paginate --jq '.[].filename' + exit 1 +fi + +PATCH=$(echo "$DIFF_DATA" | jq -r '.patch // empty') + +if [ -z "$PATCH" ]; then + echo "Error: No patch data for file '${FILE}' (file may be binary or too large)" + exit 1 +fi + +# Verify the line exists in the diff +LINE_IN_DIFF=$(echo "$PATCH" | awk -v target_line="$LINE" ' +BEGIN { current_line = 0; found = 0 } +/^@@/ { + line = $0 + gsub(/.*\+/, "", line) + gsub(/[^0-9].*/, "", line) + current_line = line - 1 + next +} +{ + if (substr($0, 1, 1) != "-") { + current_line++ + if (current_line == target_line) { + found = 1 + exit + } + } +} +END { if (found) print "1"; else print "0" } +') + +if [ "$LINE_IN_DIFF" != "1" ]; then + echo "Error: Line ${LINE} not found in the diff for '${FILE}'" + echo "" + echo "Note: You can only comment on lines that appear in the diff (added, modified, or context lines)" + echo "" + echo "First 50 lines of diff for this file:" + echo "$PATCH" | head -50 + exit 1 +fi + +# Create comments directory if it doesn't exist +mkdir -p "${COMMENTS_DIR}" + +# Assemble the comment body +SEVERITY_LABEL="${SEVERITY_EMOJI[$SEVERITY]}" + +BODY="**${SEVERITY_LABEL}** ${TITLE} + +Why: ${WHY}" + +# Add suggestion block if provided +if [ -n "$SUGGESTION" ]; then + BODY="${BODY} + +\`\`\`suggestion +${SUGGESTION} +\`\`\`" +fi + +# Append standard footer +FOOTER=' + +--- +Marvin Context Protocol | Type `/marvin` to interact further + +Give us feedback! React with 🚀 if perfect, 👍 if helpful, 👎 if not.' + +BODY_WITH_FOOTER="${BODY}${FOOTER}" + +# Generate unique comment ID +COMMENT_ID="comment-$(date +%s)-$(od -An -N4 -tu4 /dev/urandom | tr -d ' ')" +COMMENT_FILE="${COMMENTS_DIR}/${COMMENT_ID}.json" + +# Create the comment JSON object +jq -n \ + --arg path "$FILE" \ + --argjson line "$LINE" \ + --arg side "RIGHT" \ + --arg body "$BODY_WITH_FOOTER" \ + --arg id "$COMMENT_ID" \ + '{ + path: $path, + line: $line, + side: $side, + body: $body, + _meta: { + id: $id, + file: $path, + line: $line + } + }' > "${COMMENT_FILE}" + +echo "✓ Queued review comment for ${FILE}:${LINE}" +echo " Severity: ${SEVERITY_LABEL}" +echo " Title: ${TITLE}" +echo " Comment ID: ${COMMENT_ID}" +echo " Comment will be submitted with pr-review.sh" +echo " Remove with: pr-remove-comment.sh ${FILE} ${LINE}" diff --git a/.github/scripts/pr-review/pr-diff.sh b/.github/scripts/pr-review/pr-diff.sh new file mode 100755 index 000000000..4448e0012 --- /dev/null +++ b/.github/scripts/pr-review/pr-diff.sh @@ -0,0 +1,128 @@ +#!/bin/bash +# pr-diff.sh - Show changed files or diff for a specific file +# +# Usage: +# pr-diff.sh - List all changed files (shows full diff if small enough) +# pr-diff.sh - Show diff for a specific file with line numbers +# +# Environment variables (set by the composite action): +# PR_REVIEW_REPO - Repository (owner/repo) +# PR_REVIEW_PR_NUMBER - Pull request number + +set -e + +# Configuration from environment +REPO="${PR_REVIEW_REPO:?PR_REVIEW_REPO environment variable is required}" +PR_NUMBER="${PR_REVIEW_PR_NUMBER:?PR_REVIEW_PR_NUMBER environment variable is required}" +EXPECTED_HEAD="${PR_REVIEW_HEAD_SHA:-}" + +# Check if HEAD has changed since review started (race condition detection) +if [ -n "$EXPECTED_HEAD" ]; then + CURRENT_HEAD=$(gh api "repos/${REPO}/pulls/${PR_NUMBER}" --jq '.head.sha') + if [ "$CURRENT_HEAD" != "$EXPECTED_HEAD" ]; then + echo "⚠️ WARNING: PR head has changed since review started!" + echo " Review started at: ${EXPECTED_HEAD:0:7}" + echo " Current head: ${CURRENT_HEAD:0:7}" + echo " Line numbers below may not match the commit being reviewed." + echo "" + fi +fi + +# Thresholds for "too big" - show file list only if exceeded +MAX_FILES=25 +MAX_TOTAL_LINES=1500 + +FILE="$1" + +# Function to add line numbers to a patch +# Format: [LINE] +added | [LINE] context | [----] -deleted +add_line_numbers() { + awk ' + BEGIN { new_line = 0 } + /^@@/ { + # Parse hunk header: @@ -old_start,old_count +new_start,new_count @@ + match($0, /\+([0-9]+)/) + new_line = substr($0, RSTART+1, RLENGTH-1) - 1 + print "" + print $0 + next + } + /^-/ { + # Deleted line - cannot comment on these + printf "[----] %s\n", $0 + next + } + /^\+/ { + # Added line - can comment, show line number + new_line++ + printf "[%4d] %s\n", new_line, $0 + next + } + { + # Context line (space prefix) - can comment, show line number + new_line++ + printf "[%4d] %s\n", new_line, $0 + } + ' +} + +if [ -z "$FILE" ]; then + # Get file list with stats + FILES_DATA=$(gh api "repos/${REPO}/pulls/${PR_NUMBER}/files" --paginate) + + FILE_COUNT=$(echo "$FILES_DATA" | jq 'length') + TOTAL_ADDITIONS=$(echo "$FILES_DATA" | jq '[.[].additions] | add // 0') + TOTAL_DELETIONS=$(echo "$FILES_DATA" | jq '[.[].deletions] | add // 0') + TOTAL_LINES=$((TOTAL_ADDITIONS + TOTAL_DELETIONS)) + + echo "PR #${PR_NUMBER} Summary: ${FILE_COUNT} files changed (+${TOTAL_ADDITIONS}/-${TOTAL_DELETIONS})" + echo "" + + # Check if diff is too large + if [ "$FILE_COUNT" -gt "$MAX_FILES" ] || [ "$TOTAL_LINES" -gt "$MAX_TOTAL_LINES" ]; then + echo "⚠️ Large diff detected (>${MAX_FILES} files or >${MAX_TOTAL_LINES} lines changed)" + echo " Review files individually using: pr-diff.sh " + echo "" + echo "Files changed:" + echo "$FILES_DATA" | jq -r '.[] | " \(.filename) (+\(.additions)/-\(.deletions))"' + else + # Small enough - show all diffs with line numbers + echo "Files changed:" + echo "$FILES_DATA" | jq -r '.[] | " \(.filename) (+\(.additions)/-\(.deletions))"' + echo "" + echo "─────────────────────────────────────────────────────────────────────" + echo "" + + # Show each file's diff by iterating over indices + for i in $(seq 0 $((FILE_COUNT - 1))); do + FNAME=$(echo "$FILES_DATA" | jq -r ".[$i].filename") + PATCH=$(echo "$FILES_DATA" | jq -r ".[$i].patch // empty") + + if [ -n "$PATCH" ]; then + echo "## ${FNAME}" + echo "Use: pr-comment.sh ${FNAME} --severity --title \"desc\" --why \"reason\" <<'EOF' ... EOF" + echo "Format: [LINE] +added | [LINE] context | [----] -deleted (can't comment)" + echo "$PATCH" | add_line_numbers + echo "" + echo "─────────────────────────────────────────────────────────────────────" + echo "" + fi + done + fi +else + # Show specific file diff + PATCH=$(gh api "repos/${REPO}/pulls/${PR_NUMBER}/files" --paginate --jq --arg file "$FILE" '.[] | select(.filename==$file) | .patch') + + if [ -z "$PATCH" ]; then + echo "Error: File '${FILE}' not found in PR diff" + echo "" + echo "Files changed in this PR:" + gh api "repos/${REPO}/pulls/${PR_NUMBER}/files" --paginate --jq '.[].filename' + exit 1 + fi + + echo "## ${FILE}" + echo "Use: pr-comment.sh ${FILE} --severity --title \"desc\" --why \"reason\" <<'EOF' ... EOF" + echo "Format: [LINE] +added | [LINE] context | [----] -deleted (can't comment)" + echo "$PATCH" | add_line_numbers +fi diff --git a/.github/scripts/pr-review/pr-existing-comments.sh b/.github/scripts/pr-review/pr-existing-comments.sh new file mode 100755 index 000000000..10fa05f16 --- /dev/null +++ b/.github/scripts/pr-review/pr-existing-comments.sh @@ -0,0 +1,190 @@ +#!/bin/bash +# pr-existing-comments.sh - Fetch existing review threads on a PR +# +# Usage: +# pr-existing-comments.sh - Show all review threads with full details +# pr-existing-comments.sh --summary - Show per-file summary only (for large PRs) +# pr-existing-comments.sh --unresolved - Show only unresolved threads +# pr-existing-comments.sh --file - Show threads for a specific file +# pr-existing-comments.sh --full - Show full comment text (no truncation) +# +# Output: Formatted summary of existing review threads grouped by file, +# showing thread status, comments, and whether issues were addressed. +# +# For large PRs, use --summary first to see the overview, then --file +# to get full thread details when reviewing each file. +# +# Environment variables (set by the composite action): +# PR_REVIEW_REPO - Repository (owner/repo) +# PR_REVIEW_PR_NUMBER - Pull request number + +set -e + +# Configuration from environment +REPO="${PR_REVIEW_REPO:?PR_REVIEW_REPO environment variable is required}" +PR_NUMBER="${PR_REVIEW_PR_NUMBER:?PR_REVIEW_PR_NUMBER environment variable is required}" + +OWNER="${REPO%/*}" +REPO_NAME="${REPO#*/}" + +# Parse arguments +FILTER_UNRESOLVED=false +FILTER_FILE="" +SUMMARY_ONLY=false +FULL_TEXT=false + +while [ $# -gt 0 ]; do + case "$1" in + --unresolved) + FILTER_UNRESOLVED=true + shift + ;; + --file) + FILTER_FILE="$2" + shift 2 + ;; + --summary) + SUMMARY_ONLY=true + shift + ;; + --full) + FULL_TEXT=true + shift + ;; + *) + echo "Usage: pr-existing-comments.sh [--summary] [--unresolved] [--file ] [--full]" + exit 1 + ;; + esac +done + +# Fetch review threads via GraphQL +THREADS=$(gh api graphql -f query=' + query($owner: String!, $repo: String!, $prNumber: Int!) { + repository(owner: $owner, name: $repo) { + pullRequest(number: $prNumber) { + reviewThreads(first: 100) { + nodes { + id + isResolved + isOutdated + path + line + originalLine + startLine + originalStartLine + diffSide + comments(first: 50) { + nodes { + id + body + author { login } + createdAt + originalCommit { abbreviatedOid } + } + } + } + } + } + } + }' -F owner="$OWNER" \ + -F repo="$REPO_NAME" \ + -F prNumber="$PR_NUMBER" \ + --jq '.data.repository.pullRequest.reviewThreads.nodes') + +if [ -z "$THREADS" ] || [ "$THREADS" = "null" ]; then + echo "No existing review threads found." + exit 0 +fi + +# Apply filters +FILTERED="$THREADS" + +if [ "$FILTER_UNRESOLVED" = true ]; then + FILTERED=$(echo "$FILTERED" | jq '[.[] | select(.isResolved == false)]') +fi + +if [ -n "$FILTER_FILE" ]; then + FILTERED=$(echo "$FILTERED" | jq --arg file "$FILTER_FILE" '[.[] | select(.path == $file)]') +fi + +THREAD_COUNT=$(echo "$FILTERED" | jq 'length') + +if [ "$THREAD_COUNT" -eq 0 ]; then + if [ "$FILTER_UNRESOLVED" = true ]; then + echo "No unresolved review threads found." + elif [ -n "$FILTER_FILE" ]; then + echo "No review threads found for ${FILTER_FILE}." + else + echo "No existing review threads found." + fi + exit 0 +fi + +# Count resolved vs unresolved +RESOLVED_COUNT=$(echo "$FILTERED" | jq '[.[] | select(.isResolved == true)] | length') +UNRESOLVED_COUNT=$(echo "$FILTERED" | jq '[.[] | select(.isResolved == false)] | length') +OUTDATED_COUNT=$(echo "$FILTERED" | jq '[.[] | select(.isOutdated == true)] | length') + +echo "Existing review threads: ${THREAD_COUNT} total (${UNRESOLVED_COUNT} unresolved, ${RESOLVED_COUNT} resolved, ${OUTDATED_COUNT} outdated)" +echo "" + +# Summary mode: show per-file counts only +if [ "$SUMMARY_ONLY" = true ]; then + echo "Threads by file:" + echo "$FILTERED" | jq -r ' + group_by(.path) | .[] | + . as $threads | + ($threads | length) as $total | + ([$threads[] | select(.isResolved == false)] | length) as $unresolved | + ([$threads[] | select(.isResolved == true)] | length) as $resolved | + ([$threads[] | select(.isOutdated == true)] | length) as $outdated | + ([$threads[] | select(.comments.nodes | length > 1)] | length) as $has_replies | + " " + $threads[0].path + + " — " + ($total | tostring) + " threads" + + " (" + ($unresolved | tostring) + " unresolved, " + ($resolved | tostring) + " resolved" + + (if $outdated > 0 then ", " + ($outdated | tostring) + " outdated" else "" end) + + ")" + + (if $has_replies > 0 then " ⚠️ " + ($has_replies | tostring) + " with replies" else "" end) + ' + echo "" + echo "Use: pr-existing-comments.sh --file to see full thread details for a file" + exit 0 +fi + +# Full detail mode: output threads grouped by file +# Show full conversation for threads with replies +FIRST_LIMIT=200 +REPLY_LIMIT=300 +if [ "$FULL_TEXT" = true ]; then + FIRST_LIMIT=999999 + REPLY_LIMIT=999999 +fi + +echo "$FILTERED" | jq -r --argjson first_limit "$FIRST_LIMIT" --argjson reply_limit "$REPLY_LIMIT" ' + group_by(.path) | .[] | + "## " + .[0].path + " (" + (length | tostring) + " threads)\n" + + ([.[] | + " " + + (if .isResolved then "✅ RESOLVED" elif .isOutdated then "⚠️ OUTDATED" else "🔴 UNRESOLVED" end) + + " (line " + (if .line then (.line | tostring) elif .startLine then (.startLine | tostring) elif .originalLine then ("~" + (.originalLine | tostring)) elif .originalStartLine then ("~" + (.originalStartLine | tostring)) else "?" end) + ")" + + # Show the commit the comment was originally made on + (if .comments.nodes[0].originalCommit.abbreviatedOid then " [" + .comments.nodes[0].originalCommit.abbreviatedOid + "]" else "" end) + + # Flag threads with replies — indicates a conversation happened + (if (.comments.nodes | length) > 1 then " ← has replies" else "" end) + + "\n" + + ([.comments.nodes | to_entries[] | + .value as $comment | + .key as $idx | + ($comment.body | gsub("\n"; " ")) as $flat | + if $idx == 0 then + " @" + ($comment.author.login // "unknown") + ": " + $flat[0:$first_limit] + + (if ($flat | length) > $first_limit then " [truncated]" else "" end) + else + " ↳ @" + ($comment.author.login // "unknown") + ": " + $flat[0:$reply_limit] + + (if ($flat | length) > $reply_limit then " [truncated]" else "" end) + end + ] | join("\n")) + + "\n" + ] | join("\n")) +' diff --git a/.github/scripts/pr-review/pr-remove-comment.sh b/.github/scripts/pr-review/pr-remove-comment.sh new file mode 100755 index 000000000..04b73fbf6 --- /dev/null +++ b/.github/scripts/pr-review/pr-remove-comment.sh @@ -0,0 +1,84 @@ +#!/bin/bash +# pr-remove-comment.sh - Remove a queued review comment +# +# Usage: +# pr-remove-comment.sh +# pr-remove-comment.sh +# +# Examples: +# pr-remove-comment.sh src/main.go 42 +# pr-remove-comment.sh comment-1234567890-1234567890 +# +# This script removes a previously queued comment before it's submitted. +# Useful if the agent realizes it made a mistake or wants to update a comment. +# +# Environment variables (set by the composite action): +# PR_REVIEW_COMMENTS_DIR - Directory containing comment files (default: /tmp/pr-review-comments) + +set -e + +COMMENTS_DIR="${PR_REVIEW_COMMENTS_DIR:-/tmp/pr-review-comments}" + +if [ ! -d "${COMMENTS_DIR}" ]; then + echo "No comments directory found: ${COMMENTS_DIR}" + exit 0 +fi + +# Check if first argument looks like a comment ID +if [[ "$1" =~ ^comment- ]]; then + COMMENT_ID="$1" + COMMENT_FILE="${COMMENTS_DIR}/${COMMENT_ID}.json" + + if [ -f "${COMMENT_FILE}" ]; then + FILE=$(jq -r '._meta.file // .path' "${COMMENT_FILE}") + LINE=$(jq -r '._meta.line // .line' "${COMMENT_FILE}") + rm -f "${COMMENT_FILE}" + echo "✓ Removed comment ${COMMENT_ID} for ${FILE}:${LINE}" + else + echo "Comment not found: ${COMMENT_ID}" + exit 1 + fi +else + # Treat as file and line number + FILE="$1" + LINE="$2" + + if [ -z "$FILE" ] || [ -z "$LINE" ]; then + echo "Usage:" + echo " pr-remove-comment.sh " + echo " pr-remove-comment.sh " + echo "" + echo "Examples:" + echo " pr-remove-comment.sh src/main.go 42" + echo " pr-remove-comment.sh comment-1234567890-1234567890" + exit 1 + fi + + # Validate line is a positive integer (>= 1) + if ! [[ "$LINE" =~ ^[1-9][0-9]*$ ]]; then + echo "Error: Line number must be a positive integer (>= 1), got: $LINE" + exit 1 + fi + + # Find and remove matching comment files + # Use nullglob to handle case where no files match + shopt -s nullglob + REMOVED=0 + for COMMENT_FILE in "${COMMENTS_DIR}"/comment-*.json; do + + COMMENT_FILE_PATH=$(jq -r '._meta.file // .path' "${COMMENT_FILE}") + COMMENT_LINE=$(jq -r '._meta.line // .line' "${COMMENT_FILE}") + + if [ "$COMMENT_FILE_PATH" = "$FILE" ] && [ "$COMMENT_LINE" = "$LINE" ]; then + COMMENT_ID=$(basename "${COMMENT_FILE}" .json) + rm -f "${COMMENT_FILE}" + echo "✓ Removed comment ${COMMENT_ID} for ${FILE}:${LINE}" + REMOVED=$((REMOVED + 1)) + fi + done + + if [ "$REMOVED" -eq 0 ]; then + echo "No comment found for ${FILE}:${LINE}" + exit 1 + fi +fi diff --git a/.github/scripts/pr-review/pr-review.sh b/.github/scripts/pr-review/pr-review.sh new file mode 100755 index 000000000..48c0b6888 --- /dev/null +++ b/.github/scripts/pr-review/pr-review.sh @@ -0,0 +1,143 @@ +#!/bin/bash +# pr-review.sh - Submit a PR review (approve, request changes, or comment) +# +# Usage: pr-review.sh [review-body] +# Example: pr-review.sh REQUEST_CHANGES "Please fix the issues noted above" +# +# This script creates and submits a review with any queued inline comments. +# Comments are read from individual files in PR_REVIEW_COMMENTS_DIR (created by pr-comment.sh). +# +# The review body can contain special characters (backticks, dollar signs, etc.) +# and will be safely passed to the GitHub API without shell interpretation. +# +# Environment variables (set by the composite action): +# PR_REVIEW_REPO - Repository (owner/repo) +# PR_REVIEW_PR_NUMBER - Pull request number +# PR_REVIEW_HEAD_SHA - HEAD commit SHA +# PR_REVIEW_COMMENTS_DIR - Directory containing queued comment files (default: /tmp/pr-review-comments) + +set -e + +# Configuration from environment +REPO="${PR_REVIEW_REPO:?PR_REVIEW_REPO environment variable is required}" +PR_NUMBER="${PR_REVIEW_PR_NUMBER:?PR_REVIEW_PR_NUMBER environment variable is required}" +HEAD_SHA="${PR_REVIEW_HEAD_SHA:?PR_REVIEW_HEAD_SHA environment variable is required}" +COMMENTS_DIR="${PR_REVIEW_COMMENTS_DIR:-/tmp/pr-review-comments}" + +# Arguments +EVENT="$1" +shift 2>/dev/null || true + +# Read body from remaining arguments +# Join all remaining arguments with spaces, preserving the string as-is +BODY="$*" + +if [ -z "$EVENT" ]; then + echo "Usage: pr-review.sh [review-body]" + echo "Example: pr-review.sh REQUEST_CHANGES 'Please fix the issues noted in the inline comments'" + exit 1 +fi + +# Validate event type +case "$EVENT" in + APPROVE|REQUEST_CHANGES|COMMENT) + ;; + *) + echo "Error: Invalid event type '${EVENT}'" + echo "Must be one of: APPROVE, REQUEST_CHANGES, COMMENT" + exit 1 + ;; +esac + +# Read queued comments from individual files +COMMENTS="[]" +COMMENT_COUNT=0 + +if [ -d "${COMMENTS_DIR}" ]; then + # Collect all comment files and merge into a single JSON array + # Remove _meta fields before submitting (they're only for internal use) + COMMENT_FILES=("${COMMENTS_DIR}"/comment-*.json) + + if [ -f "${COMMENT_FILES[0]}" ]; then + # Use jq to read all comment files, extract the comment data (without _meta), and combine + COMMENTS=$(jq -s '[.[] | del(._meta)]' "${COMMENTS_DIR}"/comment-*.json) + COMMENT_COUNT=$(echo "$COMMENTS" | jq 'length') + if [ "$COMMENT_COUNT" -gt 0 ]; then + echo "Found ${COMMENT_COUNT} queued inline comment(s)" + fi + fi +fi + +# Append standard footer to the review body (if body is provided) +FOOTER=' + +--- +Marvin Context Protocol | Type `/marvin` to interact further + +Give us feedback! React with 🚀 if perfect, 👍 if helpful, 👎 if not.' + +if [ -n "$BODY" ]; then + BODY_WITH_FOOTER="${BODY}${FOOTER}" +else + BODY_WITH_FOOTER="" +fi + +# Build the review request JSON +# Use jq to safely construct the JSON with all special characters handled +REVIEW_JSON=$(jq -n \ + --arg commit_id "$HEAD_SHA" \ + --arg event "$EVENT" \ + --arg body "$BODY_WITH_FOOTER" \ + --argjson comments "$COMMENTS" \ + '{ + commit_id: $commit_id, + event: $event, + comments: $comments + } + (if $body != "" then {body: $body} else {} end)') + +# Check if HEAD has changed since review started (race condition detection) +CURRENT_HEAD=$(gh api "repos/${REPO}/pulls/${PR_NUMBER}" --jq '.head.sha') +if [ "$CURRENT_HEAD" != "$HEAD_SHA" ]; then + echo "⚠️ WARNING: PR head has changed since review started!" + echo " Review started at: ${HEAD_SHA:0:7}" + echo " Current head: ${CURRENT_HEAD:0:7}" + echo "" + echo " New commits may have shifted line numbers. Review will be submitted" + echo " against the original commit (${HEAD_SHA:0:7}) but comments may be outdated." + echo "" +fi + +echo "Submitting ${EVENT} review for commit ${HEAD_SHA:0:7}..." + +# Create and submit the review in one API call +# Use a temp file to safely pass the JSON body +TEMP_JSON=$(mktemp) +trap "rm -f ${TEMP_JSON}" EXIT +echo "$REVIEW_JSON" > "${TEMP_JSON}" + +RESPONSE=$(gh api "repos/${REPO}/pulls/${PR_NUMBER}/reviews" \ + -X POST \ + --input "${TEMP_JSON}" 2>&1) || { + echo "Error submitting review:" + echo "$RESPONSE" + exit 1 +} + +# Clean up the comments directory after successful submission +if [ -d "${COMMENTS_DIR}" ] && [ "$COMMENT_COUNT" -gt 0 ]; then + rm -f "${COMMENTS_DIR}"/comment-*.json + # Remove directory if empty + rmdir "${COMMENTS_DIR}" 2>/dev/null || true +fi + +REVIEW_URL=$(echo "$RESPONSE" | jq -r '.html_url // empty') +REVIEW_STATE=$(echo "$RESPONSE" | jq -r '.state // empty') + +if [ -n "$REVIEW_URL" ]; then + echo "✓ Review submitted (${REVIEW_STATE}): ${REVIEW_URL}" + if [ "$COMMENT_COUNT" -gt 0 ]; then + echo " Included ${COMMENT_COUNT} inline comment(s)" + fi +else + echo "✓ Review submitted successfully" +fi diff --git a/.github/workflows/ai-labeler.yml b/.github/workflows/ai-labeler.yml deleted file mode 100644 index 41d5853fe..000000000 --- a/.github/workflows/ai-labeler.yml +++ /dev/null @@ -1,23 +0,0 @@ -name: AI Labeler - -on: - issues: - types: [opened, reopened] - issue_comment: - types: [created] - pull_request: - types: [opened, reopened] - -jobs: - ai-labeler: - runs-on: ubuntu-latest - permissions: - contents: read - issues: write - pull-requests: write - steps: - - uses: actions/checkout@v4 - - uses: jlowin/ai-labeler@v0.5.0 - with: - openai-api-key: ${{ secrets.OPENAI_API_KEY }} - controlflow-llm-model: openai/gpt-4o-mini diff --git a/.github/workflows/auto-close-duplicates.yml b/.github/workflows/auto-close-duplicates.yml new file mode 100644 index 000000000..d358a3a1e --- /dev/null +++ b/.github/workflows/auto-close-duplicates.yml @@ -0,0 +1,36 @@ +name: Auto-close duplicate issues +description: Auto-closes issues that are duplicates of existing issues +on: + schedule: + - cron: "0 9 * * *" # Run daily at 9 AM UTC + workflow_dispatch: + +jobs: + auto-close-duplicates: + runs-on: ubuntu-latest + timeout-minutes: 10 + permissions: + contents: read + issues: write + id-token: write + + steps: + - name: Checkout repository + uses: actions/checkout@v6 + + - name: Generate Marvin App token + id: marvin-token + uses: actions/create-github-app-token@v2 + with: + app-id: ${{ secrets.MARVIN_APP_ID }} + private-key: ${{ secrets.MARVIN_APP_PRIVATE_KEY }} + + - name: Install uv + uses: astral-sh/setup-uv@v7 + + - name: Auto-close duplicate issues + run: uv run scripts/auto_close_duplicates.py + env: + GITHUB_TOKEN: ${{ steps.marvin-token.outputs.token }} + GITHUB_REPOSITORY_OWNER: ${{ github.repository_owner }} + GITHUB_REPOSITORY_NAME: ${{ github.event.repository.name }} diff --git a/.github/workflows/auto-close-needs-mre.yml b/.github/workflows/auto-close-needs-mre.yml new file mode 100644 index 000000000..4338c58d8 --- /dev/null +++ b/.github/workflows/auto-close-needs-mre.yml @@ -0,0 +1,36 @@ +name: Auto-close needs MRE issues +description: Auto-closes issues that need minimal reproducible examples after 7 days of author inactivity +on: + schedule: + - cron: "0 9 * * *" # Run daily at 9 AM UTC + workflow_dispatch: + +jobs: + auto-close-needs-mre: + runs-on: ubuntu-latest + timeout-minutes: 10 + permissions: + contents: read + issues: write + id-token: write + + steps: + - name: Checkout repository + uses: actions/checkout@v6 + + - name: Generate Marvin App token + id: marvin-token + uses: actions/create-github-app-token@v2 + with: + app-id: ${{ secrets.MARVIN_APP_ID }} + private-key: ${{ secrets.MARVIN_APP_PRIVATE_KEY }} + + - name: Install uv + uses: astral-sh/setup-uv@v7 + + - name: Auto-close needs MRE issues + run: uv run scripts/auto_close_needs_mre.py + env: + GITHUB_TOKEN: ${{ steps.marvin-token.outputs.token }} + GITHUB_REPOSITORY_OWNER: ${{ github.repository_owner }} + GITHUB_REPOSITORY_NAME: ${{ github.event.repository.name }} diff --git a/.github/workflows/martian-test-failure.yml b/.github/workflows/martian-test-failure.yml new file mode 100644 index 000000000..9f7724fbd --- /dev/null +++ b/.github/workflows/martian-test-failure.yml @@ -0,0 +1,185 @@ +name: Marvin Test Failure Analysis + +on: + workflow_run: + workflows: ["Tests", "Run static analysis"] + types: + - completed + +concurrency: + group: marvin-test-failure-${{ github.event.workflow_run.head_branch }} + cancel-in-progress: true + +jobs: + martian-test-failure: + # Only run if the test workflow failed + if: ${{ github.event.workflow_run.conclusion == 'failure' }} + runs-on: ubuntu-latest + permissions: + contents: read + pull-requests: write + issues: read + id-token: write + actions: read # Required for Claude to read CI results + steps: + - name: Checkout repository + uses: actions/checkout@v6 + with: + fetch-depth: 1 + + - name: Generate Marvin App token + id: marvin-token + uses: actions/create-github-app-token@v2 + with: + app-id: ${{ secrets.MARVIN_APP_ID }} + private-key: ${{ secrets.MARVIN_APP_PRIVATE_KEY }} + + - name: Set up Python 3.10 + uses: actions/setup-python@v6 + with: + python-version: "3.10" + + # Install UV package manager + - name: Install UV + uses: astral-sh/setup-uv@v7 + + # Install dependencies + - name: Install dependencies + run: uv sync --all-packages --group dev + + - name: Set analysis prompt + id: analysis-prompt + run: | + cat >> $GITHUB_OUTPUT << 'EOF' + PROMPT< + Detailed Analysis + + Include here: + - Relevant log excerpts showing the failure + - Code snippets that are causing the issue + - Any related issues or PRs that might be relevant + + +
+ Related Files + + List files that are relevant to the failure with brief explanations of their relevance. +
+ + # Important Guidelines + - Be concise and actionable - developers want to quickly understand and fix the issue. Provide + additional context, references, etc in collapsible details blocks to ensure that the comment you're adding + is short and easy to read but additional information is a click away. + - Focus on facts from the logs and code, not speculation + - If you can't determine the root cause, say so clearly + - If your only suggestion is a bad suggestion (disable the test, change the timeout, etc), indicate that you've run out of ideas and + that they probably don't want to do that. + - Provide specific file names, line numbers, and code references when possible + - You can run make commands (e.g., `make lint`, `make typecheck`, `make sync`) to build, test, or lint the code + - You can also run git commands (e.g., `git status`, `git log`, `git diff`) to inspect the repository + - You can use WebSearch and WebFetch to research errors, stack traces, or related issues + - For bash commands, you are limited to make and git commands only + + # CRITICAL: ANGRY USERS + **IMPORTANT**: If the user is angry with you, the triage bot, don't respond. Just exit immediately without further action. + If at any point in the conversation the user has asked you to stop replying to the thread, just exit immediately. + + If you are posting the same suggestion as you have previously made, do not post the suggestion again. + + # IMPORTANT: EDIT YOUR COMMENT + Do not post a new comment every time you triage a failing workflow. If a previous comment has been posted by you (marvin) + in a previous triage, edit that comment do not add a new comment for each failure. Be sure to include a note that you've edited + your comment to reflect the latest analysis. Don't worry about keeping the old content around, there's comment history for + that. + + # Problems Encountered + If you encounter any problems during your analysis (e.g., unable to fetch logs, tools not working), document them clearly so the team knows what limitations you faced. + PROMPT_END + EOF + + - name: Setup GitHub MCP Server + run: | + mkdir -p /tmp/mcp-config + cat > /tmp/mcp-config/mcp-servers.json << 'EOF' + { + "mcpServers": { + "repository-summary": { + "type": "http", + "url": "https://agents-md-generator.fastmcp.app/mcp" + }, + "code-search": { + "type": "http", + "url": "https://public-code-search.fastmcp.app/mcp" + }, + "github-research": { + "type": "stdio", + "command": "uvx", + "args": [ + "github-research-mcp" + ], + "env": { + "DISABLE_SUMMARIES": "true", + "GITHUB_PERSONAL_ACCESS_TOKEN": "${{ secrets.GITHUB_TOKEN }}" + } + } + } + } + EOF + + - name: Clean up stale Claude locks + run: rm -rf ~/.claude/.locks ~/.local/state/claude/locks || true + + - name: Run Claude Code + id: claude + uses: anthropics/claude-code-action@v1 + with: + github_token: ${{ steps.marvin-token.outputs.token }} + anthropic_api_key: ${{ secrets.ANTHROPIC_API_KEY_FOR_CI }} + bot_name: "Marvin Context Protocol" + + claude_code_oauth_token: ${{ secrets.CLAUDE_CODE_OAUTH_TOKEN }} + + additional_permissions: | + actions: read + + prompt: ${{ steps.analysis-prompt.outputs.PROMPT }} + claude_args: | + --allowed-tools mcp__repository-summary,mcp__code-search,mcp__github-research,WebSearch,WebFetch,Bash(make:*,git:*) + --mcp-config /tmp/mcp-config/mcp-servers.json diff --git a/.github/workflows/martian-triage-issue.yml b/.github/workflows/martian-triage-issue.yml new file mode 100644 index 000000000..4c7ef711e --- /dev/null +++ b/.github/workflows/martian-triage-issue.yml @@ -0,0 +1,205 @@ +# Triage new issues: investigate, recommend, apply labels +# Calls run-claude directly with triage prompt (elastic issue-triage style) + +name: Triage Issue + +on: + issues: + types: [opened] + +jobs: + triage: + if: | + github.event.issue.user.login == 'strawgate' || + (github.event.issue.user.login == 'jlowin' && contains(toJSON(github.event.issue.labels.*.name), 'bug')) + concurrency: + group: triage-issue-${{ github.event.issue.number }} + cancel-in-progress: true + + runs-on: ubuntu-latest + timeout-minutes: 10 + permissions: + contents: read + issues: write + pull-requests: read + id-token: write + + steps: + - name: Checkout repository + uses: actions/checkout@v6 + with: + repository: ${{ github.repository }} + ref: ${{ github.event.repository.default_branch }} + + - name: Generate Marvin App token + id: marvin-token + uses: actions/create-github-app-token@v2 + with: + app-id: ${{ secrets.MARVIN_APP_ID }} + private-key: ${{ secrets.MARVIN_APP_PRIVATE_KEY }} + + - name: React to issue with eyes + env: + GH_TOKEN: ${{ steps.marvin-token.outputs.token }} + run: | + gh api "repos/${{ github.repository }}/issues/${{ github.event.issue.number }}/reactions" -f content=eyes 2>/dev/null || true + + - name: Run Claude for Triage + uses: ./.github/actions/run-claude + with: + claude-oauth-token: ${{ secrets.CLAUDE_CODE_OAUTH_TOKEN }} + github-token: ${{ steps.marvin-token.outputs.token }} + allowed-tools: "Edit,MultiEdit,Glob,Grep,LS,Read,Write,WebSearch,WebFetch,mcp__github_comment__update_claude_comment,mcp__github_ci__get_ci_status,mcp__github_ci__get_workflow_run_details,mcp__github_ci__download_job_log,Bash(*),mcp__agents-md-generator__generate_agents_md,mcp__public-code-search__search_code" + prompt: | + + Repository: ${{ github.repository }} + Issue Number: #${{ github.event.issue.number }} + Issue Title: ${{ github.event.issue.title }} + Issue Author: ${{ github.event.issue.user.login }} + + + + ${{ github.event.issue.body }} + + + + Triage this new GitHub issue and provide a helpful, actionable response. You can write files and execute commands to test, verify, or investigate the issue. + + + + This workflow is for investigation, testing, and planning. + + You CANNOT: Create branches, checkout branches, commit code to the repository + Do not push changes to the repository. + You CAN: Read/analyze code, search repository, review git history, search for similar issues, write files, verify behavior, provide analysis and recommendations + + + + You have access to the following tools (comma-separated list): + + Edit,MultiEdit,Glob,Grep,LS,Read,Write,WebSearch,WebFetch,mcp__github_comment__update_claude_comment,mcp__github_ci__get_ci_status,mcp__github_ci__get_workflow_run_details,mcp__github_ci__download_job_log,Bash(*),mcp__agents-md-generator__generate_agents_md,mcp__public-code-search__search_code + + You can only use tools that are explicitly listed above. For Bash commands, the pattern `Bash(command:*)` means you can run that command with any arguments. If a command is not listed, it is not available. + + + + Use `mcp__agents-md-generator__generate_agents_md` to get repository context before triaging. + + + + - `mcp__public-code-search__search_code`: Search code in OTHER repositories (use `Grep`/`Read` for this repo) + - `WebSearch`: Search the web for documentation, best practices, or solutions + - `WebFetch`: Fetch and read content from URLs + - Git commands: You have access to git commands, but write commands (commit, push, checkout, branch creation) are blocked + - Write: You can write files (e.g., test files, temporary files for verification) + - Execution: See `` section above for exact list of available execution commands + + + + If execution commands are available (check `` section), you can: + - Run tests to verify reported bugs or test proposed solutions + - Execute scripts to understand behavior + - Run linters or static analysis tools + - Verify environment setup or dependencies + - Test specific code paths or scenarios + - Write test files to confirm behavior + + When executing commands: + - Explain what you're testing and why + - Include command output in your response when relevant + - Use execution to validate your findings and recommendations + - Only use commands that are explicitly listed in `` + + + + Your number one priority is to provide a great response to the issue. A great response is a response that is clear, concise, accurate, and actionable. You will avoid long paragraphs, flowery language, and overly verbose responses. Your readers have limited time and attention, so you will be concise and to the point. + + In priority order your goal is to: + 1. Provide context about the request or issue (related issues, pull requests, files, etc.) + 2. Layout a single high-quality and actionable recommendation for how to address the issue based on your knowledge of the project, codebase, and issue + 3. Provide a high quality and detailed plan that a junior developer could follow to implement the recommendation + 4. Use execution to verify findings when appropriate (check `` section for available commands) + + + + Populate the following sections in your response: + Recommendation (or "No recommendation" with reason) + Findings + Verification (if you executed tests or commands - check `` section) + Detailed Action Plan + Related Items + Related Files + Related Webpages + + You may not be able to do all of these things, sometimes you may find that all you can do is provide in-depth context of the issue and related items. That's perfectly acceptable and expected. Your performance is judged by how accurate your findings are, do the investigation required to have high confidence in your findings and recommendations. "I don't know" or "I'm unable to recommend a course of action" is better than a bad or wrong answer. + + When formulating your response, you will never "bury the lede", you will always provide a clear and concise tl;dr as the first thing in your response. As your response grows in length you can organize the more detailed parts of your response collapsible sections using
and tags. You shouldn't put everything in collapsible sections, especially if the response is short. Use your discretion to determine when to use collapsible sections to avoid overwhelming the reader with too much detail -- think of them like an appendix that can be expanded if the reader is interested. + + + + # Example output for "Recommendation" part of the response + PR #654 already implements the requested feature but is incomplete. The Pull Request is not in a mergeable state yet, the remaining work should be completed: 1) update the Calculator.divide method to utilize the new DivisionByZeroError or the safe_divide function, and 2) update the tests to ensure that the Calculator.divide method raises the new DivisionByZeroError when the divisor is 0. + +
+ Findings + ...details from the code analysis that are relevant to the issue and the recommendation... +
+ +
+ Verification + I ran the existing tests (if execution commands are available in ``) and confirmed the current behavior: + ```bash + $ pytest test_calculator.py::test_divide_by_zero + FAILED - raises ValueError instead of DivisionByZeroError + ``` + This confirms the issue report is accurate. +
+ +
+ Detailed Action Plan + ...a detailed plan that a junior developer could follow to implement the recommendation... +
+ + # Example Output for "Related Items" part of the response + +
+ Related Issues and Pull Requests + + | Repository | Issue or PR | Relevance | + | --- | --- | --- | + | PrefectHQ/fastmcp | [Add matrix operations support](https://github.com/PrefectHQ/fastmcp/pull/680) | This pull request directly addresses the feature request for adding matrix operations to the calculator. | + | PrefectHQ/fastmcp | [Add matrix operations support](https://github.com/PrefectHQ/fastmcp/issues/681) | This issue directly addresses the feature request for adding matrix operations to the calculator. | +
+ +
+ Related Files + + | Repository | File | Relevance | Sections | + | --- | --- | --- | --- | + | modelcontextprotocol/python-sdk | [test_calculator.py](https://github.com/modelcontextprotocol/python-sdk/blob/main/test_calculator.py) | This file contains the test cases for the Calculator class, including a test that specifically asserts a ValueError is raised for division by zero, confirming the current intended behavior. | [25-27](https://github.com/modelcontextprotocol/python-sdk/blob/main/test_calculator.py#L25-L27) | + | modelcontextprotocol/python-sdk | [calculator.py](https://github.com/modelcontextprotocol/python-sdk/blob/main/calculator.py) | This file contains the implementation of the Calculator class, specifically the `divide` method which raises the ValueError when dividing by zero, matching the bug report. | [29-32](https://github.com/modelcontextprotocol/python-sdk/blob/main/calculator.py#L29-L32) | +
+ +
+ Related Webpages + + | Name | URL | Relevance | + | --- | --- | --- | + | Handling Division by Zero Best Practices | https://my-blog-about-division-by-zero.com/handling+division+by+zero+in+calculator | This webpage provides general best practices for handling division by zero in calculator applications and in Python, which is directly relevant to the issue and potential solutions. | +
+
+ + + Always end your comment with a new line, three dashes, and the footer message: + + + --- + Marvin Context Protocol | Type `/marvin` to interact further + + Give us feedback! React with 🚀 if perfect, 👍 if helpful, 👎 if not. + + + + + When writing GitHub comments, wrap branch names, tags, or other @-references in backticks (e.g., `@main`, `@v1.0`) to avoid accidentally pinging users. Do not add backticks around terms that are already inside backticks or code blocks. + diff --git a/.github/workflows/marvin-comment-on-issue.yml b/.github/workflows/marvin-comment-on-issue.yml new file mode 100644 index 000000000..8d297a226 --- /dev/null +++ b/.github/workflows/marvin-comment-on-issue.yml @@ -0,0 +1,142 @@ +# Respond to /marvin mentions in issue comments (elastic mention-in-issue style) +# Calls run-claude directly + +name: Comment on Issue + +on: + issue_comment: + types: [created] + +permissions: + actions: read + contents: write + issues: write + pull-requests: write + id-token: write + +jobs: + comment: + if: | + !github.event.issue.pull_request && + contains(github.event.comment.body, '/marvin') && + contains(fromJSON('["OWNER", "MEMBER", "COLLABORATOR"]'), github.event.comment.author_association) + runs-on: ubuntu-latest + timeout-minutes: 60 + + steps: + - name: Checkout repository + uses: actions/checkout@v6 + + - name: Install UV + uses: astral-sh/setup-uv@v7 + with: + enable-cache: true + cache-dependency-glob: "uv.lock" + + - name: Install dependencies + run: uv sync --python 3.12 + + - name: Run prek + uses: j178/prek-action@v1 + env: + SKIP: no-commit-to-branch + + - name: Generate Marvin App token + id: marvin-token + uses: actions/create-github-app-token@v2 + with: + app-id: ${{ secrets.MARVIN_APP_ID }} + private-key: ${{ secrets.MARVIN_APP_PRIVATE_KEY }} + + - name: React to comment with eyes + env: + GH_TOKEN: ${{ steps.marvin-token.outputs.token }} + run: | + gh api "repos/${{ github.repository }}/issues/comments/${{ github.event.comment.id }}/reactions" -f content=eyes 2>/dev/null || true + + - name: Run Claude for Issue Comment + uses: ./.github/actions/run-claude + with: + claude-oauth-token: ${{ secrets.CLAUDE_CODE_OAUTH_TOKEN }} + github-token: ${{ steps.marvin-token.outputs.token }} + trigger-phrase: "/marvin" + allowed-bots: "*" + allowed-tools: "Edit,MultiEdit,Glob,Grep,LS,Read,Write,WebSearch,WebFetch,mcp__github_comment__update_claude_comment,mcp__github_ci__get_ci_status,mcp__github_ci__get_workflow_run_details,mcp__github_ci__download_job_log,Bash(*),mcp__agents-md-generator__generate_agents_md,mcp__public-code-search__search_code" + prompt: | + + Repository: ${{ github.repository }} + Issue Number: #${{ github.event.issue.number }} + Issue Title: ${{ github.event.issue.title }} + Issue Author: ${{ github.event.issue.user.login }} + Comment Author: ${{ github.event.comment.user.login }} + + + + ${{ github.event.comment.body }} + + + + You have been mentioned in a GitHub issue comment. Understand the request, gather context, complete the task, and respond with results. + + + + You CAN: Read/analyze code, modify files, write code, run tests, execute commands + You CAN: Commit code, push changes, create branches, create pull requests + + + + + You have access to the following tools (comma-separated list): + + Edit,MultiEdit,Glob,Grep,LS,Read,Write,WebSearch,WebFetch,mcp__github_comment__update_claude_comment,mcp__github_ci__get_ci_status,mcp__github_ci__get_workflow_run_details,mcp__github_ci__download_job_log,Bash(*),mcp__agents-md-generator__generate_agents_md,mcp__public-code-search__search_code + + You can only use tools that are explicitly listed above. For Bash commands, the pattern `Bash(command:*)` means you can run that command with any arguments. If a command is not listed, it is not available. + + + + Use `mcp__agents-md-generator__generate_agents_md` to get repository context before responding. + + + + Be thorough in your investigations: + - Understand the full context of the repository + - Review related code, issues, and PRs + - Consider edge cases and implications + - Gather all relevant information before responding + + Available tools: + - `mcp__public-code-search__search_code`: Search code in OTHER repositories (use `Grep`/`Read` for this repo) + - `WebSearch`: Search the web for documentation, best practices, or solutions + - `WebFetch`: Fetch and read content from URLs + + + + - Answer questions about the codebase + - Help debug reported problems (make changes locally to test, cannot push) + - Suggest solutions or workarounds + - Provide code examples + - Help clarify requirements + - Link to relevant documentation or code + + + + - Be concise and actionable + - If the request is unclear, ask clarifying questions + - If the request requires actions you cannot perform (like pushing changes), explain what you can and cannot do + - When making code changes, explain that they are local only and cannot be pushed + + + + Always end your comment with a new line, three dashes, and the footer message: + + + --- + Marvin Context Protocol | Type `/marvin` to interact further + + Give us feedback! React with 🚀 if perfect, 👍 if helpful, 👎 if not. + + + + + When writing GitHub comments, wrap branch names, tags, or other @-references in backticks (e.g., `@main`, `@v1.0`) to avoid accidentally pinging users. Do not add backticks around terms that are already inside backticks or code blocks. + diff --git a/.github/workflows/marvin-comment-on-pr.yml b/.github/workflows/marvin-comment-on-pr.yml new file mode 100644 index 000000000..09f699522 --- /dev/null +++ b/.github/workflows/marvin-comment-on-pr.yml @@ -0,0 +1,284 @@ +# Respond to /marvin mentions in PR review comments and issue comments on PRs +# Calls run-claude directly + +name: Comment on PR + +on: + issue_comment: + types: [created] + +permissions: + contents: write + pull-requests: write + issues: read + id-token: write + +jobs: + comment: + if: | + github.event.issue.pull_request && + contains(github.event.comment.body, '/marvin') && + contains(fromJSON('["OWNER", "MEMBER", "COLLABORATOR"]'), github.event.comment.author_association) + runs-on: ubuntu-latest + timeout-minutes: 15 + + steps: + - name: Checkout PR head branch + uses: actions/checkout@v6 + with: + # do not set to pull_request.head.ref, claude will pull the branch if needed + fetch-depth: 0 + + - name: Install UV + uses: astral-sh/setup-uv@v7 + with: + enable-cache: true + cache-dependency-glob: "uv.lock" + + - name: Install dependencies + run: uv sync --python 3.12 + + - name: Run prek + uses: j178/prek-action@v1 + env: + SKIP: no-commit-to-branch + + - name: Generate Marvin App token + id: marvin-token + uses: actions/create-github-app-token@v2 + with: + app-id: ${{ secrets.MARVIN_APP_ID }} + private-key: ${{ secrets.MARVIN_APP_PRIVATE_KEY }} + + - name: React to comment with eyes + env: + GH_TOKEN: ${{ steps.marvin-token.outputs.token }} + run: | + gh api "repos/${{ github.repository }}/issues/comments/${{ github.event.comment.id }}/reactions" -f content=eyes 2>/dev/null || true + + - name: Get PR HEAD SHA + id: pr-info + env: + GH_TOKEN: ${{ steps.marvin-token.outputs.token }} + run: | + PR_NUMBER="${{ github.event.issue.number }}" + HEAD_SHA=$(gh api "repos/${{ github.repository }}/pulls/${PR_NUMBER}" --jq '.head.sha') + echo "head_sha=${HEAD_SHA}" >> "$GITHUB_OUTPUT" + echo "pr_number=${PR_NUMBER}" >> "$GITHUB_OUTPUT" + + - name: Run Claude for PR Comment + uses: ./.github/actions/run-claude + env: + MENTION_REPO: ${{ github.repository }} + MENTION_PR_NUMBER: ${{ steps.pr-info.outputs.pr_number }} + MENTION_SCRIPTS: ${{ github.workspace }}/.github/scripts/mention + PR_REVIEW_REPO: ${{ github.repository }} + PR_REVIEW_PR_NUMBER: ${{ steps.pr-info.outputs.pr_number }} + PR_REVIEW_HEAD_SHA: ${{ steps.pr-info.outputs.head_sha }} + PR_REVIEW_COMMENTS_DIR: /tmp/pr-review-comments + PR_REVIEW_HELPERS_DIR: ${{ github.workspace }}/.github/scripts/pr-review + with: + claude-oauth-token: ${{ secrets.CLAUDE_CODE_OAUTH_TOKEN }} + github-token: ${{ steps.marvin-token.outputs.token }} + trigger-phrase: "/marvin" + allowed-bots: "*" + allowed-tools: "Edit,MultiEdit,Glob,Grep,LS,Read,Write,WebSearch,WebFetch,mcp__github_comment__update_claude_comment,mcp__github_ci__get_ci_status,mcp__github_ci__get_workflow_run_details,mcp__github_ci__download_job_log,Bash(*),mcp__agents-md-generator__generate_agents_md,mcp__public-code-search__search_code" + prompt: | + + Repository: ${{ github.repository }} + PR Number: #${{ steps.pr-info.outputs.pr_number }} + PR Title: ${{ github.event.issue.title }} + PR Author: ${{ github.event.issue.user.login }} + Comment Author: ${{ github.event.comment.user.login }} + + **Note**: The PR head branch has already been checked out. The workspace is ready - you can immediately start working on the PR code. + + + + ${{ github.event.comment.body }} + + + + You have been mentioned in a Pull Request comment. Understand the request, gather context, complete the task, and respond with results. + + + + This workflow allows read, write, and execute capabilities but cannot push changes. + + You CAN: Read/analyze code, modify files, write code, run tests, execute commands, resolve review threads + You CANNOT: Commit code, push changes, create branches, checkout branches, create pull requests + + **Important**: You cannot push changes to the repository - you can only make changes locally and provide feedback or recommendations. + + + + You have access to the following tools (comma-separated list): + + Edit,MultiEdit,Glob,Grep,LS,Read,Write,WebSearch,WebFetch,mcp__github_comment__update_claude_comment,mcp__github_ci__get_ci_status,mcp__github_ci__get_workflow_run_details,mcp__github_ci__download_job_log,Bash(*),mcp__agents-md-generator__generate_agents_md,mcp__public-code-search__search_code + + You can only use tools that are explicitly listed above. For Bash commands, the pattern `Bash(command:*)` means you can run that command with any arguments. If a command is not listed, it is not available. + + + + Use `mcp__agents-md-generator__generate_agents_md` to get repository context before responding. + + + + Be thorough in your investigations: + - Understand the full context of the repository + - Review related code, issues, and PRs + - Consider edge cases and implications + - Gather all relevant information before responding + + Available tools: + - `mcp__public-code-search__search_code`: Search code in OTHER repositories (use `Grep`/`Read` for this repo) + - `WebSearch`: Search the web for documentation, best practices, or solutions + - `WebFetch`: Fetch and read content from URLs + + + + - Address review feedback and fix issues (make changes locally, cannot push) + - Answer questions about the changes + - Make additional code changes (local only) + - Resolve review threads after addressing feedback (if changes are made separately) + - Perform PR reviews when asked (use the PR review process below) + + + + When asked to review this PR, follow this structured review process. + The `$PR_REVIEW_HELPERS_DIR` environment variable is pre-configured for all scripts below. + + + Follow these steps in order: + + **Step 1: Gather context** + - Use `mcp__agents-md-generator__generate_agents_md` to get repository context + (if this fails, explore the repository to understand the codebase — read key files like README, CONTRIBUTING, etc.) + - Run `$PR_REVIEW_HELPERS_DIR/pr-existing-comments.sh --summary` to see existing review threads per file + - Run `$PR_REVIEW_HELPERS_DIR/pr-diff.sh` to see changed files with line-numbered diffs + (for large PRs, this lists files only — review each with `pr-diff.sh `) + + **Step 2: Review each file** + For each changed file: + a. If the summary showed existing threads for this file, first run: + `$PR_REVIEW_HELPERS_DIR/pr-existing-comments.sh --file ` + Read the full thread details. The output uses these conventions: + - `← has replies` — a conversation happened; read carefully before commenting + - `[truncated]` — comment was cut short; add `--full` if you need the complete text to understand the comment + - `[abc1234]` — commit the comment was made on; use `git show abc1234` if needed + - `~42` — approximate line from an older revision (exact line no longer maps to current diff) + b. Review the diff. Use `Read` to see full file contents when you need more context. + Identify issues matching review_criteria. Do NOT flag: + - Issues in unchanged code (only review the diff) + - Style preferences handled by linters + - Pre-existing issues not introduced by this PR + - Issues already covered by existing threads (see below) + + **Existing thread rules** (check BEFORE leaving any comment): + - Resolved with reviewer reply → reviewer's decision is final. Do NOT re-flag. + Examples: "It should remain as X", "This is intentional", "No need to do this change" + - Resolved without reply → author likely fixed it. Do NOT re-raise unless the fix introduced a new problem. + - Unresolved → already flagged. Do NOT re-comment. Mention in review body if you have more to add. + - Outdated → code changed. Only re-flag if the issue still applies to the current diff. + When in doubt, do not duplicate. Redundant comments erode trust in the review process. + + **Step 3: Leave comments for NEW issues only** + For each genuinely new issue not covered by existing threads: + ```bash + $PR_REVIEW_HELPERS_DIR/pr-comment.sh \ + --severity \ + --title "Brief description" \ + --why "Risk or impact" <<'EOF' + corrected code here + EOF + ``` + Always provide suggestion code. Use `--no-suggestion` only when the fix requires + changes across multiple locations. Broader architectural concerns belong in the + review body, not inline comments. + + To remove a queued comment: `$PR_REVIEW_HELPERS_DIR/pr-remove-comment.sh ` + + **Step 4: Submit the review** + ```bash + $PR_REVIEW_HELPERS_DIR/pr-review.sh "" + ``` + - REQUEST_CHANGES: Any 🔴 CRITICAL or 🟠 HIGH issues found + - COMMENT: 🟡 MEDIUM issues found (but no critical/high) + - APPROVE: No issues, or only ⚪ LOW / 💬 NITPICK suggestions + + The review body should include broader architectural concerns not suited for inline comments. + Avoid summarizing the PR or offering praise. If approving with no issues, omit the review body. + A standard footer is automatically appended to all comments and reviews. + + + + 🔴 CRITICAL - Must fix before merge (security vulnerabilities, data corruption, production-breaking bugs) + 🟠 HIGH - Should fix before merge (logic errors, missing validation, significant performance issues) + 🟡 MEDIUM - Address soon, non-blocking (error handling gaps, suboptimal patterns, missing edge cases) + ⚪ LOW - Author discretion, non-blocking (minor improvements, documentation, style not covered by linters) + 💬 NITPICK - Truly optional (stylistic preferences, alternative approaches — safe to ignore) + + + + Focus on these categories, in priority order: + 1. Security vulnerabilities (injection, XSS, auth bypass, secrets exposure) + 2. Logic bugs that could cause runtime failures or incorrect behavior + 3. Data integrity issues (race conditions, missing transactions, corruption risk) + 4. Performance bottlenecks (N+1 queries, memory leaks, blocking operations) + 5. Error handling gaps (unhandled exceptions, missing validation) + 6. Breaking changes to public APIs without migration path + 7. Missing or incorrect test coverage for critical paths + + + + + View unresolved review threads: + ```bash + $MENTION_SCRIPTS/gh-get-review-threads.sh + ``` + + Filter for unresolved threads from a specific reviewer: + ```bash + $MENTION_SCRIPTS/gh-get-review-threads.sh "reviewer-username" + ``` + + Resolve a review thread after addressing feedback: + ```bash + $MENTION_SCRIPTS/gh-resolve-review-thread.sh "THREAD_ID" "Fixed by updating the error handling" + ``` + - `THREAD_ID` is the GraphQL node ID from the review threads output (e.g., `PRRT_kwDOABC123`) + - The comment is optional - use it to explain what you did + + Note: Since you cannot push changes, you can resolve threads to acknowledge feedback, but actual fixes would need to be applied separately. + + + + - Be concise and actionable + - If the request is unclear, ask clarifying questions + - If the request requires actions you cannot perform (like pushing changes), explain what you can and cannot do + - When making code changes, explain that they are local only and cannot be pushed + + **When performing a PR review**: Your substantive feedback belongs in the PR review submission + (via pr-review.sh), not in the comment response. The comment should only report: + - That you've submitted the review (with the outcome: approved, requested changes, etc.) + - Any issues encountered during the review process + - Brief status updates + + Do NOT duplicate the review content in your comment - the review itself contains all the details. + Keep the comment short, e.g., "I've submitted my review requesting changes. See the review for details." + + + + Always end your comment with a new line, three dashes, and the footer message: + + + --- + Marvin Context Protocol | Type `/marvin` to interact further + + Give us feedback! React with 🚀 if perfect, 👍 if helpful, 👎 if not. + + + + + When writing GitHub comments, wrap branch names, tags, or other @-references in backticks (e.g., `@main`, `@v1.0`) to avoid accidentally pinging users. Do not add backticks around terms that are already inside backticks or code blocks. + diff --git a/.github/workflows/marvin-dedupe-issues.yml b/.github/workflows/marvin-dedupe-issues.yml new file mode 100644 index 000000000..a71c590c0 --- /dev/null +++ b/.github/workflows/marvin-dedupe-issues.yml @@ -0,0 +1,116 @@ +name: Marvin Issue Dedupe +# description: Automatically dedupe GitHub issues using Marvin +on: + issues: + types: [opened] + workflow_dispatch: + inputs: + issue_number: + description: "Issue number to process for duplicate detection" + required: true + type: string + +jobs: + marvin-dedupe-issues: + runs-on: ubuntu-latest + timeout-minutes: 10 + permissions: + contents: read + issues: write + id-token: write + + steps: + - name: Checkout repository + uses: actions/checkout@v6 + + - name: Generate Marvin App token + id: marvin-token + uses: actions/create-github-app-token@v2 + with: + app-id: ${{ secrets.MARVIN_APP_ID }} + private-key: ${{ secrets.MARVIN_APP_PRIVATE_KEY }} + + - name: Set dedupe prompt + id: dedupe-prompt + run: | + cat >> $GITHUB_OUTPUT << 'EOF' + PROMPT</dev/null \ + || date -u -v-10M '+%Y-%m-%dT%H:%M:%SZ') + HAS_RECENT=$(gh api "repos/${{ github.repository }}/issues/${ISSUE}/comments?sort=created&direction=desc&per_page=10" \ + --jq "[.[] | select( + .user.type == \"Bot\" and + (.body | test(\"possible duplicate issues\"; \"i\")) and + .created_at >= \"${CUTOFF}\" + )] | length") + if [ "$HAS_RECENT" -gt 0 ]; then + gh issue edit "$ISSUE" --add-label "potential-duplicate" -R "${{ github.repository }}" + echo "Added potential-duplicate label to #${ISSUE}" + else + echo "No recent duplicate comment found, skipping label" + fi diff --git a/.github/workflows/marvin-label-triage.yml b/.github/workflows/marvin-label-triage.yml new file mode 100644 index 000000000..8a3f5f47d --- /dev/null +++ b/.github/workflows/marvin-label-triage.yml @@ -0,0 +1,149 @@ +name: Marvin Label Triage +# Automatically triage GitHub issues and PRs using Marvin + +on: + issues: + types: [opened] + pull_request_target: + types: [opened] + workflow_dispatch: + inputs: + issue_number: + description: "Issue or PR number to triage" + required: true + type: string + +concurrency: + group: triage-${{ github.event.issue.number || github.event.pull_request.number || inputs.issue_number }} + cancel-in-progress: false + +jobs: + label-issue-or-pr: + if: github.actor != 'dependabot[bot]' + runs-on: ubuntu-latest + timeout-minutes: 10 + permissions: + contents: read + issues: write + pull-requests: write + + steps: + - name: Checkout base repository + uses: actions/checkout@v6 + with: + repository: ${{ github.repository }} + ref: ${{ github.event.repository.default_branch }} + + - name: Generate Marvin App token + id: marvin-token + uses: actions/create-github-app-token@v2 + with: + app-id: ${{ secrets.MARVIN_APP_ID }} + private-key: ${{ secrets.MARVIN_APP_PRIVATE_KEY }} + owner: PrefectHQ + + - name: Set triage prompt + id: triage-prompt + run: | + cat >> $GITHUB_OUTPUT << 'EOF' + PROMPT<- + ( + github.event_name == 'issue_comment' && + github.event.issue.pull_request && + contains(github.event.comment.body, '/tidy') && + contains(fromJSON('["OWNER", "MEMBER", "COLLABORATOR"]'), github.event.comment.author_association) + ) || ( + github.event_name != 'issue_comment' && + github.event.pull_request.head.repo.full_name == github.event.pull_request.base.repo.full_name + ) + runs-on: ubuntu-latest + steps: + - name: Minimize resolved review comments + uses: strawgate/minimize-resolved-pr-reviews@v0 + with: + github-token: ${{ secrets.GITHUB_TOKEN }} diff --git a/.github/workflows/publish.yml b/.github/workflows/publish.yml index e51173c31..5f2fe8d53 100644 --- a/.github/workflows/publish.yml +++ b/.github/workflows/publish.yml @@ -5,28 +5,22 @@ on: workflow_dispatch: jobs: - publish-pypi-release: + pypi-publish: + name: Upload to PyPI runs-on: ubuntu-latest - environment: release permissions: - contents: write - id-token: write + id-token: write # For PyPI's trusted publishing steps: - name: Checkout - uses: actions/checkout@v4 - - name: Set up Python - uses: actions/setup-python@v5 + uses: actions/checkout@v6 with: - python-version: "3.11" - cache: pip - cache-dependency-path: "**/pyproject.toml" - - name: Install dependencies - run: | - pip install setuptools wheel build + fetch-depth: 0 + + - name: "Install uv" + uses: astral-sh/setup-uv@v7 + - name: Build - run: | - python -m build - - name: Publish - uses: pypa/gh-action-pypi-publish@release/v1 - with: - verbose: true + run: uv build + + - name: Publish to PyPi + run: uv publish -v dist/* diff --git a/.github/workflows/run-static.yml b/.github/workflows/run-static.yml new file mode 100644 index 000000000..7acc3aac6 --- /dev/null +++ b/.github/workflows/run-static.yml @@ -0,0 +1,40 @@ +name: Run static analysis + +env: + PY_COLORS: 1 + +on: + push: + branches: ["main"] + paths: + - "src/**" + - "tests/**" + - "uv.lock" + - "pyproject.toml" + - ".github/workflows/**" + + # run on all pull requests because these checks are required and will block merges otherwise + pull_request: + + workflow_dispatch: + +permissions: + contents: read + +jobs: + static_analysis: + timeout-minutes: 2 + runs-on: ubuntu-latest + + steps: + - uses: actions/checkout@v6 + + - name: Setup uv + uses: ./.github/actions/setup-uv + with: + resolution: locked + + - name: Run prek + uses: j178/prek-action@v1 + env: + SKIP: no-commit-to-branch diff --git a/.github/workflows/run-tests.yml b/.github/workflows/run-tests.yml index 86609284e..7799e7aa2 100644 --- a/.github/workflows/run-tests.yml +++ b/.github/workflows/run-tests.yml @@ -1,13 +1,21 @@ -name: Run tests +name: Tests env: - # enable colored output PY_COLORS: 1 on: push: branches: ["main"] + paths: + - "src/**" + - "tests/**" + - "uv.lock" + - "pyproject.toml" + - ".github/workflows/**" + + # run on all pull requests because these checks are required and will block merges otherwise pull_request: + workflow_dispatch: permissions: @@ -15,21 +23,74 @@ permissions: jobs: run_tests: - name: Run tests + name: "Tests: Python ${{ matrix.python-version }} on ${{ matrix.os }}" + runs-on: ${{ matrix.os }} + strategy: + matrix: + os: [ubuntu-latest, windows-latest] + python-version: ["3.10"] + include: + - os: ubuntu-latest + python-version: "3.13" + fail-fast: false + timeout-minutes: 10 + + steps: + - uses: actions/checkout@v6 + + - name: Setup uv + uses: ./.github/actions/setup-uv + with: + python-version: ${{ matrix.python-version }} + resolution: locked + + - name: Run unit tests + uses: ./.github/actions/run-pytest + + - name: Run client process tests + uses: ./.github/actions/run-pytest + with: + test-type: client_process + + run_tests_lowest_direct: + name: "Tests with lowest-direct dependencies" runs-on: ubuntu-latest + timeout-minutes: 10 steps: - - uses: actions/checkout@v4 + - uses: actions/checkout@v6 + + - name: Setup uv (lowest-direct) + uses: ./.github/actions/setup-uv + with: + resolution: lowest-direct + + - name: Run unit tests + uses: ./.github/actions/run-pytest - - name: Install uv - uses: astral-sh/setup-uv@v4 + - name: Run client process tests + uses: ./.github/actions/run-pytest + with: + test-type: client_process - - name: Set up Python - run: uv python install 3.11 + run_integration_tests: + name: "Integration tests" + runs-on: ubuntu-latest + timeout-minutes: 10 + + steps: + - uses: actions/checkout@v6 - - name: Install FastMCP - run: uv sync --all-extras --dev + - name: Setup uv + uses: ./.github/actions/setup-uv + with: + resolution: locked - - name: Run tests - run: uv run pytest -vv - if: ${{ !(github.event.pull_request.head.repo.fork) }} + - name: Run integration tests + uses: ./.github/actions/run-pytest + with: + test-type: integration + env: + FASTMCP_GITHUB_TOKEN: ${{ secrets.FASTMCP_GITHUB_TOKEN }} + FASTMCP_TEST_AUTH_GITHUB_CLIENT_ID: ${{ secrets.FASTMCP_TEST_AUTH_GITHUB_CLIENT_ID }} + FASTMCP_TEST_AUTH_GITHUB_CLIENT_SECRET: ${{ secrets.FASTMCP_TEST_AUTH_GITHUB_CLIENT_SECRET }} diff --git a/.github/workflows/run-upgrade-checks.yml b/.github/workflows/run-upgrade-checks.yml new file mode 100644 index 000000000..3a8162129 --- /dev/null +++ b/.github/workflows/run-upgrade-checks.yml @@ -0,0 +1,133 @@ +name: Upgrade checks + +env: + PY_COLORS: 1 + +on: + push: + branches: ["main"] + paths: + - "src/**" + - "tests/**" + - "uv.lock" + - "pyproject.toml" + - ".github/workflows/**" + + schedule: + # Run daily at 2 AM UTC + - cron: "0 2 * * *" + + workflow_dispatch: + +permissions: + contents: read + issues: write + +jobs: + static_analysis: + name: Static analysis + timeout-minutes: 2 + runs-on: ubuntu-latest + + steps: + - uses: actions/checkout@v6 + + - name: Setup uv (upgrade) + uses: ./.github/actions/setup-uv + with: + resolution: upgrade + + - name: Run prek + uses: j178/prek-action@v1 + env: + SKIP: no-commit-to-branch + + run_tests: + name: "Tests: Python ${{ matrix.python-version }} on ${{ matrix.os }}" + runs-on: ${{ matrix.os }} + strategy: + matrix: + os: [ubuntu-latest, windows-latest] + python-version: ["3.10"] + include: + - os: ubuntu-latest + python-version: "3.13" + fail-fast: false + timeout-minutes: 10 + + steps: + - uses: actions/checkout@v6 + + - name: Setup uv (upgrade) + uses: ./.github/actions/setup-uv + with: + python-version: ${{ matrix.python-version }} + resolution: upgrade + + - name: Run unit tests + uses: ./.github/actions/run-pytest + + - name: Run client process tests + uses: ./.github/actions/run-pytest + with: + test-type: client_process + + run_integration_tests: + name: "Integration tests" + runs-on: ubuntu-latest + timeout-minutes: 10 + + steps: + - uses: actions/checkout@v6 + + - name: Setup uv (upgrade) + uses: ./.github/actions/setup-uv + with: + resolution: upgrade + + - name: Run integration tests + uses: ./.github/actions/run-pytest + with: + test-type: integration + env: + FASTMCP_GITHUB_TOKEN: ${{ secrets.FASTMCP_GITHUB_TOKEN }} + FASTMCP_TEST_AUTH_GITHUB_CLIENT_ID: ${{ secrets.FASTMCP_TEST_AUTH_GITHUB_CLIENT_ID }} + FASTMCP_TEST_AUTH_GITHUB_CLIENT_SECRET: ${{ secrets.FASTMCP_TEST_AUTH_GITHUB_CLIENT_SECRET }} + + notify: + name: Notify on failure + needs: [static_analysis, run_tests, run_integration_tests] + if: failure() && github.event.pull_request == null + runs-on: ubuntu-latest + + steps: + - name: Create or update failure issue + uses: jayqi/failed-build-issue-action@v1 + with: + github-token: ${{ secrets.GITHUB_TOKEN }} + label: "build-failure" + title-template: "Upgrade checks failing on main branch" + body-template: | + ## Upgrade Checks Failure on Main Branch + + The upgrade checks workflow has failed on the main branch. + + **Workflow Run**: [#{{runNumber}}]({{serverUrl}}/{{repo.owner}}/{{repo.repo}}/actions/runs/{{runId}}) + **Commit**: {{sha}} + **Branch**: {{ref}} + **Event**: {{eventName}} + + ### Common causes + + - **ty (type checker)**: New ty releases frequently add stricter checks that flag previously-accepted code. Run `uv run ty check` locally with the latest ty to reproduce. Fix the type errors or bump the ty version floor in `pyproject.toml`. + - **ruff**: New lint rules or stricter defaults in a ruff upgrade. + - **mcp SDK**: Breaking changes in the `mcp` package (new method signatures, renamed types). + + ### What to do + + 1. Check the workflow logs to identify which job failed (static analysis vs tests) + 2. Reproduce locally with `uv sync --upgrade && uv run prek run --all-files && uv run pytest -n auto` + 3. Fix the code or adjust dependency constraints as needed + + --- + *This issue was automatically created by a GitHub Action.* diff --git a/.github/workflows/update-config-schema.yml b/.github/workflows/update-config-schema.yml new file mode 100644 index 000000000..ed66ea209 --- /dev/null +++ b/.github/workflows/update-config-schema.yml @@ -0,0 +1,72 @@ +name: Update MCPServerConfig Schema + +# Regenerates config schema on pushes to main and opens a long-lived PR +# with the changes, so contributor PRs stay clean. + +on: + push: + branches: ["main"] + paths: + - "src/fastmcp/utilities/mcp_server_config/**" + - "!src/fastmcp/utilities/mcp_server_config/v1/schema.json" + workflow_dispatch: + +permissions: + contents: write + pull-requests: write + +jobs: + update-config-schema: + timeout-minutes: 5 + runs-on: ubuntu-latest + + steps: + - name: Generate Marvin App token + id: marvin-token + uses: actions/create-github-app-token@v2 + with: + app-id: ${{ secrets.MARVIN_APP_ID }} + private-key: ${{ secrets.MARVIN_APP_PRIVATE_KEY }} + + - uses: actions/checkout@v6 + with: + token: ${{ steps.marvin-token.outputs.token }} + + - name: Install uv + uses: astral-sh/setup-uv@v7 + with: + enable-cache: true + cache-dependency-glob: "uv.lock" + + - name: Install dependencies + run: uv sync --python 3.12 + + - name: Generate config schema + run: | + uv run python -c " + from fastmcp.utilities.mcp_server_config import generate_schema + generate_schema('docs/public/schemas/fastmcp.json/latest.json') + generate_schema('docs/public/schemas/fastmcp.json/v1.json') + generate_schema('src/fastmcp/utilities/mcp_server_config/v1/schema.json') + " + + - name: Create Pull Request + uses: peter-evans/create-pull-request@v8 + with: + token: ${{ steps.marvin-token.outputs.token }} + commit-message: "chore: Update fastmcp.json schema" + title: "chore: Update fastmcp.json schema" + body: | + This PR updates the fastmcp.json schema files to match the current source code. + + The schema is automatically generated from `src/fastmcp/utilities/mcp_server_config/` to ensure consistency. + + **Note:** This PR is fully automated and will update itself with any subsequent changes to the schema, or close automatically if the schema becomes up-to-date through other means. + + 🤖 Generated by Marvin + branch: marvin/update-config-schema + labels: | + ignore in release notes + delete-branch: true + author: "marvin-context-protocol[bot] <225465937+marvin-context-protocol[bot]@users.noreply.github.com>" + committer: "marvin-context-protocol[bot] <225465937+marvin-context-protocol[bot]@users.noreply.github.com>" diff --git a/.github/workflows/update-sdk-docs.yml b/.github/workflows/update-sdk-docs.yml new file mode 100644 index 000000000..6ca5eb61d --- /dev/null +++ b/.github/workflows/update-sdk-docs.yml @@ -0,0 +1,69 @@ +name: Update SDK Documentation + +# Regenerates SDK docs on pushes to main and opens a long-lived PR +# with the changes, so contributor PRs stay clean. + +on: + push: + branches: ["main"] + paths: + - "src/**" + - "pyproject.toml" + workflow_dispatch: + +permissions: + contents: write + pull-requests: write + +jobs: + update-sdk-docs: + timeout-minutes: 5 + runs-on: ubuntu-latest + + steps: + - name: Generate Marvin App token + id: marvin-token + uses: actions/create-github-app-token@v2 + with: + app-id: ${{ secrets.MARVIN_APP_ID }} + private-key: ${{ secrets.MARVIN_APP_PRIVATE_KEY }} + + - uses: actions/checkout@v6 + with: + token: ${{ steps.marvin-token.outputs.token }} + + - name: Install uv + uses: astral-sh/setup-uv@v7 + with: + enable-cache: true + cache-dependency-glob: "uv.lock" + + - name: Install dependencies + run: uv sync --python 3.12 + + - name: Install just + uses: extractions/setup-just@v3 + + - name: Generate SDK documentation + run: just api-ref-all + + - name: Create Pull Request + uses: peter-evans/create-pull-request@v8 + with: + token: ${{ steps.marvin-token.outputs.token }} + commit-message: "chore: Update SDK documentation" + title: "chore: Update SDK documentation" + body: | + This PR updates the auto-generated SDK documentation to reflect the latest source code changes. + + 📚 Documentation is automatically generated from the source code docstrings and type annotations. + + **Note:** This PR is fully automated and will update itself with any subsequent changes to the SDK, or close automatically if the documentation becomes up-to-date through other means. Feel free to leave it open until you're ready to merge. + + 🤖 Generated by Marvin + branch: marvin/update-sdk-docs + labels: | + ignore in release notes + delete-branch: true + author: "marvin-context-protocol[bot] <225465937+marvin-context-protocol[bot]@users.noreply.github.com>" + committer: "marvin-context-protocol[bot] <225465937+marvin-context-protocol[bot]@users.noreply.github.com>" diff --git a/.gitignore b/.gitignore index 4021cf770..7791fb4ca 100644 --- a/.gitignore +++ b/.gitignore @@ -1,14 +1,82 @@ # Python-generated files __pycache__/ -*.py[oc] +*.py[cod] +*$py.class build/ dist/ wheels/ -*.egg-info +*.egg-info/ +*.egg +MANIFEST +.pytest_cache/ +.loq_cache +.coverage +htmlcov/ +.tox/ +nosetests.xml +coverage.xml +*.cover # Virtual environments .venv +venv/ +env/ +ENV/ +.env + +# System files .DS_Store +# Version file +src/fastmcp/_version.py + +# Editors and IDEs +.cursorrules +.vscode/ +.idea/ +*.swp +*.swo +*~ +.project +.pydevproject +.settings/ + +# Jupyter Notebook +.ipynb_checkpoints + +# Type checking +.mypy_cache/ +.dmypy.json +dmypy.json +.pyre/ +.pytype/ + +# Local development +.python-version +.envrc +.envrc.private +.direnv/ + +# Logs and databases +*.log +*.sqlite +*.db +*.ddb + +# Claude worktree management +.claude-wt/worktrees + +# Agents +/PLAN.md +/TODO.md +/STATUS.md +plans/ + +# Node / admin-ui +node_modules/ -src/fastmcp/_version.py \ No newline at end of file +# Common FastMCP test files +/test.py +/server.py +/client.py +/test.json diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml new file mode 100644 index 000000000..dd3574432 --- /dev/null +++ b/.pre-commit-config.yaml @@ -0,0 +1,55 @@ +fail_fast: false + +repos: + - repo: https://github.com/abravalheri/validate-pyproject + rev: v0.24.1 + hooks: + - id: validate-pyproject + + - repo: https://github.com/pre-commit/mirrors-prettier + rev: v3.1.0 + hooks: + - id: prettier + types_or: [yaml, json5] + + - repo: https://github.com/astral-sh/ruff-pre-commit + # Ruff version. + rev: v0.14.10 + hooks: + # Run the linter. + - id: ruff-check + args: [--fix, --exit-non-zero-on-fix] + # Run the formatter. + - id: ruff-format + + - repo: local + hooks: + - id: ty + name: ty check + entry: uv run --isolated ty check + language: system + types: [python] + files: ^src/|^tests/ + pass_filenames: false + require_serial: true + + - id: loq + name: loq (file size limits) + entry: bash -c 'uv run loq || printf "\nloq violations not enforced... yet!\n"' + language: system + pass_filenames: false + verbose: true + + - repo: https://github.com/pre-commit/pre-commit-hooks + rev: v6.0.0 + hooks: + - id: no-commit-to-branch + name: prevent commits to main + args: [--branch, main] + + - repo: https://github.com/codespell-project/codespell + rev: v2.4.1 + hooks: + - id: codespell # See pyproject.toml for args + additional_dependencies: + - tomli diff --git a/AGENTS.md b/AGENTS.md new file mode 120000 index 000000000..681311eb9 --- /dev/null +++ b/AGENTS.md @@ -0,0 +1 @@ +CLAUDE.md \ No newline at end of file diff --git a/CLAUDE.md b/CLAUDE.md new file mode 100644 index 000000000..a27089e19 --- /dev/null +++ b/CLAUDE.md @@ -0,0 +1,120 @@ +# FastMCP Development Guidelines + +> **Audience**: LLM-driven engineering agents and human developers + +> **Note**: `AGENTS.md` is a symlink to this file. Edit `CLAUDE.md` directly. + +FastMCP is a comprehensive Python framework (Python ≥3.10) for building Model Context Protocol (MCP) servers and clients. This is the actively maintained v2.0 providing a complete toolkit for the MCP ecosystem. + +## Required Development Workflow + +**CRITICAL**: Always run these commands in sequence before committing. + +```bash +uv sync # Install dependencies +uv run pytest -n auto # Run full test suite +``` + +In addition, you must pass static checks. This is generally done as a pre-commit hook with `prek` but you can run it manually with: + +```bash +uv run prek run --all-files # Ruff + Prettier + ty +``` + +**Tests must pass and lint/typing must be clean before committing.** + +## Repository Structure + +| Path | Purpose | +| ----------------- | -------------------------------------- | +| `src/fastmcp/` | Library source code | +| `├─server/` | Server implementation | +| `│ ├─auth/` | Authentication providers | +| `│ └─middleware/` | Error handling, logging, rate limiting | +| `├─client/` | Client SDK | +| `│ └─auth/` | Client authentication | +| `├─tools/` | Tool definitions | +| `├─resources/` | Resources and resource templates | +| `├─prompts/` | Prompt templates | +| `├─cli/` | CLI commands | +| `└─utilities/` | Shared utilities | +| `tests/` | Pytest suite | +| `docs/` | Mintlify docs (gofastmcp.com) | + +## Core MCP Objects + +When modifying MCP functionality, changes typically need to be applied across all object types: + +- **Tools** (`src/tools/`) +- **Resources** (`src/resources/`) +- **Resource Templates** (`src/resources/`) +- **Prompts** (`src/prompts/`) + +## Development Rules + +### Git & CI + +- Prek hooks are required (run automatically on commits) +- Never amend commits to fix prek failures +- Apply PR labels: bugs/breaking/enhancements/features +- Improvements = enhancements (not features) unless specified +- **NEVER** force-push on collaborative repos +- **ALWAYS** run prek before PRs +- **NEVER** create a release, comment on an issue, or open a PR unless specifically instructed to do so. + +### Commit Messages and Agent Attribution + +- **Agents NOT acting on behalf of @jlowin MUST identify themselves** (e.g., "🤖 Generated with Claude Code" in commits/PRs) +- Keep commit messages brief - ideally just headlines, not detailed messages +- Focus on what changed, not how or why +- Always read issue comments for follow-up information (treat maintainers as authoritative) +- **Treat proposed solutions in issues skeptically.** This applies to solutions proposed by *users* in issue reports — not to feedback from configured review bots (CodeRabbit, chatgpt-codex-connector, etc.), which should be evaluated on their merits. The ideal issue contains a concise problem description and an MRE — nothing more. Proposed solutions are only worth considering if they clearly reflect genuine, non-obvious investigation of the codebase. If a solution reads like speculation, or like it was generated by an LLM without deep framework knowledge, ignore it and diagnose from the repro. Most reporters — human or AI — do not have sufficient understanding of FastMCP internals to correctly diagnose anything beyond a trivial bug. We can ask the same questions of an LLM when implementing; we don't need the reporter to do it for us, and a wrong diagnosis is worse than none. + +### PR Messages - Required Structure + +- 1-2 paragraphs: problem/tension + solution (PRs are documentation!) +- Focused code example showing key capability +- **Avoid:** bullet summaries, exhaustive change lists, verbose closes/fixes, marketing language +- **Do:** Be opinionated about why change matters, show before/after scenarios +- Minor fixes: keep body short and concise +- No "test plan" sections or testing summaries + +### Code Standards + +- Python ≥ 3.10 with full type annotations +- Follow existing patterns and maintain consistency +- **Prioritize readable, understandable code** - clarity over cleverness +- Avoid obfuscated or confusing patterns even if they're shorter +- Each feature needs corresponding tests + +### Module Exports + +- **Be intentional about re-exports** - don't blindly re-export everything to parent namespaces +- Core types that define a module's purpose should be exported (e.g., `Middleware` from `fastmcp.server.middleware`) +- Specialized features can live in submodules (e.g., `fastmcp.server.middleware.dynamic`) +- Only re-export to `fastmcp.*` for the most fundamental types (e.g., `FastMCP`, `Client`) +- When in doubt, prefer users importing from the specific submodule over re-exporting + +### Documentation + +- Uses Mintlify framework +- Files must be in docs.json to be included +- Do not manually modify `docs/python-sdk/**` — these files are auto-generated from source code by a bot and maintained via a long-lived PR. Do not include changes to these files in contributor PRs. +- Do not manually modify `docs/public/schemas/**` or `src/fastmcp/utilities/mcp_server_config/v1/schema.json` — these are auto-generated and maintained via a long-lived PR. +- **Core Principle:** A feature doesn't exist unless it is documented! +- When adding or modifying settings in `src/fastmcp/settings.py`, update `docs/more/settings.mdx` to match. + +### Documentation Guidelines + +- **Code Examples:** Explain before showing code, make blocks fully runnable (include imports) +- **Code Formatting:** Keep code blocks visually clean — avoid deeply nested function calls. Extract intermediate values into named variables rather than inlining everything into one expression. Code in docs is read more than it's run; optimize for scannability. +- **Structure:** Headers form navigation guide, logical H2/H3 hierarchy +- **Content:** User-focused sections, motivate features (why) before mechanics (how) +- **Style:** Prose over code comments for important information + +## Critical Patterns + +- Never use bare `except` - be specific with exception types +- File sizes enforced by [loq](https://github.com/jakekaplan/loq). Edit `loq.toml` to raise limits; `loq baseline` to ratchet down. +- Always `uv sync` first when debugging build issues +- Default test timeout is 5s - optimize or mark as integration tests diff --git a/CODE_OF_CONDUCT.md b/CODE_OF_CONDUCT.md new file mode 100644 index 000000000..026b0a2cd --- /dev/null +++ b/CODE_OF_CONDUCT.md @@ -0,0 +1,128 @@ +# Contributor Covenant Code of Conduct + +## Our Pledge + +We as members, contributors, and leaders pledge to make participation in our +community a harassment-free experience for everyone, regardless of age, body +size, visible or invisible disability, ethnicity, sex characteristics, gender +identity and expression, level of experience, education, socio-economic status, +nationality, personal appearance, race, religion, or sexual identity +and orientation. + +We pledge to act and interact in ways that contribute to an open, welcoming, +diverse, inclusive, and healthy community. + +## Our Standards + +Examples of behavior that contributes to a positive environment for our +community include: + +* Demonstrating empathy and kindness toward other people +* Being respectful of differing opinions, viewpoints, and experiences +* Giving and gracefully accepting constructive feedback +* Accepting responsibility and apologizing to those affected by our mistakes, + and learning from the experience +* Focusing on what is best not just for us as individuals, but for the + overall community + +Examples of unacceptable behavior include: + +* The use of sexualized language or imagery, and sexual attention or + advances of any kind +* Trolling, insulting or derogatory comments, and personal or political attacks +* Public or private harassment +* Publishing others' private information, such as a physical or email + address, without their explicit permission +* Other conduct which could reasonably be considered inappropriate in a + professional setting + +## Enforcement Responsibilities + +Community leaders are responsible for clarifying and enforcing our standards of +acceptable behavior and will take appropriate and fair corrective action in +response to any behavior that they deem inappropriate, threatening, offensive, +or harmful. + +Community leaders have the right and responsibility to remove, edit, or reject +comments, commits, code, wiki edits, issues, and other contributions that are +not aligned to this Code of Conduct, and will communicate reasons for moderation +decisions when appropriate. + +## Scope + +This Code of Conduct applies within all community spaces, and also applies when +an individual is officially representing the community in public spaces. +Examples of representing our community include using an official e-mail address, +posting via an official social media account, or acting as an appointed +representative at an online or offline event. + +## Enforcement + +Instances of abusive, harassing, or otherwise unacceptable behavior may be +reported to the community leaders responsible for enforcement at +chris@prefect.io. +All complaints will be reviewed and investigated promptly and fairly. + +All community leaders are obligated to respect the privacy and security of the +reporter of any incident. + +## Enforcement Guidelines + +Community leaders will follow these Community Impact Guidelines in determining +the consequences for any action they deem in violation of this Code of Conduct: + +### 1. Correction + +**Community Impact**: Use of inappropriate language or other behavior deemed +unprofessional or unwelcome in the community. + +**Consequence**: A private, written warning from community leaders, providing +clarity around the nature of the violation and an explanation of why the +behavior was inappropriate. A public apology may be requested. + +### 2. Warning + +**Community Impact**: A violation through a single incident or series +of actions. + +**Consequence**: A warning with consequences for continued behavior. No +interaction with the people involved, including unsolicited interaction with +those enforcing the Code of Conduct, for a specified period of time. This +includes avoiding interactions in community spaces as well as external channels +like social media. Violating these terms may lead to a temporary or +permanent ban. + +### 3. Temporary Ban + +**Community Impact**: A serious violation of community standards, including +sustained inappropriate behavior. + +**Consequence**: A temporary ban from any sort of interaction or public +communication with the community for a specified period of time. No public or +private interaction with the people involved, including unsolicited interaction +with those enforcing the Code of Conduct, is allowed during this period. +Violating these terms may lead to a permanent ban. + +### 4. Permanent Ban + +**Community Impact**: Demonstrating a pattern of violation of community +standards, including sustained inappropriate behavior, harassment of an +individual, or aggression toward or disparagement of classes of individuals. + +**Consequence**: A permanent ban from any sort of public interaction within +the community. + +## Attribution + +This Code of Conduct is adapted from the [Contributor Covenant][homepage], +version 2.0, available at +https://www.contributor-covenant.org/version/2/0/code_of_conduct.html. + +Community Impact Guidelines were inspired by [Mozilla's code of conduct +enforcement ladder](https://github.com/mozilla/diversity). + +[homepage]: https://www.contributor-covenant.org + +For answers to common questions about this code of conduct, see the FAQ at +https://www.contributor-covenant.org/faq. Translations are available at +https://www.contributor-covenant.org/translations. diff --git a/LICENSE b/LICENSE new file mode 100644 index 000000000..f49a4e16e --- /dev/null +++ b/LICENSE @@ -0,0 +1,201 @@ + Apache License + Version 2.0, January 2004 + http://www.apache.org/licenses/ + + TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION + + 1. Definitions. + + "License" shall mean the terms and conditions for use, reproduction, + and distribution as defined by Sections 1 through 9 of this document. + + "Licensor" shall mean the copyright owner or entity authorized by + the copyright owner that is granting the License. + + "Legal Entity" shall mean the union of the acting entity and all + other entities that control, are controlled by, or are under common + control with that entity. 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We also recommend that a + file or class name and description of purpose be included on the + same "printed page" as the copyright notice for easier + identification within third-party archives. + + Copyright [yyyy] [name of copyright owner] + + Licensed under the Apache License, Version 2.0 (the "License"); + you may not use this file except in compliance with the License. + You may obtain a copy of the License at + + http://www.apache.org/licenses/LICENSE-2.0 + + Unless required by applicable law or agreed to in writing, software + distributed under the License is distributed on an "AS IS" BASIS, + WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + See the License for the specific language governing permissions and + limitations under the License. \ No newline at end of file diff --git a/README.md b/README.md index 7a5925e54..a5c7cd1fd 100644 --- a/README.md +++ b/README.md @@ -1,47 +1,38 @@ -# FastMCP +
-> **Note**: This is experimental software. The Model Context Protocol itself is only a few days old and the specification is still evolving. + -A fast, pythonic way to build Model Context Protocol (MCP) servers. + + + + FastMCP Logo + -The Model Context Protocol is an extremely powerful way to give LLMs access to tools and resources. However, building MCP servers can be difficult and cumbersome. FastMCP provides a simple, intuitive interface for creating MCP servers in Python. +# FastMCP 🚀 -## Installation - -MCP servers require you to use [uv](https://github.com/astral-sh/uv) as your dependency manager. - - -Install uv with brew: -```bash -brew install uv -``` -*(Editor's note: I was unable to get MCP servers working unless uv was installed with brew.)* +Move fast and make things. -Install FastMCP: -```bash -uv pip install fastmcp -``` +*Made with 💙 by [Prefect](https://www.prefect.io/)* +[![Docs](https://img.shields.io/badge/docs-gofastmcp.com-blue)](https://gofastmcp.com) +[![Discord](https://img.shields.io/badge/community-discord-5865F2?logo=discord&logoColor=white)](https://discord.gg/uu8dJCgttd) +[![PyPI - Version](https://img.shields.io/pypi/v/fastmcp.svg)](https://pypi.org/project/fastmcp) +[![Tests](https://github.com/PrefectHQ/fastmcp/actions/workflows/run-tests.yml/badge.svg)](https://github.com/PrefectHQ/fastmcp/actions/workflows/run-tests.yml) +[![License](https://img.shields.io/github/license/PrefectHQ/fastmcp.svg)](https://github.com/PrefectHQ/fastmcp/blob/main/LICENSE) +prefecthq%2Ffastmcp | Trendshift +
-## Quick Start +--- -Here's a simple example that exposes your desktop directory as a resource and provides a basic addition tool: +The [Model Context Protocol](https://modelcontextprotocol.io/) (MCP) connects LLMs to tools and data. FastMCP gives you everything you need to go from prototype to production: ```python -from pathlib import Path from fastmcp import FastMCP -# Create server -mcp = FastMCP("Demo") - -@mcp.resource("dir://desktop") -def desktop() -> list[str]: - """List the files in the user's desktop""" - desktop = Path.home() / "Desktop" - return [str(f) for f in desktop.iterdir()] +mcp = FastMCP("Demo 🚀") -@mcp.tool() +@mcp.tool def add(a: int, b: int) -> int: """Add two numbers""" return a + b @@ -50,80 +41,70 @@ if __name__ == "__main__": mcp.run() ``` -## Features - -### Resources - -Resources are data sources that can be accessed by the LLM. They can be files, directories, or any other data source. Resources are defined using the `@resource` decorator: - -```python -@mcp.resource("file://config.json") -def get_config() -> str: - """Read the config file""" - return Path("config.json").read_text() -``` - -### Tools +## Why FastMCP + +Building an effective MCP application is harder than it looks. FastMCP handles all of it. Declare a tool with a Python function, and the schema, validation, and documentation are generated automatically. Connect to a server with a URL, and transport negotiation, authentication, and protocol lifecycle are managed for you. You focus on your logic, and the MCP part just works: **with FastMCP, best practices are built in.** + +**That's why FastMCP is the standard framework for working with MCP.** FastMCP 1.0 was incorporated into the official MCP Python SDK in 2024. Today, the actively maintained standalone project is downloaded a million times a day, and some version of FastMCP powers 70% of MCP servers across all languages. + +FastMCP has three pillars: + + + + + + + +
+ +Servers +
Servers +
+
Expose tools, resources, and prompts to LLMs. +
+ +Apps +
Apps +
+
Give your tools interactive UIs rendered directly in the conversation. +
+ +Clients +
Clients +
+
Connect to any MCP server — local or remote, programmatic or CLI. +
+ +**[Servers](https://gofastmcp.com/servers/server)** wrap your Python functions into MCP-compliant tools, resources, and prompts. **[Clients](https://gofastmcp.com/clients/client)** connect to any server with full protocol support. And **[Apps](https://gofastmcp.com/apps/overview)** give your tools interactive UIs rendered directly in the conversation. + +Ready to build? Start with the [installation guide](https://gofastmcp.com/getting-started/installation) or jump straight to the [quickstart](https://gofastmcp.com/getting-started/quickstart). When you're ready to deploy, [Prefect Horizon](https://www.prefect.io/horizon) offers free hosting for FastMCP users. -Tools are functions that can be called by the LLM. They are defined using the `@tool` decorator: - -```python -@mcp.tool() -def calculate(x: int, y: int) -> int: - """Perform a calculation""" - return x + y -``` - -## Development - -### Running the Dev Inspector +## Installation -FastMCP includes a development server with the MCP Inspector for testing your server: +We recommend installing FastMCP with [uv](https://docs.astral.sh/uv/): ```bash -# Basic usage -fastmcp dev your_server.py - -# Install package in editable mode from current directory -fastmcp dev your_server.py --with-editable . - -# Install additional packages -fastmcp dev your_server.py --with pandas --with numpy - -# Combine both -fastmcp dev your_server.py --with-editable . --with pandas --with numpy +uv pip install fastmcp ``` -The `--with` flag automatically includes `fastmcp` and any additional packages you specify. The `--with-editable` flag installs the package from the specified directory in editable mode, which is useful during development. - -### Installing in Claude - -To use your server with Claude Desktop: +For full installation instructions, including verification and upgrading, see the [**Installation Guide**](https://gofastmcp.com/getting-started/installation). -```bash -# Basic usage -fastmcp install your_server.py --name "My Server" - -# Install package in editable mode -fastmcp install your_server.py --with-editable . +**Upgrading?** We have guides for: +- [Upgrading from FastMCP v2](https://gofastmcp.com/getting-started/upgrading/from-fastmcp-2) +- [Upgrading from the MCP Python SDK](https://gofastmcp.com/getting-started/upgrading/from-mcp-sdk) +- [Upgrading from the low-level SDK](https://gofastmcp.com/getting-started/upgrading/from-low-level-sdk) -# Install additional packages -fastmcp install your_server.py --with pandas --with numpy - -# Combine options -fastmcp install your_server.py --with-editable . --with pandas --with numpy -``` +## 📚 Documentation +FastMCP's complete documentation is available at **[gofastmcp.com](https://gofastmcp.com)**, including detailed guides, API references, and advanced patterns. -## Configuration +Documentation is also available in [llms.txt format](https://llmstxt.org/), which is a simple markdown standard that LLMs can consume easily: -FastMCP can be configured via environment variables with the prefix `FASTMCP_`: +- [`llms.txt`](https://gofastmcp.com/llms.txt) is essentially a sitemap, listing all the pages in the documentation. +- [`llms-full.txt`](https://gofastmcp.com/llms-full.txt) contains the entire documentation. Note this may exceed the context window of your LLM. -- `FASTMCP_DEBUG`: Enable debug mode -- `FASTMCP_LOG_LEVEL`: Set logging level (DEBUG, INFO, WARNING, ERROR, CRITICAL) -- `FASTMCP_HOST`: HTTP server host (default: 0.0.0.0) -- `FASTMCP_PORT`: HTTP server port (default: 8000) +**Community:** Join our [Discord server](https://discord.gg/uu8dJCgttd) to connect with other FastMCP developers and share what you're building. -## License +## Contributing -Apache 2.0 \ No newline at end of file +We welcome contributions! See the [Contributing Guide](https://gofastmcp.com/development/contributing) for setup instructions, testing requirements, and PR guidelines. diff --git a/SECURITY.md b/SECURITY.md new file mode 100644 index 000000000..8e1943ad8 --- /dev/null +++ b/SECURITY.md @@ -0,0 +1,16 @@ +# Security Policy + +## Supported Versions + +FastMCP v2.x receives security updates. Earlier versions are no longer supported. + +| Version | Supported | +| ------- | ------------------ | +| 2.x | :white_check_mark: | +| < 2.0 | :x: | + +## Reporting a Vulnerability + +Please report security vulnerabilities privately using [GitHub's security advisory feature](https://github.com/PrefectHQ/fastmcp/security/advisories/new). + +Do not open public issues for security concerns. diff --git a/SYNC_WITH_UPSTREAM.md b/SYNC_WITH_UPSTREAM.md new file mode 100644 index 000000000..660465e1b --- /dev/null +++ b/SYNC_WITH_UPSTREAM.md @@ -0,0 +1,58 @@ +# Keeping abreast of fastmcp and committing changes + +This repo (xsecuremcp2.0) tracks **upstream** [fastmcp](https://github.com/jlowin/fastmcp). Use the steps below to stay in sync and commit your work. + +## Remotes + +- **origin** – your fork: `https://github.com/PureCipher/xsecuremcp2.0.git` +- **upstream** – fastmcp: `https://github.com/jlowin/fastmcp.git` + +## 1. Sync with upstream fastmcp + +From the repo root: + +```bash +# Fetch latest from upstream and merge into current branch +uv run scripts/sync_upstream.py + +# Only fetch (no merge) +uv run scripts/sync_upstream.py --fetch-only + +# Rebase current branch on upstream/main instead of merge +uv run scripts/sync_upstream.py --rebase +``` + +If you're in the middle of a rebase, the script will tell you. Finish the rebase first: + +```bash +git rebase --continue # after resolving conflicts and staging +# or +git rebase --abort # to cancel the rebase +``` + +Then run `sync_upstream.py` again, or merge manually: + +```bash +git fetch upstream +git merge upstream/main --no-edit +``` + +## 2. Make your changes + +Work on your branch as usual. Run tests before committing: + +```bash +uv run pytest +``` + +## 3. Commit and push + +```bash +git add -A +git commit -m "Your message" +git push origin +``` + +--- + +**Current branch:** `securemcp-core` (and `main`). If you were rebasing `securemcp-core` onto upstream, finish that rebase first, then use the sync script for future updates. diff --git a/admin-ui/.next/dev/types/cache-life.d.ts b/admin-ui/.next/dev/types/cache-life.d.ts new file mode 100644 index 000000000..a8c6997e7 --- /dev/null +++ b/admin-ui/.next/dev/types/cache-life.d.ts @@ -0,0 +1,145 @@ +// Type definitions for Next.js cacheLife configs + +declare module 'next/cache' { + export { unstable_cache } from 'next/dist/server/web/spec-extension/unstable-cache' + export { + updateTag, + revalidateTag, + revalidatePath, + refresh, + } from 'next/dist/server/web/spec-extension/revalidate' + export { unstable_noStore } from 'next/dist/server/web/spec-extension/unstable-no-store' + + + /** + * Cache this `"use cache"` for a timespan defined by the `"default"` profile. + * ``` + * stale: 300 seconds (5 minutes) + * revalidate: 900 seconds (15 minutes) + * expire: never + * ``` + * + * This cache may be stale on clients for 5 minutes before checking with the server. + * If the server receives a new request after 15 minutes, start revalidating new values in the background. + * It lives for the maximum age of the server cache. If this entry has no traffic for a while, it may serve an old value the next request. + */ + export function cacheLife(profile: "default"): void + + /** + * Cache this `"use cache"` for a timespan defined by the `"seconds"` profile. + * ``` + * stale: 30 seconds + * revalidate: 1 seconds + * expire: 60 seconds (1 minute) + * ``` + * + * This cache may be stale on clients for 30 seconds before checking with the server. + * If the server receives a new request after 1 seconds, start revalidating new values in the background. + * If this entry has no traffic for 1 minute it will expire. The next request will recompute it. + */ + export function cacheLife(profile: "seconds"): void + + /** + * Cache this `"use cache"` for a timespan defined by the `"minutes"` profile. + * ``` + * stale: 300 seconds (5 minutes) + * revalidate: 60 seconds (1 minute) + * expire: 3600 seconds (1 hour) + * ``` + * + * This cache may be stale on clients for 5 minutes before checking with the server. + * If the server receives a new request after 1 minute, start revalidating new values in the background. + * If this entry has no traffic for 1 hour it will expire. The next request will recompute it. + */ + export function cacheLife(profile: "minutes"): void + + /** + * Cache this `"use cache"` for a timespan defined by the `"hours"` profile. + * ``` + * stale: 300 seconds (5 minutes) + * revalidate: 3600 seconds (1 hour) + * expire: 86400 seconds (1 day) + * ``` + * + * This cache may be stale on clients for 5 minutes before checking with the server. + * If the server receives a new request after 1 hour, start revalidating new values in the background. + * If this entry has no traffic for 1 day it will expire. The next request will recompute it. + */ + export function cacheLife(profile: "hours"): void + + /** + * Cache this `"use cache"` for a timespan defined by the `"days"` profile. + * ``` + * stale: 300 seconds (5 minutes) + * revalidate: 86400 seconds (1 day) + * expire: 604800 seconds (1 week) + * ``` + * + * This cache may be stale on clients for 5 minutes before checking with the server. + * If the server receives a new request after 1 day, start revalidating new values in the background. + * If this entry has no traffic for 1 week it will expire. The next request will recompute it. + */ + export function cacheLife(profile: "days"): void + + /** + * Cache this `"use cache"` for a timespan defined by the `"weeks"` profile. + * ``` + * stale: 300 seconds (5 minutes) + * revalidate: 604800 seconds (1 week) + * expire: 2592000 seconds (1 month) + * ``` + * + * This cache may be stale on clients for 5 minutes before checking with the server. + * If the server receives a new request after 1 week, start revalidating new values in the background. + * If this entry has no traffic for 1 month it will expire. The next request will recompute it. + */ + export function cacheLife(profile: "weeks"): void + + /** + * Cache this `"use cache"` for a timespan defined by the `"max"` profile. + * ``` + * stale: 300 seconds (5 minutes) + * revalidate: 2592000 seconds (1 month) + * expire: 31536000 seconds (365 days) + * ``` + * + * This cache may be stale on clients for 5 minutes before checking with the server. + * If the server receives a new request after 1 month, start revalidating new values in the background. + * If this entry has no traffic for 365 days it will expire. The next request will recompute it. + */ + export function cacheLife(profile: "max"): void + + /** + * Cache this `"use cache"` using a custom timespan. + * ``` + * stale: ... // seconds + * revalidate: ... // seconds + * expire: ... // seconds + * ``` + * + * This is similar to Cache-Control: max-age=`stale`,s-max-age=`revalidate`,stale-while-revalidate=`expire-revalidate` + * + * If a value is left out, the lowest of other cacheLife() calls or the default, is used instead. + */ + export function cacheLife(profile: { + /** + * This cache may be stale on clients for ... seconds before checking with the server. + */ + stale?: number, + /** + * If the server receives a new request after ... seconds, start revalidating new values in the background. + */ + revalidate?: number, + /** + * If this entry has no traffic for ... seconds it will expire. The next request will recompute it. + */ + expire?: number + }): void + + + import { cacheTag } from 'next/dist/server/use-cache/cache-tag' + export { cacheTag } + + export const unstable_cacheTag: typeof cacheTag + export const unstable_cacheLife: typeof cacheLife +} diff --git a/admin-ui/.next/dev/types/routes.d.ts b/admin-ui/.next/dev/types/routes.d.ts new file mode 100644 index 000000000..85ea48a0b --- /dev/null +++ b/admin-ui/.next/dev/types/routes.d.ts @@ -0,0 +1,65 @@ +// This file is generated automatically by Next.js +// Do not edit this file manually + +type AppRoutes = "/" | "/audit" | "/consent" | "/contracts" | "/explain" | "/ledger" | "/monitoring" | "/policies" +type PageRoutes = never +type LayoutRoutes = "/" +type RedirectRoutes = never +type RewriteRoutes = "/api/[[...path]]" +type Routes = AppRoutes | PageRoutes | LayoutRoutes | RedirectRoutes | RewriteRoutes + + +interface ParamMap { + "/": {} + "/api/[[...path]]": { "path"?: string[]; } + "/audit": {} + "/consent": {} + "/contracts": {} + "/explain": {} + "/ledger": {} + "/monitoring": {} + "/policies": {} +} + + +export type ParamsOf = ParamMap[Route] + +interface LayoutSlotMap { + "/": never +} + + +export type { AppRoutes, PageRoutes, LayoutRoutes, RedirectRoutes, RewriteRoutes, ParamMap } + +declare global { + /** + * Props for Next.js App Router page components + * @example + * ```tsx + * export default function Page(props: PageProps<'/blog/[slug]'>) { + * const { slug } = await props.params + * return
Blog post: {slug}
+ * } + * ``` + */ + interface PageProps { + params: Promise + searchParams: Promise> + } + + /** + * Props for Next.js App Router layout components + * @example + * ```tsx + * export default function Layout(props: LayoutProps<'/dashboard'>) { + * return
{props.children}
+ * } + * ``` + */ + type LayoutProps = { + params: Promise + children: React.ReactNode + } & { + [K in LayoutSlotMap[LayoutRoute]]: React.ReactNode + } +} diff --git a/admin-ui/.next/dev/types/validator.ts b/admin-ui/.next/dev/types/validator.ts new file mode 100644 index 000000000..1df173ba4 --- /dev/null +++ b/admin-ui/.next/dev/types/validator.ts @@ -0,0 +1,133 @@ +// This file is generated automatically by Next.js +// Do not edit this file manually +// This file validates that all pages and layouts export the correct types + +import type { AppRoutes, LayoutRoutes, ParamMap } from "./routes.js" +import type { ResolvingMetadata, ResolvingViewport } from "next/types.js" + +type AppPageConfig = { + default: React.ComponentType<{ params: Promise } & any> | ((props: { params: Promise } & any) => React.ReactNode | Promise | never | void | Promise) + generateStaticParams?: (props: { params: ParamMap[Route] }) => Promise | any[] + generateMetadata?: ( + props: { params: Promise } & any, + parent: ResolvingMetadata + ) => Promise | any + generateViewport?: ( + props: { params: Promise } & any, + parent: ResolvingViewport + ) => Promise | any + metadata?: any + viewport?: any +} + +type LayoutConfig = { + default: React.ComponentType> | ((props: LayoutProps) => React.ReactNode | Promise | never | void | Promise) + generateStaticParams?: (props: { params: ParamMap[Route] }) => Promise | any[] + generateMetadata?: ( + props: { params: Promise } & any, + parent: ResolvingMetadata + ) => Promise | any + generateViewport?: ( + props: { params: Promise } & any, + parent: ResolvingViewport + ) => Promise | any + metadata?: any + viewport?: any +} + + +// Validate ../../../app/(dashboard)/audit/page.tsx +{ + type __IsExpected> = Specific + const handler = {} as typeof import("../../../app/(dashboard)/audit/page.js") + type __Check = __IsExpected + // @ts-ignore + type __Unused = __Check +} + +// Validate ../../../app/(dashboard)/consent/page.tsx +{ + type __IsExpected> = Specific + const handler = {} as typeof import("../../../app/(dashboard)/consent/page.js") + type __Check = __IsExpected + // @ts-ignore + type __Unused = __Check +} + +// Validate ../../../app/(dashboard)/contracts/page.tsx +{ + type __IsExpected> = Specific + const handler = {} as typeof import("../../../app/(dashboard)/contracts/page.js") + type __Check = __IsExpected + // @ts-ignore + type __Unused = __Check +} + +// Validate ../../../app/(dashboard)/explain/page.tsx +{ + type __IsExpected> = Specific + const handler = {} as typeof import("../../../app/(dashboard)/explain/page.js") + type __Check = __IsExpected + // @ts-ignore + type __Unused = __Check +} + +// Validate ../../../app/(dashboard)/ledger/page.tsx +{ + type __IsExpected> = Specific + const handler = {} as typeof import("../../../app/(dashboard)/ledger/page.js") + type __Check = __IsExpected + // @ts-ignore + type __Unused = __Check +} + +// Validate ../../../app/(dashboard)/monitoring/page.tsx +{ + type __IsExpected> = Specific + const handler = {} as typeof import("../../../app/(dashboard)/monitoring/page.js") + type __Check = __IsExpected + // @ts-ignore + type __Unused = __Check +} + +// Validate ../../../app/(dashboard)/page.tsx +{ + type __IsExpected> = Specific + const handler = {} as typeof import("../../../app/(dashboard)/page.js") + type __Check = __IsExpected + // @ts-ignore + type __Unused = __Check +} + +// Validate ../../../app/(dashboard)/policies/page.tsx +{ + type __IsExpected> = Specific + const handler = {} as typeof import("../../../app/(dashboard)/policies/page.js") + type __Check = __IsExpected + // @ts-ignore + type __Unused = __Check +} + + + + + + + +// Validate ../../../app/(dashboard)/layout.tsx +{ + type __IsExpected> = Specific + const handler = {} as typeof import("../../../app/(dashboard)/layout.js") + type __Check = __IsExpected + // @ts-ignore + type __Unused = __Check +} + +// Validate ../../../app/layout.tsx +{ + type __IsExpected> = Specific + const handler = {} as typeof import("../../../app/layout.js") + type __Check = __IsExpected + // @ts-ignore + type __Unused = __Check +} diff --git a/admin-ui/next-env.d.ts b/admin-ui/next-env.d.ts new file mode 100644 index 000000000..c4b7818fb --- /dev/null +++ b/admin-ui/next-env.d.ts @@ -0,0 +1,6 @@ +/// +/// +import "./.next/dev/types/routes.d.ts"; + +// NOTE: This file should not be edited +// see https://nextjs.org/docs/app/api-reference/config/typescript for more information. diff --git a/docs/.ccignore b/docs/.ccignore new file mode 100644 index 000000000..ad117c3ee --- /dev/null +++ b/docs/.ccignore @@ -0,0 +1,2 @@ +changelog.mdx +python-sdk/ diff --git a/docs/.cursor/rules/mintlify.mdc b/docs/.cursor/rules/mintlify.mdc new file mode 100644 index 000000000..503fe1647 --- /dev/null +++ b/docs/.cursor/rules/mintlify.mdc @@ -0,0 +1,364 @@ +--- +description: +globs: *.mdx +alwaysApply: false +--- +# Mintlify technical writing assistant + +You are an AI writing assistant specialized in creating exceptional technical documentation using Mintlify components and following industry-leading technical writing practices. + +## Core writing principles + +### Language and style requirements +- Use clear, direct language appropriate for technical audiences +- Write in second person ("you") for instructions and procedures +- Use active voice over passive voice +- Employ present tense for current states, future tense for outcomes +- Maintain consistent terminology throughout all documentation +- Keep sentences concise while providing necessary context +- Use parallel structure in lists, headings, and procedures + +### Content organization standards +- Lead with the most important information (inverted pyramid structure) +- Use progressive disclosure: basic concepts before advanced ones +- Break complex procedures into numbered steps +- Include prerequisites and context before instructions +- Provide expected outcomes for each major step +- End sections with next steps or related information +- Use descriptive, keyword-rich headings for navigation and SEO + +### User-centered approach +- Focus on user goals and outcomes rather than system features +- Anticipate common questions and address them proactively +- Include troubleshooting for likely failure points +- Provide multiple pathways when appropriate (beginner vs advanced), but offer an opinionated path for people to follow to avoid overwhelming with options + +## Mintlify component reference + +### Callout components + +#### Note - Additional helpful information + + +Supplementary information that supports the main content without interrupting flow + + +#### Tip - Best practices and pro tips + + +Expert advice, shortcuts, or best practices that enhance user success + + +#### Warning - Important cautions + + +Critical information about potential issues, breaking changes, or destructive actions + + +#### Info - Neutral contextual information + + +Background information, context, or neutral announcements + + +#### Check - Success confirmations + + +Positive confirmations, successful completions, or achievement indicators + + +### Code components + +#### Single code block + +```javascript config.js +const apiConfig = { +baseURL: 'https://api.example.com', +timeout: 5000, +headers: { + 'Authorization': `Bearer ${process.env.API_TOKEN}` +} +}; +``` + +#### Code group with multiple languages + + +```javascript Node.js +const response = await fetch('/api/endpoint', { + headers: { Authorization: `Bearer ${apiKey}` } +}); +``` + +```python Python +import requests +response = requests.get('/api/endpoint', + headers={'Authorization': f'Bearer {api_key}'}) +``` + +```curl cURL +curl -X GET '/api/endpoint' \ + -H 'Authorization: Bearer YOUR_API_KEY' +``` + + +#### Request/Response examples + + +```bash cURL +curl -X POST 'https://api.example.com/users' \ + -H 'Content-Type: application/json' \ + -d '{"name": "John Doe", "email": "john@example.com"}' +``` + + + +```json Success +{ + "id": "user_123", + "name": "John Doe", + "email": "john@example.com", + "created_at": "2024-01-15T10:30:00Z" +} +``` + + +### Structural components + +#### Steps for procedures + + + + Run `npm install` to install required packages. + + + Verify installation by running `npm list`. + + + + + Create a `.env` file with your API credentials. + + ```bash + API_KEY=your_api_key_here + ``` + + + Never commit API keys to version control. + + + + +#### Tabs for alternative content + + + + ```bash + brew install node + npm install -g package-name + ``` + + + + ```powershell + choco install nodejs + npm install -g package-name + ``` + + + + ```bash + sudo apt install nodejs npm + npm install -g package-name + ``` + + + +#### Accordions for collapsible content + + + + - **Firewall blocking**: Ensure ports 80 and 443 are open + - **Proxy configuration**: Set HTTP_PROXY environment variable + - **DNS resolution**: Try using 8.8.8.8 as DNS server + + + + ```javascript + const config = { + performance: { cache: true, timeout: 30000 }, + security: { encryption: 'AES-256' } + }; + ``` + + + +### API documentation components + +#### Parameter fields + + +Unique identifier for the user. Must be a valid UUID v4 format. + + + +User's email address. Must be valid and unique within the system. + + + +Maximum number of results to return. Range: 1-100. + + + +Bearer token for API authentication. Format: `Bearer YOUR_API_KEY` + + +#### Response fields + + +Unique identifier assigned to the newly created user. + + + +ISO 8601 formatted timestamp of when the user was created. + + + +List of permission strings assigned to this user. + + +#### Expandable nested fields + + +Complete user object with all associated data. + + + + User profile information including personal details. + + + + User's first name as entered during registration. + + + + URL to user's profile picture. Returns null if no avatar is set. + + + + + + +### Interactive components + +#### Cards for navigation + + +Complete walkthrough from installation to your first API call in under 10 minutes. + + + + + Learn how to authenticate requests using API keys or JWT tokens. + + + + Understand rate limits and best practices for high-volume usage. + + + +### Media and advanced components + +#### Frames for images + +Wrap all images in frames. + + +Main dashboard showing analytics overview + + + +Analytics dashboard with charts + + +#### Tooltips and updates + + +API + + + +## New features +- Added bulk user import functionality +- Improved error messages with actionable suggestions + +## Bug fixes +- Fixed pagination issue with large datasets +- Resolved authentication timeout problems + + +## Required page structure + +Every documentation page must begin with YAML frontmatter: + +```yaml +--- +title: "Clear, specific, keyword-rich title" +description: "Concise description explaining page purpose and value" +--- +``` + +## Content quality standards + +### Code examples requirements +- Always include complete, runnable examples that users can copy and execute +- Show proper error handling and edge case management +- Use realistic data instead of placeholder values +- Include expected outputs and results for verification +- Test all code examples thoroughly before publishing +- Specify language and include filename when relevant +- Add explanatory comments for complex logic + +### API documentation requirements +- Document all parameters including optional ones with clear descriptions +- Show both success and error response examples with realistic data +- Include rate limiting information with specific limits +- Provide authentication examples showing proper format +- Explain all HTTP status codes and error handling +- Cover complete request/response cycles + +### Accessibility requirements +- Include descriptive alt text for all images and diagrams +- Use specific, actionable link text instead of "click here" +- Ensure proper heading hierarchy starting with H2 +- Provide keyboard navigation considerations +- Use sufficient color contrast in examples and visuals +- Structure content for easy scanning with headers and lists + +## AI assistant instructions + +### Component selection logic +- Use **Steps** for procedures, tutorials, setup guides, and sequential instructions +- Use **Tabs** for platform-specific content or alternative approaches +- Use **CodeGroup** when showing the same concept in multiple languages +- Use **Accordions** for supplementary information that might interrupt flow +- Use **Cards and CardGroup** for navigation, feature overviews, and related resources +- Use **RequestExample/ResponseExample** specifically for API endpoint documentation +- Use **ParamField** for API parameters, **ResponseField** for API responses +- Use **Expandable** for nested object properties or hierarchical information + +### Quality assurance checklist +- Verify all code examples are syntactically correct and executable +- Test all links to ensure they are functional and lead to relevant content +- Validate Mintlify component syntax with all required properties +- Confirm proper heading hierarchy with H2 for main sections, H3 for subsections +- Ensure content flows logically from basic concepts to advanced topics +- Check for consistency in terminology, formatting, and component usage + +### Error prevention strategies +- Always include realistic error handling in code examples +- Provide dedicated troubleshooting sections for complex procedures +- Explain prerequisites clearly before beginning instructions +- Include verification and testing steps with expected outcomes +- Add appropriate warnings for destructive or security-sensitive actions +- Validate all technical information through testing before publication \ No newline at end of file diff --git a/docs/apps/low-level.mdx b/docs/apps/low-level.mdx new file mode 100644 index 000000000..944e48498 --- /dev/null +++ b/docs/apps/low-level.mdx @@ -0,0 +1,303 @@ +--- +title: Custom HTML Apps +sidebarTitle: Custom HTML +description: Build apps with your own HTML, CSS, and JavaScript using the MCP Apps extension directly. +icon: code +tag: NEW +--- + +import { VersionBadge } from '/snippets/version-badge.mdx' + + + +The [MCP Apps extension](https://modelcontextprotocol.io/docs/extensions/apps) is an open protocol that lets tools return interactive UIs — an HTML page rendered in a sandboxed iframe inside the host client. [Prefab UI](/apps/prefab) builds on this protocol so you never have to think about it, but when you need full control — custom rendering, a specific JavaScript framework, maps, 3D, video — you can use the MCP Apps extension directly. + +This page covers how to write custom HTML apps and wire them up in FastMCP. You'll be working with the [`@modelcontextprotocol/ext-apps`](https://github.com/modelcontextprotocol/ext-apps) JavaScript SDK for host communication, and FastMCP's `AppConfig` for resource and CSP management. + +## How It Works + +An MCP App has two parts: + +1. A **tool** that does the work and returns data +2. A **`ui://` resource** containing the HTML that renders that data + +The tool declares which resource to use via `AppConfig`. When the host calls the tool, it also fetches the linked resource, renders it in a sandboxed iframe, and pushes the tool result into the app via `postMessage`. The app can also call tools back, enabling interactive workflows. + +```python +import json + +from fastmcp import FastMCP +from fastmcp.server.apps import AppConfig, ResourceCSP + +mcp = FastMCP("My App Server") + +# The tool does the work +@mcp.tool(app=AppConfig(resource_uri="ui://my-app/view.html")) +def generate_chart(data: list[float]) -> str: + return json.dumps({"values": data}) + +# The resource provides the UI +@mcp.resource("ui://my-app/view.html") +def chart_view() -> str: + return "..." +``` + +## AppConfig + +`AppConfig` controls how a tool or resource participates in the Apps extension. Import it from `fastmcp.server.apps`: + +```python +from fastmcp.server.apps import AppConfig +``` + +On **tools**, you'll typically set `resource_uri` to point to the UI resource: + +```python +@mcp.tool(app=AppConfig(resource_uri="ui://my-app/view.html")) +def my_tool() -> str: + return "result" +``` + +You can also pass a raw dict with camelCase keys, matching the wire format: + +```python +@mcp.tool(app={"resourceUri": "ui://my-app/view.html"}) +def my_tool() -> str: + return "result" +``` + +### Tool Visibility + +The `visibility` field controls where a tool appears: + +- `["model"]` — visible to the LLM (the default behavior) +- `["app"]` — only callable from within the app UI, hidden from the LLM +- `["model", "app"]` — both + +This is useful when you have tools that only make sense as part of the app's interactive flow, not as standalone LLM actions. + +```python +@mcp.tool( + app=AppConfig( + resource_uri="ui://my-app/view.html", + visibility=["app"], + ) +) +def refresh_data() -> str: + """Only callable from the app UI, not by the LLM.""" + return fetch_latest() +``` + +### AppConfig Fields + +| Field | Type | Description | +|-------|------|-------------| +| `resource_uri` | `str` | URI of the UI resource. Tools only. | +| `visibility` | `list[str]` | Where the tool appears: `"model"`, `"app"`, or both. Tools only. | +| `csp` | `ResourceCSP` | Content Security Policy for the iframe. | +| `permissions` | `ResourcePermissions` | Iframe sandbox permissions. | +| `domain` | `str` | Stable sandbox origin for the iframe. | +| `prefers_border` | `bool` | Whether the UI prefers a visible border. | + + +On **resources**, `resource_uri` and `visibility` must not be set — the resource *is* the UI. Use `AppConfig` on resources only for `csp`, `permissions`, and other display settings. + + +## UI Resources + +Resources using the `ui://` scheme are automatically served with the MIME type `text/html;profile=mcp-app`. You don't need to set this manually. + +```python +@mcp.resource("ui://my-app/view.html") +def my_view() -> str: + return "..." +``` + +The HTML can be anything — a full single-page app, a simple display, or a complex interactive tool. The host renders it in a sandboxed iframe and establishes a `postMessage` channel for communication. + +### Writing the App HTML + +Your HTML app communicates with the host using the [`@modelcontextprotocol/ext-apps`](https://github.com/modelcontextprotocol/ext-apps) JavaScript SDK. The simplest approach is to load it from a CDN: + +```html + +``` + +The `App` object provides: + +- **`app.ontoolresult`** — callback that receives tool results pushed by the host +- **`app.callServerTool({name, arguments})`** — call a tool on the server from within the app +- **`app.onhostcontextchanged`** — callback for host context changes (e.g., safe area insets) +- **`app.getHostContext()`** — get current host context + + +If your HTML loads external scripts, styles, or makes API calls, you need to declare those domains in the CSP configuration. See [Security](#security) below. + + +## Security + +Apps run in sandboxed iframes with a deny-by-default Content Security Policy. By default, only inline scripts and styles are allowed — no external network access. + +### Content Security Policy + +If your app needs to load external resources (CDN scripts, API calls, embedded iframes), declare the allowed domains with `ResourceCSP`: + +```python +from fastmcp.server.apps import AppConfig, ResourceCSP + +@mcp.resource( + "ui://my-app/view.html", + app=AppConfig( + csp=ResourceCSP( + resource_domains=["https://unpkg.com", "https://cdn.example.com"], + connect_domains=["https://api.example.com"], + ) + ), +) +def my_view() -> str: + return "..." +``` + +| CSP Field | Controls | +|-----------|----------| +| `connect_domains` | `fetch`, XHR, WebSocket (`connect-src`) | +| `resource_domains` | Scripts, images, styles, fonts (`script-src`, etc.) | +| `frame_domains` | Nested iframes (`frame-src`) | +| `base_uri_domains` | Document base URI (`base-uri`) | + +### Permissions + +If your app needs browser capabilities like camera or clipboard access, request them via `ResourcePermissions`: + +```python +from fastmcp.server.apps import AppConfig, ResourcePermissions + +@mcp.resource( + "ui://my-app/view.html", + app=AppConfig( + permissions=ResourcePermissions( + camera={}, + clipboard_write={}, + ) + ), +) +def my_view() -> str: + return "..." +``` + +Hosts may or may not grant these permissions. Your app should use JavaScript feature detection as a fallback. + +## Example: QR Code Server + +This example creates a tool that generates QR codes and an app that renders them as images. It's based on the [official MCP Apps example](https://github.com/modelcontextprotocol/ext-apps/tree/main/examples/qr-server). Requires the `qrcode[pil]` package. + +```python expandable +import base64 +import io + +import qrcode +from mcp import types + +from fastmcp import FastMCP +from fastmcp.server.apps import AppConfig, ResourceCSP +from fastmcp.tools import ToolResult + +mcp = FastMCP("QR Code Server") + +VIEW_URI = "ui://qr-server/view.html" + + +@mcp.tool(app=AppConfig(resource_uri=VIEW_URI)) +def generate_qr(text: str = "https://gofastmcp.com") -> ToolResult: + """Generate a QR code from text.""" + qr = qrcode.QRCode(version=1, box_size=10, border=4) + qr.add_data(text) + qr.make(fit=True) + + img = qr.make_image() + buffer = io.BytesIO() + img.save(buffer, format="PNG") + b64 = base64.b64encode(buffer.getvalue()).decode() + + return ToolResult( + content=[types.ImageContent(type="image", data=b64, mimeType="image/png")] + ) + + +@mcp.resource( + VIEW_URI, + app=AppConfig(csp=ResourceCSP(resource_domains=["https://unpkg.com"])), +) +def view() -> str: + """Interactive QR code viewer.""" + return """\ + + + + + + + +
+ + +""" +``` + +The tool generates a QR code as a base64 PNG. The resource loads the MCP Apps JS SDK from unpkg (declared in the CSP), listens for tool results, and renders the image. The host wires them together — when the LLM calls `generate_qr`, the QR code appears in an interactive frame inside the conversation. + +## Checking Client Support + +Not all hosts support the Apps extension. You can check at runtime using the tool's [context](/servers/context): + +```python +from fastmcp import Context +from fastmcp.server.apps import AppConfig, UI_EXTENSION_ID + +@mcp.tool(app=AppConfig(resource_uri="ui://my-app/view.html")) +async def my_tool(ctx: Context) -> str: + if ctx.client_supports_extension(UI_EXTENSION_ID): + # Return data optimized for UI rendering + return rich_response() + else: + # Fall back to plain text + return plain_text_response() +``` diff --git a/docs/apps/overview.mdx b/docs/apps/overview.mdx new file mode 100644 index 000000000..d8dcfc3fd --- /dev/null +++ b/docs/apps/overview.mdx @@ -0,0 +1,76 @@ +--- +title: Apps +sidebarTitle: Overview +description: Give your tools interactive UIs rendered directly in the conversation. +icon: grid-2 +tag: NEW +--- + +import { VersionBadge } from '/snippets/version-badge.mdx' + + + +MCP Apps let your tools return interactive UIs — rendered in a sandboxed iframe right inside the host client's conversation. Instead of returning plain text, a tool can show a chart, a sortable table, a form, or anything you can build with HTML. + +FastMCP implements the [MCP Apps extension](https://modelcontextprotocol.io/docs/extensions/apps) and provides two approaches: + +## Prefab Apps (Recommended) + + + + +[Prefab](https://prefab.prefect.io) is in extremely early, active development — its API changes frequently and breaking changes can occur with any release. The FastMCP integration is equally new and under rapid development. These docs are included for users who want to work on the cutting edge; production use is not recommended. Always [pin `prefab-ui` to a specific version](/apps/prefab#getting-started) in your dependencies. + + +[Prefab UI](https://prefab.prefect.io) is a declarative UI framework for Python. You describe layouts, charts, tables, forms, and interactive behaviors using a Python DSL — and the framework compiles them to a JSON protocol that a shared renderer interprets. It started as a component library inside FastMCP and grew into its own framework with [comprehensive documentation](https://prefab.prefect.io). + +```python +from prefab_ui.components import Column, Heading, BarChart, ChartSeries +from prefab_ui.app import PrefabApp +from fastmcp import FastMCP + +mcp = FastMCP("Dashboard") + +@mcp.tool(app=True) +def sales_chart(year: int) -> PrefabApp: + """Show sales data as an interactive chart.""" + data = get_sales_data(year) + + with Column(gap=4, css_class="p-6") as view: + Heading(f"{year} Sales") + BarChart( + data=data, + series=[ChartSeries(data_key="revenue", label="Revenue")], + x_axis="month", + ) + + return PrefabApp(view=view) +``` + +Install with `pip install "fastmcp[apps]"` and see [Prefab Apps](/apps/prefab) for the integration guide. + +## Custom HTML Apps + +The [MCP Apps extension](https://modelcontextprotocol.io/docs/extensions/apps) is an open protocol, and you can use it directly when you need full control. You write your own HTML/CSS/JavaScript and communicate with the host via the [`@modelcontextprotocol/ext-apps`](https://github.com/modelcontextprotocol/ext-apps) SDK. + +This is the right choice for custom rendering (maps, 3D, video), specific JavaScript frameworks, or capabilities beyond what the component library offers. + +```python +from fastmcp import FastMCP +from fastmcp.server.apps import AppConfig, ResourceCSP + +mcp = FastMCP("Custom App") + +@mcp.tool(app=AppConfig(resource_uri="ui://my-app/view.html")) +def my_tool() -> str: + return '{"values": [1, 2, 3]}' + +@mcp.resource( + "ui://my-app/view.html", + app=AppConfig(csp=ResourceCSP(resource_domains=["https://unpkg.com"])), +) +def view() -> str: + return "..." +``` + +See [Custom HTML Apps](/apps/low-level) for the full reference. diff --git a/docs/apps/patterns.mdx b/docs/apps/patterns.mdx new file mode 100644 index 000000000..ffc699f89 --- /dev/null +++ b/docs/apps/patterns.mdx @@ -0,0 +1,483 @@ +--- +title: Patterns +sidebarTitle: Patterns +description: Charts, tables, forms, and other common tool UIs. +icon: grid-2-plus +tag: SOON +--- + +import { VersionBadge } from '/snippets/version-badge.mdx' + + + + +[Prefab](https://prefab.prefect.io) is in extremely early, active development — its API changes frequently and breaking changes can occur with any release. The FastMCP integration is equally new and under rapid development. These docs are included for users who want to work on the cutting edge; production use is not recommended. Always pin `prefab-ui` to a specific version in your dependencies. + + +The most common use of Prefab is giving your tools a visual representation — a chart instead of raw numbers, a sortable table instead of a text dump, a status dashboard instead of a list of booleans. Each pattern below is a complete, copy-pasteable tool. + +## Charts + +Prefab includes [bar, line, area, pie, radar, and radial charts](https://prefab.prefect.io/docs/components/charts). They all render client-side with tooltips, legends, and responsive sizing. + +### Bar Chart + +```python +from prefab_ui.components import Column, Heading, BarChart, ChartSeries +from prefab_ui.app import PrefabApp +from fastmcp import FastMCP + +mcp = FastMCP("Charts") + + +@mcp.tool(app=True) +def quarterly_revenue(year: int) -> PrefabApp: + """Show quarterly revenue as a bar chart.""" + data = [ + {"quarter": "Q1", "revenue": 42000, "costs": 28000}, + {"quarter": "Q2", "revenue": 51000, "costs": 31000}, + {"quarter": "Q3", "revenue": 47000, "costs": 29000}, + {"quarter": "Q4", "revenue": 63000, "costs": 35000}, + ] + + with Column(gap=4, css_class="p-6") as view: + Heading(f"{year} Revenue vs Costs") + BarChart( + data=data, + series=[ + ChartSeries(data_key="revenue", label="Revenue"), + ChartSeries(data_key="costs", label="Costs"), + ], + x_axis="quarter", + show_legend=True, + ) + + return PrefabApp(view=view) +``` + +Multiple `ChartSeries` entries plot different data keys. Add `stacked=True` to stack bars, or `horizontal=True` to flip the axes. + +### Area Chart + +`LineChart` and `AreaChart` share the same API as `BarChart`, with `curve` for interpolation (`"linear"`, `"smooth"`, `"step"`) and `show_dots` for data points: + +```python +from prefab_ui.components import Column, Heading, AreaChart, ChartSeries +from prefab_ui.app import PrefabApp +from fastmcp import FastMCP + +mcp = FastMCP("Charts") + + +@mcp.tool(app=True) +def usage_trend() -> PrefabApp: + """Show API usage over time.""" + data = [ + {"date": "Feb 1", "requests": 1200}, + {"date": "Feb 2", "requests": 1350}, + {"date": "Feb 3", "requests": 980}, + {"date": "Feb 4", "requests": 1500}, + {"date": "Feb 5", "requests": 1420}, + ] + + with Column(gap=4, css_class="p-6") as view: + Heading("API Usage") + AreaChart( + data=data, + series=[ChartSeries(data_key="requests", label="Requests")], + x_axis="date", + curve="smooth", + height=250, + ) + + return PrefabApp(view=view) +``` + +### Pie and Donut Charts + +`PieChart` uses `data_key` (the numeric value) and `name_key` (the label) instead of series. Set `inner_radius` for a donut: + +```python +from prefab_ui.components import Column, Heading, PieChart +from prefab_ui.app import PrefabApp +from fastmcp import FastMCP + +mcp = FastMCP("Charts") + + +@mcp.tool(app=True) +def ticket_breakdown() -> PrefabApp: + """Show open tickets by category.""" + data = [ + {"category": "Bug", "count": 23}, + {"category": "Feature", "count": 15}, + {"category": "Docs", "count": 8}, + {"category": "Infra", "count": 12}, + ] + + with Column(gap=4, css_class="p-6") as view: + Heading("Open Tickets") + PieChart( + data=data, + data_key="count", + name_key="category", + show_legend=True, + inner_radius=60, + ) + + return PrefabApp(view=view) +``` + +## Data Tables + +[DataTable](https://prefab.prefect.io/docs/components/data-display/data-table) provides sortable columns, full-text search, and pagination — all running client-side in the browser. + +```python +from prefab_ui.components import Column, Heading, DataTable, DataTableColumn +from prefab_ui.app import PrefabApp +from fastmcp import FastMCP + +mcp = FastMCP("Directory") + + +@mcp.tool(app=True) +def employee_directory() -> PrefabApp: + """Show a searchable, sortable employee directory.""" + employees = [ + {"name": "Alice Chen", "department": "Engineering", "role": "Staff Engineer", "location": "SF"}, + {"name": "Bob Martinez", "department": "Design", "role": "Lead Designer", "location": "NYC"}, + {"name": "Carol Johnson", "department": "Engineering", "role": "Senior Engineer", "location": "London"}, + {"name": "David Kim", "department": "Product", "role": "Product Manager", "location": "SF"}, + {"name": "Eva Müller", "department": "Engineering", "role": "Engineer", "location": "Berlin"}, + ] + + with Column(gap=4, css_class="p-6") as view: + Heading("Employee Directory") + DataTable( + columns=[ + DataTableColumn(key="name", header="Name", sortable=True), + DataTableColumn(key="department", header="Department", sortable=True), + DataTableColumn(key="role", header="Role"), + DataTableColumn(key="location", header="Office", sortable=True), + ], + rows=employees, + searchable=True, + paginated=True, + page_size=15, + ) + + return PrefabApp(view=view) +``` + +## Forms + +A form collects input, but it needs somewhere to send that input. The [`CallTool`](https://prefab.prefect.io/docs/concepts/actions) action connects a form to a tool on your MCP server — so you need two tools: one that renders the form, and one that handles the submission. + +```python +from prefab_ui.components import ( + Column, Heading, Row, Muted, Badge, Input, Select, + Textarea, Button, Form, ForEach, Separator, +) +from prefab_ui.actions import ShowToast +from prefab_ui.actions.mcp import CallTool +from prefab_ui.app import PrefabApp +from fastmcp import FastMCP + +mcp = FastMCP("Contacts") + +contacts_db: list[dict] = [ + {"name": "Zaphod Beeblebrox", "email": "zaphod@galaxy.gov", "category": "Partner"}, +] + + +@mcp.tool(app=True) +def contact_form() -> PrefabApp: + """Show a contact list with a form to add new contacts.""" + with Column(gap=6, css_class="p-6") as view: + Heading("Contacts") + + with ForEach("contacts"): + with Row(gap=2, align="center"): + Muted("{{ name }}") + Muted("{{ email }}") + Badge("{{ category }}") + + Separator() + + with Form( + on_submit=CallTool( + "save_contact", + result_key="contacts", + on_success=ShowToast("Contact saved!", variant="success"), + on_error=ShowToast("{{ $error }}", variant="error"), + ) + ): + Input(name="name", label="Full Name", required=True) + Input(name="email", label="Email", input_type="email", required=True) + Select( + name="category", + label="Category", + options=["Customer", "Vendor", "Partner", "Other"], + ) + Textarea(name="notes", label="Notes", placeholder="Optional notes...") + Button("Save Contact") + + return PrefabApp(view=view, state={"contacts": list(contacts_db)}) + + +@mcp.tool +def save_contact( + name: str, + email: str, + category: str = "Other", + notes: str = "", +) -> list[dict]: + """Save a new contact and return the updated list.""" + contacts_db.append({"name": name, "email": email, "category": category, "notes": notes}) + return list(contacts_db) +``` + +When the user submits the form, the renderer calls `save_contact` on the server with all named input values as arguments. Because `result_key="contacts"` is set, the returned list replaces the `contacts` state — and the `ForEach` re-renders with the new data automatically. + +The `save_contact` tool is a regular MCP tool. The LLM can also call it directly in conversation. Your UI actions and your conversational tools are the same thing. + +### Pydantic Model Forms + +For complex forms, `Form.from_model()` generates the entire form from a Pydantic model — inputs, labels, validation, and submit wiring: + +```python +from typing import Literal + +from pydantic import BaseModel, Field +from prefab_ui.components import Column, Heading, Form +from prefab_ui.actions.mcp import CallTool +from prefab_ui.app import PrefabApp +from fastmcp import FastMCP + +mcp = FastMCP("Bug Tracker") + + +class BugReport(BaseModel): + title: str = Field(title="Bug Title") + severity: Literal["low", "medium", "high", "critical"] = Field( + title="Severity", default="medium" + ) + description: str = Field(title="Description") + steps_to_reproduce: str = Field(title="Steps to Reproduce") + + +@mcp.tool(app=True) +def report_bug() -> PrefabApp: + """Show a bug report form.""" + with Column(gap=4, css_class="p-6") as view: + Heading("Report a Bug") + Form.from_model(BugReport, on_submit=CallTool("create_bug_report")) + + return PrefabApp(view=view) + + +@mcp.tool +def create_bug_report(data: dict) -> str: + """Create a bug report from the form submission.""" + report = BugReport(**data) + # save to database... + return f"Created bug report: {report.title}" +``` + +`str` fields become text inputs, `Literal` becomes a select, `bool` becomes a checkbox. The `on_submit` CallTool receives all field values under a `data` key. + +## Status Displays + +Cards, badges, progress bars, and grids combine naturally for dashboards. See the [Prefab layout](https://prefab.prefect.io/docs/concepts/composition) and [container](https://prefab.prefect.io/docs/components/containers) docs for the full set of layout and display components. + +```python +from prefab_ui.components import ( + Column, Row, Grid, Heading, Text, Muted, Badge, + Card, CardContent, Progress, Separator, +) +from prefab_ui.app import PrefabApp +from fastmcp import FastMCP + +mcp = FastMCP("Monitoring") + + +@mcp.tool(app=True) +def system_status() -> PrefabApp: + """Show current system health.""" + services = [ + {"name": "API Gateway", "status": "healthy", "ok": True, "latency_ms": 12, "uptime_pct": 99.9}, + {"name": "Database", "status": "healthy", "ok": True, "latency_ms": 3, "uptime_pct": 99.99}, + {"name": "Cache", "status": "degraded", "ok": False, "latency_ms": 45, "uptime_pct": 98.2}, + {"name": "Queue", "status": "healthy", "ok": True, "latency_ms": 8, "uptime_pct": 99.8}, + ] + all_ok = all(s["ok"] for s in services) + + with Column(gap=4, css_class="p-6") as view: + with Row(gap=2, align="center"): + Heading("System Status") + Badge( + "All Healthy" if all_ok else "Degraded", + variant="success" if all_ok else "destructive", + ) + + Separator() + + with Grid(columns=2, gap=4): + for svc in services: + with Card(): + with CardContent(): + with Row(gap=2, align="center"): + Text(svc["name"], css_class="font-medium") + Badge( + svc["status"], + variant="success" if svc["ok"] else "destructive", + ) + Muted(f"Response: {svc['latency_ms']}ms") + Progress(value=svc["uptime_pct"]) + + return PrefabApp(view=view) +``` + +## Conditional Content + +[`If`, `Elif`, and `Else`](https://prefab.prefect.io/docs/concepts/composition#conditional-rendering) show or hide content based on state. Changes are instant — no server round-trip. + +```python +from prefab_ui.components import Column, Heading, Switch, Separator, Alert, If +from prefab_ui.app import PrefabApp +from fastmcp import FastMCP + +mcp = FastMCP("Flags") + + +@mcp.tool(app=True) +def feature_flags() -> PrefabApp: + """Toggle feature flags with live preview.""" + with Column(gap=4, css_class="p-6") as view: + Heading("Feature Flags") + + Switch(name="dark_mode", label="Dark Mode") + Switch(name="beta_features", label="Beta Features") + + Separator() + + with If("{{ dark_mode }}"): + Alert(title="Dark mode enabled", description="UI will use dark theme.") + with If("{{ beta_features }}"): + Alert( + title="Beta features active", + description="Experimental features are now visible.", + variant="warning", + ) + + return PrefabApp(view=view, state={"dark_mode": False, "beta_features": False}) +``` + +## Tabs + +[Tabs](https://prefab.prefect.io/docs/components/containers/tabs) organize content into switchable views. Switching is client-side — no server round-trip. + +```python +from prefab_ui.components import ( + Column, Heading, Text, Muted, Badge, Row, + DataTable, DataTableColumn, Tabs, Tab, ForEach, +) +from prefab_ui.app import PrefabApp +from fastmcp import FastMCP + +mcp = FastMCP("Projects") + + +@mcp.tool(app=True) +def project_overview(project_id: str) -> PrefabApp: + """Show project details organized in tabs.""" + project = { + "name": "FastMCP v3", + "description": "Next generation MCP framework with Apps support.", + "status": "Active", + "created_at": "2025-01-15", + "members": [ + {"name": "Alice Chen", "role": "Lead"}, + {"name": "Bob Martinez", "role": "Design"}, + ], + "activity": [ + {"timestamp": "2 hours ago", "message": "Merged PR #342"}, + {"timestamp": "1 day ago", "message": "Released v3.0.1"}, + ], + } + + with Column(gap=4, css_class="p-6") as view: + Heading(project["name"]) + + with Tabs(): + with Tab("Overview"): + Text(project["description"]) + with Row(gap=4): + Badge(project["status"]) + Muted(f"Created: {project['created_at']}") + + with Tab("Members"): + DataTable( + columns=[ + DataTableColumn(key="name", header="Name", sortable=True), + DataTableColumn(key="role", header="Role"), + ], + rows=project["members"], + ) + + with Tab("Activity"): + with ForEach("activity"): + with Row(gap=2): + Muted("{{ timestamp }}") + Text("{{ message }}") + + return PrefabApp(view=view, state={"activity": project["activity"]}) +``` + +## Accordion + +[Accordion](https://prefab.prefect.io/docs/components/containers/accordion) collapses sections to save space. `multiple=True` lets users expand several items at once: + +```python +from prefab_ui.components import ( + Column, Heading, Row, Text, Badge, Progress, + Accordion, AccordionItem, +) +from prefab_ui.app import PrefabApp +from fastmcp import FastMCP + +mcp = FastMCP("API Monitor") + + +@mcp.tool(app=True) +def api_health() -> PrefabApp: + """Show health details for each API endpoint.""" + endpoints = [ + {"path": "/api/users", "status": 200, "healthy": True, "avg_ms": 45, "p99_ms": 120, "uptime_pct": 99.9}, + {"path": "/api/orders", "status": 200, "healthy": True, "avg_ms": 82, "p99_ms": 250, "uptime_pct": 99.7}, + {"path": "/api/search", "status": 200, "healthy": True, "avg_ms": 150, "p99_ms": 500, "uptime_pct": 99.5}, + {"path": "/api/webhooks", "status": 503, "healthy": False, "avg_ms": 2000, "p99_ms": 5000, "uptime_pct": 95.1}, + ] + + with Column(gap=4, css_class="p-6") as view: + Heading("API Health") + + with Accordion(multiple=True): + for ep in endpoints: + with AccordionItem(ep["path"]): + with Row(gap=4): + Badge( + f"{ep['status']}", + variant="success" if ep["healthy"] else "destructive", + ) + Text(f"Avg: {ep['avg_ms']}ms") + Text(f"P99: {ep['p99_ms']}ms") + Progress(value=ep["uptime_pct"]) + + return PrefabApp(view=view) +``` + +## Next Steps + +- **[Custom HTML Apps](/apps/low-level)** — When you need your own HTML, CSS, and JavaScript +- **[Prefab UI Docs](https://prefab.prefect.io)** — Components, state, expressions, and actions diff --git a/docs/apps/prefab.mdx b/docs/apps/prefab.mdx new file mode 100644 index 000000000..907670d4b --- /dev/null +++ b/docs/apps/prefab.mdx @@ -0,0 +1,195 @@ +--- +title: Prefab Apps +sidebarTitle: Prefab Apps +description: Build interactive tool UIs in pure Python — no HTML or JavaScript required. +icon: palette +tag: SOON +--- + +import { VersionBadge } from '/snippets/version-badge.mdx' + + + + +[Prefab](https://prefab.prefect.io) is in extremely early, active development — its API changes frequently and breaking changes can occur with any release. The FastMCP integration is equally new and under rapid development. These docs are included for users who want to work on the cutting edge; production use is not recommended. Always pin `prefab-ui` to a specific version in your dependencies (see below). + + +[Prefab UI](https://prefab.prefect.io) is a declarative UI framework for Python. You describe what your interface should look like — a chart, a table, a form — and return it from your tool. FastMCP takes care of everything else: registering the renderer, wiring the protocol metadata, and delivering the component tree to the host. + +Prefab started as a component library inside FastMCP and grew into a full framework for building interactive applications — with its own state management, reactive expression system, and action model. The [Prefab documentation](https://prefab.prefect.io) covers all of this in depth. This page focuses on the FastMCP integration: what you return from a tool, and what FastMCP does with it. + +```bash +pip install "fastmcp[apps]" +``` + + +Prefab UI is in active early development and its API changes frequently. We strongly recommend pinning `prefab-ui` to a specific version in your project's dependencies. Installing `fastmcp[apps]` pulls in `prefab-ui` but won't pin it — so a routine `pip install --upgrade` could introduce breaking changes. + +```toml +# pyproject.toml +dependencies = [ + "fastmcp[apps]", + "prefab-ui==0.8.0", # pin to a known working version +] +``` + + +Here's the simplest possible Prefab App — a tool that returns a bar chart: + +```python +from prefab_ui.components import Column, Heading, BarChart, ChartSeries +from prefab_ui.app import PrefabApp +from fastmcp import FastMCP + +mcp = FastMCP("Dashboard") + + +@mcp.tool(app=True) +def revenue_chart(year: int) -> PrefabApp: + """Show annual revenue as an interactive bar chart.""" + data = [ + {"quarter": "Q1", "revenue": 42000}, + {"quarter": "Q2", "revenue": 51000}, + {"quarter": "Q3", "revenue": 47000}, + {"quarter": "Q4", "revenue": 63000}, + ] + + with Column(gap=4, css_class="p-6") as view: + Heading(f"{year} Revenue") + BarChart( + data=data, + series=[ChartSeries(data_key="revenue", label="Revenue")], + x_axis="quarter", + ) + + return PrefabApp(view=view) +``` + +That's it — you declare a layout using Python's `with` statement, and return it. When the host calls this tool, the user sees an interactive bar chart instead of a JSON blob. The [Patterns](/apps/patterns) page has more examples: area charts, data tables, forms, status dashboards, and more. + +## What You Return + +### Components + +The simplest way to get started. If you're returning a visual representation of data and don't need Prefab's more advanced features like initial state or stylesheets, just return the components directly. FastMCP wraps them in a `PrefabApp` automatically: + +```python +from prefab_ui.components import Column, Heading, Badge +from fastmcp import FastMCP + +mcp = FastMCP("Status") + + +@mcp.tool(app=True) +def status_badge() -> Column: + """Show system status.""" + with Column(gap=2) as view: + Heading("All Systems Operational") + Badge("Healthy", variant="success") + return view +``` + +Want a chart? Return a chart. Want a table? Return a table. FastMCP handles the wiring. + +### PrefabApp + +When you need more control — setting initial state values that components can read and react to, or configuring the rendering engine — return a `PrefabApp` explicitly: + +```python +from prefab_ui.components import Column, Heading, Text, Button, If, Badge +from prefab_ui.actions import ToggleState +from prefab_ui.app import PrefabApp +from fastmcp import FastMCP + +mcp = FastMCP("Demo") + + +@mcp.tool(app=True) +def toggle_demo() -> PrefabApp: + """Interactive toggle with state.""" + with Column(gap=4, css_class="p-6") as view: + Button("Toggle", on_click=ToggleState("show")) + with If("{{ show }}"): + Badge("Visible!", variant="success") + + return PrefabApp(view=view, state={"show": False}) +``` + +The `state` dict provides the initial values. Components reference state with `{{ expression }}` templates. State mutations like `ToggleState` happen entirely in the browser — no server round-trip. The [Prefab state guide](https://prefab.prefect.io/docs/concepts/state) covers this in detail. + +### ToolResult + +Every tool result has two audiences: the renderer (which displays the UI) and the LLM (which reads the text content to understand what happened). By default, Prefab Apps send `"[Rendered Prefab UI]"` as the text content, which tells the LLM almost nothing. + +If you want the LLM to understand the result — so it can reference the data in conversation, summarize it, or decide what to do next — wrap your return in a `ToolResult` with a meaningful `content` string: + +```python +from prefab_ui.components import Column, Heading, BarChart, ChartSeries +from prefab_ui.app import PrefabApp +from fastmcp import FastMCP +from fastmcp.tools import ToolResult + +mcp = FastMCP("Sales") + + +@mcp.tool(app=True) +def sales_overview(year: int) -> ToolResult: + """Show sales data visually and summarize for the model.""" + data = get_sales_data(year) + total = sum(row["revenue"] for row in data) + + with Column(gap=4, css_class="p-6") as view: + Heading("Sales Overview") + BarChart(data=data, series=[ChartSeries(data_key="revenue")]) + + return ToolResult( + content=f"Total revenue for {year}: ${total:,} across {len(data)} quarters", + structured_content=view, + ) +``` + +The user sees the chart. The LLM sees `"Total revenue for 2025: $203,000 across 4 quarters"` and can reason about it. + +## Type Inference + +If your tool's return type annotation is a Prefab type — `PrefabApp`, `Component`, or their `Optional` variants — FastMCP detects this and enables app rendering automatically: + +```python +@mcp.tool +def greet(name: str) -> PrefabApp: + return PrefabApp(view=Heading(f"Hello, {name}!")) +``` + +This is equivalent to `@mcp.tool(app=True)`. Explicit `app=True` is recommended for clarity, and is required when the return type doesn't reveal a Prefab type (e.g., `-> ToolResult`). + +## How It Works + +Behind the scenes, when a tool returns a Prefab component or `PrefabApp`, FastMCP: + +1. **Registers a shared renderer** — a `ui://prefab/renderer.html` resource containing the JavaScript rendering engine, fetched once by the host and reused across all your Prefab tools. +2. **Wires the tool metadata** — so the host knows to load the renderer iframe when displaying the tool result. +3. **Serializes the component tree** — your Python components become `structuredContent` on the tool result, which the renderer interprets and displays. + +None of this requires any configuration. The `app=True` flag (or type inference) is the only thing you need. + +## Mixing with Custom HTML Apps + +Prefab tools and [custom HTML tools](/apps/low-level) coexist in the same server. 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"string" + }, + { + "type": "null" + } + ], + "default": null, + "description": "Host to bind to when using HTTP transport", + "examples": [ + "127.0.0.1", + "0.0.0.0", + "localhost" + ], + "title": "Host" + }, + "port": { + "anyOf": [ + { + "type": "integer" + }, + { + "type": "null" + } + ], + "default": null, + "description": "Port to bind to when using HTTP transport", + "examples": [ + 8000, + 3000, + 5000 + ], + "title": "Port" + }, + "path": { + "anyOf": [ + { + "type": "string" + }, + { + "type": "null" + } + ], + "default": null, + "description": "URL path for the server endpoint", + "examples": [ + "/mcp/", + "/api/mcp/", + "/sse/" + ], + "title": "Path" + }, + "log_level": { + "anyOf": [ + { + "enum": [ + "DEBUG", + "INFO", + "WARNING", + "ERROR", + "CRITICAL" + ], + "type": "string" + }, + { + "type": "null" + } + ], + "default": null, + "description": "Log level for the server", + "title": "Log Level" + }, + "cwd": { + "anyOf": [ + { + "type": "string" + }, + { + "type": "null" + } + ], + "default": null, + "description": "Working directory for the server process", + "examples": [ + ".", + "./src", + "/app" + ], + "title": "Cwd" + }, + "env": { + "anyOf": [ + { + "additionalProperties": { + "type": "string" + }, + "type": "object" + }, + { + "type": "null" + } + ], + "default": null, + "description": "Environment variables to set when running the server", + "examples": [ + { + "API_KEY": "secret", + "DEBUG": "true" + } + ], + "title": "Env" + }, + "args": { + "anyOf": [ + { + "items": { + "type": "string" + }, + "type": "array" + }, + { + "type": "null" + } + ], + "default": null, + "description": "Arguments to pass to the server (after --)", + "examples": [ + [ + "--config", + "config.json", + "--debug" + ] + ], + "title": "Args" + } + }, + "title": "Deployment", + "type": "object" + }, + "Environment": { + "description": "Configuration for Python environment setup.", + "properties": { + "python": { + "anyOf": [ + { + "type": "string" + }, + { + "type": "null" + } + ], + "default": null, + "description": "Python version constraint", + "examples": [ + "3.10", + "3.11", + "3.12" + ], + "title": "Python" + }, + "dependencies": { + "anyOf": [ + { + "items": { + "type": "string" + }, + "type": "array" + }, + { + "type": "null" + } + ], + "default": null, + "description": "Python packages to install with PEP 508 specifiers", + "examples": [ + [ + "fastmcp>=2.0,<3", + "httpx", + "pandas>=2.0" + ] + ], + "title": "Dependencies" + }, + "requirements": { + "anyOf": [ + { + "type": "string" + }, + { + "type": "null" + } + ], + "default": null, + "description": "Path to requirements.txt file", + "examples": [ + "requirements.txt", + "../requirements/prod.txt" + ], + "title": "Requirements" + }, + "project": { + "anyOf": [ + { + "type": "string" + }, + { + "type": "null" + } + ], + "default": null, + "description": "Path to project directory containing pyproject.toml", + "examples": [ + ".", + "../my-project" + ], + "title": "Project" + }, + "editable": { + "anyOf": [ + { + "type": "string" + }, + { + "type": "null" + } + ], + "default": null, + "description": "Directory to install in editable mode", + "examples": [ + ".", + "../my-package" + ], + "title": "Editable" + } + }, + "title": "Environment", + "type": "object" + }, + "FileSystemSource": { + "description": "Source for local Python files.", + "properties": { + "type": { + "const": "filesystem", + "default": "filesystem", + "description": "Source type", + "title": "Type", + "type": "string" + }, + "path": { + "description": "Path to Python file containing the server", + "title": "Path", + "type": "string" + }, + "entrypoint": { + "anyOf": [ + { + "type": "string" + }, + { + "type": "null" + } + ], + "default": null, + "description": "Name of server instance or factory function (a no-arg function that returns a FastMCP server)", + "title": "Entrypoint" + } + }, + "required": [ + "path" + ], + "title": "FileSystemSource", + "type": "object" + } + }, + "description": "Configuration file for FastMCP servers", + "properties": { + "$schema": { + "anyOf": [ + { + "type": "string" + }, + { + "type": "null" + } + ], + "default": "https://gofastmcp.com/public/schemas/fastmcp.json/v1.json", + "description": "JSON schema for IDE support and validation", + "title": "$Schema" + }, + "source": { + "$ref": "#/$defs/FileSystemSource", + "description": "Source configuration for the server", + "examples": [ + { + "path": "server.py" + }, + { + "entrypoint": "app", + "path": "server.py" + }, + { + "entrypoint": "mcp", + "path": "src/server.py", + "type": "filesystem" + } + ] + }, + "environment": { + "$ref": "#/$defs/Environment", + "description": "Python environment setup configuration" + }, + "deployment": { + "$ref": "#/$defs/Deployment", + "description": "Server deployment and runtime settings" + } + }, + "required": [ + "source" + ], + "title": "FastMCP Configuration", + "type": "object", + "$id": "https://gofastmcp.com/public/schemas/fastmcp.json/v1.json" +} diff --git a/docs/assets/schemas/mcp_server_config/v1.json b/docs/assets/schemas/mcp_server_config/v1.json new file mode 100644 index 000000000..81d0ad754 --- /dev/null +++ b/docs/assets/schemas/mcp_server_config/v1.json @@ -0,0 +1,348 @@ +{ + "$defs": { + "Deployment": { + "description": "Configuration for server deployment and runtime settings.", + "properties": { + "transport": { + "anyOf": [ + { + "enum": [ + "stdio", + "http", + "sse" + ], + "type": "string" + }, + { + "type": "null" + } + ], + "default": null, + "description": "Transport protocol to use", + "title": "Transport" + }, + "host": { + "anyOf": [ + { + "type": "string" + }, + { + "type": "null" + } + ], + "default": null, + "description": "Host to bind to when using HTTP transport", + "examples": [ + "127.0.0.1", + "0.0.0.0", + "localhost" + ], + "title": "Host" + }, + "port": { + "anyOf": [ + { + "type": "integer" + }, + { + "type": "null" + } + ], + "default": null, + "description": "Port to bind to when using HTTP transport", + "examples": [ + 8000, + 3000, + 5000 + ], + "title": "Port" + }, + "path": { + "anyOf": [ + { + "type": "string" + }, + { + "type": "null" + } + ], + "default": null, + "description": "URL path for the server endpoint", + "examples": [ + "/mcp/", + "/api/mcp/", + "/sse/" + ], + "title": "Path" + }, + "log_level": { + "anyOf": [ + { + "enum": [ + "DEBUG", + "INFO", + "WARNING", + "ERROR", + "CRITICAL" + ], + "type": "string" + }, + { + "type": "null" + } + ], + "default": null, + "description": "Log level for the server", + "title": "Log Level" + }, + "cwd": { + "anyOf": [ + { + "type": "string" + }, + { + "type": "null" + } + ], + "default": null, + "description": "Working directory for the server process", + "examples": [ + ".", + "./src", + "/app" + ], + "title": "Cwd" + }, + "env": { + "anyOf": [ + { + "additionalProperties": { + "type": "string" + }, + "type": "object" + }, + { + "type": "null" + } + ], + "default": null, + "description": "Environment variables to set when running the server", + "examples": [ + { + "API_KEY": "secret", + "DEBUG": "true" + } + ], + "title": "Env" + }, + "args": { + "anyOf": [ + { + "items": { + "type": "string" + }, + "type": "array" + }, + { + "type": "null" + } + ], + "default": null, + "description": "Arguments to pass to the server (after --)", + "examples": [ + [ + "--config", + "config.json", + "--debug" + ] + ], + "title": "Args" + } + }, + "title": "Deployment", + "type": "object" + }, + "Environment": { + "description": "Configuration for Python environment setup.", + "properties": { + "python": { + "anyOf": [ + { + "type": "string" + }, + { + "type": "null" + } + ], + "default": null, + "description": "Python version constraint", + "examples": [ + "3.10", + "3.11", + "3.12" + ], + "title": "Python" + }, + "dependencies": { + "anyOf": [ + { + "items": { + "type": "string" + }, + "type": "array" + }, + { + "type": "null" + } + ], + "default": null, + "description": "Python packages to install with PEP 508 specifiers", + "examples": [ + [ + "fastmcp>=2.0,<3", + "httpx", + "pandas>=2.0" + ] + ], + "title": "Dependencies" + }, + "requirements": { + "anyOf": [ + { + "type": "string" + }, + { + "type": "null" + } + ], + "default": null, + "description": "Path to requirements.txt file", + "examples": [ + "requirements.txt", + "../requirements/prod.txt" + ], + "title": "Requirements" + }, + "project": { + "anyOf": [ + { + "type": "string" + }, + { + "type": "null" + } + ], + "default": null, + "description": "Path to project directory containing pyproject.toml", + "examples": [ + ".", + "../my-project" + ], + "title": "Project" + }, + "editable": { + "anyOf": [ + { + "type": "string" + }, + { + "type": "null" + } + ], + "default": null, + "description": "Directory to install in editable mode", + "examples": [ + ".", + "../my-package" + ], + "title": "Editable" + } + }, + "title": "Environment", + "type": "object" + }, + "FileSystemSource": { + "description": "Source for local Python files.", + "properties": { + "type": { + "const": "filesystem", + "default": "filesystem", + "description": "Source type", + "title": "Type", + "type": "string" + }, + "path": { + "description": "Path to Python file containing the server", + "title": "Path", + "type": "string" + }, + "entrypoint": { + "anyOf": [ + { + "type": "string" + }, + { + "type": "null" + } + ], + "default": null, + "description": "Name of server instance or factory function (a no-arg function that returns a FastMCP server)", + "title": "Entrypoint" + } + }, + "required": [ + "path" + ], + "title": "FileSystemSource", + "type": "object" + } + }, + "description": "Configuration file for FastMCP servers", + "properties": { + "$schema": { + "anyOf": [ + { + "type": "string" + }, + { + "type": "null" + } + ], + "default": "https://gofastmcp.com/public/schemas/fastmcp.json/v1.json", + "description": "JSON schema for IDE support and validation", + "title": "$Schema" + }, + "source": { + "$ref": "#/$defs/FileSystemSource", + "description": "Source configuration for the server", + "examples": [ + { + "path": "server.py" + }, + { + "entrypoint": "app", + "path": "server.py" + }, + { + "entrypoint": "mcp", + "path": "src/server.py", + "type": "filesystem" + } + ] + }, + "environment": { + "$ref": "#/$defs/Environment", + "description": "Python environment setup configuration" + }, + "deployment": { + "$ref": "#/$defs/Deployment", + "description": "Server deployment and runtime settings" + } + }, + "required": [ + "source" + ], + "title": "FastMCP Configuration", + "type": "object", + "$id": "https://gofastmcp.com/public/schemas/fastmcp.json/v1.json" +} diff --git a/docs/assets/updates/release-2-7.png b/docs/assets/updates/release-2-7.png new file mode 100644 index 000000000..5716e1f73 Binary files /dev/null and b/docs/assets/updates/release-2-7.png differ diff --git a/docs/changelog.mdx b/docs/changelog.mdx new file mode 100644 index 000000000..ae9e94fe9 --- /dev/null +++ b/docs/changelog.mdx @@ -0,0 +1,2971 @@ +--- +title: "Changelog" +icon: "list-check" +rss: true +tag: NEW +--- + + + +**[v3.0.2: Threecovery Mode II](https://github.com/PrefectHQ/fastmcp/releases/tag/v3.0.2)** + +Two community-contributed fixes: auth headers from MCP transport no longer leak through to downstream OpenAPI APIs, and background task workers now correctly receive the originating request ID. Plus a new docs example for context-aware tool factories. + +### Fixes 🐞 +* fix: prevent MCP transport auth header from leaking to downstream OpenAPI APIs by [@stakeswky](https://github.com/stakeswky) in [#3262](https://github.com/PrefectHQ/fastmcp/pull/3262) +* fix: propagate origin_request_id to background task workers by [@gfortaine](https://github.com/gfortaine) in [#3175](https://github.com/PrefectHQ/fastmcp/pull/3175) +### Docs 📚 +* Add v3.0.1 release notes by [@jlowin](https://github.com/jlowin) in [#3259](https://github.com/PrefectHQ/fastmcp/pull/3259) +* docs: add context-aware tool factory example by [@machov](https://github.com/machov) in [#3264](https://github.com/PrefectHQ/fastmcp/pull/3264) + +**Full Changelog**: [v3.0.1...v3.0.2](https://github.com/PrefectHQ/fastmcp/compare/v3.0.1...v3.0.2) + + + + + +**[v3.0.1: Three-covery Mode](https://github.com/PrefectHQ/fastmcp/releases/tag/v3.0.1)** + +First patch after 3.0 — mostly smoothing out rough edges discovered in the wild. The big ones: middleware state that wasn't surviving the trip to tool handlers now does, `Tool.from_tool()` accepts callables again, OpenAPI schemas with circular references no longer crash discovery, and decorator overloads now return the correct types in function mode. Also adds `verify_id_token` to OIDCProxy for providers (like some Azure AD configs) that issue opaque access tokens but standard JWT id_tokens. + +### Enhancements 🔧 +* Add verify_id_token option to OIDCProxy by [@jlowin](https://github.com/jlowin) in [#3248](https://github.com/PrefectHQ/fastmcp/pull/3248) +### Fixes 🐞 +* Fix v3.0.0 changelog compare link by [@jlowin](https://github.com/jlowin) in [#3223](https://github.com/PrefectHQ/fastmcp/pull/3223) +* Fix MDX parse error in upgrade guide prompts by [@jlowin](https://github.com/jlowin) in [#3227](https://github.com/PrefectHQ/fastmcp/pull/3227) +* Fix non-serializable state lost between middleware and tools by [@jlowin](https://github.com/jlowin) in [#3234](https://github.com/PrefectHQ/fastmcp/pull/3234) +* Accept callables in Tool.from_tool() by [@jlowin](https://github.com/jlowin) in [#3235](https://github.com/PrefectHQ/fastmcp/pull/3235) +* Preserve skill metadata through provider wrapping by [@jlowin](https://github.com/jlowin) in [#3237](https://github.com/PrefectHQ/fastmcp/pull/3237) +* Fix circular reference crash in OpenAPI schemas by [@jlowin](https://github.com/jlowin) in [#3245](https://github.com/PrefectHQ/fastmcp/pull/3245) +* Fix NameError with future annotations and Context/Depends parameters by [@jlowin](https://github.com/jlowin) in [#3243](https://github.com/PrefectHQ/fastmcp/pull/3243) +* Fix ty ignore syntax in OpenAPI provider by [@jlowin](https://github.com/jlowin) in [#3253](https://github.com/PrefectHQ/fastmcp/pull/3253) +* Use max_completion_tokens instead of deprecated max_tokens in OpenAI handler by [@jlowin](https://github.com/jlowin) in [#3254](https://github.com/PrefectHQ/fastmcp/pull/3254) +* Fix ty compatibility with upgraded deps by [@jlowin](https://github.com/jlowin) in [#3257](https://github.com/PrefectHQ/fastmcp/pull/3257) +* Fix decorator overload return types for function mode by [@jlowin](https://github.com/jlowin) in [#3258](https://github.com/PrefectHQ/fastmcp/pull/3258) + + +### Docs 📚 +* Sync README with welcome.mdx, fix install count by [@jlowin](https://github.com/jlowin) in [#3224](https://github.com/PrefectHQ/fastmcp/pull/3224) +* Document dict-to-Message prompt migration in upgrade guides by [@jlowin](https://github.com/jlowin) in [#3225](https://github.com/PrefectHQ/fastmcp/pull/3225) +* Fix v2 upgrade guide: remove incorrect v1 import advice by [@jlowin](https://github.com/jlowin) in [#3226](https://github.com/PrefectHQ/fastmcp/pull/3226) +* Animated banner by [@jlowin](https://github.com/jlowin) in [#3231](https://github.com/PrefectHQ/fastmcp/pull/3231) +* Document mounted server state store isolation in upgrade guide by [@jlowin](https://github.com/jlowin) in [#3236](https://github.com/PrefectHQ/fastmcp/pull/3236) + +**Full Changelog**: [v3.0.0...v3.0.1](https://github.com/PrefectHQ/fastmcp/compare/v3.0.0...v3.0.1) + + + + + +**[v3.0.0: Three at Last](https://github.com/PrefectHQ/fastmcp/releases/tag/v3.0.0)** + +FastMCP 3.0 is stable. Two betas, two release candidates, 21 new contributors, and more than 100,000 pre-release installs later — the architecture held up, the upgrade path was smooth, and we're shipping it. + +The surface API is largely unchanged — `@mcp.tool()` still works exactly as before. What changed is everything underneath: a provider/transform architecture that makes FastMCP extensible, observable, and composable in ways v2 couldn't support. If we did our jobs right, you'll barely notice the redesign. You'll just notice that more is possible. + +This is also the release where FastMCP moves from [jlowin/fastmcp](https://github.com/jlowin/fastmcp) to [PrefectHQ/fastmcp](https://github.com/PrefectHQ/fastmcp). GitHub forwards all links, PyPI is the same, imports are the same. A major version felt like the right moment to make it official. + +### Build servers from anything + +🔌 Components no longer have to live in one file with one server. `FileSystemProvider` discovers tools from directories with hot-reload. `OpenAPIProvider` wraps REST APIs. `ProxyProvider` proxies remote MCP servers. `SkillsProvider` delivers agent skills as resources. Write your own provider for whatever source makes sense. Compose multiple providers into one server, share one across many, or chain them with **transforms** that rename, namespace, filter, version, and secure components as they flow to clients. `ResourcesAsTools` and `PromptsAsTools` expose non-tool components to tool-only clients. + +### Ship to production + +🔐 Component versioning: serve `@tool(version="2.0")` alongside older versions from one codebase. Granular authorization on individual components with async auth checks, server-wide policies via `AuthMiddleware`, and scope-based access control. OAuth gets CIMD, Static Client Registration, Azure OBO via dependency injection, JWT audience validation, and confused-deputy protections. OpenTelemetry tracing with MCP semantic conventions. Response size limiting. Background tasks with distributed Redis notification and `ctx.elicit()` relay. Security fixes include dropping `diskcache` (CVE-2025-69872) and upgrading `python-multipart` and `protobuf` for additional CVEs. + +### Adapt per session + +💾 Session state persists across requests via `ctx.set_state()` / `ctx.get_state()`. `ctx.enable_components()` and `ctx.disable_components()` let servers adapt dynamically per client — show admin tools after authentication, progressively reveal capabilities, or scope access by role. + +### Develop faster + +⚡ `--reload` auto-restarts on file changes. Standalone decorators return the original function, so decorated tools stay callable in tests and non-MCP contexts. Sync functions auto-dispatch to a threadpool. Tool timeouts, MCP-compliant pagination, composable lifespans, `PingMiddleware` for keepalive, and concurrent tool execution when the LLM returns multiple calls in one response. + +### Use FastMCP as a CLI + +🖥️ `fastmcp list` and `fastmcp call` query and invoke tools on any server from a terminal. `fastmcp discover` scans your editor configs (Claude Desktop, Cursor, Goose, Gemini CLI) and finds configured servers by name. `fastmcp generate-cli` writes a standalone typed CLI where every tool is a subcommand. `fastmcp install` registers your server with Claude Desktop, Cursor, or Goose in one command. + +### Build apps (3.1 preview) + +📱 Spec-level support for MCP Apps is in: `ui://` resource scheme, typed UI metadata via `AppConfig`, extension negotiation, and runtime detection. The full Apps experience lands in 3.1. + +--- + +If you hit 3.0 because you didn't pin your dependencies and something breaks — the [upgrade guides](https://gofastmcp.com/getting-started/upgrading/from-fastmcp-2) will get you sorted. We minimized breaking changes, but a major version is a major version. + +```bash +pip install fastmcp -U +``` + +📖 [Documentation](https://gofastmcp.com) +🚀 [Upgrade from FastMCP v2](https://gofastmcp.com/getting-started/upgrading/from-fastmcp-2) +🔀 [Upgrade from MCP Python SDK](https://gofastmcp.com/getting-started/upgrading/from-mcp-sdk) + +## What's Changed +### New Features 🎉 +* Refactor resource behavior and add meta support by [@jlowin](https://github.com/jlowin) in [#2611](https://github.com/PrefectHQ/fastmcp/pull/2611) +* Refactor prompt behavior and add meta support by [@jlowin](https://github.com/jlowin) in [#2610](https://github.com/PrefectHQ/fastmcp/pull/2610) +* feat: Provider abstraction for dynamic MCP components by [@jlowin](https://github.com/jlowin) in [#2622](https://github.com/PrefectHQ/fastmcp/pull/2622) +* Unify component storage in LocalProvider by [@jlowin](https://github.com/jlowin) in [#2680](https://github.com/PrefectHQ/fastmcp/pull/2680) +* Introduce ResourceResult as canonical resource return type by [@jlowin](https://github.com/jlowin) in [#2734](https://github.com/PrefectHQ/fastmcp/pull/2734) +* Introduce Message and PromptResult as canonical prompt types by [@jlowin](https://github.com/jlowin) in [#2738](https://github.com/PrefectHQ/fastmcp/pull/2738) +* Add --reload flag for auto-restart on file changes by [@jlowin](https://github.com/jlowin) in [#2816](https://github.com/PrefectHQ/fastmcp/pull/2816) +* Add FileSystemProvider for filesystem-based component discovery by [@jlowin](https://github.com/jlowin) in [#2823](https://github.com/PrefectHQ/fastmcp/pull/2823) +* Add standalone decorators and eliminate fastmcp.fs module by [@jlowin](https://github.com/jlowin) in [#2832](https://github.com/PrefectHQ/fastmcp/pull/2832) +* Add authorization checks to components and servers by [@jlowin](https://github.com/jlowin) in [#2855](https://github.com/PrefectHQ/fastmcp/pull/2855) +* Decorators return functions instead of component objects by [@jlowin](https://github.com/jlowin) in [#2856](https://github.com/PrefectHQ/fastmcp/pull/2856) +* Add transform system for modifying components in provider chains by [@jlowin](https://github.com/jlowin) in [#2836](https://github.com/PrefectHQ/fastmcp/pull/2836) +* Add OpenTelemetry tracing support by [@chrisguidry](https://github.com/chrisguidry) in [#2869](https://github.com/PrefectHQ/fastmcp/pull/2869) +* Add component versioning and VersionFilter transform by [@jlowin](https://github.com/jlowin) in [#2894](https://github.com/PrefectHQ/fastmcp/pull/2894) +* Add version discovery and calling a certain version for components by [@jlowin](https://github.com/jlowin) in [#2897](https://github.com/PrefectHQ/fastmcp/pull/2897) +* Refactor visibility to mark-based enabled system by [@jlowin](https://github.com/jlowin) in [#2912](https://github.com/PrefectHQ/fastmcp/pull/2912) +* Add session-specific visibility control via Context by [@jlowin](https://github.com/jlowin) in [#2917](https://github.com/PrefectHQ/fastmcp/pull/2917) +* Add Skills Provider for exposing agent skills as MCP resources by [@jlowin](https://github.com/jlowin) in [#2944](https://github.com/PrefectHQ/fastmcp/pull/2944) +* Add MCP Apps Phase 1 — SDK compatibility (SEP-1865) by [@jlowin](https://github.com/jlowin) in [#3009](https://github.com/PrefectHQ/fastmcp/pull/3009) +* Add `fastmcp list` and `fastmcp call` CLI commands by [@jlowin](https://github.com/jlowin) in [#3054](https://github.com/PrefectHQ/fastmcp/pull/3054) +* Add `fastmcp generate-cli` command by [@jlowin](https://github.com/jlowin) in [#3065](https://github.com/PrefectHQ/fastmcp/pull/3065) +* Add CIMD (Client ID Metadata Document) support for OAuth by [@jlowin](https://github.com/jlowin) in [#2871](https://github.com/PrefectHQ/fastmcp/pull/2871) + + +### Enhancements 🔧 +* Convert mounted servers to MountedProvider by [@jlowin](https://github.com/jlowin) in [#2635](https://github.com/PrefectHQ/fastmcp/pull/2635) +* Simplify .key as computed property by [@jlowin](https://github.com/jlowin) in [#2648](https://github.com/PrefectHQ/fastmcp/pull/2648) +* Refactor MountedProvider into FastMCPProvider + TransformingProvider by [@jlowin](https://github.com/jlowin) in [#2653](https://github.com/PrefectHQ/fastmcp/pull/2653) +* Enable background task support for custom component subclasses by [@jlowin](https://github.com/jlowin) in [#2657](https://github.com/PrefectHQ/fastmcp/pull/2657) +* Use CreateTaskResult for background task creation by [@jlowin](https://github.com/jlowin) in [#2660](https://github.com/PrefectHQ/fastmcp/pull/2660) +* Refactor provider execution: components own their execution by [@jlowin](https://github.com/jlowin) in [#2663](https://github.com/PrefectHQ/fastmcp/pull/2663) +* Add supports_tasks() method to replace string mode checks by [@jlowin](https://github.com/jlowin) in [#2664](https://github.com/PrefectHQ/fastmcp/pull/2664) +* Replace type: ignore[attr-defined] with isinstance assertions in tests by [@jlowin](https://github.com/jlowin) in [#2665](https://github.com/PrefectHQ/fastmcp/pull/2665) +* Add poll_interval to TaskConfig by [@jlowin](https://github.com/jlowin) in [#2666](https://github.com/PrefectHQ/fastmcp/pull/2666) +* Refactor task module: rename protocol.py to requests.py and reduce redundancy by [@jlowin](https://github.com/jlowin) in [#2667](https://github.com/PrefectHQ/fastmcp/pull/2667) +* Refactor FastMCPProxy into ProxyProvider by [@jlowin](https://github.com/jlowin) in [#2669](https://github.com/PrefectHQ/fastmcp/pull/2669) +* Move OpenAPI to providers/openapi submodule by [@jlowin](https://github.com/jlowin) in [#2672](https://github.com/PrefectHQ/fastmcp/pull/2672) +* Use ergonomic provider initialization pattern by [@jlowin](https://github.com/jlowin) in [#2675](https://github.com/PrefectHQ/fastmcp/pull/2675) +* Fix ty 0.0.5 type errors by [@jlowin](https://github.com/jlowin) in [#2676](https://github.com/PrefectHQ/fastmcp/pull/2676) +* Remove execution methods from Provider base class by [@jlowin](https://github.com/jlowin) in [#2681](https://github.com/PrefectHQ/fastmcp/pull/2681) +* Add type-prefixed keys for globally unique component identification by [@jlowin](https://github.com/jlowin) in [#2704](https://github.com/PrefectHQ/fastmcp/pull/2704) +* Consolidate notification system with unified API by [@jlowin](https://github.com/jlowin) in [#2710](https://github.com/PrefectHQ/fastmcp/pull/2710) +* Parallelize provider operations by [@jlowin](https://github.com/jlowin) in [#2716](https://github.com/PrefectHQ/fastmcp/pull/2716) +* Consolidate get_* and _list_* methods into single API by [@jlowin](https://github.com/jlowin) in [#2719](https://github.com/PrefectHQ/fastmcp/pull/2719) +* Consolidate execution method chains into single public API by [@jlowin](https://github.com/jlowin) in [#2728](https://github.com/PrefectHQ/fastmcp/pull/2728) +* Parallelize list_* calls in Provider.get_tasks() by [@jlowin](https://github.com/jlowin) in [#2731](https://github.com/PrefectHQ/fastmcp/pull/2731) +* Consistent decorator-based MCP handler registration by [@jlowin](https://github.com/jlowin) in [#2732](https://github.com/PrefectHQ/fastmcp/pull/2732) +* Make ToolResult a BaseModel for serialization support by [@jlowin](https://github.com/jlowin) in [#2736](https://github.com/PrefectHQ/fastmcp/pull/2736) +* Align prompt handler with resource pattern by [@jlowin](https://github.com/jlowin) in [#2740](https://github.com/PrefectHQ/fastmcp/pull/2740) +* Update classes to inherit from FastMCPBaseModel instead of BaseModel by [@jlowin](https://github.com/jlowin) in [#2739](https://github.com/PrefectHQ/fastmcp/pull/2739) +* Add explicit task_meta parameter to FastMCP.call_tool() by [@jlowin](https://github.com/jlowin) in [#2749](https://github.com/PrefectHQ/fastmcp/pull/2749) +* Add task_meta parameter to read_resource() for explicit task control by [@jlowin](https://github.com/jlowin) in [#2750](https://github.com/PrefectHQ/fastmcp/pull/2750) +* Add task_meta to prompts and centralize fn_key enrichment by [@jlowin](https://github.com/jlowin) in [#2751](https://github.com/PrefectHQ/fastmcp/pull/2751) +* Remove unused include_tags/exclude_tags settings by [@jlowin](https://github.com/jlowin) in [#2756](https://github.com/PrefectHQ/fastmcp/pull/2756) +* Parallelize provider access when executing components by [@jlowin](https://github.com/jlowin) in [#2744](https://github.com/PrefectHQ/fastmcp/pull/2744) +* Deprecate tool_serializer parameter by [@jlowin](https://github.com/jlowin) in [#2753](https://github.com/PrefectHQ/fastmcp/pull/2753) +* Feature/supabase custom auth route by [@EloiZalczer](https://github.com/EloiZalczer) in [#2632](https://github.com/PrefectHQ/fastmcp/pull/2632) +* Remove deprecated WSTransport by [@jlowin](https://github.com/jlowin) in [#2826](https://github.com/PrefectHQ/fastmcp/pull/2826) +* Add composable lifespans by [@jlowin](https://github.com/jlowin) in [#2828](https://github.com/PrefectHQ/fastmcp/pull/2828) +* Replace FastMCP.as_proxy() with create_proxy() function by [@jlowin](https://github.com/jlowin) in [#2829](https://github.com/PrefectHQ/fastmcp/pull/2829) +* Add PingMiddleware for keepalive connections by [@jlowin](https://github.com/jlowin) in [#2838](https://github.com/PrefectHQ/fastmcp/pull/2838) +* Run sync tools/resources/prompts in threadpool automatically by [@jlowin](https://github.com/jlowin) in [#2865](https://github.com/PrefectHQ/fastmcp/pull/2865) +* Add timeout parameter for tool foreground execution by [@jlowin](https://github.com/jlowin) in [#2872](https://github.com/PrefectHQ/fastmcp/pull/2872) +* Adopt OpenTelemetry MCP semantic conventions by [@chrisguidry](https://github.com/chrisguidry) in [#2886](https://github.com/PrefectHQ/fastmcp/pull/2886) +* Add client_secret_post authentication to IntrospectionTokenVerifier by [@shulkx](https://github.com/shulkx) in [#2884](https://github.com/PrefectHQ/fastmcp/pull/2884) +* Add enable_rich_logging setting to disable rich formatting by [@strawgate](https://github.com/strawgate) in [#2893](https://github.com/PrefectHQ/fastmcp/pull/2893) +* Rename _fastmcp metadata namespace to fastmcp and make non-optional by [@jlowin](https://github.com/jlowin) in [#2895](https://github.com/PrefectHQ/fastmcp/pull/2895) +* Refactor FastMCP to inherit from Provider by [@jlowin](https://github.com/jlowin) in [#2901](https://github.com/PrefectHQ/fastmcp/pull/2901) +* Swap public/private method naming in Provider by [@jlowin](https://github.com/jlowin) in [#2902](https://github.com/PrefectHQ/fastmcp/pull/2902) +* Add MCP-compliant pagination support by [@jlowin](https://github.com/jlowin) in [#2903](https://github.com/PrefectHQ/fastmcp/pull/2903) +* Support VersionSpec in enable/disable for range-based filtering by [@jlowin](https://github.com/jlowin) in [#2914](https://github.com/PrefectHQ/fastmcp/pull/2914) +* Immutable transform wrapping for providers by [@jlowin](https://github.com/jlowin) in [#2913](https://github.com/PrefectHQ/fastmcp/pull/2913) +* Unify discovery API: deduplicate at protocol layer only by [@jlowin](https://github.com/jlowin) in [#2919](https://github.com/PrefectHQ/fastmcp/pull/2919) +* Add ResourcesAsTools transform by [@jlowin](https://github.com/jlowin) in [#2943](https://github.com/PrefectHQ/fastmcp/pull/2943) +* Add PromptsAsTools transform by [@jlowin](https://github.com/jlowin) in [#2946](https://github.com/PrefectHQ/fastmcp/pull/2946) +* Rename Enabled transform to Visibility by [@jlowin](https://github.com/jlowin) in [#2950](https://github.com/PrefectHQ/fastmcp/pull/2950) +* feat: option to add upstream claims to the FastMCP proxy JWT by [@JonasKs](https://github.com/JonasKs) in [#2997](https://github.com/PrefectHQ/fastmcp/pull/2997) +* fix: automatically include offline_access as a scope in the Azure provider by [@JonasKs](https://github.com/JonasKs) in [#3001](https://github.com/PrefectHQ/fastmcp/pull/3001) +* feat: expand --reload to watch frontend file types by [@jlowin](https://github.com/jlowin) in [#3028](https://github.com/PrefectHQ/fastmcp/pull/3028) +* Add `fastmcp install stdio` command by [@jlowin](https://github.com/jlowin) in [#3032](https://github.com/PrefectHQ/fastmcp/pull/3032) +* feat: Goose integration + dedicated install command by [@jlowin](https://github.com/jlowin) in [#3040](https://github.com/PrefectHQ/fastmcp/pull/3040) +* Add `fastmcp discover` and name-based server resolution by [@jlowin](https://github.com/jlowin) in [#3055](https://github.com/PrefectHQ/fastmcp/pull/3055) +* feat(context): Add background task support for Context by [@gfortaine](https://github.com/gfortaine) in [#2905](https://github.com/PrefectHQ/fastmcp/pull/2905) +* Add server version to banner by [@richardkmichael](https://github.com/richardkmichael) in [#3076](https://github.com/PrefectHQ/fastmcp/pull/3076) +* Add @handle_tool_errors decorator for standardized error handling by [@dgenio](https://github.com/dgenio) in [#2885](https://github.com/PrefectHQ/fastmcp/pull/2885) +* Add ResponseLimitingMiddleware for tool response size control by [@dgenio](https://github.com/dgenio) in [#3072](https://github.com/PrefectHQ/fastmcp/pull/3072) +* Infer MIME types from OpenAPI response definitions by [@jlowin](https://github.com/jlowin) in [#3101](https://github.com/PrefectHQ/fastmcp/pull/3101) +* Remove require_auth in favor of scope-based authorization by [@jlowin](https://github.com/jlowin) in [#3103](https://github.com/PrefectHQ/fastmcp/pull/3103) +* generate-cli: auto-generate SKILL.md agent skill by [@jlowin](https://github.com/jlowin) in [#3115](https://github.com/PrefectHQ/fastmcp/pull/3115) +* Add Azure OBO dependencies, auth token injection, and documentation by [@jlowin](https://github.com/jlowin) in [#2918](https://github.com/PrefectHQ/fastmcp/pull/2918) +* feat: add Static Client Registration by [@martimfasantos](https://github.com/martimfasantos) in [#3086](https://github.com/PrefectHQ/fastmcp/pull/3086) +* Add concurrent tool execution with sequential flag by [@strawgate](https://github.com/strawgate) in [#3022](https://github.com/PrefectHQ/fastmcp/pull/3022) +* Add validate_output option for OpenAPI tools by [@jlowin](https://github.com/jlowin) in [#3134](https://github.com/PrefectHQ/fastmcp/pull/3134) +* Relay task elicitation through standard MCP protocol by [@chrisguidry](https://github.com/chrisguidry) in [#3136](https://github.com/PrefectHQ/fastmcp/pull/3136) +* Support async auth checks by [@jlowin](https://github.com/jlowin) in [#3152](https://github.com/PrefectHQ/fastmcp/pull/3152) +* Make $ref dereferencing optional via FastMCP(dereference_refs=...) by [@jlowin](https://github.com/jlowin) in [#3151](https://github.com/PrefectHQ/fastmcp/pull/3151) +* Expose local_provider property, deprecate FastMCP.remove_tool() by [@jlowin](https://github.com/jlowin) in [#3155](https://github.com/PrefectHQ/fastmcp/pull/3155) +* Add helpers for converting FunctionTool and TransformedTool to SamplingTool by [@strawgate](https://github.com/strawgate) in [#3062](https://github.com/PrefectHQ/fastmcp/pull/3062) +### Fixes 🐞 +* Let FastMCPError propagate from dependencies by [@chrisguidry](https://github.com/chrisguidry) in [#2646](https://github.com/PrefectHQ/fastmcp/pull/2646) +* Fix task execution for tools with custom names by [@chrisguidry](https://github.com/chrisguidry) in [#2645](https://github.com/PrefectHQ/fastmcp/pull/2645) +* fix: check the cause of the tool error by [@rjolaverria](https://github.com/rjolaverria) in [#2674](https://github.com/PrefectHQ/fastmcp/pull/2674) +* Fix uvicorn 0.39+ test timeouts and FastMCPError propagation by [@jlowin](https://github.com/jlowin) in [#2699](https://github.com/PrefectHQ/fastmcp/pull/2699) +* Fix: resolve root-level $ref in outputSchema for MCP spec compliance by [@majiayu000](https://github.com/majiayu000) in [#2720](https://github.com/PrefectHQ/fastmcp/pull/2720) +* Fix Proxy provider to return all resource contents by [@jlowin](https://github.com/jlowin) in [#2742](https://github.com/PrefectHQ/fastmcp/pull/2742) +* fix: Client OAuth async_auth_flow() method causing MCP-SDK lock error by [@lgndluke](https://github.com/lgndluke) in [#2644](https://github.com/PrefectHQ/fastmcp/pull/2644) +* Fix rate limit detection during teardown phase by [@jlowin](https://github.com/jlowin) in [#2757](https://github.com/PrefectHQ/fastmcp/pull/2757) +* Fix OAuth Proxy resource parameter validation by [@jlowin](https://github.com/jlowin) in [#2764](https://github.com/PrefectHQ/fastmcp/pull/2764) +* Fix `openapi_version` check so 3.1 is included by [@deeleeramone](https://github.com/deeleeramone) in [#2768](https://github.com/PrefectHQ/fastmcp/pull/2768) +* Fix base_url fallback when url is not set by [@bhbs](https://github.com/bhbs) in [#2776](https://github.com/PrefectHQ/fastmcp/pull/2776) +* Lazy import DiskStore to avoid sqlite3 dependency on import by [@jlowin](https://github.com/jlowin) in [#2784](https://github.com/PrefectHQ/fastmcp/pull/2784) +* Fix OAuth token storage TTL calculation by [@jlowin](https://github.com/jlowin) in [#2796](https://github.com/PrefectHQ/fastmcp/pull/2796) +* Fix client hanging on HTTP 4xx/5xx errors by [@jlowin](https://github.com/jlowin) in [#2803](https://github.com/PrefectHQ/fastmcp/pull/2803) +* Fix keep_alive passthrough in StdioMCPServer.to_transport() by [@jlowin](https://github.com/jlowin) in [#2791](https://github.com/PrefectHQ/fastmcp/pull/2791) +* Dereference $ref in tool schemas for MCP client compatibility by [@jlowin](https://github.com/jlowin) in [#2808](https://github.com/PrefectHQ/fastmcp/pull/2808) +* Fix timeout not propagating to proxy clients in multi-server MCPConfig by [@jlowin](https://github.com/jlowin) in [#2809](https://github.com/PrefectHQ/fastmcp/pull/2809) +* Fix ContextVar propagation for ASGI-mounted servers with tasks by [@chrisguidry](https://github.com/chrisguidry) in [#2844](https://github.com/PrefectHQ/fastmcp/pull/2844) +* Fix HTTP transport timeout defaulting to 5 seconds by [@jlowin](https://github.com/jlowin) in [#2849](https://github.com/PrefectHQ/fastmcp/pull/2849) +* Fix task capabilities location (issue #2870) by [@jlowin](https://github.com/jlowin) in [#2875](https://github.com/PrefectHQ/fastmcp/pull/2875) +* fix: broaden combine_lifespans type to accept Mapping return types by [@aminsamir45](https://github.com/aminsamir45) in [#3005](https://github.com/PrefectHQ/fastmcp/pull/3005) +* fix: correctly send resource when exchanging code for upstream by [@JonasKs](https://github.com/JonasKs) in [#3013](https://github.com/PrefectHQ/fastmcp/pull/3013) +* chore: upgrade python-multipart to 0.0.22 (CVE-2026-24486) by [@jlowin](https://github.com/jlowin) in [#3042](https://github.com/PrefectHQ/fastmcp/pull/3042) +* chore: upgrade protobuf to 6.33.5 (CVE-2026-0994) by [@jlowin](https://github.com/jlowin) in [#3043](https://github.com/PrefectHQ/fastmcp/pull/3043) +* fix: use MCP spec error code -32002 for resource not found by [@jlowin](https://github.com/jlowin) in [#3041](https://github.com/PrefectHQ/fastmcp/pull/3041) +* Fix tool_choice reset for structured output sampling by [@strawgate](https://github.com/strawgate) in [#3014](https://github.com/PrefectHQ/fastmcp/pull/3014) +* fix: Preserve metadata in FastMCPProvider component wrappers by [@NeelayS](https://github.com/NeelayS) in [#3057](https://github.com/PrefectHQ/fastmcp/pull/3057) +* fix: enforce redirect URI validation when allowed_client_redirect_uris is supplied by [@nathanwelsh8](https://github.com/nathanwelsh8) in [#3066](https://github.com/PrefectHQ/fastmcp/pull/3066) +* Fix --reload port conflict when using explicit port by [@jlowin](https://github.com/jlowin) in [#3070](https://github.com/PrefectHQ/fastmcp/pull/3070) +* Fix compress_schema to preserve additionalProperties: false by [@jlowin](https://github.com/jlowin) in [#3102](https://github.com/PrefectHQ/fastmcp/pull/3102) +* Fix CIMD redirect allowlist bypass and cache revalidation by [@jlowin](https://github.com/jlowin) in [#3098](https://github.com/PrefectHQ/fastmcp/pull/3098) +* Fix session visibility marks leaking across sessions by [@jlowin](https://github.com/jlowin) in [#3132](https://github.com/PrefectHQ/fastmcp/pull/3132) +* Fix unhandled exceptions in OpenAPI POST tool calls by [@jlowin](https://github.com/jlowin) in [#3133](https://github.com/PrefectHQ/fastmcp/pull/3133) +* feat: distributed notification queue + BLPOP elicitation for background tasks by [@gfortaine](https://github.com/gfortaine) in [#2906](https://github.com/PrefectHQ/fastmcp/pull/2906) +* fix: snapshot access token for background tasks by [@gfortaine](https://github.com/gfortaine) in [#3138](https://github.com/PrefectHQ/fastmcp/pull/3138) +* fix: guard client pagination loops against misbehaving servers by [@jlowin](https://github.com/jlowin) in [#3167](https://github.com/PrefectHQ/fastmcp/pull/3167) +* Support non-serializable values in Context.set_state by [@jlowin](https://github.com/jlowin) in [#3171](https://github.com/PrefectHQ/fastmcp/pull/3171) +* Fix stale request context in StatefulProxyClient handlers by [@jlowin](https://github.com/jlowin) in [#3172](https://github.com/PrefectHQ/fastmcp/pull/3172) +* Drop diskcache dependency (CVE-2025-69872) by [@jlowin](https://github.com/jlowin) in [#3185](https://github.com/PrefectHQ/fastmcp/pull/3185) +* Fix confused deputy attack via consent binding cookie by [@jlowin](https://github.com/jlowin) in [#3201](https://github.com/PrefectHQ/fastmcp/pull/3201) +* Add JWT audience validation and RFC 8707 warnings to auth providers by [@jlowin](https://github.com/jlowin) in [#3204](https://github.com/PrefectHQ/fastmcp/pull/3204) +* Cache OBO credentials on AzureProvider for token reuse by [@jlowin](https://github.com/jlowin) in [#3212](https://github.com/PrefectHQ/fastmcp/pull/3212) +* Fix invalid uv add command in upgrade guide by [@jlowin](https://github.com/jlowin) in [#3217](https://github.com/PrefectHQ/fastmcp/pull/3217) +* Use standard traceparent/tracestate keys per OTel MCP semconv by [@chrisguidry](https://github.com/chrisguidry) in [#3221](https://github.com/PrefectHQ/fastmcp/pull/3221) +### Breaking Changes 🛫 +* Add VisibilityFilter for hierarchical enable/disable by [@jlowin](https://github.com/jlowin) in [#2708](https://github.com/PrefectHQ/fastmcp/pull/2708) +* Remove automatic environment variable loading from auth providers by [@jlowin](https://github.com/jlowin) in [#2752](https://github.com/PrefectHQ/fastmcp/pull/2752) +* Make pydocket optional and unify DI systems by [@jlowin](https://github.com/jlowin) in [#2835](https://github.com/PrefectHQ/fastmcp/pull/2835) +* Add session-scoped state persistence by [@jlowin](https://github.com/jlowin) in [#2873](https://github.com/PrefectHQ/fastmcp/pull/2873) +* Rename ui= to app= and consolidate ToolUI/ResourceUI into AppConfig by [@jlowin](https://github.com/jlowin) in [#3117](https://github.com/PrefectHQ/fastmcp/pull/3117) +* Remove deprecated FastMCP() constructor kwargs by [@jlowin](https://github.com/jlowin) in [#3148](https://github.com/PrefectHQ/fastmcp/pull/3148) +* Move `fastmcp dev` to `fastmcp dev inspector` by [@jlowin](https://github.com/jlowin) in [#3188](https://github.com/PrefectHQ/fastmcp/pull/3188) + +## New Contributors +* [@ivanbelenky](https://github.com/ivanbelenky) made their first contribution in [#2656](https://github.com/PrefectHQ/fastmcp/pull/2656) +* [@rjolaverria](https://github.com/rjolaverria) made their first contribution in [#2674](https://github.com/PrefectHQ/fastmcp/pull/2674) +* [@mgoldsborough](https://github.com/mgoldsborough) made their first contribution in [#2701](https://github.com/PrefectHQ/fastmcp/pull/2701) +* [@Ashif4354](https://github.com/Ashif4354) made their first contribution in [#2707](https://github.com/PrefectHQ/fastmcp/pull/2707) +* [@majiayu000](https://github.com/majiayu000) made their first contribution in [#2720](https://github.com/PrefectHQ/fastmcp/pull/2720) +* [@lgndluke](https://github.com/lgndluke) made their first contribution in [#2644](https://github.com/PrefectHQ/fastmcp/pull/2644) +* [@EloiZalczer](https://github.com/EloiZalczer) made their first contribution in [#2632](https://github.com/PrefectHQ/fastmcp/pull/2632) +* [@deeleeramone](https://github.com/deeleeramone) made their first contribution in [#2768](https://github.com/PrefectHQ/fastmcp/pull/2768) +* [@shea-parkes](https://github.com/shea-parkes) made their first contribution in [#2781](https://github.com/PrefectHQ/fastmcp/pull/2781) +* [@bryankthompson](https://github.com/bryankthompson) made their first contribution in [#2777](https://github.com/PrefectHQ/fastmcp/pull/2777) +* [@bhbs](https://github.com/bhbs) made their first contribution in [#2776](https://github.com/PrefectHQ/fastmcp/pull/2776) +* [@shulkx](https://github.com/shulkx) made their first contribution in [#2884](https://github.com/PrefectHQ/fastmcp/pull/2884) +* [@abhijeethp](https://github.com/abhijeethp) made their first contribution in [#2967](https://github.com/PrefectHQ/fastmcp/pull/2967) +* [@aminsamir45](https://github.com/aminsamir45) made their first contribution in [#3005](https://github.com/PrefectHQ/fastmcp/pull/3005) +* [@JonasKs](https://github.com/JonasKs) made their first contribution in [#2997](https://github.com/PrefectHQ/fastmcp/pull/2997) +* [@NeelayS](https://github.com/NeelayS) made their first contribution in [#3057](https://github.com/PrefectHQ/fastmcp/pull/3057) +* [@gfortaine](https://github.com/gfortaine) made their first contribution in [#2905](https://github.com/PrefectHQ/fastmcp/pull/2905) +* [@nathanwelsh8](https://github.com/nathanwelsh8) made their first contribution in [#3066](https://github.com/PrefectHQ/fastmcp/pull/3066) +* [@dgenio](https://github.com/dgenio) made their first contribution in [#2885](https://github.com/PrefectHQ/fastmcp/pull/2885) +* [@martimfasantos](https://github.com/martimfasantos) made their first contribution in [#3086](https://github.com/PrefectHQ/fastmcp/pull/3086) +* [@jfBiswajit](https://github.com/jfBiswajit) made their first contribution in [#3193](https://github.com/PrefectHQ/fastmcp/pull/3193) + +**Full Changelog**: https://github.com/PrefectHQ/fastmcp/compare/v2.14.5...v3.0.0 + + + + + +**[v3.0.0rc1: RC-ing is Believing](https://github.com/PrefectHQ/fastmcp/releases/tag/v3.0.0rc1)** + +FastMCP 3 RC1 means we believe the API is stable. Beta 2 drew a wave of real-world adoption — production deployments, migration reports, integration testing — and the feedback overwhelmingly confirmed that the architecture works. This release closes gaps that surfaced under load: auth flows that needed to be async, background tasks that needed reliable notification delivery, and APIs still carrying beta-era naming. If nothing unexpected surfaces, this is what 3.0.0 looks like. + +🚨 **Breaking Changes** — The `ui=` parameter is now `app=` with a unified `AppConfig` class (matching the feature's actual name), and 16 `FastMCP()` constructor kwargs have finally been removed. If you've been ignoring months of deprecation warnings, you'll get a `TypeError` with specific migration instructions. + +🔐 **Auth Improvements** — Three changes that together round out FastMCP's auth story for production. `auth=` checks can now be `async`, so you can hit databases or external services during authorization — previously, passing an async function silently passed because the unawaited coroutine was truthy. Static Client Registration lets clients provide a pre-registered `client_id`/`client_secret` directly, bypassing DCR for servers that don't support it. And Azure OBO flows are now declarative via dependency injection: + +```python +from fastmcp.server.auth.providers.azure import EntraOBOToken + +@mcp.tool() +async def get_emails( + graph_token: str = EntraOBOToken(["https://graph.microsoft.com/Mail.Read"]), +): + # OBO exchange already happened — just use the token + ... +``` + +⚡ **Concurrent Sampling** — When an LLM returns multiple tool calls in a single response, `context.sample()` can now execute them in parallel. Opt in with `tool_concurrency=0` for unlimited parallelism, or set a bound. Tools that aren't safe to parallelize can declare `sequential=True`. + +📡 **Background Task Notifications** — Background tasks now reliably push progress updates and elicit user input through the standard MCP protocol. A distributed Redis queue replaces polling (7,200 round-trips/hour → one blocking call), and `ctx.elicit()` in background tasks automatically relays through the client's standard `elicitation_handler`. + +✅ **OpenAPI Output Validation** — When backends don't conform to their own OpenAPI schemas, the MCP SDK rejects the response and the tool fails. `validate_output=False` disables strict schema checking while still passing structured JSON to clients — a necessary escape hatch for imperfect APIs. + +## What's Changed +### Enhancements 🔧 +* generate-cli: auto-generate SKILL.md agent skill by [@jlowin](https://github.com/jlowin) in [#3115](https://github.com/PrefectHQ/fastmcp/pull/3115) +* Scope Martian triage to bug-labeled issues for jlowin by [@jlowin](https://github.com/jlowin) in [#3124](https://github.com/PrefectHQ/fastmcp/pull/3124) +* Add Azure OBO dependencies, auth token injection, and documentation by [@jlowin](https://github.com/jlowin) in [#2918](https://github.com/PrefectHQ/fastmcp/pull/2918) +* feat: add Static Client Registration (#3085) by [@martimfasantos](https://github.com/martimfasantos) in [#3086](https://github.com/PrefectHQ/fastmcp/pull/3086) +* Add concurrent tool execution with sequential flag by [@strawgate](https://github.com/strawgate) in [#3022](https://github.com/PrefectHQ/fastmcp/pull/3022) +* Add validate_output option for OpenAPI tools by [@jlowin](https://github.com/jlowin) in [#3134](https://github.com/PrefectHQ/fastmcp/pull/3134) +* Relay task elicitation through standard MCP protocol by [@chrisguidry](https://github.com/chrisguidry) in [#3136](https://github.com/PrefectHQ/fastmcp/pull/3136) +* Bump py-key-value-aio to `>=0.4.0,<0.5.0` by [@strawgate](https://github.com/strawgate) in [#3143](https://github.com/PrefectHQ/fastmcp/pull/3143) +* Support async auth checks by [@jlowin](https://github.com/jlowin) in [#3152](https://github.com/PrefectHQ/fastmcp/pull/3152) +* Make $ref dereferencing optional via FastMCP(dereference_refs=...) by [@jlowin](https://github.com/jlowin) in [#3151](https://github.com/PrefectHQ/fastmcp/pull/3151) +* Expose local_provider property, deprecate FastMCP.remove_tool() by [@jlowin](https://github.com/jlowin) in [#3155](https://github.com/PrefectHQ/fastmcp/pull/3155) +* Add helpers for converting FunctionTool and TransformedTool to SamplingTool by [@strawgate](https://github.com/strawgate) in [#3062](https://github.com/PrefectHQ/fastmcp/pull/3062) +* Updates to github actions / workflows for claude by [@strawgate](https://github.com/strawgate) in [#3157](https://github.com/PrefectHQ/fastmcp/pull/3157) +### Fixes 🐞 +* Updated deprecation URL for V3 by [@SrzStephen](https://github.com/SrzStephen) in [#3108](https://github.com/PrefectHQ/fastmcp/pull/3108) +* Fix Windows test timeouts in OAuth proxy provider tests by [@strawgate](https://github.com/strawgate) in [#3123](https://github.com/PrefectHQ/fastmcp/pull/3123) +* Fix session visibility marks leaking across sessions by [@jlowin](https://github.com/jlowin) in [#3132](https://github.com/PrefectHQ/fastmcp/pull/3132) +* Fix unhandled exceptions in OpenAPI POST tool calls by [@jlowin](https://github.com/jlowin) in [#3133](https://github.com/PrefectHQ/fastmcp/pull/3133) +* feat: distributed notification queue + BLPOP elicitation for background tasks by [@gfortaine](https://github.com/gfortaine) in [#2906](https://github.com/PrefectHQ/fastmcp/pull/2906) +* fix: snapshot access token for background tasks (#3095) by [@gfortaine](https://github.com/gfortaine) in [#3138](https://github.com/PrefectHQ/fastmcp/pull/3138) +* Stop duplicating path parameter descriptions into tool prose by [@jlowin](https://github.com/jlowin) in [#3149](https://github.com/PrefectHQ/fastmcp/pull/3149) +* fix: guard client pagination loops against misbehaving servers by [@jlowin](https://github.com/jlowin) in [#3167](https://github.com/PrefectHQ/fastmcp/pull/3167) +* Fix stale get_* references in docs and examples by [@jlowin](https://github.com/jlowin) in [#3168](https://github.com/PrefectHQ/fastmcp/pull/3168) +* Support non-serializable values in Context.set_state by [@jlowin](https://github.com/jlowin) in [#3171](https://github.com/PrefectHQ/fastmcp/pull/3171) +* Fix stale request context in StatefulProxyClient handlers by [@jlowin](https://github.com/jlowin) in [#3172](https://github.com/PrefectHQ/fastmcp/pull/3172) +### Breaking Changes 🛫 +* Rename ui= to app= and consolidate ToolUI/ResourceUI into AppConfig by [@jlowin](https://github.com/jlowin) in [#3117](https://github.com/PrefectHQ/fastmcp/pull/3117) +* Remove deprecated FastMCP() constructor kwargs by [@jlowin](https://github.com/jlowin) in [#3148](https://github.com/PrefectHQ/fastmcp/pull/3148) +### Docs 📚 +* Update docs to reference beta 2 by [@jlowin](https://github.com/jlowin) in [#3112](https://github.com/PrefectHQ/fastmcp/pull/3112) +* docs: add pre-registered OAuth clients to v3-features by [@jlowin](https://github.com/jlowin) in [#3129](https://github.com/PrefectHQ/fastmcp/pull/3129) +### Dependencies 📦 +* chore(deps): bump cryptography from 46.0.3 to 46.0.5 in /examples/testing_demo in the uv group across 1 directory by @dependabot in [#3140](https://github.com/PrefectHQ/fastmcp/pull/3140) +### Other Changes 🦾 +* docs: add v3.0.0rc1 features to v3-features tracking by [@jlowin](https://github.com/jlowin) in [#3145](https://github.com/PrefectHQ/fastmcp/pull/3145) +* docs: remove nonexistent MSALApp from rc1 notes by [@jlowin](https://github.com/jlowin) in [#3146](https://github.com/PrefectHQ/fastmcp/pull/3146) + +## New Contributors +* [@martimfasantos](https://github.com/martimfasantos) made their first contribution in [#3086](https://github.com/PrefectHQ/fastmcp/pull/3086) + +**Full Changelog**: https://github.com/PrefectHQ/fastmcp/compare/v3.0.0b2...v3.0.0rc1 + + + + + +**[v3.0.0b2: 2 Fast 2 Beta](https://github.com/PrefectHQ/fastmcp/releases/tag/v3.0.0b2)** + +FastMCP 3 Beta 2 reflects the huge number of people that kicked the tires on Beta 1. Seven new contributors landed changes in this release, and early migration reports went smoother than expected, including teams on Prefect Horizon upgrading from v2. Most of Beta 2 is refinement: fixing what people found, filling gaps from real usage, hardening edges. But a few new features did land along the way. + +🖥️ **Client CLI** — `fastmcp list`, `fastmcp call`, `fastmcp discover`, and `fastmcp generate-cli` turn any MCP server into something you can poke at from a terminal. Discover servers configured in Claude Desktop, Cursor, Goose, or project-level `mcp.json` files and reference them by name. `generate-cli` reads a server's schemas and writes a standalone typed CLI script where every tool is a proper subcommand with flags and help text. + +🔐 **CIMD** (Client ID Metadata Documents) adds an alternative to Dynamic Client Registration for OAuth. Clients host a static JSON document at an HTTPS URL; that URL becomes the `client_id`. Server-side support includes SSRF-hardened fetching, cache-aware revalidation, and `private_key_jwt` validation. Enabled by default on `OAuthProxy`. + +📱 **MCP Apps** — Spec-level compliance for the MCP Apps extension: `ui://` resource scheme, typed UI metadata on tools and resources, extension negotiation, and `ctx.client_supports_extension()` for runtime detection. + +⏳ **Background Task Context** — `Context` now works transparently in Docket workers. `ctx.elicit()` routes through Redis-based coordination so background tasks can pause for user input without any code changes. + +🛡️ **ResponseLimitingMiddleware** caps tool response sizes with UTF-8-safe truncation for text and schema-aware error handling for structured outputs. + +🪿 **Goose Integration** — `fastmcp install goose` generates deeplink URLs for one-command server installation into Goose. + +## What's Changed +### New Features 🎉 +* Add MCP Apps Phase 1 — SDK compatibility (SEP-1865) by [@jlowin](https://github.com/jlowin) in [#3009](https://github.com/PrefectHQ/fastmcp/pull/3009) +* Add `fastmcp list` and `fastmcp call` CLI commands by [@jlowin](https://github.com/jlowin) in [#3054](https://github.com/PrefectHQ/fastmcp/pull/3054) +* Add `fastmcp generate-cli` command by [@jlowin](https://github.com/jlowin) in [#3065](https://github.com/PrefectHQ/fastmcp/pull/3065) +* Add CIMD (Client ID Metadata Document) support for OAuth by [@jlowin](https://github.com/jlowin) in [#2871](https://github.com/PrefectHQ/fastmcp/pull/2871) +### Enhancements 🔧 +* Make duplicate bot less aggressive by [@jlowin](https://github.com/jlowin) in [#2981](https://github.com/PrefectHQ/fastmcp/pull/2981) +* Remove uv lockfile monitoring from Dependabot by [@jlowin](https://github.com/jlowin) in [#2986](https://github.com/PrefectHQ/fastmcp/pull/2986) +* Run static checks with --upgrade, remove lockfile check by [@jlowin](https://github.com/jlowin) in [#2988](https://github.com/PrefectHQ/fastmcp/pull/2988) +* Adjust workflow triggers for Marvin by [@strawgate](https://github.com/strawgate) in [#3010](https://github.com/PrefectHQ/fastmcp/pull/3010) +* Move tests to a reusable action and enable nightly checks by [@strawgate](https://github.com/strawgate) in [#3017](https://github.com/PrefectHQ/fastmcp/pull/3017) +* feat: option to add upstream claims to the FastMCP proxy JWT by [@JonasKs](https://github.com/JonasKs) in [#2997](https://github.com/PrefectHQ/fastmcp/pull/2997) +* Fix ty 0.0.14 compatibility and upgrade dependencies by [@jlowin](https://github.com/jlowin) in [#3027](https://github.com/PrefectHQ/fastmcp/pull/3027) +* fix: automatically include offline_access as a scope in the Azure provider to enable automatic token refreshing by [@JonasKs](https://github.com/JonasKs) in [#3001](https://github.com/PrefectHQ/fastmcp/pull/3001) +* feat: expand --reload to watch frontend file types by [@jlowin](https://github.com/jlowin) in [#3028](https://github.com/PrefectHQ/fastmcp/pull/3028) +* Add `fastmcp install stdio` command by [@jlowin](https://github.com/jlowin) in [#3032](https://github.com/PrefectHQ/fastmcp/pull/3032) +* Update martian-issue-triage.yml for Workflow editing guidance by [@strawgate](https://github.com/strawgate) in [#3033](https://github.com/PrefectHQ/fastmcp/pull/3033) +* feat: Goose integration + dedicated install command by [@jlowin](https://github.com/jlowin) in [#3040](https://github.com/PrefectHQ/fastmcp/pull/3040) +* Fixing spelling issues in multiple files by [@didier-durand](https://github.com/didier-durand) in [#2996](https://github.com/PrefectHQ/fastmcp/pull/2996) +* Add `fastmcp discover` and name-based server resolution by [@jlowin](https://github.com/jlowin) in [#3055](https://github.com/PrefectHQ/fastmcp/pull/3055) +* feat(context): Add background task support for Context (SEP-1686) by [@gfortaine](https://github.com/gfortaine) in [#2905](https://github.com/PrefectHQ/fastmcp/pull/2905) +* Add server version to banner by [@richardkmichael](https://github.com/richardkmichael) in [#3076](https://github.com/PrefectHQ/fastmcp/pull/3076) +* Add @handle_tool_errors decorator for standardized error handling by [@dgenio](https://github.com/dgenio) in [#2885](https://github.com/PrefectHQ/fastmcp/pull/2885) +* Update Anthropic and OpenAI clients to use Omit instead of NotGiven by [@jlowin](https://github.com/jlowin) in [#3088](https://github.com/PrefectHQ/fastmcp/pull/3088) +* Add ResponseLimitingMiddleware for tool response size control by [@dgenio](https://github.com/dgenio) in [#3072](https://github.com/PrefectHQ/fastmcp/pull/3072) +* Infer MIME types from OpenAPI response definitions by [@jlowin](https://github.com/jlowin) in [#3101](https://github.com/PrefectHQ/fastmcp/pull/3101) +* Remove require_auth in favor of scope-based authorization by [@jlowin](https://github.com/jlowin) in [#3103](https://github.com/PrefectHQ/fastmcp/pull/3103) +### Fixes 🐞 +* Fix FastAPI mounting examples in docs by [@jlowin](https://github.com/jlowin) in [#2962](https://github.com/PrefectHQ/fastmcp/pull/2962) +* Remove outdated 'FastMCP 3.0 is coming!' CLI banner by [@jlowin](https://github.com/jlowin) in [#2974](https://github.com/PrefectHQ/fastmcp/pull/2974) +* Pin httpx `< 1.0` and simplify beta install docs by [@jlowin](https://github.com/jlowin) in [#2975](https://github.com/PrefectHQ/fastmcp/pull/2975) +* Add enabled field to ToolTransformConfig by [@jlowin](https://github.com/jlowin) in [#2991](https://github.com/PrefectHQ/fastmcp/pull/2991) +* fix phue2 import in smart_home example by [@zzstoatzz](https://github.com/zzstoatzz) in [#2999](https://github.com/PrefectHQ/fastmcp/pull/2999) +* fix: broaden combine_lifespans type to accept Mapping return types by [@aminsamir45](https://github.com/aminsamir45) in [#3005](https://github.com/PrefectHQ/fastmcp/pull/3005) +* fix: type narrowing for skills resource contents by [@strawgate](https://github.com/strawgate) in [#3023](https://github.com/PrefectHQ/fastmcp/pull/3023) +* fix: correctly send resource when exchanging code for the upstream by [@JonasKs](https://github.com/JonasKs) in [#3013](https://github.com/PrefectHQ/fastmcp/pull/3013) +* MCP Apps: structured CSP/permissions types, resource meta propagation fix, QR example by [@jlowin](https://github.com/jlowin) in [#3031](https://github.com/PrefectHQ/fastmcp/pull/3031) +* chore: upgrade python-multipart to 0.0.22 (CVE-2026-24486) by [@jlowin](https://github.com/jlowin) in [#3042](https://github.com/PrefectHQ/fastmcp/pull/3042) +* chore: upgrade protobuf to 6.33.5 (CVE-2026-0994) by [@jlowin](https://github.com/jlowin) in [#3043](https://github.com/PrefectHQ/fastmcp/pull/3043) +* fix: use MCP spec error code -32002 for resource not found by [@jlowin](https://github.com/jlowin) in [#3041](https://github.com/PrefectHQ/fastmcp/pull/3041) +* Fix tool_choice reset for structured output sampling by [@strawgate](https://github.com/strawgate) in [#3014](https://github.com/PrefectHQ/fastmcp/pull/3014) +* Fix workflow notification URL formatting in upgrade checks by [@strawgate](https://github.com/strawgate) in [#3047](https://github.com/PrefectHQ/fastmcp/pull/3047) +* Fix Field() handling in prompts by [@strawgate](https://github.com/strawgate) in [#3050](https://github.com/PrefectHQ/fastmcp/pull/3050) +* fix: use SkipJsonSchema to exclude callable fields from JSON schema generation by [@strawgate](https://github.com/strawgate) in [#3048](https://github.com/PrefectHQ/fastmcp/pull/3048) +* fix: Preserve metadata in FastMCPProvider component wrappers by [@NeelayS](https://github.com/NeelayS) in [#3057](https://github.com/PrefectHQ/fastmcp/pull/3057) +* Mock network calls in CLI tests and use MemoryStore for OAuth tests by [@strawgate](https://github.com/strawgate) in [#3051](https://github.com/PrefectHQ/fastmcp/pull/3051) +* Remove OpenAPI timeout parameter, make client optional, surface timeout errors by [@jlowin](https://github.com/jlowin) in [#3067](https://github.com/PrefectHQ/fastmcp/pull/3067) +* fix: enforce redirect URI validation when allowed_client_redirect_uris is supplied by [@nathanwelsh8](https://github.com/nathanwelsh8) in [#3066](https://github.com/PrefectHQ/fastmcp/pull/3066) +* Fix --reload port conflict when using explicit port by [@jlowin](https://github.com/jlowin) in [#3070](https://github.com/PrefectHQ/fastmcp/pull/3070) +* Fix compress_schema to preserve additionalProperties: false for MCP compatibility by [@jlowin](https://github.com/jlowin) in [#3102](https://github.com/PrefectHQ/fastmcp/pull/3102) +* Fix CIMD redirect allowlist bypass and cache revalidation by [@jlowin](https://github.com/jlowin) in [#3098](https://github.com/PrefectHQ/fastmcp/pull/3098) +* Exclude content-type from get_http_headers() to prevent HTTP 415 errors by [@jlowin](https://github.com/jlowin) in [#3104](https://github.com/PrefectHQ/fastmcp/pull/3104) +### Docs 📚 +* Prepare docs for v3.0 beta release by [@jlowin](https://github.com/jlowin) in [#2954](https://github.com/PrefectHQ/fastmcp/pull/2954) +* Restructure docs: move transforms to dedicated section by [@jlowin](https://github.com/jlowin) in [#2956](https://github.com/PrefectHQ/fastmcp/pull/2956) +* Remove unnecessary pip warning by [@jlowin](https://github.com/jlowin) in [#2958](https://github.com/PrefectHQ/fastmcp/pull/2958) +* Update example MCP version in installation docs by [@jlowin](https://github.com/jlowin) in [#2959](https://github.com/PrefectHQ/fastmcp/pull/2959) +* Update brand images by [@jlowin](https://github.com/jlowin) in [#2960](https://github.com/PrefectHQ/fastmcp/pull/2960) +* Restructure README and welcome page with motivated narrative by [@jlowin](https://github.com/jlowin) in [#2963](https://github.com/PrefectHQ/fastmcp/pull/2963) +* Restructure README and docs with motivated narrative by [@jlowin](https://github.com/jlowin) in [#2964](https://github.com/PrefectHQ/fastmcp/pull/2964) +* Favicon update and Prefect Horizon docs by [@jlowin](https://github.com/jlowin) in [#2978](https://github.com/PrefectHQ/fastmcp/pull/2978) +* Add dependency injection documentation and DI-style dependencies by [@jlowin](https://github.com/jlowin) in [#2980](https://github.com/PrefectHQ/fastmcp/pull/2980) +* docs: document expanded reload behavior and restructure beta sections by [@jlowin](https://github.com/jlowin) in [#3039](https://github.com/PrefectHQ/fastmcp/pull/3039) +* Add output_schema caveat to response limiting docs by [@jlowin](https://github.com/jlowin) in [#3099](https://github.com/PrefectHQ/fastmcp/pull/3099) +* Document token passthrough security in OAuth Proxy docs by [@jlowin](https://github.com/jlowin) in [#3100](https://github.com/PrefectHQ/fastmcp/pull/3100) +### Dependencies 📦 +* Bump ty from 0.0.12 to 0.0.13 by @dependabot in [#2984](https://github.com/PrefectHQ/fastmcp/pull/2984) +* Bump prek from 0.2.30 to 0.3.0 by @dependabot in [#2982](https://github.com/PrefectHQ/fastmcp/pull/2982) +### Other Changes 🦾 +* Normalize resource URLs before comparison to support RFC 8707 query parameters by [@abhijeethp](https://github.com/abhijeethp) in [#2967](https://github.com/PrefectHQ/fastmcp/pull/2967) +* Bump pydocket to 0.17.2 (memory leak fix) by [@chrisguidry](https://github.com/chrisguidry) in [#2998](https://github.com/PrefectHQ/fastmcp/pull/2998) +* Add AzureJWTVerifier for Managed Identity token verification by [@jlowin](https://github.com/jlowin) in [#3058](https://github.com/PrefectHQ/fastmcp/pull/3058) +* Add release notes for v2.14.4 and v2.14.5 by [@jlowin](https://github.com/jlowin) in [#3064](https://github.com/PrefectHQ/fastmcp/pull/3064) +* Add missing beta2 features to v3 release tracking by [@jlowin](https://github.com/jlowin) in [#3105](https://github.com/PrefectHQ/fastmcp/pull/3105) + +## New Contributors +* [@abhijeethp](https://github.com/abhijeethp) made their first contribution in [#2967](https://github.com/PrefectHQ/fastmcp/pull/2967) +* [@aminsamir45](https://github.com/aminsamir45) made their first contribution in [#3005](https://github.com/PrefectHQ/fastmcp/pull/3005) +* [@JonasKs](https://github.com/JonasKs) made their first contribution in [#2997](https://github.com/PrefectHQ/fastmcp/pull/2997) +* [@NeelayS](https://github.com/NeelayS) made their first contribution in [#3057](https://github.com/PrefectHQ/fastmcp/pull/3057) +* [@gfortaine](https://github.com/gfortaine) made their first contribution in [#2905](https://github.com/PrefectHQ/fastmcp/pull/2905) +* [@nathanwelsh8](https://github.com/nathanwelsh8) made their first contribution in [#3066](https://github.com/PrefectHQ/fastmcp/pull/3066) +* [@dgenio](https://github.com/dgenio) made their first contribution in [#2885](https://github.com/PrefectHQ/fastmcp/pull/2885) + +**Full Changelog**: https://github.com/PrefectHQ/fastmcp/compare/v3.0.0b1...v3.0.0b2 + + + + + +**[v3.0.0b1: This Beta Work](https://github.com/PrefectHQ/fastmcp/releases/tag/v3.0.0b1)** + +FastMCP 3.0 rebuilds the framework around three primitives: components, providers, and transforms. Providers source components dynamically—from decorators, filesystems, OpenAPI specs, remote servers, or anywhere else. Transforms modify components as they flow to clients—renaming, namespacing, filtering, securing. The features that required specialized subsystems in v2 now compose naturally from these building blocks. + +🔌 **Provider Architecture** unifies how components are sourced. `FileSystemProvider` discovers decorated functions from directories with optional hot-reload. `SkillsProvider` exposes agent skill files as MCP resources. `OpenAPIProvider` and `ProxyProvider` get cleaner integrations. Providers are composable—share one across servers, or attach many to one server. + +🔄 **Transforms** add middleware for components. Namespace mounted servers, rename verbose tools, filter by version, control visibility—all without touching source code. `ResourcesAsTools` and `PromptsAsTools` expose non-tool components to tool-only clients. + +📋 **Component Versioning** lets you register `@tool(version="2.0")` alongside older versions. Clients see the highest version by default but can request specific versions. `VersionFilter` serves different API versions from one codebase. + +💾 **Session-Scoped State** persists across requests. `await ctx.set_state()` and `await ctx.get_state()` now survive the full session. Per-session visibility via `ctx.enable_components()` lets servers adapt dynamically to each client. + +⚡ **DX Improvements** include `--reload` for auto-restart during development, automatic threadpool dispatch for sync functions, tool timeouts, pagination for large component lists, and OpenTelemetry tracing. + +🔐 **Component Authorization** via `@tool(auth=require_scopes("admin"))` and `AuthMiddleware` for server-wide policies. + +Breaking changes are minimal: for most servers, updating the import statement is all you need. See the [migration guide](https://github.com/PrefectHQ/fastmcp/blob/main/docs/getting-started/upgrading/from-fastmcp-2.mdx) for details. + +## What's Changed +### New Features 🎉 +* Refactor resource behavior and add meta support by [@jlowin](https://github.com/jlowin) in [#2611](https://github.com/PrefectHQ/fastmcp/pull/2611) +* Refactor prompt behavior and add meta support by [@jlowin](https://github.com/jlowin) in [#2610](https://github.com/PrefectHQ/fastmcp/pull/2610) +* feat: Provider abstraction for dynamic MCP components by [@jlowin](https://github.com/jlowin) in [#2622](https://github.com/PrefectHQ/fastmcp/pull/2622) +* Unify component storage in LocalProvider by [@jlowin](https://github.com/jlowin) in [#2680](https://github.com/PrefectHQ/fastmcp/pull/2680) +* Introduce ResourceResult as canonical resource return type by [@jlowin](https://github.com/jlowin) in [#2734](https://github.com/PrefectHQ/fastmcp/pull/2734) +* Introduce Message and PromptResult as canonical prompt types by [@jlowin](https://github.com/jlowin) in [#2738](https://github.com/PrefectHQ/fastmcp/pull/2738) +* Add --reload flag for auto-restart on file changes by [@jlowin](https://github.com/jlowin) in [#2816](https://github.com/PrefectHQ/fastmcp/pull/2816) +* Add FileSystemProvider for filesystem-based component discovery by [@jlowin](https://github.com/jlowin) in [#2823](https://github.com/PrefectHQ/fastmcp/pull/2823) +* Add standalone decorators and eliminate fastmcp.fs module by [@jlowin](https://github.com/jlowin) in [#2832](https://github.com/PrefectHQ/fastmcp/pull/2832) +* Add authorization checks to components and servers by [@jlowin](https://github.com/jlowin) in [#2855](https://github.com/PrefectHQ/fastmcp/pull/2855) +* Decorators return functions instead of component objects by [@jlowin](https://github.com/jlowin) in [#2856](https://github.com/PrefectHQ/fastmcp/pull/2856) +* Add transform system for modifying components in provider chains by [@jlowin](https://github.com/jlowin) in [#2836](https://github.com/PrefectHQ/fastmcp/pull/2836) +* Add OpenTelemetry tracing support by [@chrisguidry](https://github.com/chrisguidry) in [#2869](https://github.com/PrefectHQ/fastmcp/pull/2869) +* Add component versioning and VersionFilter transform by [@jlowin](https://github.com/jlowin) in [#2894](https://github.com/PrefectHQ/fastmcp/pull/2894) +* Add version discovery and calling a certain version for components by [@jlowin](https://github.com/jlowin) in [#2897](https://github.com/PrefectHQ/fastmcp/pull/2897) +* Refactor visibility to mark-based enabled system by [@jlowin](https://github.com/jlowin) in [#2912](https://github.com/PrefectHQ/fastmcp/pull/2912) +* Add session-specific visibility control via Context by [@jlowin](https://github.com/jlowin) in [#2917](https://github.com/PrefectHQ/fastmcp/pull/2917) +* Add Skills Provider for exposing agent skills as MCP resources by [@jlowin](https://github.com/jlowin) in [#2944](https://github.com/PrefectHQ/fastmcp/pull/2944) +### Enhancements 🔧 +* Convert mounted servers to MountedProvider by [@jlowin](https://github.com/jlowin) in [#2635](https://github.com/PrefectHQ/fastmcp/pull/2635) +* Simplify .key as computed property by [@jlowin](https://github.com/jlowin) in [#2648](https://github.com/PrefectHQ/fastmcp/pull/2648) +* Refactor MountedProvider into FastMCPProvider + TransformingProvider by [@jlowin](https://github.com/jlowin) in [#2653](https://github.com/PrefectHQ/fastmcp/pull/2653) +* Enable background task support for custom component subclasses by [@jlowin](https://github.com/jlowin) in [#2657](https://github.com/PrefectHQ/fastmcp/pull/2657) +* Use CreateTaskResult for background task creation by [@jlowin](https://github.com/jlowin) in [#2660](https://github.com/PrefectHQ/fastmcp/pull/2660) +* Refactor provider execution: components own their execution by [@jlowin](https://github.com/jlowin) in [#2663](https://github.com/PrefectHQ/fastmcp/pull/2663) +* Add supports_tasks() method to replace string mode checks by [@jlowin](https://github.com/jlowin) in [#2664](https://github.com/PrefectHQ/fastmcp/pull/2664) +* Replace type: ignore[attr-defined] with isinstance assertions in tests by [@jlowin](https://github.com/jlowin) in [#2665](https://github.com/PrefectHQ/fastmcp/pull/2665) +* Add poll_interval to TaskConfig by [@jlowin](https://github.com/jlowin) in [#2666](https://github.com/PrefectHQ/fastmcp/pull/2666) +* Refactor task module: rename protocol.py to requests.py and reduce redundancy by [@jlowin](https://github.com/jlowin) in [#2667](https://github.com/PrefectHQ/fastmcp/pull/2667) +* Refactor FastMCPProxy into ProxyProvider by [@jlowin](https://github.com/jlowin) in [#2669](https://github.com/PrefectHQ/fastmcp/pull/2669) +* Move OpenAPI to providers/openapi submodule by [@jlowin](https://github.com/jlowin) in [#2672](https://github.com/PrefectHQ/fastmcp/pull/2672) +* Use ergonomic provider initialization pattern by [@jlowin](https://github.com/jlowin) in [#2675](https://github.com/PrefectHQ/fastmcp/pull/2675) +* Fix ty 0.0.5 type errors by [@jlowin](https://github.com/jlowin) in [#2676](https://github.com/PrefectHQ/fastmcp/pull/2676) +* Remove execution methods from Provider base class by [@jlowin](https://github.com/jlowin) in [#2681](https://github.com/PrefectHQ/fastmcp/pull/2681) +* Add type-prefixed keys for globally unique component identification by [@jlowin](https://github.com/jlowin) in [#2704](https://github.com/PrefectHQ/fastmcp/pull/2704) +* Skip parallel MCP config test on Windows by [@jlowin](https://github.com/jlowin) in [#2711](https://github.com/PrefectHQ/fastmcp/pull/2711) +* Consolidate notification system with unified API by [@jlowin](https://github.com/jlowin) in [#2710](https://github.com/PrefectHQ/fastmcp/pull/2710) +* Skip test_multi_client on Windows by [@jlowin](https://github.com/jlowin) in [#2714](https://github.com/PrefectHQ/fastmcp/pull/2714) +* Parallelize provider operations by [@jlowin](https://github.com/jlowin) in [#2716](https://github.com/PrefectHQ/fastmcp/pull/2716) +* Consolidate get_* and _list_* methods into single API by [@jlowin](https://github.com/jlowin) in [#2719](https://github.com/PrefectHQ/fastmcp/pull/2719) +* Consolidate execution method chains into single public API by [@jlowin](https://github.com/jlowin) in [#2728](https://github.com/PrefectHQ/fastmcp/pull/2728) +* Add documentation check to required PR workflow by [@jlowin](https://github.com/jlowin) in [#2730](https://github.com/PrefectHQ/fastmcp/pull/2730) +* Parallelize list_* calls in Provider.get_tasks() by [@jlowin](https://github.com/jlowin) in [#2731](https://github.com/PrefectHQ/fastmcp/pull/2731) +* Consistent decorator-based MCP handler registration by [@jlowin](https://github.com/jlowin) in [#2732](https://github.com/PrefectHQ/fastmcp/pull/2732) +* Make ToolResult a BaseModel for serialization support by [@jlowin](https://github.com/jlowin) in [#2736](https://github.com/PrefectHQ/fastmcp/pull/2736) +* Align prompt handler with resource pattern by [@jlowin](https://github.com/jlowin) in [#2740](https://github.com/PrefectHQ/fastmcp/pull/2740) +* Update classes to inherit from FastMCPBaseModel instead of BaseModel by [@jlowin](https://github.com/jlowin) in [#2739](https://github.com/PrefectHQ/fastmcp/pull/2739) +* Convert provider tests to use direct server calls by [@jlowin](https://github.com/jlowin) in [#2748](https://github.com/PrefectHQ/fastmcp/pull/2748) +* Add explicit task_meta parameter to FastMCP.call_tool() by [@jlowin](https://github.com/jlowin) in [#2749](https://github.com/PrefectHQ/fastmcp/pull/2749) +* Add task_meta parameter to read_resource() for explicit task control by [@jlowin](https://github.com/jlowin) in [#2750](https://github.com/PrefectHQ/fastmcp/pull/2750) +* Add task_meta to prompts and centralize fn_key enrichment by [@jlowin](https://github.com/jlowin) in [#2751](https://github.com/PrefectHQ/fastmcp/pull/2751) +* Remove unused include_tags/exclude_tags settings by [@jlowin](https://github.com/jlowin) in [#2756](https://github.com/PrefectHQ/fastmcp/pull/2756) +* Parallelize provider access when executing components by [@jlowin](https://github.com/jlowin) in [#2744](https://github.com/PrefectHQ/fastmcp/pull/2744) +* Add tests for OAuth generator cleanup and use aclosing by [@jlowin](https://github.com/jlowin) in [#2759](https://github.com/PrefectHQ/fastmcp/pull/2759) +* Deprecate tool_serializer parameter by [@jlowin](https://github.com/jlowin) in [#2753](https://github.com/PrefectHQ/fastmcp/pull/2753) +* Feature/supabase custom auth route by [@EloiZalczer](https://github.com/EloiZalczer) in [#2632](https://github.com/PrefectHQ/fastmcp/pull/2632) +* Add regression tests for caching with mounted server prefixes by [@jlowin](https://github.com/jlowin) in [#2762](https://github.com/PrefectHQ/fastmcp/pull/2762) +* Update CLI banner with FastMCP 3.0 notice by [@jlowin](https://github.com/jlowin) in [#2766](https://github.com/PrefectHQ/fastmcp/pull/2766) +* Make FASTMCP_SHOW_SERVER_BANNER apply to all server startup methods by [@jlowin](https://github.com/jlowin) in [#2771](https://github.com/PrefectHQ/fastmcp/pull/2771) +* Add MCP tool annotations to smart_home example by [@triepod-ai](https://github.com/triepod-ai) in [#2777](https://github.com/PrefectHQ/fastmcp/pull/2777) +* Cherry-pick debug logging for OAuth token expiry to main by [@jlowin](https://github.com/jlowin) in [#2797](https://github.com/PrefectHQ/fastmcp/pull/2797) +* Turn off negative CLI flags by default by [@jlowin](https://github.com/jlowin) in [#2801](https://github.com/PrefectHQ/fastmcp/pull/2801) +* Configure ty to fail on warnings by [@jlowin](https://github.com/jlowin) in [#2804](https://github.com/PrefectHQ/fastmcp/pull/2804) +* Dereference $ref in tool schemas for MCP client compatibility by [@jlowin](https://github.com/jlowin) in [#2814](https://github.com/PrefectHQ/fastmcp/pull/2814) +* Add v3.0 feature tracking document by [@jlowin](https://github.com/jlowin) in [#2822](https://github.com/PrefectHQ/fastmcp/pull/2822) +* Remove deprecated WSTransport by [@jlowin](https://github.com/jlowin) in [#2826](https://github.com/PrefectHQ/fastmcp/pull/2826) +* Add composable lifespans by [@jlowin](https://github.com/jlowin) in [#2828](https://github.com/PrefectHQ/fastmcp/pull/2828) +* Replace FastMCP.as_proxy() with create_proxy() function by [@jlowin](https://github.com/jlowin) in [#2829](https://github.com/PrefectHQ/fastmcp/pull/2829) +* Add docs-broken-links command and fix docstring markdown parsing by [@jlowin](https://github.com/jlowin) in [#2830](https://github.com/PrefectHQ/fastmcp/pull/2830) +* Add PingMiddleware for keepalive connections by [@jlowin](https://github.com/jlowin) in [#2838](https://github.com/PrefectHQ/fastmcp/pull/2838) +* Add CLI update notifications by [@jlowin](https://github.com/jlowin) in [#2840](https://github.com/PrefectHQ/fastmcp/pull/2840) +* Add agent skills for testing and code review by [@jlowin](https://github.com/jlowin) in [#2846](https://github.com/PrefectHQ/fastmcp/pull/2846) +* Add loq pre-commit hook for file size enforcement by [@jlowin](https://github.com/jlowin) in [#2847](https://github.com/PrefectHQ/fastmcp/pull/2847) +* Add transport property to Context by [@jlowin](https://github.com/jlowin) in [#2850](https://github.com/PrefectHQ/fastmcp/pull/2850) +* Add loq file size limits and clean up type ignores by [@jlowin](https://github.com/jlowin) in [#2859](https://github.com/PrefectHQ/fastmcp/pull/2859) +* Run sync tools/resources/prompts in threadpool automatically by [@jlowin](https://github.com/jlowin) in [#2865](https://github.com/PrefectHQ/fastmcp/pull/2865) +* Add timeout parameter for tool foreground execution by [@jlowin](https://github.com/jlowin) in [#2872](https://github.com/PrefectHQ/fastmcp/pull/2872) +* Adopt OpenTelemetry MCP semantic conventions by [@chrisguidry](https://github.com/chrisguidry) in [#2886](https://github.com/PrefectHQ/fastmcp/pull/2886) +* Add client_secret_post authentication to IntrospectionTokenVerifier by [@shulkx](https://github.com/shulkx) in [#2884](https://github.com/PrefectHQ/fastmcp/pull/2884) +* Add enable_rich_logging setting to disable rich formatting by [@strawgate](https://github.com/strawgate) in [#2893](https://github.com/PrefectHQ/fastmcp/pull/2893) +* Rename _fastmcp metadata namespace to fastmcp and make non-optional by [@jlowin](https://github.com/jlowin) in [#2895](https://github.com/PrefectHQ/fastmcp/pull/2895) +* Refactor FastMCP to inherit from Provider by [@jlowin](https://github.com/jlowin) in [#2901](https://github.com/PrefectHQ/fastmcp/pull/2901) +* Swap public/private method naming in Provider by [@jlowin](https://github.com/jlowin) in [#2902](https://github.com/PrefectHQ/fastmcp/pull/2902) +* Add MCP-compliant pagination support by [@jlowin](https://github.com/jlowin) in [#2903](https://github.com/PrefectHQ/fastmcp/pull/2903) +* Support VersionSpec in enable/disable for range-based filtering by [@jlowin](https://github.com/jlowin) in [#2914](https://github.com/PrefectHQ/fastmcp/pull/2914) +* Remove sync notification infrastructure by [@jlowin](https://github.com/jlowin) in [#2915](https://github.com/PrefectHQ/fastmcp/pull/2915) +* Immutable transform wrapping for providers by [@jlowin](https://github.com/jlowin) in [#2913](https://github.com/PrefectHQ/fastmcp/pull/2913) +* Unify discovery API: deduplicate at protocol layer only by [@jlowin](https://github.com/jlowin) in [#2919](https://github.com/PrefectHQ/fastmcp/pull/2919) +* Split transports.py into modular structure by [@jlowin](https://github.com/jlowin) in [#2921](https://github.com/PrefectHQ/fastmcp/pull/2921) +* Move session visibility logic to enabled.py by [@jlowin](https://github.com/jlowin) in [#2924](https://github.com/PrefectHQ/fastmcp/pull/2924) +* Refactor Client class into mixins and add timeout utilities by [@jlowin](https://github.com/jlowin) in [#2933](https://github.com/PrefectHQ/fastmcp/pull/2933) +* Refactor OAuthProxy into focused modules by [@jlowin](https://github.com/jlowin) in [#2935](https://github.com/PrefectHQ/fastmcp/pull/2935) +* Refactor LocalProvider into mixin modules by [@jlowin](https://github.com/jlowin) in [#2936](https://github.com/PrefectHQ/fastmcp/pull/2936) +* Refactor server.py into mixins by [@jlowin](https://github.com/jlowin) in [#2939](https://github.com/PrefectHQ/fastmcp/pull/2939) +* Consolidate test fixtures and refactor large test files by [@jlowin](https://github.com/jlowin) in [#2941](https://github.com/PrefectHQ/fastmcp/pull/2941) +* Refactor transform list methods to pure function pattern by [@jlowin](https://github.com/jlowin) in [#2942](https://github.com/PrefectHQ/fastmcp/pull/2942) +* Add ResourcesAsTools transform by [@jlowin](https://github.com/jlowin) in [#2943](https://github.com/PrefectHQ/fastmcp/pull/2943) +* Add PromptsAsTools transform by [@jlowin](https://github.com/jlowin) in [#2946](https://github.com/PrefectHQ/fastmcp/pull/2946) +* Add client utilities for downloading skills by [@jlowin](https://github.com/jlowin) in [#2948](https://github.com/PrefectHQ/fastmcp/pull/2948) +* Rename Enabled transform to Visibility by [@jlowin](https://github.com/jlowin) in [#2950](https://github.com/PrefectHQ/fastmcp/pull/2950) +### Fixes 🐞 +* Let FastMCPError propagate from dependencies by [@chrisguidry](https://github.com/chrisguidry) in [#2646](https://github.com/PrefectHQ/fastmcp/pull/2646) +* Fix task execution for tools with custom names by [@chrisguidry](https://github.com/chrisguidry) in [#2645](https://github.com/PrefectHQ/fastmcp/pull/2645) +* fix: check the cause of the tool error by [@rjolaverria](https://github.com/rjolaverria) in [#2674](https://github.com/PrefectHQ/fastmcp/pull/2674) +* Bump pydocket to 0.16.3 for task cancellation support by [@chrisguidry](https://github.com/chrisguidry) in [#2683](https://github.com/PrefectHQ/fastmcp/pull/2683) +* Fix uvicorn 0.39+ test timeouts and FastMCPError propagation by [@jlowin](https://github.com/jlowin) in [#2699](https://github.com/PrefectHQ/fastmcp/pull/2699) +* Fix Prefect website URL in docs footer by [@mgoldsborough](https://github.com/mgoldsborough) in [#2701](https://github.com/PrefectHQ/fastmcp/pull/2701) +* Fix: resolve root-level $ref in outputSchema for MCP spec compliance by [@majiayu000](https://github.com/majiayu000) in [#2720](https://github.com/PrefectHQ/fastmcp/pull/2720) +* Fix Provider.get_tasks() to include custom component subclasses by [@jlowin](https://github.com/jlowin) in [#2729](https://github.com/PrefectHQ/fastmcp/pull/2729) +* Fix Proxy provider to return all resource contents by [@jlowin](https://github.com/jlowin) in [#2742](https://github.com/PrefectHQ/fastmcp/pull/2742) +* Fix prompt return type documentation by [@jlowin](https://github.com/jlowin) in [#2741](https://github.com/PrefectHQ/fastmcp/pull/2741) +* fix: Client OAuth async_auth_flow() method causing MCP-SDK self.context.lock error. by [@lgndluke](https://github.com/lgndluke) in [#2644](https://github.com/PrefectHQ/fastmcp/pull/2644) +* Fix rate limit detection during teardown phase by [@jlowin](https://github.com/jlowin) in [#2757](https://github.com/PrefectHQ/fastmcp/pull/2757) +* fix: set pytest-asyncio default fixture loop scope to function by [@jlowin](https://github.com/jlowin) in [#2758](https://github.com/PrefectHQ/fastmcp/pull/2758) +* Fix OAuth Proxy resource parameter validation by [@jlowin](https://github.com/jlowin) in [#2764](https://github.com/PrefectHQ/fastmcp/pull/2764) +* [BugFix] Fix `openapi_version` Check So 3.1 Is Included by [@deeleeramone](https://github.com/deeleeramone) in [#2768](https://github.com/PrefectHQ/fastmcp/pull/2768) +* Fix titled enum elicitation schema to comply with MCP spec by [@jlowin](https://github.com/jlowin) in [#2773](https://github.com/PrefectHQ/fastmcp/pull/2773) +* Fix base_url fallback when url is not set by [@bhbs](https://github.com/bhbs) in [#2776](https://github.com/PrefectHQ/fastmcp/pull/2776) +* Lazy import DiskStore to avoid sqlite3 dependency on import by [@jlowin](https://github.com/jlowin) in [#2784](https://github.com/PrefectHQ/fastmcp/pull/2784) +* Fix OAuth token storage TTL calculation by [@jlowin](https://github.com/jlowin) in [#2796](https://github.com/PrefectHQ/fastmcp/pull/2796) +* Use consistent refresh_ttl for JTI mapping store by [@jlowin](https://github.com/jlowin) in [#2799](https://github.com/PrefectHQ/fastmcp/pull/2799) +* Return 401 for invalid_grant token errors per MCP spec by [@jlowin](https://github.com/jlowin) in [#2800](https://github.com/PrefectHQ/fastmcp/pull/2800) +* Fix client hanging on HTTP 4xx/5xx errors by [@jlowin](https://github.com/jlowin) in [#2803](https://github.com/PrefectHQ/fastmcp/pull/2803) +* Fix unawaited coroutine warning and treat as test error by [@jlowin](https://github.com/jlowin) in [#2806](https://github.com/PrefectHQ/fastmcp/pull/2806) +* Fix keep_alive passthrough in StdioMCPServer.to_transport() by [@jlowin](https://github.com/jlowin) in [#2791](https://github.com/PrefectHQ/fastmcp/pull/2791) +* Dereference $ref in tool schemas for MCP client compatibility by [@jlowin](https://github.com/jlowin) in [#2808](https://github.com/PrefectHQ/fastmcp/pull/2808) +* Prefix Redis keys with docket name for ACL isolation by [@chrisguidry](https://github.com/chrisguidry) in [#2811](https://github.com/PrefectHQ/fastmcp/pull/2811) +* fix smart_home example: HueAttributes schema and deprecated prefix by [@zzstoatzz](https://github.com/zzstoatzz) in [#2818](https://github.com/PrefectHQ/fastmcp/pull/2818) +* Fix redirect URI validation docs to match implementation by [@jlowin](https://github.com/jlowin) in [#2824](https://github.com/PrefectHQ/fastmcp/pull/2824) +* Fix timeout not propagating to proxy clients in multi-server MCPConfig by [@jlowin](https://github.com/jlowin) in [#2809](https://github.com/PrefectHQ/fastmcp/pull/2809) +* Fix ContextVar propagation for ASGI-mounted servers with tasks by [@chrisguidry](https://github.com/chrisguidry) in [#2844](https://github.com/PrefectHQ/fastmcp/pull/2844) +* Fix HTTP transport timeout defaulting to 5 seconds by [@jlowin](https://github.com/jlowin) in [#2849](https://github.com/PrefectHQ/fastmcp/pull/2849) +* Fix decorator error messages to link to correct doc pages by [@jlowin](https://github.com/jlowin) in [#2858](https://github.com/PrefectHQ/fastmcp/pull/2858) +* Fix task capabilities location (issue #2870) by [@jlowin](https://github.com/jlowin) in [#2875](https://github.com/PrefectHQ/fastmcp/pull/2875) +* Bump the uv group across 1 directory with 2 updates by [@dependabot](https://github.com/dependabot)\[bot\] in [#2890](https://github.com/PrefectHQ/fastmcp/pull/2890) +### Breaking Changes 🛫 +* Add VisibilityFilter for hierarchical enable/disable by [@jlowin](https://github.com/jlowin) in [#2708](https://github.com/PrefectHQ/fastmcp/pull/2708) +* Remove automatic environment variable loading from auth providers by [@jlowin](https://github.com/jlowin) in [#2752](https://github.com/PrefectHQ/fastmcp/pull/2752) +* Make pydocket optional and unify DI systems by [@jlowin](https://github.com/jlowin) in [#2835](https://github.com/PrefectHQ/fastmcp/pull/2835) +* Add session-scoped state persistence by [@jlowin](https://github.com/jlowin) in [#2873](https://github.com/PrefectHQ/fastmcp/pull/2873) +### Docs 📚 +* Undocumented `McpError` exceptions by [@ivanbelenky](https://github.com/ivanbelenky) in [#2656](https://github.com/PrefectHQ/fastmcp/pull/2656) +* docs(server): add http to transport options in run() method docstring by [@Ashif4354](https://github.com/Ashif4354) in [#2707](https://github.com/PrefectHQ/fastmcp/pull/2707) +* Add v3 breaking changes notice to README by [@jlowin](https://github.com/jlowin) in [#2712](https://github.com/PrefectHQ/fastmcp/pull/2712) +* Add changelog entries for v2.13.1 through v2.14.1 by [@jlowin](https://github.com/jlowin) in [#2725](https://github.com/PrefectHQ/fastmcp/pull/2725) +* Reorganize docs around provider architecture by [@jlowin](https://github.com/jlowin) in [#2723](https://github.com/PrefectHQ/fastmcp/pull/2723) +* Fix documentation to use 'meta' instead of '_meta' for MCP spec field by [@jlowin](https://github.com/jlowin) in [#2735](https://github.com/PrefectHQ/fastmcp/pull/2735) +* Enhance documentation on tool transformation by [@shea-parkes](https://github.com/shea-parkes) in [#2781](https://github.com/PrefectHQ/fastmcp/pull/2781) +* Add FastMCP 4.0 preview to documentation by [@jlowin](https://github.com/jlowin) in [#2831](https://github.com/PrefectHQ/fastmcp/pull/2831) +* Add release notes for v2.14.2 and v2.14.3 by [@jlowin](https://github.com/jlowin) in [#2852](https://github.com/PrefectHQ/fastmcp/pull/2852) +* Add missing 3.0.0 version badges and document tasks extra by [@jlowin](https://github.com/jlowin) in [#2866](https://github.com/PrefectHQ/fastmcp/pull/2866) +* Fix custom provider docs to show correct interface by [@jlowin](https://github.com/jlowin) in [#2920](https://github.com/PrefectHQ/fastmcp/pull/2920) +* Update v3 features that were missed in PRs by [@jlowin](https://github.com/jlowin) in [#2947](https://github.com/PrefectHQ/fastmcp/pull/2947) +* Restructure documentation for FastMCP 3.0 by [@jlowin](https://github.com/jlowin) in [#2951](https://github.com/PrefectHQ/fastmcp/pull/2951) +* Fix broken documentation links by [@jlowin](https://github.com/jlowin) in [#2952](https://github.com/PrefectHQ/fastmcp/pull/2952) +* Clarify installation for FastMCP 3.0 beta by [@jlowin](https://github.com/jlowin) in [#2953](https://github.com/PrefectHQ/fastmcp/pull/2953) +### Dependencies 📦 +* Bump peter-evans/create-pull-request from 7 to 8 by [@dependabot](https://github.com/dependabot)\[bot\] in [#2623](https://github.com/PrefectHQ/fastmcp/pull/2623) +* Bump ty to 0.0.7+ by [@jlowin](https://github.com/jlowin) in [#2737](https://github.com/PrefectHQ/fastmcp/pull/2737) +* Bump the uv group across 1 directory with 4 updates by [@dependabot](https://github.com/dependabot)\[bot\] in [#2891](https://github.com/PrefectHQ/fastmcp/pull/2891) + +## New Contributors +* [@ivanbelenky](https://github.com/ivanbelenky) made their first contribution in [#2656](https://github.com/PrefectHQ/fastmcp/pull/2656) +* [@rjolaverria](https://github.com/rjolaverria) made their first contribution in [#2674](https://github.com/PrefectHQ/fastmcp/pull/2674) +* [@mgoldsborough](https://github.com/mgoldsborough) made their first contribution in [#2701](https://github.com/PrefectHQ/fastmcp/pull/2701) +* [@Ashif4354](https://github.com/Ashif4354) made their first contribution in [#2707](https://github.com/PrefectHQ/fastmcp/pull/2707) +* [@majiayu000](https://github.com/majiayu000) made their first contribution in [#2720](https://github.com/PrefectHQ/fastmcp/pull/2720) +* [@lgndluke](https://github.com/lgndluke) made their first contribution in [#2644](https://github.com/PrefectHQ/fastmcp/pull/2644) +* [@EloiZalczer](https://github.com/EloiZalczer) made their first contribution in [#2632](https://github.com/PrefectHQ/fastmcp/pull/2632) +* [@deeleeramone](https://github.com/deeleeramone) made their first contribution in [#2768](https://github.com/PrefectHQ/fastmcp/pull/2768) +* [@shea-parkes](https://github.com/shea-parkes) made their first contribution in [#2781](https://github.com/PrefectHQ/fastmcp/pull/2781) +* [@triepod-ai](https://github.com/triepod-ai) made their first contribution in [#2777](https://github.com/PrefectHQ/fastmcp/pull/2777) +* [@bhbs](https://github.com/bhbs) made their first contribution in [#2776](https://github.com/PrefectHQ/fastmcp/pull/2776) +* [@shulkx](https://github.com/shulkx) made their first contribution in [#2884](https://github.com/PrefectHQ/fastmcp/pull/2884) + +**Full Changelog**: [v2.14.1...v3.0.0b1](https://github.com/PrefectHQ/fastmcp/compare/v2.14.1...v3.0.0b1) + + + + + +**[v2.14.5: Sealed Docket](https://github.com/PrefectHQ/fastmcp/releases/tag/v2.14.5)** + +Fixes a memory leak in the memory:// docket broker where cancelled tasks accumulated instead of being cleaned up. Bumps pydocket to ≥0.17.2. + +## What's Changed +### Enhancements 🔧 +* Bump pydocket to 0.17.2 (memory leak fix) by [@chrisguidry](https://github.com/chrisguidry) in [#2992](https://github.com/PrefectHQ/fastmcp/pull/2992) + +**Full Changelog**: [v2.14.4...v2.14.5](https://github.com/PrefectHQ/fastmcp/compare/v2.14.4...v2.14.5) + + + + + +**[v2.14.4: Package Deal](https://github.com/PrefectHQ/fastmcp/releases/tag/v2.14.4)** + +Fixes a fresh install bug where the packaging library was missing as a direct dependency, plus backports from 3.x for $ref dereferencing in tool schemas and a task capabilities location fix. + +## What's Changed +### Enhancements 🔧 +* Add release notes for v2.14.2 and v2.14.3 by [@jlowin](https://github.com/jlowin) in [#2851](https://github.com/PrefectHQ/fastmcp/pull/2851) +### Fixes 🐞 +* Backport: Dereference $ref in tool schemas for MCP client compatibility by [@jlowin](https://github.com/jlowin) in [#2861](https://github.com/PrefectHQ/fastmcp/pull/2861) +* Fix task capabilities location (issue #2870) by [@jlowin](https://github.com/jlowin) in [#2874](https://github.com/PrefectHQ/fastmcp/pull/2874) +* Add missing packaging dependency by [@jlowin](https://github.com/jlowin) in [#2989](https://github.com/PrefectHQ/fastmcp/pull/2989) + +**Full Changelog**: [v2.14.3...v2.14.4](https://github.com/PrefectHQ/fastmcp/compare/v2.14.3...v2.14.4) + + + + + +**[v2.14.3: Time After Timeout](https://github.com/PrefectHQ/fastmcp/releases/tag/v2.14.3)** + +Sometimes five seconds just isn't enough. This release fixes an HTTP transport bug that was cutting connections short, along with OAuth and Redis fixes, better ASGI support, and CLI update notifications so you never miss a beat. + +## What's Changed +### Enhancements 🔧 +* Add debug logging for OAuth token expiry diagnostics by [@jlowin](https://github.com/jlowin) in [#2789](https://github.com/PrefectHQ/fastmcp/pull/2789) +* Add CLI update notifications by [@jlowin](https://github.com/jlowin) in [#2839](https://github.com/PrefectHQ/fastmcp/pull/2839) +* Use pip instead of uv pip in upgrade instructions by [@jlowin](https://github.com/jlowin) in [#2841](https://github.com/PrefectHQ/fastmcp/pull/2841) +### Fixes 🐞 +* Backport OAuth token storage TTL fix to release/2.x by [@jlowin](https://github.com/jlowin) in [#2798](https://github.com/PrefectHQ/fastmcp/pull/2798) +* Prefix Redis keys with docket name for ACL isolation (2.x backport) by [@chrisguidry](https://github.com/chrisguidry) in [#2812](https://github.com/PrefectHQ/fastmcp/pull/2812) +* Fix ContextVar propagation for ASGI-mounted servers with tasks by [@chrisguidry](https://github.com/chrisguidry) in [#2843](https://github.com/PrefectHQ/fastmcp/pull/2843) +* Fix HTTP transport timeout defaulting to 5 seconds by [@jlowin](https://github.com/jlowin) in [#2848](https://github.com/PrefectHQ/fastmcp/pull/2848) + +**Full Changelog**: [v2.14.2...v2.14.3](https://github.com/PrefectHQ/fastmcp/compare/v2.14.2...v2.14.3) + + + + + +**[v2.14.2: Port Authority](https://github.com/PrefectHQ/fastmcp/releases/tag/v2.14.2)** + +FastMCP 2.14.2 brings a wave of community contributions safely into the 2.x line. A variety of important fixes backported from 3.0 work improve OpenAPI 3.1 compatibility, MCP spec compliance for output schemas and elicitation, and correct a subtle base_url fallback issue. The CLI now gently reminds you that FastMCP 3.0 is on the horizon. + +## What's Changed +### Enhancements 🔧 +* Pin MCP under 2.x by [@jlowin](https://github.com/jlowin) in [#2709](https://github.com/PrefectHQ/fastmcp/pull/2709) +* Add auth_route parameter to SupabaseProvider by [@EloiZalczer](https://github.com/EloiZalczer) in [#2760](https://github.com/PrefectHQ/fastmcp/pull/2760) +* Update CLI banner with FastMCP 3.0 notice by [@jlowin](https://github.com/jlowin) in [#2765](https://github.com/PrefectHQ/fastmcp/pull/2765) +### Fixes 🐞 +* Let FastMCPError propagate unchanged from managers by [@jlowin](https://github.com/jlowin) in [#2697](https://github.com/PrefectHQ/fastmcp/pull/2697) +* Fix test cleanup for uvicorn 0.39+ context isolation by [@jlowin](https://github.com/jlowin) in [#2696](https://github.com/PrefectHQ/fastmcp/pull/2696) +* Bump pydocket to 0.16.3 to fix worker cleanup race condition by [@chrisguidry](https://github.com/chrisguidry) in [#2700](https://github.com/PrefectHQ/fastmcp/pull/2700) +* Fix Prefect website URL in docs footer by [@mgoldsborough](https://github.com/mgoldsborough) in [#2705](https://github.com/PrefectHQ/fastmcp/pull/2705) +* Fix: resolve root-level $ref in outputSchema for MCP spec compliance by [@majiayu000](https://github.com/majiayu000) in [#2727](https://github.com/PrefectHQ/fastmcp/pull/2727) +* Fix OAuth Proxy resource parameter validation by [@jlowin](https://github.com/jlowin) in [#2763](https://github.com/PrefectHQ/fastmcp/pull/2763) +* Fix openapi_version check to include 3.1 by [@deeleeramone](https://github.com/deeleeramone) in [#2769](https://github.com/PrefectHQ/fastmcp/pull/2769) +* Fix titled enum elicitation schema to comply with MCP spec by [@jlowin](https://github.com/jlowin) in [#2774](https://github.com/PrefectHQ/fastmcp/pull/2774) +* Fix base_url fallback when url is not set by [@bhbs](https://github.com/bhbs) in [#2782](https://github.com/PrefectHQ/fastmcp/pull/2782) +* Lazy import DiskStore to avoid sqlite3 dependency on import by [@jlowin](https://github.com/jlowin) in [#2785](https://github.com/PrefectHQ/fastmcp/pull/2785) +### Docs 📚 +* Add v3 breaking changes notice to README and docs by [@jlowin](https://github.com/jlowin) in [#2713](https://github.com/PrefectHQ/fastmcp/pull/2713) +* Add changelog entries for v2.13.1 through v2.14.1 by [@jlowin](https://github.com/jlowin) in [#2724](https://github.com/PrefectHQ/fastmcp/pull/2724) +* conference to 2.x branch by [@aaazzam](https://github.com/aaazzam) in [#2787](https://github.com/PrefectHQ/fastmcp/pull/2787) + +**Full Changelog**: [v2.14.1...v2.14.2](https://github.com/PrefectHQ/fastmcp/compare/v2.14.1...v2.14.2) + + + + + +**[v2.14.1: 'Tis a Gift to Be Sample](https://github.com/PrefectHQ/fastmcp/releases/tag/v2.14.1)** + +FastMCP 2.14.1 introduces sampling with tools (SEP-1577), enabling servers to pass tools to `ctx.sample()` for agentic workflows where the LLM can automatically execute tool calls in a loop. The new `ctx.sample_step()` method provides single LLM calls that return `SampleStep` objects for custom control flow, while `result_type` enables structured outputs via validated Pydantic models. + +🤖 **AnthropicSamplingHandler** joins the existing OpenAI handler, providing multi-provider sampling support out of the box. + +⚡ **OpenAISamplingHandler promoted** from experimental status—sampling handlers are now production-ready with a unified API. + +## What's Changed +### New Features 🎉 +* Sampling with tools by [@jlowin](https://github.com/jlowin) in [#2538](https://github.com/PrefectHQ/fastmcp/pull/2538) +* Add AnthropicSamplingHandler by [@jlowin](https://github.com/jlowin) in [#2677](https://github.com/PrefectHQ/fastmcp/pull/2677) +### Enhancements 🔧 +* Add Python 3.13 to ubuntu CI by [@jlowin](https://github.com/jlowin) in [#2648](https://github.com/PrefectHQ/fastmcp/pull/2648) +* Remove legacy task initialization workaround by [@jlowin](https://github.com/jlowin) in [#2649](https://github.com/PrefectHQ/fastmcp/pull/2649) +* Consolidate session state reset logic by [@jlowin](https://github.com/jlowin) in [#2651](https://github.com/PrefectHQ/fastmcp/pull/2651) +* Unify SamplingHandler; promote OpenAI from experimental by [@jlowin](https://github.com/jlowin) in [#2656](https://github.com/PrefectHQ/fastmcp/pull/2656) +* Add `tool_names` parameter to mount() for name customization by [@jlowin](https://github.com/jlowin) in [#2660](https://github.com/PrefectHQ/fastmcp/pull/2660) +* Use streamable HTTP client API from MCP SDK by [@jlowin](https://github.com/jlowin) in [#2678](https://github.com/PrefectHQ/fastmcp/pull/2678) +* Deprecate `exclude_args` in favor of Depends() by [@jlowin](https://github.com/jlowin) in [#2693](https://github.com/PrefectHQ/fastmcp/pull/2693) +### Fixes 🐞 +* Fix prompt tasks to return mcp.types.PromptMessage by [@jlowin](https://github.com/jlowin) in [#2650](https://github.com/PrefectHQ/fastmcp/pull/2650) +* Fix Windows test warnings by [@jlowin](https://github.com/jlowin) in [#2653](https://github.com/PrefectHQ/fastmcp/pull/2653) +* Cleanup cancelled connection startup by [@jlowin](https://github.com/jlowin) in [#2679](https://github.com/PrefectHQ/fastmcp/pull/2679) +* Fix tool choice bug in sampling examples by [@shawnthapa](https://github.com/shawnthapa) in [#2686](https://github.com/PrefectHQ/fastmcp/pull/2686) +### Docs 📚 +* Simplify Docket tip wording by [@chrisguidry](https://github.com/chrisguidry) in [#2662](https://github.com/PrefectHQ/fastmcp/pull/2662) +### Other Changes 🦾 +* Bump pydocket to ≥0.15.5 by [@jlowin](https://github.com/jlowin) in [#2694](https://github.com/PrefectHQ/fastmcp/pull/2694) + +## New Contributors +* [@shawnthapa](https://github.com/shawnthapa) made their first contribution in [#2686](https://github.com/PrefectHQ/fastmcp/pull/2686) + +**Full Changelog**: [v2.14.0...v2.14.1](https://github.com/PrefectHQ/fastmcp/compare/v2.14.0...v2.14.1) + + + + + +**[v2.14.0: Task and You Shall Receive](https://github.com/PrefectHQ/fastmcp/releases/tag/v2.14.0)** + +FastMCP 2.14 begins adopting the MCP 2025-11-25 specification, introducing protocol-native background tasks (SEP-1686) that enable long-running operations to report progress without blocking clients. The experimental OpenAPI parser graduates to standard, the `OpenAISamplingHandler` is promoted from experimental, and deprecated APIs accumulated across the 2.x series are removed. + +⏳ **Background Tasks** let you add `task=True` to any async tool decorator to run operations in the background with progress tracking. Powered by [Docket](https://github.com/chrisguidry/docket), an enterprise task scheduler handling millions of concurrent tasks daily—in-memory backends work out-of-the-box, and Redis URLs enable persistence and horizontal scaling. + +🔧 **OpenAPI Parser Promoted** from experimental to standard with improved performance through single-pass schema processing and cleaner abstractions. + +📋 **MCP 2025-11-25 Specification Support** including SSE polling and event resumability (SEP-1699), multi-select enum elicitation schemas (SEP-1330), default values for elicitation (SEP-1034), and tool name validation at registration time (SEP-986). + +## Breaking Changes +- Docket is always enabled; task execution is forbidden through proxies +- Task protocol enabled by default +- Removed deprecated settings, imports, and methods accumulated across 2.x series + +## What's Changed +### New Features 🎉 +* OpenAPI parser is now the default by [@jlowin](https://github.com/jlowin) in [#2583](https://github.com/PrefectHQ/fastmcp/pull/2583) +* Implement SEP-1686: Background Tasks by [@jlowin](https://github.com/jlowin) in [#2550](https://github.com/PrefectHQ/fastmcp/pull/2550) +### Enhancements 🔧 +* Expose InitializeResult in middleware by [@jlowin](https://github.com/jlowin) in [#2562](https://github.com/PrefectHQ/fastmcp/pull/2562) +* Update MCP SDK auth compatibility by [@jlowin](https://github.com/jlowin) in [#2574](https://github.com/PrefectHQ/fastmcp/pull/2574) +* Validate tool names at registration (SEP-986) by [@jlowin](https://github.com/jlowin) in [#2588](https://github.com/PrefectHQ/fastmcp/pull/2588) +* Support SEP-1034 and SEP-1330 for elicitation by [@jlowin](https://github.com/jlowin) in [#2595](https://github.com/PrefectHQ/fastmcp/pull/2595) +* Implement SSE polling (SEP-1699) by [@jlowin](https://github.com/jlowin) in [#2612](https://github.com/PrefectHQ/fastmcp/pull/2612) +* Expose session ID callback by [@jlowin](https://github.com/jlowin) in [#2628](https://github.com/PrefectHQ/fastmcp/pull/2628) +### Fixes 🐞 +* Fix OAuth metadata discovery by [@jlowin](https://github.com/jlowin) in [#2565](https://github.com/PrefectHQ/fastmcp/pull/2565) +* Fix fastapi.cli package structure by [@jlowin](https://github.com/jlowin) in [#2570](https://github.com/PrefectHQ/fastmcp/pull/2570) +* Correct OAuth error codes by [@jlowin](https://github.com/jlowin) in [#2578](https://github.com/PrefectHQ/fastmcp/pull/2578) +* Prevent function signature modification by [@jlowin](https://github.com/jlowin) in [#2590](https://github.com/PrefectHQ/fastmcp/pull/2590) +* Fix proxy client kwargs by [@jlowin](https://github.com/jlowin) in [#2605](https://github.com/PrefectHQ/fastmcp/pull/2605) +* Fix nested server routing by [@jlowin](https://github.com/jlowin) in [#2618](https://github.com/PrefectHQ/fastmcp/pull/2618) +* Use access token expiry fallback by [@jlowin](https://github.com/jlowin) in [#2635](https://github.com/PrefectHQ/fastmcp/pull/2635) +* Handle transport cleanup exceptions by [@jlowin](https://github.com/jlowin) in [#2642](https://github.com/PrefectHQ/fastmcp/pull/2642) +### Docs 📚 +* Add OCI and Supabase integration docs by [@jlowin](https://github.com/jlowin) in [#2580](https://github.com/PrefectHQ/fastmcp/pull/2580) +* Add v2.14.0 upgrade guide by [@jlowin](https://github.com/jlowin) in [#2598](https://github.com/PrefectHQ/fastmcp/pull/2598) +* Rewrite background tasks documentation by [@jlowin](https://github.com/jlowin) in [#2620](https://github.com/PrefectHQ/fastmcp/pull/2620) +* Document read-only tool patterns by [@jlowin](https://github.com/jlowin) in [#2632](https://github.com/PrefectHQ/fastmcp/pull/2632) + +## New Contributors +11 total contributors including 7 first-time participants. + +**Full Changelog**: [v2.13.3...v2.14.0](https://github.com/PrefectHQ/fastmcp/compare/v2.13.3...v2.14.0) + + + + + +**[v2.13.3: Pin-ish Line](https://github.com/PrefectHQ/fastmcp/releases/tag/v2.13.3)** + +FastMCP 2.13.3 pins `mcp<1.23` as a precautionary measure. MCP SDK 1.23 introduced changes related to the November 25, 2025 MCP protocol update that break certain FastMCP patches and workarounds, particularly around OAuth implementation details. FastMCP 2.14 introduces proper support for the updated protocol and requires `mcp>=1.23`. + +## What's Changed +### Fixes 🐞 +* Pin MCP SDK below 1.23 by [@jlowin](https://github.com/jlowin) in [#2545](https://github.com/PrefectHQ/fastmcp/pull/2545) + +**Full Changelog**: [v2.13.2...v2.13.3](https://github.com/PrefectHQ/fastmcp/compare/v2.13.2...v2.13.3) + + + + + +**[v2.13.2: Refreshing Changes](https://github.com/PrefectHQ/fastmcp/releases/tag/v2.13.2)** + +FastMCP 2.13.2 polishes the authentication stack with improvements to token refresh, scope handling, and multi-instance deployments. Discord was added as a built-in OAuth provider, Azure and Google token handling became more reliable, and proxy classes now properly forward icons and titles. + +## What's Changed +### New Features 🎉 +* Add Discord OAuth provider by [@jlowin](https://github.com/jlowin) in [#2480](https://github.com/PrefectHQ/fastmcp/pull/2480) +### Enhancements 🔧 +* Descope Provider updates for new well-known URLs by [@anvibanga](https://github.com/anvibanga) in [#2465](https://github.com/PrefectHQ/fastmcp/pull/2465) +* Scalekit provider improvements by [@jlowin](https://github.com/jlowin) in [#2472](https://github.com/PrefectHQ/fastmcp/pull/2472) +* Add CSP customization for consent screens by [@jlowin](https://github.com/jlowin) in [#2488](https://github.com/PrefectHQ/fastmcp/pull/2488) +* Add icon support to proxy classes by [@jlowin](https://github.com/jlowin) in [#2495](https://github.com/PrefectHQ/fastmcp/pull/2495) +### Fixes 🐞 +* Google Provider now defaults to refresh token support by [@jlowin](https://github.com/jlowin) in [#2468](https://github.com/PrefectHQ/fastmcp/pull/2468) +* Fix Azure OAuth token refresh with unprefixed scopes by [@jlowin](https://github.com/jlowin) in [#2475](https://github.com/PrefectHQ/fastmcp/pull/2475) +* Prevent `$defs` mutation during tool transforms by [@jlowin](https://github.com/jlowin) in [#2482](https://github.com/PrefectHQ/fastmcp/pull/2482) +* Fix OAuth proxy refresh token storage for multi-instance deployments by [@jlowin](https://github.com/jlowin) in [#2490](https://github.com/PrefectHQ/fastmcp/pull/2490) +* Fix stale token issue after OAuth refresh by [@jlowin](https://github.com/jlowin) in [#2498](https://github.com/PrefectHQ/fastmcp/pull/2498) +* Fix Azure provider OIDC scope handling by [@jlowin](https://github.com/jlowin) in [#2505](https://github.com/PrefectHQ/fastmcp/pull/2505) + +## New Contributors +7 new contributors made their first FastMCP contributions in this release. + +**Full Changelog**: [v2.13.1...v2.13.2](https://github.com/PrefectHQ/fastmcp/compare/v2.13.1...v2.13.2) + + + + + +**[v2.13.1: Heavy Meta](https://github.com/PrefectHQ/fastmcp/releases/tag/v2.13.1)** + +FastMCP 2.13.1 introduces meta parameter support for `ToolResult`, enabling tools to return supplementary metadata alongside results. This supports emerging use cases like OpenAI's Apps SDK. The release also brings improved OAuth functionality with custom token verifiers including a new DebugTokenVerifier, and adds OCI and Supabase authentication providers. + +🏷️ **Meta parameters for ToolResult** enable tools to return supplementary metadata alongside results, supporting patterns like OpenAI's Apps SDK integration. + +🔐 **Custom token verifiers** with DebugTokenVerifier for development, plus Azure Government support through a `base_authority` parameter and Supabase authentication algorithm configuration. + +🔒 **Security fixes** address CVE-2025-61920 through authlib updates and validate Cursor deeplink URLs using safer Windows APIs. + +## What's Changed +### New Features 🎉 +* Add meta parameter support for ToolResult by [@jlowin](https://github.com/jlowin) in [#2350](https://github.com/PrefectHQ/fastmcp/pull/2350) +* Add OCI authentication provider by [@jlowin](https://github.com/jlowin) in [#2365](https://github.com/PrefectHQ/fastmcp/pull/2365) +* Add Supabase authentication provider by [@jlowin](https://github.com/jlowin) in [#2378](https://github.com/PrefectHQ/fastmcp/pull/2378) +### Enhancements 🔧 +* Add custom token verifier support to OIDCProxy by [@jlowin](https://github.com/jlowin) in [#2355](https://github.com/PrefectHQ/fastmcp/pull/2355) +* Add DebugTokenVerifier for development by [@jlowin](https://github.com/jlowin) in [#2362](https://github.com/PrefectHQ/fastmcp/pull/2362) +* Add Azure Government support via base_authority parameter by [@jlowin](https://github.com/jlowin) in [#2385](https://github.com/PrefectHQ/fastmcp/pull/2385) +* Add Supabase authentication algorithm configuration by [@jlowin](https://github.com/jlowin) in [#2392](https://github.com/PrefectHQ/fastmcp/pull/2392) +### Fixes 🐞 +* Security: Update authlib for CVE-2025-61920 by [@jlowin](https://github.com/jlowin) in [#2398](https://github.com/PrefectHQ/fastmcp/pull/2398) +* Validate Cursor deeplink URLs using safer Windows APIs by [@jlowin](https://github.com/jlowin) in [#2405](https://github.com/PrefectHQ/fastmcp/pull/2405) +* Exclude MCP SDK 1.21.1 due to integration test failures by [@jlowin](https://github.com/jlowin) in [#2422](https://github.com/PrefectHQ/fastmcp/pull/2422) + +## New Contributors +18 new contributors joined in this release across 70+ pull requests. + +**Full Changelog**: [v2.13.0...v2.13.1](https://github.com/PrefectHQ/fastmcp/compare/v2.13.0...v2.13.1) + + + + + +**[v2.13.0: Cache Me If You Can](https://github.com/PrefectHQ/fastmcp/releases/tag/v2.13.0)** + +FastMCP 2.13 "Cache Me If You Can" represents a fundamental maturation of the framework. After months of community feedback on authentication and state management, this release delivers the infrastructure FastMCP needs to handle production workloads: persistent storage, response caching, and pragmatic OAuth improvements that reflect real-world deployment challenges. + +💾 **Pluggable storage backends** bring persistent state to FastMCP servers. Built on [py-key-value-aio](https://github.com/strawgate/py-key-value), a new library from FastMCP maintainer Bill Easton ([@strawgate](https://github.com/strawgate)), the storage layer provides encrypted disk storage by default, platform-aware token management, and a simple key-value interface for application state. We're excited to bring this elegantly designed library into the FastMCP ecosystem - it's both powerful and remarkably easy to use, including wrappers to add encryption, TTLs, caching, and more to backends ranging from Elasticsearch, Redis, DynamoDB, filesystem, in-memory, and more! OAuth providers now automatically persist tokens across restarts, and developers can store arbitrary state without reaching for external databases. This foundation enables long-running sessions, cached credentials, and stateful applications built on MCP. + +🔐 **OAuth maturity** brings months of production learnings into the framework. The new consent screen prevents confused deputy and authorization bypass attacks discovered in earlier versions while providing a clean UX with customizable branding. The OAuth proxy now issues its own tokens with automatic key derivation from client secrets, and RFC 7662 token introspection support enables enterprise auth flows. Path prefix mounting enables OAuth-protected servers to integrate into existing web applications under custom paths like `/api`, and MCP 1.17+ compliance with RFC 9728 ensures protocol compatibility. Combined with improved error handling and platform-aware token storage, OAuth is now production-ready and security-hardened for serious applications. + +FastMCP now supports out-of-the-box authentication with: +- **[WorkOS](https://gofastmcp.com/integrations/workos)** and **[AuthKit](https://gofastmcp.com/integrations/authkit)** +- **[GitHub](https://gofastmcp.com/integrations/github)** +- **[Google](https://gofastmcp.com/integrations/google)** +- **[Azure](https://gofastmcp.com/integrations/azure)** (Entra ID) +- **[AWS Cognito](https://gofastmcp.com/integrations/aws-cognito)** +- **[Auth0](https://gofastmcp.com/integrations/auth0)** +- **[Descope](https://gofastmcp.com/integrations/descope)** +- **[Scalekit](https://gofastmcp.com/integrations/scalekit)** +- **[JWTs](https://gofastmcp.com/servers/auth/token-verification#jwt-token-verification)** +- **[RFC 7662 token introspection](https://gofastmcp.com/servers/auth/token-verification#token-introspection-protocol)** + +⚡ **Response Caching Middleware** dramatically improves performance for expensive operations. Cache tool and resource responses with configurable TTLs, reducing redundant API calls and speeding up repeated queries. + +🔄 **Server lifespans** provide proper initialization and cleanup hooks that run once per server instance instead of per client session. This fixes a long-standing source of confusion in the MCP SDK and enables proper resource management for database connections, background tasks, and other server-level state. Note: this is a breaking behavioral change if you were using the `lifespan` parameter. + +✨ **Developer experience improvements** include Pydantic input validation for better type safety, icon support for richer UX, RFC 6570 query parameters for resource templates, improved Context API methods (list_resources, list_prompts, get_prompt), and async file/directory resources. + +This release includes contributions from **20** new contributors and represents the largest feature set in a while. Thank you to everyone who tested preview builds and filed issues - your feedback shaped these improvements! + +**Full Changelog**: [v2.12.5...v2.13.0](https://github.com/PrefectHQ/fastmcp/compare/v2.12.5...v2.13.0) + + + + + +**[v2.12.5: Safety Pin](https://github.com/PrefectHQ/fastmcp/releases/tag/v2.12.5)** + +FastMCP 2.12.5 is a point release that pins the MCP SDK version below 1.17, which introduced a change affecting FastMCP users with auth providers mounted as part of a larger application. This ensures the `.well-known` payload appears in the expected location when using FastMCP authentication providers with composite applications. + +## What's Changed + +### Fixes 🐞 +* Pin MCP SDK version below 1.17 by [@jlowin](https://github.com/jlowin) in [a1b2c3d](https://github.com/PrefectHQ/fastmcp/commit/dab2b316ddc3883b7896a86da21cacb68da01e5c) + +**Full Changelog**: [v2.12.4...v2.12.5](https://github.com/PrefectHQ/fastmcp/compare/v2.12.4...v2.12.5) + + + + + +**[v2.12.4: OIDC What You Did There](https://github.com/PrefectHQ/fastmcp/releases/tag/v2.12.4)** + +FastMCP 2.12.4 adds comprehensive OIDC support and expands authentication options with AWS Cognito and Descope providers. The release also includes improvements to logging middleware, URL handling for nested resources, persistent OAuth client registration storage, and various fixes to the experimental OpenAPI parser. + +## What's Changed +### New Features 🎉 +* feat: Add support for OIDC configuration by [@ruhulio](https://github.com/ruhulio) in [#1817](https://github.com/PrefectHQ/fastmcp/pull/1817) +### Enhancements 🔧 +* feat: Move the Starlette context middleware to the front by [@akkuman](https://github.com/akkuman) in [#1812](https://github.com/PrefectHQ/fastmcp/pull/1812) +* Refactor Logging and Structured Logging Middleware by [@strawgate](https://github.com/strawgate) in [#1805](https://github.com/PrefectHQ/fastmcp/pull/1805) +* Update pull_request_template.md by [@jlowin](https://github.com/jlowin) in [#1824](https://github.com/PrefectHQ/fastmcp/pull/1824) +* chore: Set redirect_path default in function by [@ruhulio](https://github.com/ruhulio) in [#1833](https://github.com/PrefectHQ/fastmcp/pull/1833) +* feat: Set instructions in code by [@attiks](https://github.com/attiks) in [#1838](https://github.com/PrefectHQ/fastmcp/pull/1838) +* Automatically Create inline Snapshots by [@strawgate](https://github.com/strawgate) in [#1779](https://github.com/PrefectHQ/fastmcp/pull/1779) +* chore: Cleanup Auth0 redirect_path initialization by [@ruhulio](https://github.com/ruhulio) in [#1842](https://github.com/PrefectHQ/fastmcp/pull/1842) +* feat: Add support for Descope Authentication by [@anvibanga](https://github.com/anvibanga) in [#1853](https://github.com/PrefectHQ/fastmcp/pull/1853) +* Update descope version badges by [@jlowin](https://github.com/jlowin) in [#1870](https://github.com/PrefectHQ/fastmcp/pull/1870) +* Update welcome images by [@jlowin](https://github.com/jlowin) in [#1884](https://github.com/PrefectHQ/fastmcp/pull/1884) +* Fix rounded edges of image by [@jlowin](https://github.com/jlowin) in [#1886](https://github.com/PrefectHQ/fastmcp/pull/1886) +* optimize test suite by [@zzstoatzz](https://github.com/zzstoatzz) in [#1893](https://github.com/PrefectHQ/fastmcp/pull/1893) +* Enhancement: client completions support context_arguments by [@isijoe](https://github.com/isijoe) in [#1906](https://github.com/PrefectHQ/fastmcp/pull/1906) +* Update Descope icon by [@anvibanga](https://github.com/anvibanga) in [#1912](https://github.com/PrefectHQ/fastmcp/pull/1912) +* Add AWS Cognito OAuth Provider for Enterprise Authentication by [@stephaneberle9](https://github.com/stephaneberle9) in [#1873](https://github.com/PrefectHQ/fastmcp/pull/1873) +* Fix typos discovered by codespell by [@cclauss](https://github.com/cclauss) in [#1922](https://github.com/PrefectHQ/fastmcp/pull/1922) +* Use lowercase namespace for fastmcp logger by [@jlowin](https://github.com/jlowin) in [#1791](https://github.com/PrefectHQ/fastmcp/pull/1791) +### Fixes 🐞 +* Update quickstart.mdx by [@radi-dev](https://github.com/radi-dev) in [#1821](https://github.com/PrefectHQ/fastmcp/pull/1821) +* Remove extraneous union import by [@jlowin](https://github.com/jlowin) in [#1823](https://github.com/PrefectHQ/fastmcp/pull/1823) +* Delay import of Provider classes until FastMCP Server Creation by [@strawgate](https://github.com/strawgate) in [#1820](https://github.com/PrefectHQ/fastmcp/pull/1820) +* fix: correct documentation link in deprecation warning by [@strawgate](https://github.com/strawgate) in [#1828](https://github.com/PrefectHQ/fastmcp/pull/1828) +* fix: Increase default 3s timeout on Pytest by [@dacamposol](https://github.com/dacamposol) in [#1866](https://github.com/PrefectHQ/fastmcp/pull/1866) +* fix: Improve URL handling in OIDCConfiguration by [@ruhulio](https://github.com/ruhulio) in [#1850](https://github.com/PrefectHQ/fastmcp/pull/1850) +* fix: correct typing for on_read_resource middleware method by [@strawgate](https://github.com/strawgate) in [#1858](https://github.com/PrefectHQ/fastmcp/pull/1858) +* feat(experimental/openapi): replace $ref in additionalProperties; add tests by [@jlowin](https://github.com/jlowin) in [#1735](https://github.com/PrefectHQ/fastmcp/pull/1735) +* Honor client supplied scopes during registration by [@dmikusa](https://github.com/dmikusa) in [#1860](https://github.com/PrefectHQ/fastmcp/pull/1860) +* Fix: FastAPI list parameter parsing in experimental OpenAPI parser by [@jlowin](https://github.com/jlowin) in [#1834](https://github.com/PrefectHQ/fastmcp/pull/1834) +* Add log level support for stdio and HTTP transports by [@jlowin](https://github.com/jlowin) in [#1840](https://github.com/PrefectHQ/fastmcp/pull/1840) +* Fix OAuth pre-flight check to accept HTTP 200 responses by [@jlowin](https://github.com/jlowin) in [#1874](https://github.com/PrefectHQ/fastmcp/pull/1874) +* Fix: Preserve OpenAPI parameter descriptions in experimental parser by [@shlomo666](https://github.com/shlomo666) in [#1877](https://github.com/PrefectHQ/fastmcp/pull/1877) +* Add persistent storage for OAuth client registrations by [@jlowin](https://github.com/jlowin) in [#1879](https://github.com/PrefectHQ/fastmcp/pull/1879) +* docs: update release dates based on github releases by [@lodu](https://github.com/lodu) in [#1890](https://github.com/PrefectHQ/fastmcp/pull/1890) +* Small updates to Sampling types by [@strawgate](https://github.com/strawgate) in [#1882](https://github.com/PrefectHQ/fastmcp/pull/1882) +* remove lockfile smart_home example by [@zzstoatzz](https://github.com/zzstoatzz) in [#1892](https://github.com/PrefectHQ/fastmcp/pull/1892) +* Fix: Remove JSON schema title metadata while preserving parameters named 'title' by [@jlowin](https://github.com/jlowin) in [#1872](https://github.com/PrefectHQ/fastmcp/pull/1872) +* Fix: get_resource_url nested URL handling by [@raphael-linx](https://github.com/raphael-linx) in [#1914](https://github.com/PrefectHQ/fastmcp/pull/1914) +* Clean up code for creating the resource url by [@jlowin](https://github.com/jlowin) in [#1916](https://github.com/PrefectHQ/fastmcp/pull/1916) +* Fix route count logging in OpenAPI server by [@zzstoatzz](https://github.com/zzstoatzz) in [#1928](https://github.com/PrefectHQ/fastmcp/pull/1928) +### Docs 📚 +* docs: make Gemini CLI integration discoverable by [@jackwotherspoon](https://github.com/jackwotherspoon) in [#1827](https://github.com/PrefectHQ/fastmcp/pull/1827) +* docs: update NEW tags for AI assistant integrations by [@jackwotherspoon](https://github.com/jackwotherspoon) in [#1829](https://github.com/PrefectHQ/fastmcp/pull/1829) +* Update wordmark by [@jlowin](https://github.com/jlowin) in [#1832](https://github.com/PrefectHQ/fastmcp/pull/1832) +* docs: improve OAuth and OIDC Proxy documentation by [@jlowin](https://github.com/jlowin) in [#1880](https://github.com/PrefectHQ/fastmcp/pull/1880) +* Update readme + welcome docs by [@jlowin](https://github.com/jlowin) in [#1883](https://github.com/PrefectHQ/fastmcp/pull/1883) +* Update dark mode image in README by [@jlowin](https://github.com/jlowin) in [#1885](https://github.com/PrefectHQ/fastmcp/pull/1885) + +## New Contributors +* [@radi-dev](https://github.com/radi-dev) made their first contribution in [#1821](https://github.com/PrefectHQ/fastmcp/pull/1821) +* [@akkuman](https://github.com/akkuman) made their first contribution in [#1812](https://github.com/PrefectHQ/fastmcp/pull/1812) +* [@ruhulio](https://github.com/ruhulio) made their first contribution in [#1817](https://github.com/PrefectHQ/fastmcp/pull/1817) +* [@attiks](https://github.com/attiks) made their first contribution in [#1838](https://github.com/PrefectHQ/fastmcp/pull/1838) +* [@anvibanga](https://github.com/anvibanga) made their first contribution in [#1853](https://github.com/PrefectHQ/fastmcp/pull/1853) +* [@shlomo666](https://github.com/shlomo666) made their first contribution in [#1877](https://github.com/PrefectHQ/fastmcp/pull/1877) +* [@lodu](https://github.com/lodu) made their first contribution in [#1890](https://github.com/PrefectHQ/fastmcp/pull/1890) +* [@isijoe](https://github.com/isijoe) made their first contribution in [#1906](https://github.com/PrefectHQ/fastmcp/pull/1906) +* [@raphael-linx](https://github.com/raphael-linx) made their first contribution in [#1914](https://github.com/PrefectHQ/fastmcp/pull/1914) +* [@stephaneberle9](https://github.com/stephaneberle9) made their first contribution in [#1873](https://github.com/PrefectHQ/fastmcp/pull/1873) +* [@cclauss](https://github.com/cclauss) made their first contribution in [#1922](https://github.com/PrefectHQ/fastmcp/pull/1922) + +**Full Changelog**: [v2.12.3...v2.12.4](https://github.com/PrefectHQ/fastmcp/compare/v2.12.3...v2.12.4) + + + + + +**[v2.12.3: Double Time](https://github.com/PrefectHQ/fastmcp/releases/tag/v2.12.3)** + +FastMCP 2.12.3 focuses on performance and developer experience improvements based on community feedback. This release includes optimized auth provider imports that reduce server startup time, enhanced OIDC authentication flows with proper token management, and several reliability fixes for OAuth proxy configurations. The addition of automatic inline snapshot creation significantly improves the testing experience for contributors. + +## What's Changed +### New Features 🎉 +* feat: Support setting MCP log level via transport configuration by [@jlowin](https://github.com/jlowin) in [#1756](https://github.com/PrefectHQ/fastmcp/pull/1756) +### Enhancements 🔧 +* Add client-side auth support for mcp install cursor command by [@jlowin](https://github.com/jlowin) in [#1747](https://github.com/PrefectHQ/fastmcp/pull/1747) +* Automatically Create inline Snapshots by [@strawgate](https://github.com/strawgate) in [#1779](https://github.com/PrefectHQ/fastmcp/pull/1779) +* Use lowercase namespace for fastmcp logger by [@jlowin](https://github.com/jlowin) in [#1791](https://github.com/PrefectHQ/fastmcp/pull/1791) +### Fixes 🐞 +* fix: correct merge mistake during auth0 refactor by [@strawgate](https://github.com/strawgate) in [#1742](https://github.com/PrefectHQ/fastmcp/pull/1742) +* Remove extraneous union import by [@jlowin](https://github.com/jlowin) in [#1823](https://github.com/PrefectHQ/fastmcp/pull/1823) +* Delay import of Provider classes until FastMCP Server Creation by [@strawgate](https://github.com/strawgate) in [#1820](https://github.com/PrefectHQ/fastmcp/pull/1820) +* fix: refactor OIDC configuration provider for proper token management by [@strawgate](https://github.com/strawgate) in [#1751](https://github.com/PrefectHQ/fastmcp/pull/1751) +* Fix smart_home example imports by [@strawgate](https://github.com/strawgate) in [#1753](https://github.com/PrefectHQ/fastmcp/pull/1753) +* fix: correct oauth proxy initialization of client by [@strawgate](https://github.com/strawgate) in [#1759](https://github.com/PrefectHQ/fastmcp/pull/1759) +* Fix: return empty string when prompts have no arguments by [@jlowin](https://github.com/jlowin) in [#1766](https://github.com/PrefectHQ/fastmcp/pull/1766) +* Fix async server callbacks by [@strawgate](https://github.com/strawgate) in [#1774](https://github.com/PrefectHQ/fastmcp/pull/1774) +* Fix error when retrieving Completion API errors by [@strawgate](https://github.com/strawgate) in [#1785](https://github.com/PrefectHQ/fastmcp/pull/1785) +* fix: correct documentation link in deprecation warning by [@strawgate](https://github.com/strawgate) in [#1828](https://github.com/PrefectHQ/fastmcp/pull/1828) +### Docs 📚 +* Add migration docs for 2.12 by [@jlowin](https://github.com/jlowin) in [#1745](https://github.com/PrefectHQ/fastmcp/pull/1745) +* Update docs for default sampling implementation to mention OpenAI API Key by [@strawgate](https://github.com/strawgate) in [#1763](https://github.com/PrefectHQ/fastmcp/pull/1763) +* Add tip about sampling prompts and user_context to sampling documentation by [@jlowin](https://github.com/jlowin) in [#1764](https://github.com/PrefectHQ/fastmcp/pull/1764) +* Update quickstart.mdx by [@radi-dev](https://github.com/radi-dev) in [#1821](https://github.com/PrefectHQ/fastmcp/pull/1821) +### Other Changes 🦾 +* Replace Marvin with Claude Code in CI by [@jlowin](https://github.com/jlowin) in [#1800](https://github.com/PrefectHQ/fastmcp/pull/1800) +* Refactor logging and structured logging middleware by [@strawgate](https://github.com/strawgate) in [#1805](https://github.com/PrefectHQ/fastmcp/pull/1805) +* feat: Move the Starlette context middleware to the front by [@akkuman](https://github.com/akkuman) in [#1812](https://github.com/PrefectHQ/fastmcp/pull/1812) +* feat: Add support for OIDC configuration by [@ruhulio](https://github.com/ruhulio) in [#1817](https://github.com/PrefectHQ/fastmcp/pull/1817) + +## New Contributors +* [@radi-dev](https://github.com/radi-dev) made their first contribution in [#1821](https://github.com/PrefectHQ/fastmcp/pull/1821) +* [@akkuman](https://github.com/akkuman) made their first contribution in [#1812](https://github.com/PrefectHQ/fastmcp/pull/1812) +* [@ruhulio](https://github.com/ruhulio) made their first contribution in [#1817](https://github.com/PrefectHQ/fastmcp/pull/1817) + +**Full Changelog**: [v2.12.2...v2.12.3](https://github.com/PrefectHQ/fastmcp/compare/v2.12.2...v2.12.3) + + + + + +**[v2.12.2: Perchance to Stream](https://github.com/PrefectHQ/fastmcp/releases/tag/v2.12.2)** + +This is a hotfix for a bug where the `streamable-http` transport was not recognized as a valid option in `fastmcp.json` configuration files, despite being supported by the CLI. This resulted in a parsing error when the CLI arguments were merged against the configuration spec. + +## What's Changed +### Fixes 🐞 +* Fix streamable-http transport validation in fastmcp.json config by [@jlowin](https://github.com/jlowin) in [#1739](https://github.com/PrefectHQ/fastmcp/pull/1739) + +**Full Changelog**: [v2.12.1...v2.12.2](https://github.com/PrefectHQ/fastmcp/compare/v2.12.1...v2.12.2) + + + + + +**[v2.12.1: OAuth to Joy](https://github.com/PrefectHQ/fastmcp/releases/tag/v2.12.1)** + +FastMCP 2.12.1 strengthens the OAuth proxy implementation based on extensive community testing and feedback. This release improves client storage reliability, adds PKCE forwarding for enhanced security, introduces configurable token endpoint authentication methods, and expands scope handling—all addressing real-world integration challenges discovered since 2.12.0. The enhanced test suite with mock providers ensures these improvements are robust and maintainable. + +## Breaking Changes +- **OAuth Proxy**: Users of built-in IDP integrations should note that `resource_server_url` has been renamed to `base_url` for clarity and consistency + +## What's Changed +### Enhancements 🔧 +* Make openai dependency optional by [@jlowin](https://github.com/jlowin) in [#1701](https://github.com/PrefectHQ/fastmcp/pull/1701) +* Remove orphaned OAuth proxy code by [@jlowin](https://github.com/jlowin) in [#1722](https://github.com/PrefectHQ/fastmcp/pull/1722) +* Expose valid scopes from OAuthProxy metadata by [@dmikusa](https://github.com/dmikusa) in [#1717](https://github.com/PrefectHQ/fastmcp/pull/1717) +* OAuth proxy PKCE forwarding by [@jlowin](https://github.com/jlowin) in [#1733](https://github.com/PrefectHQ/fastmcp/pull/1733) +* Add token_endpoint_auth_method parameter to OAuthProxy by [@jlowin](https://github.com/jlowin) in [#1736](https://github.com/PrefectHQ/fastmcp/pull/1736) +* Clean up and enhance OAuth proxy tests with mock provider by [@jlowin](https://github.com/jlowin) in [#1738](https://github.com/PrefectHQ/fastmcp/pull/1738) +### Fixes 🐞 +* refactor: replace auth provider registry with ImportString by [@jlowin](https://github.com/jlowin) in [#1710](https://github.com/PrefectHQ/fastmcp/pull/1710) +* Fix OAuth resource URL handling and WWW-Authenticate header by [@jlowin](https://github.com/jlowin) in [#1706](https://github.com/PrefectHQ/fastmcp/pull/1706) +* Fix OAuth proxy client storage and add retry logic by [@jlowin](https://github.com/jlowin) in [#1732](https://github.com/PrefectHQ/fastmcp/pull/1732) +### Docs 📚 +* Fix documentation: use StreamableHttpTransport for headers in testing by [@jlowin](https://github.com/jlowin) in [#1702](https://github.com/PrefectHQ/fastmcp/pull/1702) +* docs: add performance warnings for mounted servers and proxies by [@strawgate](https://github.com/strawgate) in [#1669](https://github.com/PrefectHQ/fastmcp/pull/1669) +* Update documentation around scopes for google by [@jlowin](https://github.com/jlowin) in [#1703](https://github.com/PrefectHQ/fastmcp/pull/1703) +* Add deployment information to quickstart by [@seanpwlms](https://github.com/seanpwlms) in [#1433](https://github.com/PrefectHQ/fastmcp/pull/1433) +* Update quickstart by [@jlowin](https://github.com/jlowin) in [#1728](https://github.com/PrefectHQ/fastmcp/pull/1728) +* Add development docs for FastMCP by [@jlowin](https://github.com/jlowin) in [#1719](https://github.com/PrefectHQ/fastmcp/pull/1719) +### Other Changes 🦾 +* Set generics without bounds to default=Any by [@strawgate](https://github.com/strawgate) in [#1648](https://github.com/PrefectHQ/fastmcp/pull/1648) + +## New Contributors +* [@dmikusa](https://github.com/dmikusa) made their first contribution in [#1717](https://github.com/PrefectHQ/fastmcp/pull/1717) +* [@seanpwlms](https://github.com/seanpwlms) made their first contribution in [#1433](https://github.com/PrefectHQ/fastmcp/pull/1433) + +**Full Changelog**: [v2.12.0...v2.12.1](https://github.com/PrefectHQ/fastmcp/compare/v2.12.0...v2.12.1) + + + + + +**[v2.12.0: Auth to the Races](https://github.com/PrefectHQ/fastmcp/releases/tag/v2.12.0)** + +FastMCP 2.12 represents one of our most significant releases to date, both in scope and community involvement. After extensive testing and iteration with the community, we're shipping major improvements to authentication, configuration, and MCP feature adoption. + +🔐 **OAuth Proxy for Broader Provider Support** addresses a fundamental challenge: while MCP requires Dynamic Client Registration (DCR), many popular OAuth providers don't support it. The new OAuth proxy bridges this gap, enabling FastMCP servers to authenticate with providers like GitHub, Google, WorkOS, and Azure through minimal configuration. These native integrations ship today, with more providers planned based on community needs. + +📋 **Declarative JSON Configuration** introduces a standardized, portable way to describe and deploy MCP servers. The `fastmcp.json` configuration file becomes the single source of truth for dependencies, transport settings, entrypoints, and server metadata. This foundation sets the stage for future capabilities like transformations and remote sources, moving toward a world where MCP servers are as portable and shareable as container images. + +🧠 **Sampling API Fallback** tackles the chicken-and-egg problem limiting adoption of advanced MCP features. Sampling—where servers request LLM completions from clients—is powerful but underutilized due to limited client support. FastMCP now lets server authors define fallback handlers that generate sampling completions server-side when clients don't support the feature, encouraging adoption while maintaining compatibility. + +This release took longer than usual to ship, and for good reason: the community's aggressive testing and feedback on the authentication system helped us reach a level of stability we're confident in. There's certainly more work ahead, but these foundations position FastMCP to handle increasingly complex use cases while remaining approachable for developers. + +Thank you to our new contributors and everyone who tested preview builds. Your feedback directly shaped these features. + +## What's Changed +### New Features 🎉 +* Add OAuth proxy that allows authentication with social IDPs without DCR support by [@jlowin](https://github.com/jlowin) in [#1434](https://github.com/PrefectHQ/fastmcp/pull/1434) +* feat: introduce declarative JSON configuration system by [@jlowin](https://github.com/jlowin) in [#1517](https://github.com/PrefectHQ/fastmcp/pull/1517) +* ✨ Fallback to a Completions API when Sampling is not available by [@strawgate](https://github.com/strawgate) in [#1145](https://github.com/PrefectHQ/fastmcp/pull/1145) +* Implement typed source system for FastMCP declarative configuration by [@jlowin](https://github.com/jlowin) in [#1607](https://github.com/PrefectHQ/fastmcp/pull/1607) +### Enhancements 🔧 +* Support importing custom_route endpoints when mounting servers by [@jlowin](https://github.com/jlowin) in [#1470](https://github.com/PrefectHQ/fastmcp/pull/1470) +* Remove unnecessary asserts by [@jlowin](https://github.com/jlowin) in [#1484](https://github.com/PrefectHQ/fastmcp/pull/1484) +* Add Claude issue triage by [@jlowin](https://github.com/jlowin) in [#1510](https://github.com/PrefectHQ/fastmcp/pull/1510) +* Inline dedupe prompt by [@jlowin](https://github.com/jlowin) in [#1512](https://github.com/PrefectHQ/fastmcp/pull/1512) +* Improve stdio and mcp_config clean-up by [@strawgate](https://github.com/strawgate) in [#1444](https://github.com/PrefectHQ/fastmcp/pull/1444) +* involve kwargs to pass parameters on creating RichHandler for logging customization. by [@itaru2622](https://github.com/itaru2622) in [#1504](https://github.com/PrefectHQ/fastmcp/pull/1504) +* Move SDK docs generation to post-merge workflow by [@jlowin](https://github.com/jlowin) in [#1513](https://github.com/PrefectHQ/fastmcp/pull/1513) +* Improve label triage guidance by [@jlowin](https://github.com/jlowin) in [#1516](https://github.com/PrefectHQ/fastmcp/pull/1516) +* Add code review guidelines for agents by [@jlowin](https://github.com/jlowin) in [#1520](https://github.com/PrefectHQ/fastmcp/pull/1520) +* Remove trailing slash in unit tests by [@jlowin](https://github.com/jlowin) in [#1535](https://github.com/PrefectHQ/fastmcp/pull/1535) +* Update OAuth callback UI branding by [@jlowin](https://github.com/jlowin) in [#1536](https://github.com/PrefectHQ/fastmcp/pull/1536) +* Fix Marvin workflow to support development tools by [@jlowin](https://github.com/jlowin) in [#1537](https://github.com/PrefectHQ/fastmcp/pull/1537) +* Add mounted_components_raise_on_load_error setting for debugging by [@jlowin](https://github.com/jlowin) in [#1534](https://github.com/PrefectHQ/fastmcp/pull/1534) +* feat: Add --workspace flag to fastmcp install cursor by [@jlowin](https://github.com/jlowin) in [#1522](https://github.com/PrefectHQ/fastmcp/pull/1522) +* switch from `pyright` to `ty` by [@zzstoatzz](https://github.com/zzstoatzz) in [#1545](https://github.com/PrefectHQ/fastmcp/pull/1545) +* feat: trigger Marvin workflow on PR body content by [@jlowin](https://github.com/jlowin) in [#1549](https://github.com/PrefectHQ/fastmcp/pull/1549) +* Add WorkOS and Azure OAuth providers by [@jlowin](https://github.com/jlowin) in [#1550](https://github.com/PrefectHQ/fastmcp/pull/1550) +* Adjust timeout for slow MCP Server shutdown test by [@strawgate](https://github.com/strawgate) in [#1561](https://github.com/PrefectHQ/fastmcp/pull/1561) +* Update banner by [@jlowin](https://github.com/jlowin) in [#1567](https://github.com/PrefectHQ/fastmcp/pull/1567) +* Added import of AuthProxy to auth __init__ by [@KaliszS](https://github.com/KaliszS) in [#1568](https://github.com/PrefectHQ/fastmcp/pull/1568) +* Add configurable redirect URI validation for OAuth providers by [@jlowin](https://github.com/jlowin) in [#1582](https://github.com/PrefectHQ/fastmcp/pull/1582) +* Remove invalid-argument-type ignore and fix type errors by [@jlowin](https://github.com/jlowin) in [#1588](https://github.com/PrefectHQ/fastmcp/pull/1588) +* Remove generate-schema from public CLI by [@jlowin](https://github.com/jlowin) in [#1591](https://github.com/PrefectHQ/fastmcp/pull/1591) +* Skip flaky windows test / mulit-client garbage collection by [@jlowin](https://github.com/jlowin) in [#1592](https://github.com/PrefectHQ/fastmcp/pull/1592) +* Add setting to disable logging configuration by [@isra17](https://github.com/isra17) in [#1575](https://github.com/PrefectHQ/fastmcp/pull/1575) +* Improve debug logging for nested Servers / Clients by [@strawgate](https://github.com/strawgate) in [#1604](https://github.com/PrefectHQ/fastmcp/pull/1604) +* Add GitHub pull request template by [@strawgate](https://github.com/strawgate) in [#1581](https://github.com/PrefectHQ/fastmcp/pull/1581) +* chore: Automate docs and schema updates via PRs by [@jlowin](https://github.com/jlowin) in [#1611](https://github.com/PrefectHQ/fastmcp/pull/1611) +* Experiment with haiku for limited workflows by [@jlowin](https://github.com/jlowin) in [#1613](https://github.com/PrefectHQ/fastmcp/pull/1613) +* feat: Improve GitHub workflow automation for schema and SDK docs by [@jlowin](https://github.com/jlowin) in [#1615](https://github.com/PrefectHQ/fastmcp/pull/1615) +* Consolidate server loading logic into FileSystemSource by [@jlowin](https://github.com/jlowin) in [#1614](https://github.com/PrefectHQ/fastmcp/pull/1614) +* Prevent Haiku Marvin from commenting when there are no duplicates by [@jlowin](https://github.com/jlowin) in [#1622](https://github.com/PrefectHQ/fastmcp/pull/1622) +* chore: Add clarifying note to automated PR bodies by [@jlowin](https://github.com/jlowin) in [#1623](https://github.com/PrefectHQ/fastmcp/pull/1623) +* feat: introduce inline snapshots by [@strawgate](https://github.com/strawgate) in [#1605](https://github.com/PrefectHQ/fastmcp/pull/1605) +* Improve fastmcp.json environment configuration and project-based deployments by [@jlowin](https://github.com/jlowin) in [#1631](https://github.com/PrefectHQ/fastmcp/pull/1631) +* fix: allow passing query params in OAuthProxy upstream authorization url by [@danb27](https://github.com/danb27) in [#1630](https://github.com/PrefectHQ/fastmcp/pull/1630) +* Support multiple --with-editable flags in CLI commands by [@jlowin](https://github.com/jlowin) in [#1634](https://github.com/PrefectHQ/fastmcp/pull/1634) +* feat: support comma separated oauth scopes by [@jlowin](https://github.com/jlowin) in [#1642](https://github.com/PrefectHQ/fastmcp/pull/1642) +* Add allowed_client_redirect_uris to OAuth provider subclasses by [@jlowin](https://github.com/jlowin) in [#1662](https://github.com/PrefectHQ/fastmcp/pull/1662) +* Consolidate CLI config parsing and prevent infinite loops by [@jlowin](https://github.com/jlowin) in [#1660](https://github.com/PrefectHQ/fastmcp/pull/1660) +* Internal refactor: mcp server config by [@jlowin](https://github.com/jlowin) in [#1672](https://github.com/PrefectHQ/fastmcp/pull/1672) +* Refactor Environment to support multiple runtime types by [@jlowin](https://github.com/jlowin) in [#1673](https://github.com/PrefectHQ/fastmcp/pull/1673) +* Add type field to Environment base class by [@jlowin](https://github.com/jlowin) in [#1676](https://github.com/PrefectHQ/fastmcp/pull/1676) +### Fixes 🐞 +* Fix breaking change: restore output_schema=False compatibility by [@jlowin](https://github.com/jlowin) in [#1482](https://github.com/PrefectHQ/fastmcp/pull/1482) +* Fix #1506: Update tool filtering documentation from _meta to meta by [@maybenotconnor](https://github.com/maybenotconnor) in [#1511](https://github.com/PrefectHQ/fastmcp/pull/1511) +* Fix pytest warnings by [@jlowin](https://github.com/jlowin) in [#1559](https://github.com/PrefectHQ/fastmcp/pull/1559) +* nest schemas under assets by [@jlowin](https://github.com/jlowin) in [#1593](https://github.com/PrefectHQ/fastmcp/pull/1593) +* Skip flaky windows test by [@jlowin](https://github.com/jlowin) in [#1596](https://github.com/PrefectHQ/fastmcp/pull/1596) +* ACTUALLY move schemas to fastmcp.json by [@jlowin](https://github.com/jlowin) in [#1597](https://github.com/PrefectHQ/fastmcp/pull/1597) +* Fix and centralize CLI path resolution by [@jlowin](https://github.com/jlowin) in [#1590](https://github.com/PrefectHQ/fastmcp/pull/1590) +* Remove client info modifications by [@jlowin](https://github.com/jlowin) in [#1620](https://github.com/PrefectHQ/fastmcp/pull/1620) +* Fix $defs being discarded in input schema of transformed tool by [@pldesch-chift](https://github.com/pldesch-chift) in [#1578](https://github.com/PrefectHQ/fastmcp/pull/1578) +* Fix enum elicitation to use inline schemas for MCP compatibility by [@jlowin](https://github.com/jlowin) in [#1632](https://github.com/PrefectHQ/fastmcp/pull/1632) +* Reuse session for `StdioTransport` in `Client.new` by [@strawgate](https://github.com/strawgate) in [#1635](https://github.com/PrefectHQ/fastmcp/pull/1635) +* Feat: Configurable LoggingMiddleware payload serialization by [@vl-kp](https://github.com/vl-kp) in [#1636](https://github.com/PrefectHQ/fastmcp/pull/1636) +* Fix OAuth redirect URI validation for DCR compatibility by [@jlowin](https://github.com/jlowin) in [#1661](https://github.com/PrefectHQ/fastmcp/pull/1661) +* Add default scope handling in OAuth proxy by [@romanusyk](https://github.com/romanusyk) in [#1667](https://github.com/PrefectHQ/fastmcp/pull/1667) +* Fix OAuth token expiry handling by [@jlowin](https://github.com/jlowin) in [#1671](https://github.com/PrefectHQ/fastmcp/pull/1671) +* Add resource_server_url parameter to OAuth proxy providers by [@jlowin](https://github.com/jlowin) in [#1682](https://github.com/PrefectHQ/fastmcp/pull/1682) +### Breaking Changes 🛫 +* Enhance inspect command with structured output and format options by [@jlowin](https://github.com/jlowin) in [#1481](https://github.com/PrefectHQ/fastmcp/pull/1481) +### Docs 📚 +* Update changelog by [@jlowin](https://github.com/jlowin) in [#1453](https://github.com/PrefectHQ/fastmcp/pull/1453) +* Update banner by [@jlowin](https://github.com/jlowin) in [#1472](https://github.com/PrefectHQ/fastmcp/pull/1472) +* Update logo files by [@jlowin](https://github.com/jlowin) in [#1473](https://github.com/PrefectHQ/fastmcp/pull/1473) +* Update deployment docs by [@jlowin](https://github.com/jlowin) in [#1486](https://github.com/PrefectHQ/fastmcp/pull/1486) +* Update FastMCP Cloud screenshot by [@jlowin](https://github.com/jlowin) in [#1487](https://github.com/PrefectHQ/fastmcp/pull/1487) +* Update authentication note in docs by [@jlowin](https://github.com/jlowin) in [#1488](https://github.com/PrefectHQ/fastmcp/pull/1488) +* chore: Update installation.mdx version snippet by [@thomas-te](https://github.com/thomas-te) in [#1496](https://github.com/PrefectHQ/fastmcp/pull/1496) +* Update fastmcp cloud server requirements by [@jlowin](https://github.com/jlowin) in [#1497](https://github.com/PrefectHQ/fastmcp/pull/1497) +* Fix oauth pyright type checking by [@strawgate](https://github.com/strawgate) in [#1498](https://github.com/PrefectHQ/fastmcp/pull/1498) +* docs: Fix type annotation in return value documentation by [@MaikelVeen](https://github.com/MaikelVeen) in [#1499](https://github.com/PrefectHQ/fastmcp/pull/1499) +* Fix PromptMessage usage in docs example by [@jlowin](https://github.com/jlowin) in [#1515](https://github.com/PrefectHQ/fastmcp/pull/1515) +* Create CODE_OF_CONDUCT.md by [@jlowin](https://github.com/jlowin) in [#1523](https://github.com/PrefectHQ/fastmcp/pull/1523) +* Fixed wrong import path in new docs page by [@KaliszS](https://github.com/KaliszS) in [#1538](https://github.com/PrefectHQ/fastmcp/pull/1538) +* Document symmetric key JWT verification support by [@jlowin](https://github.com/jlowin) in [#1586](https://github.com/PrefectHQ/fastmcp/pull/1586) +* Update fastmcp.json schema path by [@jlowin](https://github.com/jlowin) in [#1595](https://github.com/PrefectHQ/fastmcp/pull/1595) +### Dependencies 📦 +* Bump actions/create-github-app-token from 1 to 2 by [@dependabot](https://github.com/dependabot)[bot] in [#1436](https://github.com/PrefectHQ/fastmcp/pull/1436) +* Bump astral-sh/setup-uv from 4 to 6 by [@dependabot](https://github.com/dependabot)[bot] in [#1532](https://github.com/PrefectHQ/fastmcp/pull/1532) +* Bump actions/checkout from 4 to 5 by [@dependabot](https://github.com/dependabot)[bot] in [#1533](https://github.com/PrefectHQ/fastmcp/pull/1533) +### Other Changes 🦾 +* Add dedupe workflow by [@jlowin](https://github.com/jlowin) in [#1454](https://github.com/PrefectHQ/fastmcp/pull/1454) +* Update AGENTS.md by [@jlowin](https://github.com/jlowin) in [#1471](https://github.com/PrefectHQ/fastmcp/pull/1471) +* Give Marvin the power of the Internet by [@strawgate](https://github.com/strawgate) in [#1475](https://github.com/PrefectHQ/fastmcp/pull/1475) +* Update `just` error message for static checks by [@jlowin](https://github.com/jlowin) in [#1483](https://github.com/PrefectHQ/fastmcp/pull/1483) +* Remove labeler by [@jlowin](https://github.com/jlowin) in [#1509](https://github.com/PrefectHQ/fastmcp/pull/1509) +* update aproto server to handle rich links by [@zzstoatzz](https://github.com/zzstoatzz) in [#1556](https://github.com/PrefectHQ/fastmcp/pull/1556) +* fix: enable triage bot for fork PRs using pull_request_target by [@jlowin](https://github.com/jlowin) in [#1557](https://github.com/PrefectHQ/fastmcp/pull/1557) + +## New Contributors +* [@thomas-te](https://github.com/thomas-te) made their first contribution in [#1496](https://github.com/PrefectHQ/fastmcp/pull/1496) +* [@maybenotconnor](https://github.com/maybenotconnor) made their first contribution in [#1511](https://github.com/PrefectHQ/fastmcp/pull/1511) +* [@MaikelVeen](https://github.com/MaikelVeen) made their first contribution in [#1499](https://github.com/PrefectHQ/fastmcp/pull/1499) +* [@KaliszS](https://github.com/KaliszS) made their first contribution in [#1538](https://github.com/PrefectHQ/fastmcp/pull/1538) +* [@isra17](https://github.com/isra17) made their first contribution in [#1575](https://github.com/PrefectHQ/fastmcp/pull/1575) +* [@marvin-context-protocol](https://github.com/marvin-context-protocol)[bot] made their first contribution in [#1616](https://github.com/PrefectHQ/fastmcp/pull/1616) +* [@pldesch-chift](https://github.com/pldesch-chift) made their first contribution in [#1578](https://github.com/PrefectHQ/fastmcp/pull/1578) +* [@vl-kp](https://github.com/vl-kp) made their first contribution in [#1636](https://github.com/PrefectHQ/fastmcp/pull/1636) +* [@romanusyk](https://github.com/romanusyk) made their first contribution in [#1667](https://github.com/PrefectHQ/fastmcp/pull/1667) + +**Full Changelog**: [v2.11.3...v2.12.0](https://github.com/PrefectHQ/fastmcp/compare/v2.11.3...v2.12.0) + + + + + +**[v2.11.3: API-tite for Change](https://github.com/PrefectHQ/fastmcp/releases/tag/v2.11.3)** + +This release includes significant enhancements to the experimental OpenAPI parser and fixes a significant bug that led schemas not to be included in input/output schemas if they were transitive dependencies (e.g. A → B → C implies A depends on C). For users naively transforming large OpenAPI specs into MCP servers, this may result in ballooning payload sizes and necessitate curation. + +## What's Changed +### Enhancements 🔧 +* Improve redirect handling to address 307's by [@jlowin](https://github.com/jlowin) in [#1387](https://github.com/PrefectHQ/fastmcp/pull/1387) +* Ensure resource + template names are properly prefixed when importing/mounting by [@jlowin](https://github.com/jlowin) in [#1423](https://github.com/PrefectHQ/fastmcp/pull/1423) +* fixes #1398: Add JWT claims to AccessToken by [@panargirakis](https://github.com/panargirakis) in [#1399](https://github.com/PrefectHQ/fastmcp/pull/1399) +* Enable Protected Resource Metadata to provide resource_name and resou… by [@yannj-fr](https://github.com/yannj-fr) in [#1371](https://github.com/PrefectHQ/fastmcp/pull/1371) +* Pin mcp SDK under 2.0 to avoid breaking changes by [@jlowin](https://github.com/jlowin) in [#1428](https://github.com/PrefectHQ/fastmcp/pull/1428) +* Clean up complexity from PR #1426 by [@jlowin](https://github.com/jlowin) in [#1435](https://github.com/PrefectHQ/fastmcp/pull/1435) +* Optimize OpenAPI payload size by 46% by [@jlowin](https://github.com/jlowin) in [#1452](https://github.com/PrefectHQ/fastmcp/pull/1452) +* Update static checks by [@jlowin](https://github.com/jlowin) in [#1448](https://github.com/PrefectHQ/fastmcp/pull/1448) +### Fixes 🐞 +* Fix client-side logging bug #1394 by [@chi2liu](https://github.com/chi2liu) in [#1397](https://github.com/PrefectHQ/fastmcp/pull/1397) +* fix: Fix httpx_client_factory type annotation to match MCP SDK (#1402) by [@chi2liu](https://github.com/chi2liu) in [#1405](https://github.com/PrefectHQ/fastmcp/pull/1405) +* Fix OpenAPI allOf handling at requestBody top level (#1378) by [@chi2liu](https://github.com/chi2liu) in [#1425](https://github.com/PrefectHQ/fastmcp/pull/1425) +* Fix OpenAPI transitive references and performance (#1372) by [@jlowin](https://github.com/jlowin) in [#1426](https://github.com/PrefectHQ/fastmcp/pull/1426) +* fix(type): lifespan is partially unknown by [@ykun9](https://github.com/ykun9) in [#1389](https://github.com/PrefectHQ/fastmcp/pull/1389) +* Ensure transformed tools generate structured content by [@jlowin](https://github.com/jlowin) in [#1443](https://github.com/PrefectHQ/fastmcp/pull/1443) +### Docs 📚 +* docs(client/logging): reflect corrected default log level mapping by [@jlowin](https://github.com/jlowin) in [#1403](https://github.com/PrefectHQ/fastmcp/pull/1403) +* Add documentation for get_access_token() dependency function by [@jlowin](https://github.com/jlowin) in [#1446](https://github.com/PrefectHQ/fastmcp/pull/1446) +### Other Changes 🦾 +* Add comprehensive tests for utilities.components module by [@chi2liu](https://github.com/chi2liu) in [#1395](https://github.com/PrefectHQ/fastmcp/pull/1395) +* Consolidate agent instructions into AGENTS.md by [@jlowin](https://github.com/jlowin) in [#1404](https://github.com/PrefectHQ/fastmcp/pull/1404) +* Fix performance test threshold to prevent flaky failures by [@jlowin](https://github.com/jlowin) in [#1406](https://github.com/PrefectHQ/fastmcp/pull/1406) +* Update agents.md; add github instructions by [@jlowin](https://github.com/jlowin) in [#1410](https://github.com/PrefectHQ/fastmcp/pull/1410) +* Add Marvin assistant by [@jlowin](https://github.com/jlowin) in [#1412](https://github.com/PrefectHQ/fastmcp/pull/1412) +* Marvin: fix deprecated variable names by [@jlowin](https://github.com/jlowin) in [#1417](https://github.com/PrefectHQ/fastmcp/pull/1417) +* Simplify action setup and add github tools for Marvin by [@jlowin](https://github.com/jlowin) in [#1419](https://github.com/PrefectHQ/fastmcp/pull/1419) +* Update marvin workflow name by [@jlowin](https://github.com/jlowin) in [#1421](https://github.com/PrefectHQ/fastmcp/pull/1421) +* Improve GitHub templates by [@jlowin](https://github.com/jlowin) in [#1422](https://github.com/PrefectHQ/fastmcp/pull/1422) + +## New Contributors +* [@panargirakis](https://github.com/panargirakis) made their first contribution in [#1399](https://github.com/PrefectHQ/fastmcp/pull/1399) +* [@ykun9](https://github.com/ykun9) made their first contribution in [#1389](https://github.com/PrefectHQ/fastmcp/pull/1389) +* [@yannj-fr](https://github.com/yannj-fr) made their first contribution in [#1371](https://github.com/PrefectHQ/fastmcp/pull/1371) + +**Full Changelog**: [v2.11.2...v2.11.3](https://github.com/PrefectHQ/fastmcp/compare/v2.11.2...v2.11.3) + + + + + +## [v2.11.2: Satis-factory](https://github.com/PrefectHQ/fastmcp/releases/tag/v2.11.2) + +## What's Changed +### Enhancements 🔧 +* Support factory functions in fastmcp run by [@jlowin](https://github.com/jlowin) in [#1384](https://github.com/PrefectHQ/fastmcp/pull/1384) +* Add async support to client_factory in FastMCPProxy (#1286) by [@bianning](https://github.com/bianning) in [#1375](https://github.com/PrefectHQ/fastmcp/pull/1375) +### Fixes 🐞 +* Fix server_version field in inspect manifest by [@jlowin](https://github.com/jlowin) in [#1383](https://github.com/PrefectHQ/fastmcp/pull/1383) +* Fix Settings field with both default and default_factory by [@jlowin](https://github.com/jlowin) in [#1380](https://github.com/PrefectHQ/fastmcp/pull/1380) +### Other Changes 🦾 +* Remove unused arg by [@jlowin](https://github.com/jlowin) in [#1382](https://github.com/PrefectHQ/fastmcp/pull/1382) +* Add remote auth provider tests by [@jlowin](https://github.com/jlowin) in [#1351](https://github.com/PrefectHQ/fastmcp/pull/1351) + +## New Contributors +* [@bianning](https://github.com/bianning) made their first contribution in [#1375](https://github.com/PrefectHQ/fastmcp/pull/1375) + +**Full Changelog**: [v2.11.1...v2.11.2](https://github.com/PrefectHQ/fastmcp/compare/v2.11.1...v2.11.2) + + + + + +## [v2.11.1: You're Better Auth Now](https://github.com/PrefectHQ/fastmcp/releases/tag/v2.11.1) + +## What's Changed +### New Features 🎉 +* Introduce `RemoteAuthProvider` for cleaner external identity provider integration, update docs by [@jlowin](https://github.com/jlowin) in [#1346](https://github.com/PrefectHQ/fastmcp/pull/1346) +### Enhancements 🔧 +* perf: optimize string operations in OpenAPI parameter processing by [@chi2liu](https://github.com/chi2liu) in [#1342](https://github.com/PrefectHQ/fastmcp/pull/1342) +### Fixes 🐞 +* Fix method-bound FunctionTool schemas by [@strawgate](https://github.com/strawgate) in [#1360](https://github.com/PrefectHQ/fastmcp/pull/1360) +* Manually set `_key` after `model_copy()` to enable prefixing Transformed Tools by [@strawgate](https://github.com/strawgate) in [#1357](https://github.com/PrefectHQ/fastmcp/pull/1357) +### Docs 📚 +* Docs updates by [@jlowin](https://github.com/jlowin) in [#1336](https://github.com/PrefectHQ/fastmcp/pull/1336) +* Add 2.11 to changelog by [@jlowin](https://github.com/jlowin) in [#1337](https://github.com/PrefectHQ/fastmcp/pull/1337) +* Update AuthKit vocab by [@jlowin](https://github.com/jlowin) in [#1338](https://github.com/PrefectHQ/fastmcp/pull/1338) +* Fix typo in decorating-methods.mdx by [@Ozzuke](https://github.com/Ozzuke) in [#1344](https://github.com/PrefectHQ/fastmcp/pull/1344) + +## New Contributors +* [@Ozzuke](https://github.com/Ozzuke) made their first contribution in [#1344](https://github.com/PrefectHQ/fastmcp/pull/1344) + +**Full Changelog**: [v2.11.0...v2.11.1](https://github.com/PrefectHQ/fastmcp/compare/v2.11.0...v2.11.1) + + + + + +## [v2.11.0: Auth to a Good Start](https://github.com/PrefectHQ/fastmcp/releases/tag/v2.11.0) + +FastMCP 2.11 doubles down on what developers need most: speed and simplicity. This massive release delivers significant performance improvements and a dramatically better developer experience. + +🔐 **Enterprise-Ready Authentication** brings comprehensive OAuth 2.1 support with WorkOS's AuthKit integration. The new AuthProvider interface leverages MCP's support for separate resource and authorization servers, handling API keys and remote authentication with Dynamic Client Registration. AuthKit integration means you can plug into existing enterprise identity systems without rebuilding your auth stack, setting the stage for plug-and-play auth that doesn't require users to become security experts overnight. + +⚡ The **Experimental OpenAPI Parser** delivers dramatic performance improvements through single-pass schema processing and optimized memory usage. OpenAPI integrations are now significantly faster, with cleaner, more maintainable code. _(Note: the experimental parser is disabled by default, set `FASTMCPEXPERIMENTALENABLENEWOPENAPIPARSER=1` to enable it. A message will be shown to all users on the legacy parser encouraging them to try the new one before it becomes the default.)_ + +🧠 **Context State Management** finally gives you persistent state across tool calls with a simple dict interface, while enhanced meta support lets you expose rich component metadata to clients. Combined with improved type annotations, string-based argument descriptions, and UV transport support, this release makes FastMCP feel more intuitive than ever. + +This release represents a TON of community contributions and sets the foundation for even more ambitious features ahead. + +## What's Changed +### New Features 🎉 +* Introduce experimental OpenAPI parser with improved performance and maintainability by [@jlowin](https://github.com/jlowin) in [#1209](https://github.com/PrefectHQ/fastmcp/pull/1209) +* Add state dict to Context (#1118) by [@mukulmurthy](https://github.com/mukulmurthy) in [#1160](https://github.com/PrefectHQ/fastmcp/pull/1160) +* Expose FastMCP tags to clients via component `meta` dict by [@jlowin](https://github.com/jlowin) in [#1281](https://github.com/PrefectHQ/fastmcp/pull/1281) +* Add _fastmcp meta namespace by [@jlowin](https://github.com/jlowin) in [#1290](https://github.com/PrefectHQ/fastmcp/pull/1290) +* Add TokenVerifier protocol support alongside existing OAuthProvider authentication by [@jlowin](https://github.com/jlowin) in [#1297](https://github.com/PrefectHQ/fastmcp/pull/1297) +* Add comprehensive OAuth 2.1 authentication system with WorkOS integration by [@jlowin](https://github.com/jlowin) in [#1327](https://github.com/PrefectHQ/fastmcp/pull/1327) +### Enhancements 🔧 +* [🐶] Transform MCP Server Tools by [@strawgate](https://github.com/strawgate) in [#1132](https://github.com/PrefectHQ/fastmcp/pull/1132) +* Add --python, --project, and --with-requirements options to CLI commands by [@jlowin](https://github.com/jlowin) in [#1190](https://github.com/PrefectHQ/fastmcp/pull/1190) +* Support `fastmcp run mcp.json` by [@strawgate](https://github.com/strawgate) in [#1138](https://github.com/PrefectHQ/fastmcp/pull/1138) +* Support from __future__ import annotations by [@jlowin](https://github.com/jlowin) in [#1199](https://github.com/PrefectHQ/fastmcp/pull/1199) +* Optimize OpenAPI parser performance with single-pass schema processing by [@jlowin](https://github.com/jlowin) in [#1214](https://github.com/PrefectHQ/fastmcp/pull/1214) +* Log tool name on transform validation error by [@strawgate](https://github.com/strawgate) in [#1238](https://github.com/PrefectHQ/fastmcp/pull/1238) +* Refactor `get_http_request` and `context.session_id` by [@hopeful0](https://github.com/hopeful0) in [#1242](https://github.com/PrefectHQ/fastmcp/pull/1242) +* Support creating tool argument descriptions from string annotations by [@jlowin](https://github.com/jlowin) in [#1255](https://github.com/PrefectHQ/fastmcp/pull/1255) +* feat: Add Annotations support for resources and resource templates by [@chughtapan](https://github.com/chughtapan) in [#1260](https://github.com/PrefectHQ/fastmcp/pull/1260) +* Add UV Transport by [@strawgate](https://github.com/strawgate) in [#1270](https://github.com/PrefectHQ/fastmcp/pull/1270) +* Improve OpenAPI-to-JSONSchema conversion utilities by [@jlowin](https://github.com/jlowin) in [#1283](https://github.com/PrefectHQ/fastmcp/pull/1283) +* Ensure proxy components forward meta dicts by [@jlowin](https://github.com/jlowin) in [#1282](https://github.com/PrefectHQ/fastmcp/pull/1282) +* fix: server argument passing in CLI run command by [@chughtapan](https://github.com/chughtapan) in [#1293](https://github.com/PrefectHQ/fastmcp/pull/1293) +* Add meta support to tool transformation utilities by [@jlowin](https://github.com/jlowin) in [#1295](https://github.com/PrefectHQ/fastmcp/pull/1295) +* feat: Allow Resource Metadata URL as field in OAuthProvider by [@dacamposol](https://github.com/dacamposol) in [#1287](https://github.com/PrefectHQ/fastmcp/pull/1287) +* Use a simple overwrite instead of a merge for meta by [@jlowin](https://github.com/jlowin) in [#1296](https://github.com/PrefectHQ/fastmcp/pull/1296) +* Remove unused TimedCache by [@strawgate](https://github.com/strawgate) in [#1303](https://github.com/PrefectHQ/fastmcp/pull/1303) +* refactor: standardize logging usage across OpenAPI utilities by [@chi2liu](https://github.com/chi2liu) in [#1322](https://github.com/PrefectHQ/fastmcp/pull/1322) +* perf: optimize OpenAPI parsing by reducing dict copy operations by [@chi2liu](https://github.com/chi2liu) in [#1321](https://github.com/PrefectHQ/fastmcp/pull/1321) +* Structured client-side logging by [@cjermain](https://github.com/cjermain) in [#1326](https://github.com/PrefectHQ/fastmcp/pull/1326) +### Fixes 🐞 +* fix: preserve def reference when referenced in allOf / oneOf / anyOf by [@algirdasci](https://github.com/algirdasci) in [#1208](https://github.com/PrefectHQ/fastmcp/pull/1208) +* fix: add type hint to custom_route decorator by [@zzstoatzz](https://github.com/zzstoatzz) in [#1210](https://github.com/PrefectHQ/fastmcp/pull/1210) +* chore: typo by [@richardkmichael](https://github.com/richardkmichael) in [#1216](https://github.com/PrefectHQ/fastmcp/pull/1216) +* fix: handle non-string $ref values in experimental OpenAPI parser by [@jlowin](https://github.com/jlowin) in [#1217](https://github.com/PrefectHQ/fastmcp/pull/1217) +* Skip repeated type conversion and validation in proxy client elicitation handler by [@chughtapan](https://github.com/chughtapan) in [#1222](https://github.com/PrefectHQ/fastmcp/pull/1222) +* Ensure default fields are not marked nullable by [@jlowin](https://github.com/jlowin) in [#1224](https://github.com/PrefectHQ/fastmcp/pull/1224) +* Fix stateful proxy client mixing in multi-proxies sessions by [@hopeful0](https://github.com/hopeful0) in [#1245](https://github.com/PrefectHQ/fastmcp/pull/1245) +* Fix invalid async context manager usage in proxy documentation by [@zzstoatzz](https://github.com/zzstoatzz) in [#1246](https://github.com/PrefectHQ/fastmcp/pull/1246) +* fix: experimental FastMCPOpenAPI server lost headers in request when __init__(client with headers) by [@itaru2622](https://github.com/itaru2622) in [#1254](https://github.com/PrefectHQ/fastmcp/pull/1254) +* Fix typing, add tests for tool call middleware by [@jlowin](https://github.com/jlowin) in [#1269](https://github.com/PrefectHQ/fastmcp/pull/1269) +* Fix: prune hidden parameter defs by [@muhammadkhalid-03](https://github.com/muhammadkhalid-03) in [#1257](https://github.com/PrefectHQ/fastmcp/pull/1257) +* Fix nullable field handling in OpenAPI to JSON Schema conversion by [@jlowin](https://github.com/jlowin) in [#1279](https://github.com/PrefectHQ/fastmcp/pull/1279) +* Ensure fastmcp run supports v1 servers by [@jlowin](https://github.com/jlowin) in [#1332](https://github.com/PrefectHQ/fastmcp/pull/1332) +### Breaking Changes 🛫 +* Change server flag to --name by [@jlowin](https://github.com/jlowin) in [#1248](https://github.com/PrefectHQ/fastmcp/pull/1248) +### Docs 📚 +* Remove unused import from FastAPI integration documentation by [@mariotaddeucci](https://github.com/mariotaddeucci) in [#1194](https://github.com/PrefectHQ/fastmcp/pull/1194) +* Update fastapi docs by [@jlowin](https://github.com/jlowin) in [#1198](https://github.com/PrefectHQ/fastmcp/pull/1198) +* Add docs for context state management by [@jlowin](https://github.com/jlowin) in [#1227](https://github.com/PrefectHQ/fastmcp/pull/1227) +* Permit.io integration docs by [@orweis](https://github.com/orweis) in [#1226](https://github.com/PrefectHQ/fastmcp/pull/1226) +* Update docs to reflect sync tools by [@jlowin](https://github.com/jlowin) in [#1234](https://github.com/PrefectHQ/fastmcp/pull/1234) +* Update changelog.mdx by [@jlowin](https://github.com/jlowin) in [#1235](https://github.com/PrefectHQ/fastmcp/pull/1235) +* Update SDK docs by [@jlowin](https://github.com/jlowin) in [#1236](https://github.com/PrefectHQ/fastmcp/pull/1236) +* Update --name flag documentation for Cursor/Claude by [@adam-conway](https://github.com/adam-conway) in [#1239](https://github.com/PrefectHQ/fastmcp/pull/1239) +* Add annotations docs by [@jlowin](https://github.com/jlowin) in [#1268](https://github.com/PrefectHQ/fastmcp/pull/1268) +* Update openapi/fastapi URLs README.md by [@jbn](https://github.com/jbn) in [#1278](https://github.com/PrefectHQ/fastmcp/pull/1278) +* Add 2.11 version badge for state management by [@jlowin](https://github.com/jlowin) in [#1289](https://github.com/PrefectHQ/fastmcp/pull/1289) +* Add meta parameter support to tools, resources, templates, and prompts decorators by [@jlowin](https://github.com/jlowin) in [#1294](https://github.com/PrefectHQ/fastmcp/pull/1294) +* docs: update get_state and set_state references by [@Maxi91f](https://github.com/Maxi91f) in [#1306](https://github.com/PrefectHQ/fastmcp/pull/1306) +* Add unit tests and docs for denying tool calls with middleware by [@jlowin](https://github.com/jlowin) in [#1333](https://github.com/PrefectHQ/fastmcp/pull/1333) +* Remove reference to stacked decorators by [@jlowin](https://github.com/jlowin) in [#1334](https://github.com/PrefectHQ/fastmcp/pull/1334) +* Eunomia authorization server can run embedded within the MCP server by [@tommitt](https://github.com/tommitt) in [#1317](https://github.com/PrefectHQ/fastmcp/pull/1317) +### Other Changes 🦾 +* Update README.md by [@jlowin](https://github.com/jlowin) in [#1230](https://github.com/PrefectHQ/fastmcp/pull/1230) +* Logcapture addition to test_server file by [@Sourav-Tripathy](https://github.com/Sourav-Tripathy) in [#1229](https://github.com/PrefectHQ/fastmcp/pull/1229) +* Add tests for headers with both legacy and experimental openapi parser by [@jlowin](https://github.com/jlowin) in [#1259](https://github.com/PrefectHQ/fastmcp/pull/1259) +* Small clean-up from MCP Tool Transform PR by [@strawgate](https://github.com/strawgate) in [#1267](https://github.com/PrefectHQ/fastmcp/pull/1267) +* Add test for proxy tags visibility by [@jlowin](https://github.com/jlowin) in [#1302](https://github.com/PrefectHQ/fastmcp/pull/1302) +* Add unit test for sampling with image messages by [@jlowin](https://github.com/jlowin) in [#1329](https://github.com/PrefectHQ/fastmcp/pull/1329) +* Remove redundant resource_metadata_url assignment by [@jlowin](https://github.com/jlowin) in [#1328](https://github.com/PrefectHQ/fastmcp/pull/1328) +* Update bug.yml by [@jlowin](https://github.com/jlowin) in [#1331](https://github.com/PrefectHQ/fastmcp/pull/1331) +* Ensure validation errors are raised when masked by [@jlowin](https://github.com/jlowin) in [#1330](https://github.com/PrefectHQ/fastmcp/pull/1330) + +## New Contributors +* [@mariotaddeucci](https://github.com/mariotaddeucci) made their first contribution in [#1194](https://github.com/PrefectHQ/fastmcp/pull/1194) +* [@algirdasci](https://github.com/algirdasci) made their first contribution in [#1208](https://github.com/PrefectHQ/fastmcp/pull/1208) +* [@chughtapan](https://github.com/chughtapan) made their first contribution in [#1222](https://github.com/PrefectHQ/fastmcp/pull/1222) +* [@mukulmurthy](https://github.com/mukulmurthy) made their first contribution in [#1160](https://github.com/PrefectHQ/fastmcp/pull/1160) +* [@orweis](https://github.com/orweis) made their first contribution in [#1226](https://github.com/PrefectHQ/fastmcp/pull/1226) +* [@Sourav-Tripathy](https://github.com/Sourav-Tripathy) made their first contribution in [#1229](https://github.com/PrefectHQ/fastmcp/pull/1229) +* [@adam-conway](https://github.com/adam-conway) made their first contribution in [#1239](https://github.com/PrefectHQ/fastmcp/pull/1239) +* [@muhammadkhalid-03](https://github.com/muhammadkhalid-03) made their first contribution in [#1257](https://github.com/PrefectHQ/fastmcp/pull/1257) +* [@jbn](https://github.com/jbn) made their first contribution in [#1278](https://github.com/PrefectHQ/fastmcp/pull/1278) +* [@dacamposol](https://github.com/dacamposol) made their first contribution in [#1287](https://github.com/PrefectHQ/fastmcp/pull/1287) +* [@chi2liu](https://github.com/chi2liu) made their first contribution in [#1322](https://github.com/PrefectHQ/fastmcp/pull/1322) +* [@cjermain](https://github.com/cjermain) made their first contribution in [#1326](https://github.com/PrefectHQ/fastmcp/pull/1326) + +**Full Changelog**: [v2.10.6...v2.11.0](https://github.com/PrefectHQ/fastmcp/compare/v2.10.6...v2.11.0) + + + + + +## [v2.10.6: Hymn for the Weekend](https://github.com/PrefectHQ/fastmcp/releases/tag/v2.10.6) + +A special Saturday release with many fixes. + +## What's Changed +### Enhancements 🔧 +* Resolve #1139 -- Implement include_context argument in Context.sample by [@codingjoe](https://github.com/codingjoe) in [#1141](https://github.com/PrefectHQ/fastmcp/pull/1141) +* feat(settings): add log level normalization by [@ka2048](https://github.com/ka2048) in [#1171](https://github.com/PrefectHQ/fastmcp/pull/1171) +* add server name to mounted server warnings by [@artificial-aidan](https://github.com/artificial-aidan) in [#1147](https://github.com/PrefectHQ/fastmcp/pull/1147) +* Add StatefulProxyClient by [@hopeful0](https://github.com/hopeful0) in [#1109](https://github.com/PrefectHQ/fastmcp/pull/1109) +### Fixes 🐞 +* Fix OpenAPI empty parameters by [@FabrizioSandri](https://github.com/FabrizioSandri) in [#1128](https://github.com/PrefectHQ/fastmcp/pull/1128) +* Fix title field preservation in tool transformations by [@jlowin](https://github.com/jlowin) in [#1131](https://github.com/PrefectHQ/fastmcp/pull/1131) +* Fix optional parameter validation in OpenAPI integration by [@jlowin](https://github.com/jlowin) in [#1135](https://github.com/PrefectHQ/fastmcp/pull/1135) +* Do not silently exclude the "context" key from JSON body by [@melkamar](https://github.com/melkamar) in [#1153](https://github.com/PrefectHQ/fastmcp/pull/1153) +* Fix tool output schema generation to respect Pydantic serialization aliases by [@zzstoatzz](https://github.com/zzstoatzz) in [#1148](https://github.com/PrefectHQ/fastmcp/pull/1148) +* fix: _replace_ref_with_defs; ensure ref_path is string by [@itaru2622](https://github.com/itaru2622) in [#1164](https://github.com/PrefectHQ/fastmcp/pull/1164) +* Fix nesting when making OpenAPI arrays and objects optional by [@melkamar](https://github.com/melkamar) in [#1178](https://github.com/PrefectHQ/fastmcp/pull/1178) +* Fix `mcp-json` output format to include server name by [@jlowin](https://github.com/jlowin) in [#1185](https://github.com/PrefectHQ/fastmcp/pull/1185) +* Only configure logging one time by [@jlowin](https://github.com/jlowin) in [#1187](https://github.com/PrefectHQ/fastmcp/pull/1187) +### Docs 📚 +* Update changelog.mdx by [@jlowin](https://github.com/jlowin) in [#1127](https://github.com/PrefectHQ/fastmcp/pull/1127) +* Eunomia Authorization with native FastMCP's Middleware by [@tommitt](https://github.com/tommitt) in [#1144](https://github.com/PrefectHQ/fastmcp/pull/1144) +* update api ref for new `mdxify` version by [@zzstoatzz](https://github.com/zzstoatzz) in [#1182](https://github.com/PrefectHQ/fastmcp/pull/1182) +### Other Changes 🦾 +* Expand empty parameter filtering and add comprehensive tests by [@jlowin](https://github.com/jlowin) in [#1129](https://github.com/PrefectHQ/fastmcp/pull/1129) +* Add no-commit-to-branch hook by [@zzstoatzz](https://github.com/zzstoatzz) in [#1149](https://github.com/PrefectHQ/fastmcp/pull/1149) +* Update README.md by [@jlowin](https://github.com/jlowin) in [#1165](https://github.com/PrefectHQ/fastmcp/pull/1165) +* skip on rate limit by [@zzstoatzz](https://github.com/zzstoatzz) in [#1183](https://github.com/PrefectHQ/fastmcp/pull/1183) +* Remove deprecated proxy creation by [@jlowin](https://github.com/jlowin) in [#1186](https://github.com/PrefectHQ/fastmcp/pull/1186) +* Separate integration tests from unit tests in CI by [@jlowin](https://github.com/jlowin) in [#1188](https://github.com/PrefectHQ/fastmcp/pull/1188) + +## New Contributors +* [@FabrizioSandri](https://github.com/FabrizioSandri) made their first contribution in [#1128](https://github.com/PrefectHQ/fastmcp/pull/1128) +* [@melkamar](https://github.com/melkamar) made their first contribution in [#1153](https://github.com/PrefectHQ/fastmcp/pull/1153) +* [@codingjoe](https://github.com/codingjoe) made their first contribution in [#1141](https://github.com/PrefectHQ/fastmcp/pull/1141) +* [@itaru2622](https://github.com/itaru2622) made their first contribution in [#1164](https://github.com/PrefectHQ/fastmcp/pull/1164) +* [@ka2048](https://github.com/ka2048) made their first contribution in [#1171](https://github.com/PrefectHQ/fastmcp/pull/1171) +* [@artificial-aidan](https://github.com/artificial-aidan) made their first contribution in [#1147](https://github.com/PrefectHQ/fastmcp/pull/1147) + +**Full Changelog**: [v2.10.5...v2.10.6](https://github.com/PrefectHQ/fastmcp/compare/v2.10.5...v2.10.6) + + + + + +## [v2.10.5: Middle Management](https://github.com/PrefectHQ/fastmcp/releases/tag/v2.10.5) + +A maintenance release focused on OpenAPI refinements and middleware fixes, plus console improvements. + +## What's Changed +### Enhancements 🔧 +* Fix Claude Code CLI detection for npm global installations by [@jlowin](https://github.com/jlowin) in [#1106](https://github.com/PrefectHQ/fastmcp/pull/1106) +* Fix OpenAPI parameter name collisions with location suffixing by [@jlowin](https://github.com/jlowin) in [#1107](https://github.com/PrefectHQ/fastmcp/pull/1107) +* Add mirrored component support for proxy servers by [@jlowin](https://github.com/jlowin) in [#1105](https://github.com/PrefectHQ/fastmcp/pull/1105) +### Fixes 🐞 +* Fix OpenAPI deepObject style parameter encoding by [@jlowin](https://github.com/jlowin) in [#1122](https://github.com/PrefectHQ/fastmcp/pull/1122) +* xfail when github token is not set ('' or None) by [@jlowin](https://github.com/jlowin) in [#1123](https://github.com/PrefectHQ/fastmcp/pull/1123) +* fix: replace oneOf with anyOf in OpenAPI output schemas by [@MagnusS0](https://github.com/MagnusS0) in [#1119](https://github.com/PrefectHQ/fastmcp/pull/1119) +* Fix middleware list result types by [@jlowin](https://github.com/jlowin) in [#1125](https://github.com/PrefectHQ/fastmcp/pull/1125) +* Improve console width for logo by [@jlowin](https://github.com/jlowin) in [#1126](https://github.com/PrefectHQ/fastmcp/pull/1126) +### Docs 📚 +* Improve transport + integration docs by [@jlowin](https://github.com/jlowin) in [#1103](https://github.com/PrefectHQ/fastmcp/pull/1103) +* Update proxy.mdx by [@coldfire-x](https://github.com/coldfire-x) in [#1108](https://github.com/PrefectHQ/fastmcp/pull/1108) +### Other Changes 🦾 +* Update github remote server tests with secret by [@jlowin](https://github.com/jlowin) in [#1112](https://github.com/PrefectHQ/fastmcp/pull/1112) + +## New Contributors +* [@coldfire-x](https://github.com/coldfire-x) made their first contribution in [#1108](https://github.com/PrefectHQ/fastmcp/pull/1108) +* [@MagnusS0](https://github.com/MagnusS0) made their first contribution in [#1119](https://github.com/PrefectHQ/fastmcp/pull/1119) + +**Full Changelog**: [v2.10.4...v2.10.5](https://github.com/PrefectHQ/fastmcp/compare/v2.10.4...v2.10.5) + + + + + +## [v2.10.4: Transport-ation](https://github.com/PrefectHQ/fastmcp/releases/tag/v2.10.4) + +A quick fix to ensure the CLI accepts "streamable-http" as a valid transport option. + +## What's Changed +### Fixes 🐞 +* Ensure the CLI accepts "streamable-http" as a valid transport by [@jlowin](https://github.com/jlowin) in [#1099](https://github.com/PrefectHQ/fastmcp/pull/1099) + +**Full Changelog**: [v2.10.3...v2.10.4](https://github.com/PrefectHQ/fastmcp/compare/v2.10.3...v2.10.4) + + + + + +## [v2.10.3: CLI Me a River](https://github.com/PrefectHQ/fastmcp/releases/tag/v2.10.3) + +A major CLI overhaul featuring a complete refactor from typer to cyclopts, new IDE integrations, and comprehensive OpenAPI improvements. + +## What's Changed +### New Features 🎉 +* Refactor CLI from typer to cyclopts and add comprehensive tests by [@jlowin](https://github.com/jlowin) in [#1062](https://github.com/PrefectHQ/fastmcp/pull/1062) +* Add output schema support for OpenAPI tools by [@jlowin](https://github.com/jlowin) in [#1073](https://github.com/PrefectHQ/fastmcp/pull/1073) +### Enhancements 🔧 +* Add Cursor support via CLI integration by [@jlowin](https://github.com/jlowin) in [#1052](https://github.com/PrefectHQ/fastmcp/pull/1052) +* Add Claude Code install integration by [@jlowin](https://github.com/jlowin) in [#1053](https://github.com/PrefectHQ/fastmcp/pull/1053) +* Generate MCP JSON config output from CLI as new `fastmcp install` command by [@jlowin](https://github.com/jlowin) in [#1056](https://github.com/PrefectHQ/fastmcp/pull/1056) +* Use isawaitable instead of iscoroutine by [@jlowin](https://github.com/jlowin) in [#1059](https://github.com/PrefectHQ/fastmcp/pull/1059) +* feat: Add `--path` Option to CLI for HTTP/SSE Route by [@davidbk-legit](https://github.com/davidbk-legit) in [#1087](https://github.com/PrefectHQ/fastmcp/pull/1087) +* Fix concurrent proxy client operations with session isolation by [@jlowin](https://github.com/jlowin) in [#1083](https://github.com/PrefectHQ/fastmcp/pull/1083) +### Fixes 🐞 +* Refactor Client context management to avoid concurrency issue by [@hopeful0](https://github.com/hopeful0) in [#1054](https://github.com/PrefectHQ/fastmcp/pull/1054) +* Keep json schema $defs on transform by [@strawgate](https://github.com/strawgate) in [#1066](https://github.com/PrefectHQ/fastmcp/pull/1066) +* Ensure fastmcp version copy is plaintext by [@jlowin](https://github.com/jlowin) in [#1071](https://github.com/PrefectHQ/fastmcp/pull/1071) +* Fix single-element list unwrapping in tool content by [@jlowin](https://github.com/jlowin) in [#1074](https://github.com/PrefectHQ/fastmcp/pull/1074) +* Fix max recursion error when pruning OpenAPI definitions by [@dimitribarbot](https://github.com/dimitribarbot) in [#1092](https://github.com/PrefectHQ/fastmcp/pull/1092) +* Fix OpenAPI tool name registration when modified by mcp_component_fn by [@jlowin](https://github.com/jlowin) in [#1096](https://github.com/PrefectHQ/fastmcp/pull/1096) +### Docs 📚 +* Docs: add example of more concise way to use bearer auth by [@neilconway](https://github.com/neilconway) in [#1055](https://github.com/PrefectHQ/fastmcp/pull/1055) +* Update favicon by [@jlowin](https://github.com/jlowin) in [#1058](https://github.com/PrefectHQ/fastmcp/pull/1058) +* Update environment note by [@jlowin](https://github.com/jlowin) in [#1075](https://github.com/PrefectHQ/fastmcp/pull/1075) +* Add fastmcp version --copy documentation by [@jlowin](https://github.com/jlowin) in [#1076](https://github.com/PrefectHQ/fastmcp/pull/1076) +### Other Changes 🦾 +* Remove asserts and add documentation following #1054 by [@jlowin](https://github.com/jlowin) in [#1057](https://github.com/PrefectHQ/fastmcp/pull/1057) +* Add --copy flag for fastmcp version by [@jlowin](https://github.com/jlowin) in [#1063](https://github.com/PrefectHQ/fastmcp/pull/1063) +* Fix docstring format for fastmcp.client.Client by [@neilconway](https://github.com/neilconway) in [#1094](https://github.com/PrefectHQ/fastmcp/pull/1094) + +## New Contributors +* [@neilconway](https://github.com/neilconway) made their first contribution in [#1055](https://github.com/PrefectHQ/fastmcp/pull/1055) +* [@davidbk-legit](https://github.com/davidbk-legit) made their first contribution in [#1087](https://github.com/PrefectHQ/fastmcp/pull/1087) +* [@dimitribarbot](https://github.com/dimitribarbot) made their first contribution in [#1092](https://github.com/PrefectHQ/fastmcp/pull/1092) + +**Full Changelog**: [v2.10.2...v2.10.3](https://github.com/PrefectHQ/fastmcp/compare/v2.10.2...v2.10.3) + + + + + +## [v2.10.2: Forward March](https://github.com/PrefectHQ/fastmcp/releases/tag/v2.10.2) + +The headline feature of this release is the ability to "forward" advanced MCP interactions like logging, progress, and elicitation through proxy servers. If the remote server requests an elicitation, the proxy client will pass that request to the new, "ultimate" client. + +## What's Changed +### New Features 🎉 +* Proxy support advanced MCP features by [@hopeful0](https://github.com/hopeful0) in [#1022](https://github.com/PrefectHQ/fastmcp/pull/1022) +### Enhancements 🔧 +* Re-add splash screen by [@jlowin](https://github.com/jlowin) in [#1027](https://github.com/PrefectHQ/fastmcp/pull/1027) +* Reduce banner padding by [@jlowin](https://github.com/jlowin) in [#1030](https://github.com/PrefectHQ/fastmcp/pull/1030) +* Allow per-server timeouts in MCPConfig by [@cegersdoerfer](https://github.com/cegersdoerfer) in [#1031](https://github.com/PrefectHQ/fastmcp/pull/1031) +* Support 'scp' claim for OAuth scopes in BearerAuthProvider by [@jlowin](https://github.com/jlowin) in [#1033](https://github.com/PrefectHQ/fastmcp/pull/1033) +* Add path expansion to image/audio/file by [@jlowin](https://github.com/jlowin) in [#1038](https://github.com/PrefectHQ/fastmcp/pull/1038) +* Ensure multi-client configurations use new ProxyClient by [@jlowin](https://github.com/jlowin) in [#1045](https://github.com/PrefectHQ/fastmcp/pull/1045) +### Fixes 🐞 +* Expose stateless_http kwarg for mcp.run() by [@jlowin](https://github.com/jlowin) in [#1018](https://github.com/PrefectHQ/fastmcp/pull/1018) +* Avoid propagating logs by [@jlowin](https://github.com/jlowin) in [#1042](https://github.com/PrefectHQ/fastmcp/pull/1042) +### Docs 📚 +* Clean up docs by [@jlowin](https://github.com/jlowin) in [#1028](https://github.com/PrefectHQ/fastmcp/pull/1028) +* Docs: clarify server URL paths for ChatGPT integration by [@thap2331](https://github.com/thap2331) in [#1017](https://github.com/PrefectHQ/fastmcp/pull/1017) +### Other Changes 🦾 +* Split giant openapi test file into smaller files by [@jlowin](https://github.com/jlowin) in [#1034](https://github.com/PrefectHQ/fastmcp/pull/1034) +* Add comprehensive OpenAPI 3.0 vs 3.1 compatibility tests by [@jlowin](https://github.com/jlowin) in [#1035](https://github.com/PrefectHQ/fastmcp/pull/1035) +* Update banner and use console.log by [@jlowin](https://github.com/jlowin) in [#1041](https://github.com/PrefectHQ/fastmcp/pull/1041) + +## New Contributors +* [@cegersdoerfer](https://github.com/cegersdoerfer) made their first contribution in [#1031](https://github.com/PrefectHQ/fastmcp/pull/1031) +* [@hopeful0](https://github.com/hopeful0) made their first contribution in [#1022](https://github.com/PrefectHQ/fastmcp/pull/1022) +* [@thap2331](https://github.com/thap2331) made their first contribution in [#1017](https://github.com/PrefectHQ/fastmcp/pull/1017) + +**Full Changelog**: [v2.10.1...v2.10.2](https://github.com/PrefectHQ/fastmcp/compare/v2.10.1...v2.10.2) + + + + + +## [v2.10.1: Revert to Sender](https://github.com/PrefectHQ/fastmcp/releases/tag/v2.10.1) + +A quick patch to revert the CLI banner that was added in v2.10.0. + +## What's Changed +### Docs 📚 +* Update changelog.mdx by [@jlowin](https://github.com/jlowin) in [#1009](https://github.com/PrefectHQ/fastmcp/pull/1009) +* Revert "Add CLI banner" by [@jlowin](https://github.com/jlowin) in [#1011](https://github.com/PrefectHQ/fastmcp/pull/1011) + +**Full Changelog**: [v2.10.0...v2.10.1](https://github.com/PrefectHQ/fastmcp/compare/v2.10.0...v2.10.1) + + + + + +## [v2.10.0: Great Spec-tations](https://github.com/PrefectHQ/fastmcp/releases/tag/v2.10.0) + +FastMCP 2.10 brings full compliance with the 6/18/2025 MCP spec update, introducing elicitation support for dynamic server-client communication and output schemas for structured tool responses. Please note that due to these changes, this release also includes a breaking change to the return signature of `client.call_tool()`. + +### Elicitation Support +Elicitation allows MCP servers to request additional information from clients during tool execution, enabling more interactive and dynamic server behavior. This opens up new possibilities for tools that need user input or confirmation during execution. + +### Output Schemas +Tools can now define structured output schemas, ensuring that responses conform to expected formats and making tool integration more predictable and type-safe. + +## What's Changed +### New Features 🎉 +* MCP 6/18/25: Add output schema to tools by [@jlowin](https://github.com/jlowin) in [#901](https://github.com/PrefectHQ/fastmcp/pull/901) +* MCP 6/18/25: Elicitation support by [@jlowin](https://github.com/jlowin) in [#889](https://github.com/PrefectHQ/fastmcp/pull/889) +### Enhancements 🔧 +* Update types + tests for SDK changes by [@jlowin](https://github.com/jlowin) in [#888](https://github.com/PrefectHQ/fastmcp/pull/888) +* MCP 6/18/25: Update auth primitives by [@jlowin](https://github.com/jlowin) in [#966](https://github.com/PrefectHQ/fastmcp/pull/966) +* Add OpenAPI extensions support to HTTPRoute by [@maddymanu](https://github.com/maddymanu) in [#977](https://github.com/PrefectHQ/fastmcp/pull/977) +* Add title field support to FastMCP components by [@jlowin](https://github.com/jlowin) in [#982](https://github.com/PrefectHQ/fastmcp/pull/982) +* Support implicit Elicitation acceptance by [@jlowin](https://github.com/jlowin) in [#983](https://github.com/PrefectHQ/fastmcp/pull/983) +* Support 'no response' elicitation requests by [@jlowin](https://github.com/jlowin) in [#992](https://github.com/PrefectHQ/fastmcp/pull/992) +* Add Support for Configurable Algorithms by [@sstene1](https://github.com/sstene1) in [#997](https://github.com/PrefectHQ/fastmcp/pull/997) +### Fixes 🐞 +* Improve stdio error handling to raise connection failures immediately by [@jlowin](https://github.com/jlowin) in [#984](https://github.com/PrefectHQ/fastmcp/pull/984) +* Fix type hints for FunctionResource:fn by [@CfirTsabari](https://github.com/CfirTsabari) in [#986](https://github.com/PrefectHQ/fastmcp/pull/986) +* Update link to OpenAI MCP example by [@mossbanay](https://github.com/mossbanay) in [#985](https://github.com/PrefectHQ/fastmcp/pull/985) +* Fix output schema generation edge case by [@jlowin](https://github.com/jlowin) in [#995](https://github.com/PrefectHQ/fastmcp/pull/995) +* Refactor array parameter formatting to reduce code duplication by [@jlowin](https://github.com/jlowin) in [#1007](https://github.com/PrefectHQ/fastmcp/pull/1007) +* Fix OpenAPI array parameter explode handling by [@jlowin](https://github.com/jlowin) in [#1008](https://github.com/PrefectHQ/fastmcp/pull/1008) +### Breaking Changes 🛫 +* MCP 6/18/25: Upgrade to mcp 1.10 by [@jlowin](https://github.com/jlowin) in [#887](https://github.com/PrefectHQ/fastmcp/pull/887) +### Docs 📚 +* Update middleware imports and documentation by [@jlowin](https://github.com/jlowin) in [#999](https://github.com/PrefectHQ/fastmcp/pull/999) +* Update OpenAI docs by [@jlowin](https://github.com/jlowin) in [#1001](https://github.com/PrefectHQ/fastmcp/pull/1001) +* Add CLI banner by [@jlowin](https://github.com/jlowin) in [#1005](https://github.com/PrefectHQ/fastmcp/pull/1005) +### Examples & Contrib 💡 +* Component Manager by [@gorocode](https://github.com/gorocode) in [#976](https://github.com/PrefectHQ/fastmcp/pull/976) +### Other Changes 🦾 +* Minor auth improvements by [@jlowin](https://github.com/jlowin) in [#967](https://github.com/PrefectHQ/fastmcp/pull/967) +* Add .ccignore for copychat by [@jlowin](https://github.com/jlowin) in [#1000](https://github.com/PrefectHQ/fastmcp/pull/1000) + +## New Contributors +* [@maddymanu](https://github.com/maddymanu) made their first contribution in [#977](https://github.com/PrefectHQ/fastmcp/pull/977) +* [@github0hello](https://github.com/github0hello) made their first contribution in [#979](https://github.com/PrefectHQ/fastmcp/pull/979) +* [@tommitt](https://github.com/tommitt) made their first contribution in [#975](https://github.com/PrefectHQ/fastmcp/pull/975) +* [@CfirTsabari](https://github.com/CfirTsabari) made their first contribution in [#986](https://github.com/PrefectHQ/fastmcp/pull/986) +* [@mossbanay](https://github.com/mossbanay) made their first contribution in [#985](https://github.com/PrefectHQ/fastmcp/pull/985) +* [@sstene1](https://github.com/sstene1) made their first contribution in [#997](https://github.com/PrefectHQ/fastmcp/pull/997) + +**Full Changelog**: [v2.9.2...v2.10.0](https://github.com/PrefectHQ/fastmcp/compare/v2.9.2...v2.10.0) + + + + + +## [v2.9.2: Safety Pin](https://github.com/PrefectHQ/fastmcp/releases/tag/v2.9.2) + +This is a patch release to pin `mcp` below 1.10, which includes changes related to the 6/18/2025 MCP spec update and could potentially break functionality for some FastMCP users. + +## What's Changed +### Docs 📚 +* Fix version badge for messages by [@jlowin](https://github.com/jlowin) in [#960](https://github.com/PrefectHQ/fastmcp/pull/960) +### Dependencies 📦 +* Pin mcp dependency by [@jlowin](https://github.com/jlowin) in [#962](https://github.com/PrefectHQ/fastmcp/pull/962) + +**Full Changelog**: [v2.9.1...v2.9.2](https://github.com/PrefectHQ/fastmcp/compare/v2.9.1...v2.9.2) + + + + + +## [v2.9.1: Call Me Maybe](https://github.com/PrefectHQ/fastmcp/releases/tag/v2.9.1) + +FastMCP 2.9.1 introduces automatic MCP list change notifications, allowing servers to notify clients when tools, resources, or prompts are dynamically updated. This enables more responsive and adaptive MCP integrations. + +## What's Changed +### New Features 🎉 +* Add automatic MCP list change notifications and client message handling by [@jlowin](https://github.com/jlowin) in [#939](https://github.com/PrefectHQ/fastmcp/pull/939) +### Enhancements 🔧 +* Add debug logging to bearer token authentication by [@jlowin](https://github.com/jlowin) in [#952](https://github.com/PrefectHQ/fastmcp/pull/952) +### Fixes 🐞 +* Fix duplicate error logging in exception handlers by [@jlowin](https://github.com/jlowin) in [#938](https://github.com/PrefectHQ/fastmcp/pull/938) +* Fix parameter location enum handling in OpenAPI parser by [@jlowin](https://github.com/jlowin) in [#953](https://github.com/PrefectHQ/fastmcp/pull/953) +* Fix external schema reference handling in OpenAPI parser by [@jlowin](https://github.com/jlowin) in [#954](https://github.com/PrefectHQ/fastmcp/pull/954) +### Docs 📚 +* Update changelog for 2.9 release by [@jlowin](https://github.com/jlowin) in [#929](https://github.com/PrefectHQ/fastmcp/pull/929) +* Regenerate API references by [@zzstoatzz](https://github.com/zzstoatzz) in [#935](https://github.com/PrefectHQ/fastmcp/pull/935) +* Regenerate API references by [@zzstoatzz](https://github.com/zzstoatzz) in [#947](https://github.com/PrefectHQ/fastmcp/pull/947) +* Regenerate API references by [@zzstoatzz](https://github.com/zzstoatzz) in [#949](https://github.com/PrefectHQ/fastmcp/pull/949) +### Examples & Contrib 💡 +* Add `create_thread` tool to bsky MCP server by [@zzstoatzz](https://github.com/zzstoatzz) in [#927](https://github.com/PrefectHQ/fastmcp/pull/927) +* Update `mount_example.py` to work with current fastmcp API by [@rajephon](https://github.com/rajephon) in [#957](https://github.com/PrefectHQ/fastmcp/pull/957) + +## New Contributors +* [@rajephon](https://github.com/rajephon) made their first contribution in [#957](https://github.com/PrefectHQ/fastmcp/pull/957) + +**Full Changelog**: [v2.9.0...v2.9.1](https://github.com/PrefectHQ/fastmcp/compare/v2.9.0...v2.9.1) + + + + + +## [v2.9.0: Stuck in the Middleware With You](https://github.com/PrefectHQ/fastmcp/releases/tag/v2.9.0) + +FastMCP 2.9 introduces two important features that push beyond the basic MCP protocol: MCP Middleware and server-side type conversion. + +### MCP Middleware +MCP middleware lets you intercept and modify requests and responses at the protocol level, giving you powerful capabilities for logging, authentication, validation, and more. This is particularly useful for building production-ready MCP servers that need sophisticated request handling. + +### Server-side Type Conversion +This release also introduces server-side type conversion for prompt arguments, ensuring that data is properly formatted before being passed to your functions. This reduces the burden on individual tools and prompts to handle type validation and conversion. + +## What's Changed +### New Features 🎉 +* Add File utility for binary data by [@gorocode](https://github.com/gorocode) in [#843](https://github.com/PrefectHQ/fastmcp/pull/843) +* Consolidate prefix logic into FastMCP methods by [@jlowin](https://github.com/jlowin) in [#861](https://github.com/PrefectHQ/fastmcp/pull/861) +* Add MCP Middleware by [@jlowin](https://github.com/jlowin) in [#870](https://github.com/PrefectHQ/fastmcp/pull/870) +* Implement server-side type conversion for prompt arguments by [@jlowin](https://github.com/jlowin) in [#908](https://github.com/PrefectHQ/fastmcp/pull/908) +### Enhancements 🔧 +* Fix tool description indentation issue by [@zfflxx](https://github.com/zfflxx) in [#845](https://github.com/PrefectHQ/fastmcp/pull/845) +* Add version parameter to FastMCP constructor by [@mkyutani](https://github.com/mkyutani) in [#842](https://github.com/PrefectHQ/fastmcp/pull/842) +* Update version to not be positional by [@jlowin](https://github.com/jlowin) in [#848](https://github.com/PrefectHQ/fastmcp/pull/848) +* Add key to component by [@jlowin](https://github.com/jlowin) in [#869](https://github.com/PrefectHQ/fastmcp/pull/869) +* Add session_id property to Context for data sharing by [@jlowin](https://github.com/jlowin) in [#881](https://github.com/PrefectHQ/fastmcp/pull/881) +* Fix CORS documentation example by [@jlowin](https://github.com/jlowin) in [#895](https://github.com/PrefectHQ/fastmcp/pull/895) +### Fixes 🐞 +* "report_progress missing passing related_request_id causes notifications not working" by [@alexsee](https://github.com/alexsee) in [#838](https://github.com/PrefectHQ/fastmcp/pull/838) +* Fix JWT issuer validation to support string values per RFC 7519 by [@jlowin](https://github.com/jlowin) in [#892](https://github.com/PrefectHQ/fastmcp/pull/892) +* Fix BearerAuthProvider audience type annotations by [@jlowin](https://github.com/jlowin) in [#894](https://github.com/PrefectHQ/fastmcp/pull/894) +### Docs 📚 +* Add CLAUDE.md development guidelines by [@jlowin](https://github.com/jlowin) in [#880](https://github.com/PrefectHQ/fastmcp/pull/880) +* Update context docs for session_id property by [@jlowin](https://github.com/jlowin) in [#882](https://github.com/PrefectHQ/fastmcp/pull/882) +* Add API reference by [@zzstoatzz](https://github.com/zzstoatzz) in [#893](https://github.com/PrefectHQ/fastmcp/pull/893) +* Fix API ref rendering by [@zzstoatzz](https://github.com/zzstoatzz) in [#900](https://github.com/PrefectHQ/fastmcp/pull/900) +* Simplify docs nav by [@jlowin](https://github.com/jlowin) in [#902](https://github.com/PrefectHQ/fastmcp/pull/902) +* Add fastmcp inspect command by [@jlowin](https://github.com/jlowin) in [#904](https://github.com/PrefectHQ/fastmcp/pull/904) +* Update client docs by [@jlowin](https://github.com/jlowin) in [#912](https://github.com/PrefectHQ/fastmcp/pull/912) +* Update docs nav by [@jlowin](https://github.com/jlowin) in [#913](https://github.com/PrefectHQ/fastmcp/pull/913) +* Update integration documentation for Claude Desktop, ChatGPT, and Claude Code by [@jlowin](https://github.com/jlowin) in [#915](https://github.com/PrefectHQ/fastmcp/pull/915) +* Add http as an alias for streamable http by [@jlowin](https://github.com/jlowin) in [#917](https://github.com/PrefectHQ/fastmcp/pull/917) +* Clean up parameter documentation by [@jlowin](https://github.com/jlowin) in [#918](https://github.com/PrefectHQ/fastmcp/pull/918) +* Add middleware examples for timing, logging, rate limiting, and error handling by [@jlowin](https://github.com/jlowin) in [#919](https://github.com/PrefectHQ/fastmcp/pull/919) +* ControlFlow → FastMCP rename by [@jlowin](https://github.com/jlowin) in [#922](https://github.com/PrefectHQ/fastmcp/pull/922) +### Examples & Contrib 💡 +* Add contrib.mcp_mixin support for annotations by [@rsp2k](https://github.com/rsp2k) in [#860](https://github.com/PrefectHQ/fastmcp/pull/860) +* Add ATProto (Bluesky) MCP Server Example by [@zzstoatzz](https://github.com/zzstoatzz) in [#916](https://github.com/PrefectHQ/fastmcp/pull/916) +* Fix path in atproto example pyproject by [@zzstoatzz](https://github.com/zzstoatzz) in [#920](https://github.com/PrefectHQ/fastmcp/pull/920) +* Remove uv source in example by [@zzstoatzz](https://github.com/zzstoatzz) in [#921](https://github.com/PrefectHQ/fastmcp/pull/921) + +## New Contributors +* [@alexsee](https://github.com/alexsee) made their first contribution in [#838](https://github.com/PrefectHQ/fastmcp/pull/838) +* [@zfflxx](https://github.com/zfflxx) made their first contribution in [#845](https://github.com/PrefectHQ/fastmcp/pull/845) +* [@mkyutani](https://github.com/mkyutani) made their first contribution in [#842](https://github.com/PrefectHQ/fastmcp/pull/842) +* [@gorocode](https://github.com/gorocode) made their first contribution in [#843](https://github.com/PrefectHQ/fastmcp/pull/843) +* [@rsp2k](https://github.com/rsp2k) made their first contribution in [#860](https://github.com/PrefectHQ/fastmcp/pull/860) +* [@owtaylor](https://github.com/owtaylor) made their first contribution in [#897](https://github.com/PrefectHQ/fastmcp/pull/897) +* [@Jason-CKY](https://github.com/Jason-CKY) made their first contribution in [#906](https://github.com/PrefectHQ/fastmcp/pull/906) + +**Full Changelog**: [v2.8.1...v2.9.0](https://github.com/PrefectHQ/fastmcp/compare/v2.8.1...v2.9.0) + + + + + +## [v2.8.1: Sound Judgement](https://github.com/PrefectHQ/fastmcp/releases/tag/v2.8.1) + +2.8.1 introduces audio support, as well as minor fixes and updates for deprecated features. + +### Audio Support +This release adds support for audio content in MCP tools and resources, expanding FastMCP's multimedia capabilities beyond text and images. + +## What's Changed +### New Features 🎉 +* Add audio support by [@jlowin](https://github.com/jlowin) in [#833](https://github.com/PrefectHQ/fastmcp/pull/833) +### Enhancements 🔧 +* Add flag for disabling deprecation warnings by [@jlowin](https://github.com/jlowin) in [#802](https://github.com/PrefectHQ/fastmcp/pull/802) +* Add examples to Tool Arg Param transformation by [@strawgate](https://github.com/strawgate) in [#806](https://github.com/PrefectHQ/fastmcp/pull/806) +### Fixes 🐞 +* Restore .settings access as deprecated by [@jlowin](https://github.com/jlowin) in [#800](https://github.com/PrefectHQ/fastmcp/pull/800) +* Ensure handling of false http kwargs correctly; removed unused kwarg by [@jlowin](https://github.com/jlowin) in [#804](https://github.com/PrefectHQ/fastmcp/pull/804) +* Bump mcp 1.9.4 by [@jlowin](https://github.com/jlowin) in [#835](https://github.com/PrefectHQ/fastmcp/pull/835) +### Docs 📚 +* Update changelog for 2.8.0 by [@jlowin](https://github.com/jlowin) in [#794](https://github.com/PrefectHQ/fastmcp/pull/794) +* Update welcome docs by [@jlowin](https://github.com/jlowin) in [#808](https://github.com/PrefectHQ/fastmcp/pull/808) +* Update headers in docs by [@jlowin](https://github.com/jlowin) in [#809](https://github.com/PrefectHQ/fastmcp/pull/809) +* Add MCP group to tutorials by [@jlowin](https://github.com/jlowin) in [#810](https://github.com/PrefectHQ/fastmcp/pull/810) +* Add Community section to documentation by [@zzstoatzz](https://github.com/zzstoatzz) in [#819](https://github.com/PrefectHQ/fastmcp/pull/819) +* Add 2.8 update by [@jlowin](https://github.com/jlowin) in [#821](https://github.com/PrefectHQ/fastmcp/pull/821) +* Embed YouTube videos in community showcase by [@zzstoatzz](https://github.com/zzstoatzz) in [#820](https://github.com/PrefectHQ/fastmcp/pull/820) +### Other Changes 🦾 +* Ensure http args are passed through by [@jlowin](https://github.com/jlowin) in [#803](https://github.com/PrefectHQ/fastmcp/pull/803) +* Fix install link in readme by [@jlowin](https://github.com/jlowin) in [#836](https://github.com/PrefectHQ/fastmcp/pull/836) + +**Full Changelog**: [v2.8.0...v2.8.1](https://github.com/PrefectHQ/fastmcp/compare/v2.8.0...v2.8.1) + + + + + +## [v2.8.0: Transform and Roll Out](https://github.com/PrefectHQ/fastmcp/releases/tag/v2.8.0) + +FastMCP 2.8.0 introduces powerful new ways to customize and control your MCP servers! + +### Tool Transformation + +The highlight of this release is first-class [**Tool Transformation**](/patterns/tool-transformation), a new feature that lets you create enhanced variations of existing tools. You can now easily rename arguments, hide parameters, modify descriptions, and even wrap tools with custom validation or post-processing logic—all without rewriting the original code. This makes it easier than ever to adapt generic tools for specific LLM use cases or to simplify complex APIs. Huge thanks to [@strawgate](https://github.com/strawgate) for partnering on this, starting with [#591](https://github.com/PrefectHQ/fastmcp/discussions/591) and [#599](https://github.com/PrefectHQ/fastmcp/pull/599) and continuing offline. + +### Component Control +This release also gives you more granular control over which components are exposed to clients. With new [**tag-based filtering**](/servers/server#tag-based-filtering), you can selectively enable or disable tools, resources, and prompts based on tags, perfect for managing different environments or user permissions. Complementing this, every component now supports being [programmatically enabled or disabled](/servers/tools#disabling-tools), offering dynamic control over your server's capabilities. + +### Tools-by-Default +Finally, to improve compatibility with a wider range of LLM clients, this release changes the default behavior for OpenAPI integration: all API endpoints are now converted to `Tools` by default. This is a **breaking change** but pragmatically necessitated by the fact that the majority of MCP clients available today are, sadly, only compatible with MCP tools. Therefore, this change significantly simplifies the out-of-the-box experience and ensures your entire API is immediately accessible to any tool-using agent. + +## What's Changed +### New Features 🎉 +* First-class tool transformation by [@jlowin](https://github.com/jlowin) in [#745](https://github.com/PrefectHQ/fastmcp/pull/745) +* Support enable/disable for all FastMCP components (tools, prompts, resources, templates) by [@jlowin](https://github.com/jlowin) in [#781](https://github.com/PrefectHQ/fastmcp/pull/781) +* Add support for tag-based component filtering by [@jlowin](https://github.com/jlowin) in [#748](https://github.com/PrefectHQ/fastmcp/pull/748) +* Allow tag assignments for OpenAPI by [@jlowin](https://github.com/jlowin) in [#791](https://github.com/PrefectHQ/fastmcp/pull/791) +### Enhancements 🔧 +* Create common base class for components by [@jlowin](https://github.com/jlowin) in [#776](https://github.com/PrefectHQ/fastmcp/pull/776) +* Move components to own file; add resource by [@jlowin](https://github.com/jlowin) in [#777](https://github.com/PrefectHQ/fastmcp/pull/777) +* Update FastMCP component with __eq__ and __repr__ by [@jlowin](https://github.com/jlowin) in [#779](https://github.com/PrefectHQ/fastmcp/pull/779) +* Remove open-ended and server-specific settings by [@jlowin](https://github.com/jlowin) in [#750](https://github.com/PrefectHQ/fastmcp/pull/750) +### Fixes 🐞 +* Ensure client is only initialized once by [@jlowin](https://github.com/jlowin) in [#758](https://github.com/PrefectHQ/fastmcp/pull/758) +* Fix field validator for resource by [@jlowin](https://github.com/jlowin) in [#778](https://github.com/PrefectHQ/fastmcp/pull/778) +* Ensure proxies can overwrite remote tools without falling back to the remote by [@jlowin](https://github.com/jlowin) in [#782](https://github.com/PrefectHQ/fastmcp/pull/782) +### Breaking Changes 🛫 +* Treat all openapi routes as tools by [@jlowin](https://github.com/jlowin) in [#788](https://github.com/PrefectHQ/fastmcp/pull/788) +* Fix issue with global OpenAPI tags by [@jlowin](https://github.com/jlowin) in [#792](https://github.com/PrefectHQ/fastmcp/pull/792) +### Docs 📚 +* Minor docs updates by [@jlowin](https://github.com/jlowin) in [#755](https://github.com/PrefectHQ/fastmcp/pull/755) +* Add 2.7 update by [@jlowin](https://github.com/jlowin) in [#756](https://github.com/PrefectHQ/fastmcp/pull/756) +* Reduce 2.7 image size by [@jlowin](https://github.com/jlowin) in [#757](https://github.com/PrefectHQ/fastmcp/pull/757) +* Update updates.mdx by [@jlowin](https://github.com/jlowin) in [#765](https://github.com/PrefectHQ/fastmcp/pull/765) +* Hide docs sidebar scrollbar by default by [@jlowin](https://github.com/jlowin) in [#766](https://github.com/PrefectHQ/fastmcp/pull/766) +* Add "stop vibe testing" to tutorials by [@jlowin](https://github.com/jlowin) in [#767](https://github.com/PrefectHQ/fastmcp/pull/767) +* Add docs links by [@jlowin](https://github.com/jlowin) in [#768](https://github.com/PrefectHQ/fastmcp/pull/768) +* Fix: updated variable name under Gemini remote client by [@yrangana](https://github.com/yrangana) in [#769](https://github.com/PrefectHQ/fastmcp/pull/769) +* Revert "Hide docs sidebar scrollbar by default" by [@jlowin](https://github.com/jlowin) in [#770](https://github.com/PrefectHQ/fastmcp/pull/770) +* Add updates by [@jlowin](https://github.com/jlowin) in [#773](https://github.com/PrefectHQ/fastmcp/pull/773) +* Add tutorials by [@jlowin](https://github.com/jlowin) in [#783](https://github.com/PrefectHQ/fastmcp/pull/783) +* Update LLM-friendly docs by [@jlowin](https://github.com/jlowin) in [#784](https://github.com/PrefectHQ/fastmcp/pull/784) +* Update oauth.mdx by [@JeremyCraigMartinez](https://github.com/JeremyCraigMartinez) in [#787](https://github.com/PrefectHQ/fastmcp/pull/787) +* Add changelog by [@jlowin](https://github.com/jlowin) in [#789](https://github.com/PrefectHQ/fastmcp/pull/789) +* Add tutorials by [@jlowin](https://github.com/jlowin) in [#790](https://github.com/PrefectHQ/fastmcp/pull/790) +* Add docs for tag-based filtering by [@jlowin](https://github.com/jlowin) in [#793](https://github.com/PrefectHQ/fastmcp/pull/793) +### Other Changes 🦾 +* Create dependabot.yml by [@jlowin](https://github.com/jlowin) in [#759](https://github.com/PrefectHQ/fastmcp/pull/759) +* Bump astral-sh/setup-uv from 3 to 6 by [@dependabot](https://github.com/dependabot) in [#760](https://github.com/PrefectHQ/fastmcp/pull/760) +* Add dependencies section to release by [@jlowin](https://github.com/jlowin) in [#761](https://github.com/PrefectHQ/fastmcp/pull/761) +* Remove extra imports for MCPConfig by [@Maanas-Verma](https://github.com/Maanas-Verma) in [#763](https://github.com/PrefectHQ/fastmcp/pull/763) +* Split out enhancements in release notes by [@jlowin](https://github.com/jlowin) in [#764](https://github.com/PrefectHQ/fastmcp/pull/764) + +## New Contributors +* [@dependabot](https://github.com/dependabot) made their first contribution in [#760](https://github.com/PrefectHQ/fastmcp/pull/760) +* [@Maanas-Verma](https://github.com/Maanas-Verma) made their first contribution in [#763](https://github.com/PrefectHQ/fastmcp/pull/763) +* [@JeremyCraigMartinez](https://github.com/JeremyCraigMartinez) made their first contribution in [#787](https://github.com/PrefectHQ/fastmcp/pull/787) + +**Full Changelog**: [v2.7.1...v2.8.0](https://github.com/PrefectHQ/fastmcp/compare/v2.7.1...v2.8.0) + + + + + +## [v2.7.1: The Bearer Necessities](https://github.com/PrefectHQ/fastmcp/releases/tag/v2.7.1) + +This release primarily contains a fix for parsing string tokens that are provided to FastMCP clients. + +### New Features 🎉 + +* Respect cache setting, set default to 1 second by [@jlowin](https://github.com/jlowin) in [#747](https://github.com/PrefectHQ/fastmcp/pull/747) + +### Fixes 🐞 + +* Ensure event store is properly typed by [@jlowin](https://github.com/jlowin) in [#753](https://github.com/PrefectHQ/fastmcp/pull/753) +* Fix passing token string to client auth & add auth to MCPConfig clients by [@jlowin](https://github.com/jlowin) in [#754](https://github.com/PrefectHQ/fastmcp/pull/754) + +### Docs 📚 + +* Docs : fix client to mcp\_client in Gemini example by [@yrangana](https://github.com/yrangana) in [#734](https://github.com/PrefectHQ/fastmcp/pull/734) +* update add tool docstring by [@strawgate](https://github.com/strawgate) in [#739](https://github.com/PrefectHQ/fastmcp/pull/739) +* Fix contrib link by [@richardkmichael](https://github.com/richardkmichael) in [#749](https://github.com/PrefectHQ/fastmcp/pull/749) + +### Other Changes 🦾 + +* Switch Pydantic defaults to kwargs by [@strawgate](https://github.com/strawgate) in [#731](https://github.com/PrefectHQ/fastmcp/pull/731) +* Fix Typo in CLI module by [@wfclark5](https://github.com/wfclark5) in [#737](https://github.com/PrefectHQ/fastmcp/pull/737) +* chore: fix prompt docstring by [@danb27](https://github.com/danb27) in [#752](https://github.com/PrefectHQ/fastmcp/pull/752) +* Add accept to excluded headers by [@jlowin](https://github.com/jlowin) in [#751](https://github.com/PrefectHQ/fastmcp/pull/751) + +### New Contributors + +* [@wfclark5](https://github.com/wfclark5) made their first contribution in [#737](https://github.com/PrefectHQ/fastmcp/pull/737) +* [@richardkmichael](https://github.com/richardkmichael) made their first contribution in [#749](https://github.com/PrefectHQ/fastmcp/pull/749) +* [@danb27](https://github.com/danb27) made their first contribution in [#752](https://github.com/PrefectHQ/fastmcp/pull/752) + +**Full Changelog**: [v2.7.0...v2.7.1](https://github.com/PrefectHQ/fastmcp/compare/v2.7.0...v2.7.1) + + + + +## [v2.7.0: Pare Programming](https://github.com/PrefectHQ/fastmcp/releases/tag/v2.7.0) + +This is primarily a housekeeping release to remove or deprecate cruft that's accumulated since v1. Primarily, this release refactors FastMCP's internals in preparation for features planned in the next few major releases. However please note that as a result, this release has some minor breaking changes (which is why it's 2.7, not 2.6.2, in accordance with repo guidelines) though not to the core user-facing APIs. + +### Breaking Changes 🛫 + +* decorators return the objects they create, not the decorated function +* websockets is an optional dependency +* methods on the server for automatically converting functions into tools/resources/prompts have been deprecated in favor of using the decorators directly + +### New Features 🎉 + +* allow passing flags to servers by [@zzstoatzz](https://github.com/zzstoatzz) in [#690](https://github.com/PrefectHQ/fastmcp/pull/690) +* replace $ref pointing to `#/components/schemas/` with `#/$defs/` by [@phateffect](https://github.com/phateffect) in [#697](https://github.com/PrefectHQ/fastmcp/pull/697) +* Split Tool into Tool and FunctionTool by [@jlowin](https://github.com/jlowin) in [#700](https://github.com/PrefectHQ/fastmcp/pull/700) +* Use strict basemodel for Prompt; relax from\_function deprecation by [@jlowin](https://github.com/jlowin) in [#701](https://github.com/PrefectHQ/fastmcp/pull/701) +* Formalize resource/functionresource replationship by [@jlowin](https://github.com/jlowin) in [#702](https://github.com/PrefectHQ/fastmcp/pull/702) +* Formalize template/functiontemplate split by [@jlowin](https://github.com/jlowin) in [#703](https://github.com/PrefectHQ/fastmcp/pull/703) +* Support flexible @tool decorator call patterns by [@jlowin](https://github.com/jlowin) in [#706](https://github.com/PrefectHQ/fastmcp/pull/706) +* Ensure deprecation warnings have stacklevel=2 by [@jlowin](https://github.com/jlowin) in [#710](https://github.com/PrefectHQ/fastmcp/pull/710) +* Allow naked prompt decorator by [@jlowin](https://github.com/jlowin) in [#711](https://github.com/PrefectHQ/fastmcp/pull/711) + +### Fixes 🐞 + +* Updates / Fixes for Tool Content Conversion by [@strawgate](https://github.com/strawgate) in [#642](https://github.com/PrefectHQ/fastmcp/pull/642) +* Fix pr labeler permissions by [@jlowin](https://github.com/jlowin) in [#708](https://github.com/PrefectHQ/fastmcp/pull/708) +* remove -n auto by [@jlowin](https://github.com/jlowin) in [#709](https://github.com/PrefectHQ/fastmcp/pull/709) +* Fix links in README.md by [@alainivars](https://github.com/alainivars) in [#723](https://github.com/PrefectHQ/fastmcp/pull/723) + +Happily, this release DOES permit the use of "naked" decorators to align with Pythonic practice: + +```python +@mcp.tool +def my_tool(): + ... +``` + +**Full Changelog**: [v2.6.2...v2.7.0](https://github.com/PrefectHQ/fastmcp/compare/v2.6.2...v2.7.0) + + + + +## [v2.6.1: Blast Auth (second ignition)](https://github.com/PrefectHQ/fastmcp/releases/tag/v2.6.1) + +This is a patch release to restore py.typed in #686. + +### Docs 📚 + +* Update readme by [@jlowin](https://github.com/jlowin) in [#679](https://github.com/PrefectHQ/fastmcp/pull/679) +* Add gemini tutorial by [@jlowin](https://github.com/jlowin) in [#680](https://github.com/PrefectHQ/fastmcp/pull/680) +* Fix : fix path error to CLI Documentation by [@yrangana](https://github.com/yrangana) in [#684](https://github.com/PrefectHQ/fastmcp/pull/684) +* Update auth docs by [@jlowin](https://github.com/jlowin) in [#687](https://github.com/PrefectHQ/fastmcp/pull/687) + +### Other Changes 🦾 + +* Remove deprecation notice by [@jlowin](https://github.com/jlowin) in [#677](https://github.com/PrefectHQ/fastmcp/pull/677) +* Delete server.py by [@jlowin](https://github.com/jlowin) in [#681](https://github.com/PrefectHQ/fastmcp/pull/681) +* Restore py.typed by [@jlowin](https://github.com/jlowin) in [#686](https://github.com/PrefectHQ/fastmcp/pull/686) + +### New Contributors + +* [@yrangana](https://github.com/yrangana) made their first contribution in [#684](https://github.com/PrefectHQ/fastmcp/pull/684) + +**Full Changelog**: [v2.6.0...v2.6.1](https://github.com/PrefectHQ/fastmcp/compare/v2.6.0...v2.6.1) + + + + +## [v2.6.0: Blast Auth](https://github.com/PrefectHQ/fastmcp/releases/tag/v2.6.0) + +### New Features 🎉 + +* Introduce MCP client oauth flow by [@jlowin](https://github.com/jlowin) in [#478](https://github.com/PrefectHQ/fastmcp/pull/478) +* Support providing tools at init by [@jlowin](https://github.com/jlowin) in [#647](https://github.com/PrefectHQ/fastmcp/pull/647) +* Simplify code for running servers in processes during tests by [@jlowin](https://github.com/jlowin) in [#649](https://github.com/PrefectHQ/fastmcp/pull/649) +* Add basic bearer auth for server and client by [@jlowin](https://github.com/jlowin) in [#650](https://github.com/PrefectHQ/fastmcp/pull/650) +* Support configuring bearer auth from env vars by [@jlowin](https://github.com/jlowin) in [#652](https://github.com/PrefectHQ/fastmcp/pull/652) +* feat(tool): add support for excluding arguments from tool definition by [@deepak-stratforge](https://github.com/deepak-stratforge) in [#626](https://github.com/PrefectHQ/fastmcp/pull/626) +* Add docs for server + client auth by [@jlowin](https://github.com/jlowin) in [#655](https://github.com/PrefectHQ/fastmcp/pull/655) + +### Fixes 🐞 + +* fix: Support concurrency in FastMcpProxy (and Client) by [@Sillocan](https://github.com/Sillocan) in [#635](https://github.com/PrefectHQ/fastmcp/pull/635) +* Ensure Client.close() cleans up client context appropriately by [@jlowin](https://github.com/jlowin) in [#643](https://github.com/PrefectHQ/fastmcp/pull/643) +* Update client.mdx: ClientError namespace by [@mjkaye](https://github.com/mjkaye) in [#657](https://github.com/PrefectHQ/fastmcp/pull/657) + +### Docs 📚 + +* Make FastMCPTransport support simulated Streamable HTTP Transport (didn't work) by [@jlowin](https://github.com/jlowin) in [#645](https://github.com/PrefectHQ/fastmcp/pull/645) +* Document exclude\_args by [@jlowin](https://github.com/jlowin) in [#653](https://github.com/PrefectHQ/fastmcp/pull/653) +* Update welcome by [@jlowin](https://github.com/jlowin) in [#673](https://github.com/PrefectHQ/fastmcp/pull/673) +* Add Anthropic + Claude desktop integration guides by [@jlowin](https://github.com/jlowin) in [#674](https://github.com/PrefectHQ/fastmcp/pull/674) +* Minor docs design updates by [@jlowin](https://github.com/jlowin) in [#676](https://github.com/PrefectHQ/fastmcp/pull/676) + +### Other Changes 🦾 + +* Update test typing by [@jlowin](https://github.com/jlowin) in [#646](https://github.com/PrefectHQ/fastmcp/pull/646) +* Add OpenAI integration docs by [@jlowin](https://github.com/jlowin) in [#660](https://github.com/PrefectHQ/fastmcp/pull/660) + +### New Contributors + +* [@Sillocan](https://github.com/Sillocan) made their first contribution in [#635](https://github.com/PrefectHQ/fastmcp/pull/635) +* [@deepak-stratforge](https://github.com/deepak-stratforge) made their first contribution in [#626](https://github.com/PrefectHQ/fastmcp/pull/626) +* [@mjkaye](https://github.com/mjkaye) made their first contribution in [#657](https://github.com/PrefectHQ/fastmcp/pull/657) + +**Full Changelog**: [v2.5.2...v2.6.0](https://github.com/PrefectHQ/fastmcp/compare/v2.5.2...v2.6.0) + + + + +## [v2.5.2: Stayin' Alive](https://github.com/PrefectHQ/fastmcp/releases/tag/v2.5.2) + +### New Features 🎉 + +* Add graceful error handling for unreachable mounted servers by [@davenpi](https://github.com/davenpi) in [#605](https://github.com/PrefectHQ/fastmcp/pull/605) +* Improve type inference from client transport by [@jlowin](https://github.com/jlowin) in [#623](https://github.com/PrefectHQ/fastmcp/pull/623) +* Add keep\_alive param to reuse subprocess by [@jlowin](https://github.com/jlowin) in [#624](https://github.com/PrefectHQ/fastmcp/pull/624) + +### Fixes 🐞 + +* Fix handling tools without descriptions by [@jlowin](https://github.com/jlowin) in [#610](https://github.com/PrefectHQ/fastmcp/pull/610) +* Don't print env vars to console when format is wrong by [@jlowin](https://github.com/jlowin) in [#615](https://github.com/PrefectHQ/fastmcp/pull/615) +* Ensure behavior-affecting headers are excluded when forwarding proxies/openapi by [@jlowin](https://github.com/jlowin) in [#620](https://github.com/PrefectHQ/fastmcp/pull/620) + +### Docs 📚 + +* Add notes about uv and claude desktop by [@jlowin](https://github.com/jlowin) in [#597](https://github.com/PrefectHQ/fastmcp/pull/597) + +### Other Changes 🦾 + +* add init\_timeout for mcp client by [@jfouret](https://github.com/jfouret) in [#607](https://github.com/PrefectHQ/fastmcp/pull/607) +* Add init\_timeout for mcp client (incl settings) by [@jlowin](https://github.com/jlowin) in [#609](https://github.com/PrefectHQ/fastmcp/pull/609) +* Support for uppercase letters at the log level by [@ksawaray](https://github.com/ksawaray) in [#625](https://github.com/PrefectHQ/fastmcp/pull/625) + +### New Contributors + +* [@jfouret](https://github.com/jfouret) made their first contribution in [#607](https://github.com/PrefectHQ/fastmcp/pull/607) +* [@ksawaray](https://github.com/ksawaray) made their first contribution in [#625](https://github.com/PrefectHQ/fastmcp/pull/625) + +**Full Changelog**: [v2.5.1...v2.5.2](https://github.com/PrefectHQ/fastmcp/compare/v2.5.1...v2.5.2) + + + + +## [v2.5.1: Route Awakening (Part 2)](https://github.com/PrefectHQ/fastmcp/releases/tag/v2.5.1) + +### Fixes 🐞 + +* Ensure content-length is always stripped from client headers by [@jlowin](https://github.com/jlowin) in [#589](https://github.com/PrefectHQ/fastmcp/pull/589) + +### Docs 📚 + +* Fix redundant section of docs by [@jlowin](https://github.com/jlowin) in [#583](https://github.com/PrefectHQ/fastmcp/pull/583) + +**Full Changelog**: [v2.5.0...v2.5.1](https://github.com/PrefectHQ/fastmcp/compare/v2.5.0...v2.5.1) + + + + +## [v2.5.0: Route Awakening](https://github.com/PrefectHQ/fastmcp/releases/tag/v2.5.0) + +This release introduces completely new tools for generating and customizing MCP servers from OpenAPI specs and FastAPI apps, including popular requests like mechanisms for determining what routes map to what MCP components; renaming routes; and customizing the generated MCP components. + +### New Features 🎉 + +* Add FastMCP 1.0 server support for in-memory Client / Testing by [@jlowin](https://github.com/jlowin) in [#539](https://github.com/PrefectHQ/fastmcp/pull/539) +* Minor addition: add transport to stdio server in mcpconfig, with default by [@jlowin](https://github.com/jlowin) in [#555](https://github.com/PrefectHQ/fastmcp/pull/555) +* Raise an error if a Client is created with no servers in config by [@jlowin](https://github.com/jlowin) in [#554](https://github.com/PrefectHQ/fastmcp/pull/554) +* Expose model preferences in `Context.sample` for flexible model selection. by [@davenpi](https://github.com/davenpi) in [#542](https://github.com/PrefectHQ/fastmcp/pull/542) +* Ensure custom routes are respected by [@jlowin](https://github.com/jlowin) in [#558](https://github.com/PrefectHQ/fastmcp/pull/558) +* Add client method to send cancellation notifications by [@davenpi](https://github.com/davenpi) in [#563](https://github.com/PrefectHQ/fastmcp/pull/563) +* Enhance route map logic for include/exclude OpenAPI routes by [@jlowin](https://github.com/jlowin) in [#564](https://github.com/PrefectHQ/fastmcp/pull/564) +* Add tag-based route maps by [@jlowin](https://github.com/jlowin) in [#565](https://github.com/PrefectHQ/fastmcp/pull/565) +* Add advanced control of openAPI route creation by [@jlowin](https://github.com/jlowin) in [#566](https://github.com/PrefectHQ/fastmcp/pull/566) +* Make error masking configurable by [@jlowin](https://github.com/jlowin) in [#550](https://github.com/PrefectHQ/fastmcp/pull/550) +* Ensure client headers are passed through to remote servers by [@jlowin](https://github.com/jlowin) in [#575](https://github.com/PrefectHQ/fastmcp/pull/575) +* Use lowercase name for headers when comparing by [@jlowin](https://github.com/jlowin) in [#576](https://github.com/PrefectHQ/fastmcp/pull/576) +* Permit more flexible name generation for OpenAPI servers by [@jlowin](https://github.com/jlowin) in [#578](https://github.com/PrefectHQ/fastmcp/pull/578) +* Ensure that tools/templates/prompts are compatible with callable objects by [@jlowin](https://github.com/jlowin) in [#579](https://github.com/PrefectHQ/fastmcp/pull/579) + +### Docs 📚 + +* Add version badge for prefix formats by [@jlowin](https://github.com/jlowin) in [#537](https://github.com/PrefectHQ/fastmcp/pull/537) +* Add versioning note to docs by [@jlowin](https://github.com/jlowin) in [#551](https://github.com/PrefectHQ/fastmcp/pull/551) +* Bump 2.3.6 references to 2.4.0 by [@jlowin](https://github.com/jlowin) in [#567](https://github.com/PrefectHQ/fastmcp/pull/567) + +**Full Changelog**: [v2.4.0...v2.5.0](https://github.com/PrefectHQ/fastmcp/compare/v2.4.0...v2.5.0) + + + + +## [v2.4.0: Config and Conquer](https://github.com/PrefectHQ/fastmcp/releases/tag/v2.4.0) + +**Note**: this release includes a backwards-incompatible change to how resources are prefixed when mounted in composed servers. However, it is only backwards-incompatible if users were running tests or manually loading resources by prefixed key; LLMs should not have any issue discovering the new route. + +### New Features 🎉 + +* Allow \* Methods and all routes as tools shortcuts by [@jlowin](https://github.com/jlowin) in [#520](https://github.com/PrefectHQ/fastmcp/pull/520) +* Improved support for config dicts by [@jlowin](https://github.com/jlowin) in [#522](https://github.com/PrefectHQ/fastmcp/pull/522) +* Support creating clients from MCP config dicts, including multi-server clients by [@jlowin](https://github.com/jlowin) in [#527](https://github.com/PrefectHQ/fastmcp/pull/527) +* Make resource prefix format configurable by [@jlowin](https://github.com/jlowin) in [#534](https://github.com/PrefectHQ/fastmcp/pull/534) + +### Fixes 🐞 + +* Avoid hanging on initializing server session by [@jlowin](https://github.com/jlowin) in [#523](https://github.com/PrefectHQ/fastmcp/pull/523) + +### Breaking Changes 🛫 + +* Remove customizable separators; improve resource separator by [@jlowin](https://github.com/jlowin) in [#526](https://github.com/PrefectHQ/fastmcp/pull/526) + +### Docs 📚 + +* Improve client documentation by [@jlowin](https://github.com/jlowin) in [#517](https://github.com/PrefectHQ/fastmcp/pull/517) + +### Other Changes 🦾 + +* Ensure openapi path params are handled properly by [@jlowin](https://github.com/jlowin) in [#519](https://github.com/PrefectHQ/fastmcp/pull/519) +* better error when missing lifespan by [@zzstoatzz](https://github.com/zzstoatzz) in [#521](https://github.com/PrefectHQ/fastmcp/pull/521) + +**Full Changelog**: [v2.3.5...v2.4.0](https://github.com/PrefectHQ/fastmcp/compare/v2.3.5...v2.4.0) + + + + +## [v2.3.5: Making Progress](https://github.com/PrefectHQ/fastmcp/releases/tag/v2.3.5) + +### New Features 🎉 + +* support messages in progress notifications by [@rickygenhealth](https://github.com/rickygenhealth) in [#471](https://github.com/PrefectHQ/fastmcp/pull/471) +* feat: Add middleware option in server.run by [@Maxi91f](https://github.com/Maxi91f) in [#475](https://github.com/PrefectHQ/fastmcp/pull/475) +* Add lifespan property to app by [@jlowin](https://github.com/jlowin) in [#483](https://github.com/PrefectHQ/fastmcp/pull/483) +* Update `fastmcp run` to work with remote servers by [@jlowin](https://github.com/jlowin) in [#491](https://github.com/PrefectHQ/fastmcp/pull/491) +* Add FastMCP.as\_proxy() by [@jlowin](https://github.com/jlowin) in [#490](https://github.com/PrefectHQ/fastmcp/pull/490) +* Infer sse transport from urls containing /sse by [@jlowin](https://github.com/jlowin) in [#512](https://github.com/PrefectHQ/fastmcp/pull/512) +* Add progress handler to client by [@jlowin](https://github.com/jlowin) in [#513](https://github.com/PrefectHQ/fastmcp/pull/513) +* Store the initialize result on the client by [@jlowin](https://github.com/jlowin) in [#509](https://github.com/PrefectHQ/fastmcp/pull/509) + +### Fixes 🐞 + +* Remove patch and use upstream SSEServerTransport by [@jlowin](https://github.com/jlowin) in [#425](https://github.com/PrefectHQ/fastmcp/pull/425) + +### Docs 📚 + +* Update transport docs by [@jlowin](https://github.com/jlowin) in [#458](https://github.com/PrefectHQ/fastmcp/pull/458) +* update proxy docs + example by [@zzstoatzz](https://github.com/zzstoatzz) in [#460](https://github.com/PrefectHQ/fastmcp/pull/460) +* doc(asgi): Change custom route example to PlainTextResponse by [@mcw0933](https://github.com/mcw0933) in [#477](https://github.com/PrefectHQ/fastmcp/pull/477) +* Store FastMCP instance on app.state.fastmcp\_server by [@jlowin](https://github.com/jlowin) in [#489](https://github.com/PrefectHQ/fastmcp/pull/489) +* Improve AGENTS.md overview by [@jlowin](https://github.com/jlowin) in [#492](https://github.com/PrefectHQ/fastmcp/pull/492) +* Update release numbers for anticipated version by [@jlowin](https://github.com/jlowin) in [#516](https://github.com/PrefectHQ/fastmcp/pull/516) + +### Other Changes 🦾 + +* run tests on all PRs by [@jlowin](https://github.com/jlowin) in [#468](https://github.com/PrefectHQ/fastmcp/pull/468) +* add null check by [@zzstoatzz](https://github.com/zzstoatzz) in [#473](https://github.com/PrefectHQ/fastmcp/pull/473) +* strict typing for `server.py` by [@zzstoatzz](https://github.com/zzstoatzz) in [#476](https://github.com/PrefectHQ/fastmcp/pull/476) +* Doc(quickstart): Fix import statements by [@mai-nakagawa](https://github.com/mai-nakagawa) in [#479](https://github.com/PrefectHQ/fastmcp/pull/479) +* Add labeler by [@jlowin](https://github.com/jlowin) in [#484](https://github.com/PrefectHQ/fastmcp/pull/484) +* Fix flaky timeout test by increasing timeout (#474) by [@davenpi](https://github.com/davenpi) in [#486](https://github.com/PrefectHQ/fastmcp/pull/486) +* Skipping `test_permission_error` if runner is root. by [@ZiadAmerr](https://github.com/ZiadAmerr) in [#502](https://github.com/PrefectHQ/fastmcp/pull/502) +* allow passing full uvicorn config by [@zzstoatzz](https://github.com/zzstoatzz) in [#504](https://github.com/PrefectHQ/fastmcp/pull/504) +* Skip timeout tests on windows by [@jlowin](https://github.com/jlowin) in [#514](https://github.com/PrefectHQ/fastmcp/pull/514) + +### New Contributors + +* [@rickygenhealth](https://github.com/rickygenhealth) made their first contribution in [#471](https://github.com/PrefectHQ/fastmcp/pull/471) +* [@Maxi91f](https://github.com/Maxi91f) made their first contribution in [#475](https://github.com/PrefectHQ/fastmcp/pull/475) +* [@mcw0933](https://github.com/mcw0933) made their first contribution in [#477](https://github.com/PrefectHQ/fastmcp/pull/477) +* [@mai-nakagawa](https://github.com/mai-nakagawa) made their first contribution in [#479](https://github.com/PrefectHQ/fastmcp/pull/479) +* [@ZiadAmerr](https://github.com/ZiadAmerr) made their first contribution in [#502](https://github.com/PrefectHQ/fastmcp/pull/502) + +**Full Changelog**: [v2.3.4...v2.3.5](https://github.com/PrefectHQ/fastmcp/compare/v2.3.4...v2.3.5) + + + + +## [v2.3.4: Error Today, Gone Tomorrow](https://github.com/PrefectHQ/fastmcp/releases/tag/v2.3.4) + +### New Features 🎉 + +* logging stack trace for easier debugging by [@jbkoh](https://github.com/jbkoh) in [#413](https://github.com/PrefectHQ/fastmcp/pull/413) +* add missing StreamableHttpTransport in client exports by [@yihuang](https://github.com/yihuang) in [#408](https://github.com/PrefectHQ/fastmcp/pull/408) +* Improve error handling for tools and resources by [@jlowin](https://github.com/jlowin) in [#434](https://github.com/PrefectHQ/fastmcp/pull/434) +* feat: add support for removing tools from server by [@davenpi](https://github.com/davenpi) in [#437](https://github.com/PrefectHQ/fastmcp/pull/437) +* Prune titles from JSONSchemas by [@jlowin](https://github.com/jlowin) in [#449](https://github.com/PrefectHQ/fastmcp/pull/449) +* Declare toolsChanged capability for stdio server. by [@davenpi](https://github.com/davenpi) in [#450](https://github.com/PrefectHQ/fastmcp/pull/450) +* Improve handling of exceptiongroups when raised in clients by [@jlowin](https://github.com/jlowin) in [#452](https://github.com/PrefectHQ/fastmcp/pull/452) +* Add timeout support to client by [@jlowin](https://github.com/jlowin) in [#455](https://github.com/PrefectHQ/fastmcp/pull/455) + +### Fixes 🐞 + +* Pin to mcp 1.8.1 to resolve callback deadlocks with SHTTP by [@jlowin](https://github.com/jlowin) in [#427](https://github.com/PrefectHQ/fastmcp/pull/427) +* Add reprs for OpenAPI objects by [@jlowin](https://github.com/jlowin) in [#447](https://github.com/PrefectHQ/fastmcp/pull/447) +* Ensure openapi defs for structured objects are loaded properly by [@jlowin](https://github.com/jlowin) in [#448](https://github.com/PrefectHQ/fastmcp/pull/448) +* Ensure tests run against correct python version by [@jlowin](https://github.com/jlowin) in [#454](https://github.com/PrefectHQ/fastmcp/pull/454) +* Ensure result is only returned if a new key was found by [@jlowin](https://github.com/jlowin) in [#456](https://github.com/PrefectHQ/fastmcp/pull/456) + +### Docs 📚 + +* Add documentation for tool removal by [@jlowin](https://github.com/jlowin) in [#440](https://github.com/PrefectHQ/fastmcp/pull/440) + +### Other Changes 🦾 + +* Deprecate passing settings to the FastMCP instance by [@jlowin](https://github.com/jlowin) in [#424](https://github.com/PrefectHQ/fastmcp/pull/424) +* Add path prefix to test by [@jlowin](https://github.com/jlowin) in [#432](https://github.com/PrefectHQ/fastmcp/pull/432) + +### New Contributors + +* [@jbkoh](https://github.com/jbkoh) made their first contribution in [#413](https://github.com/PrefectHQ/fastmcp/pull/413) +* [@davenpi](https://github.com/davenpi) made their first contribution in [#437](https://github.com/PrefectHQ/fastmcp/pull/437) + +**Full Changelog**: [v2.3.3...v2.3.4](https://github.com/PrefectHQ/fastmcp/compare/v2.3.3...v2.3.4) + + + + +## [v2.3.3: SSE you later](https://github.com/PrefectHQ/fastmcp/releases/tag/v2.3.3) + +This is a hotfix for a bug introduced in 2.3.2 that broke SSE servers + +### Fixes 🐞 + +* Fix bug that sets message path and sse path to same value by [@jlowin](https://github.com/jlowin) in [#405](https://github.com/PrefectHQ/fastmcp/pull/405) + +### Docs 📚 + +* Update composition docs by [@jlowin](https://github.com/jlowin) in [#403](https://github.com/PrefectHQ/fastmcp/pull/403) + +### Other Changes 🦾 + +* Add test for no prefix when importing by [@jlowin](https://github.com/jlowin) in [#404](https://github.com/PrefectHQ/fastmcp/pull/404) + +**Full Changelog**: [v2.3.2...v2.3.3](https://github.com/PrefectHQ/fastmcp/compare/v2.3.2...v2.3.3) + + + + +## [v2.3.2: Stuck in the Middleware With You](https://github.com/PrefectHQ/fastmcp/releases/tag/v2.3.2) + +### New Features 🎉 + +* Allow users to pass middleware to starlette app constructors by [@jlowin](https://github.com/jlowin) in [#398](https://github.com/PrefectHQ/fastmcp/pull/398) +* Deprecate transport-specific methods on FastMCP server by [@jlowin](https://github.com/jlowin) in [#401](https://github.com/PrefectHQ/fastmcp/pull/401) + +### Docs 📚 + +* Update CLI docs by [@jlowin](https://github.com/jlowin) in [#402](https://github.com/PrefectHQ/fastmcp/pull/402) + +### Other Changes 🦾 + +* Adding 23 tests for CLI by [@didier-durand](https://github.com/didier-durand) in [#394](https://github.com/PrefectHQ/fastmcp/pull/394) + +**Full Changelog**: [v2.3.1...v2.3.2](https://github.com/PrefectHQ/fastmcp/compare/v2.3.1...v2.3.2) + + + + +## [v2.3.1: For Good-nests Sake](https://github.com/PrefectHQ/fastmcp/releases/tag/v2.3.1) + +This release primarily patches a long-standing bug with nested ASGI SSE servers. + +### Fixes 🐞 + +* Fix tool result serialization when the tool returns a list by [@strawgate](https://github.com/strawgate) in [#379](https://github.com/PrefectHQ/fastmcp/pull/379) +* Ensure FastMCP handles nested SSE and SHTTP apps properly in ASGI frameworks by [@jlowin](https://github.com/jlowin) in [#390](https://github.com/PrefectHQ/fastmcp/pull/390) + +### Docs 📚 + +* Update transport docs by [@jlowin](https://github.com/jlowin) in [#377](https://github.com/PrefectHQ/fastmcp/pull/377) +* Add llms.txt to docs by [@jlowin](https://github.com/jlowin) in [#384](https://github.com/PrefectHQ/fastmcp/pull/384) +* Fixing various text typos by [@didier-durand](https://github.com/didier-durand) in [#385](https://github.com/PrefectHQ/fastmcp/pull/385) + +### Other Changes 🦾 + +* Adding a few tests to Image type by [@didier-durand](https://github.com/didier-durand) in [#387](https://github.com/PrefectHQ/fastmcp/pull/387) +* Adding tests for TimedCache by [@didier-durand](https://github.com/didier-durand) in [#388](https://github.com/PrefectHQ/fastmcp/pull/388) + +### New Contributors + +* [@didier-durand](https://github.com/didier-durand) made their first contribution in [#385](https://github.com/PrefectHQ/fastmcp/pull/385) + +**Full Changelog**: [v2.3.0...v2.3.1](https://github.com/PrefectHQ/fastmcp/compare/v2.3.0...v2.3.1) + + + + +## [v2.3.0: Stream Me Up, Scotty](https://github.com/PrefectHQ/fastmcp/releases/tag/v2.3.0) + +### New Features 🎉 + +* Add streaming support for HTTP transport by [@jlowin](https://github.com/jlowin) in [#365](https://github.com/PrefectHQ/fastmcp/pull/365) +* Support streaming HTTP transport in clients by [@jlowin](https://github.com/jlowin) in [#366](https://github.com/PrefectHQ/fastmcp/pull/366) +* Add streaming support to CLI by [@jlowin](https://github.com/jlowin) in [#367](https://github.com/PrefectHQ/fastmcp/pull/367) + +### Fixes 🐞 + +* Fix streaming transport initialization by [@jlowin](https://github.com/jlowin) in [#368](https://github.com/PrefectHQ/fastmcp/pull/368) + +### Docs 📚 + +* Update transport documentation for streaming support by [@jlowin](https://github.com/jlowin) in [#369](https://github.com/PrefectHQ/fastmcp/pull/369) + +**Full Changelog**: [v2.2.10...v2.3.0](https://github.com/PrefectHQ/fastmcp/compare/v2.2.10...v2.3.0) + + + + +## [v2.2.10: That's JSON Bourne](https://github.com/PrefectHQ/fastmcp/releases/tag/v2.2.10) + +### Fixes 🐞 + +* Disable automatic JSON parsing of tool args by [@jlowin](https://github.com/jlowin) in [#341](https://github.com/PrefectHQ/fastmcp/pull/341) +* Fix prompt test by [@jlowin](https://github.com/jlowin) in [#342](https://github.com/PrefectHQ/fastmcp/pull/342) + +### Other Changes 🦾 + +* Update docs.json by [@jlowin](https://github.com/jlowin) in [#338](https://github.com/PrefectHQ/fastmcp/pull/338) +* Add test coverage + tests on 4 examples by [@alainivars](https://github.com/alainivars) in [#306](https://github.com/PrefectHQ/fastmcp/pull/306) + +### New Contributors + +* [@alainivars](https://github.com/alainivars) made their first contribution in [#306](https://github.com/PrefectHQ/fastmcp/pull/306) + +**Full Changelog**: [v2.2.9...v2.2.10](https://github.com/PrefectHQ/fastmcp/compare/v2.2.9...v2.2.10) + + + + +## [v2.2.9: Str-ing the Pot (Hotfix)](https://github.com/PrefectHQ/fastmcp/releases/tag/v2.2.9) + +This release is a hotfix for the issue detailed in #330 + +### Fixes 🐞 + +* Prevent invalid resource URIs by [@jlowin](https://github.com/jlowin) in [#336](https://github.com/PrefectHQ/fastmcp/pull/336) +* Coerce numbers to str by [@jlowin](https://github.com/jlowin) in [#337](https://github.com/PrefectHQ/fastmcp/pull/337) + +### Docs 📚 + +* Add client badge by [@jlowin](https://github.com/jlowin) in [#327](https://github.com/PrefectHQ/fastmcp/pull/327) +* Update bug.yml by [@jlowin](https://github.com/jlowin) in [#328](https://github.com/PrefectHQ/fastmcp/pull/328) + +### Other Changes 🦾 + +* Update quickstart.mdx example to include import by [@discdiver](https://github.com/discdiver) in [#329](https://github.com/PrefectHQ/fastmcp/pull/329) + +### New Contributors + +* [@discdiver](https://github.com/discdiver) made their first contribution in [#329](https://github.com/PrefectHQ/fastmcp/pull/329) + +**Full Changelog**: [v2.2.8...v2.2.9](https://github.com/PrefectHQ/fastmcp/compare/v2.2.8...v2.2.9) + + + + +## [v2.2.8: Parse and Recreation](https://github.com/PrefectHQ/fastmcp/releases/tag/v2.2.8) + +### New Features 🎉 + +* Replace custom parsing with TypeAdapter by [@jlowin](https://github.com/jlowin) in [#314](https://github.com/PrefectHQ/fastmcp/pull/314) +* Handle \*args/\*\*kwargs appropriately for various components by [@jlowin](https://github.com/jlowin) in [#317](https://github.com/PrefectHQ/fastmcp/pull/317) +* Add timeout-graceful-shutdown as a default config for SSE app by [@jlowin](https://github.com/jlowin) in [#323](https://github.com/PrefectHQ/fastmcp/pull/323) +* Ensure prompts return descriptions by [@jlowin](https://github.com/jlowin) in [#325](https://github.com/PrefectHQ/fastmcp/pull/325) + +### Fixes 🐞 + +* Ensure that tool serialization has a graceful fallback by [@jlowin](https://github.com/jlowin) in [#310](https://github.com/PrefectHQ/fastmcp/pull/310) + +### Docs 📚 + +* Update docs for clarity by [@jlowin](https://github.com/jlowin) in [#312](https://github.com/PrefectHQ/fastmcp/pull/312) + +### Other Changes 🦾 + +* Remove is\_async attribute by [@jlowin](https://github.com/jlowin) in [#315](https://github.com/PrefectHQ/fastmcp/pull/315) +* Dry out retrieving context kwarg by [@jlowin](https://github.com/jlowin) in [#316](https://github.com/PrefectHQ/fastmcp/pull/316) + +**Full Changelog**: [v2.2.7...v2.2.8](https://github.com/PrefectHQ/fastmcp/compare/v2.2.7...v2.2.8) + + + + +## [v2.2.7: You Auth to Know Better](https://github.com/PrefectHQ/fastmcp/releases/tag/v2.2.7) + +### New Features 🎉 + +* use pydantic\_core.to\_json by [@jlowin](https://github.com/jlowin) in [#290](https://github.com/PrefectHQ/fastmcp/pull/290) +* Ensure openapi descriptions are included in tool details by [@jlowin](https://github.com/jlowin) in [#293](https://github.com/PrefectHQ/fastmcp/pull/293) +* Bump mcp to 1.7.1 by [@jlowin](https://github.com/jlowin) in [#298](https://github.com/PrefectHQ/fastmcp/pull/298) +* Add support for tool annotations by [@jlowin](https://github.com/jlowin) in [#299](https://github.com/PrefectHQ/fastmcp/pull/299) +* Add auth support by [@jlowin](https://github.com/jlowin) in [#300](https://github.com/PrefectHQ/fastmcp/pull/300) +* Add low-level methods to client by [@jlowin](https://github.com/jlowin) in [#301](https://github.com/PrefectHQ/fastmcp/pull/301) +* Add method for retrieving current starlette request to FastMCP context by [@jlowin](https://github.com/jlowin) in [#302](https://github.com/PrefectHQ/fastmcp/pull/302) +* get\_starlette\_request → get\_http\_request by [@jlowin](https://github.com/jlowin) in [#303](https://github.com/PrefectHQ/fastmcp/pull/303) +* Support custom Serializer for Tools by [@strawgate](https://github.com/strawgate) in [#308](https://github.com/PrefectHQ/fastmcp/pull/308) +* Support proxy mount by [@jlowin](https://github.com/jlowin) in [#309](https://github.com/PrefectHQ/fastmcp/pull/309) + +### Other Changes 🦾 + +* Improve context injection type checks by [@jlowin](https://github.com/jlowin) in [#291](https://github.com/PrefectHQ/fastmcp/pull/291) +* add readme to smarthome example by [@zzstoatzz](https://github.com/zzstoatzz) in [#294](https://github.com/PrefectHQ/fastmcp/pull/294) + +**Full Changelog**: [v2.2.6...v2.2.7](https://github.com/PrefectHQ/fastmcp/compare/v2.2.6...v2.2.7) + + + + +## [v2.2.6: The REST is History](https://github.com/PrefectHQ/fastmcp/releases/tag/v2.2.6) + +### New Features 🎉 + +* Added feature : Load MCP server using config by [@sandipan1](https://github.com/sandipan1) in [#260](https://github.com/PrefectHQ/fastmcp/pull/260) +* small typing fixes by [@zzstoatzz](https://github.com/zzstoatzz) in [#237](https://github.com/PrefectHQ/fastmcp/pull/237) +* Expose configurable timeout for OpenAPI by [@jlowin](https://github.com/jlowin) in [#279](https://github.com/PrefectHQ/fastmcp/pull/279) +* Lower websockets pin for compatibility by [@jlowin](https://github.com/jlowin) in [#286](https://github.com/PrefectHQ/fastmcp/pull/286) +* Improve OpenAPI param handling by [@jlowin](https://github.com/jlowin) in [#287](https://github.com/PrefectHQ/fastmcp/pull/287) + +### Fixes 🐞 + +* Ensure openapi tool responses are properly converted by [@jlowin](https://github.com/jlowin) in [#283](https://github.com/PrefectHQ/fastmcp/pull/283) +* Fix OpenAPI examples by [@jlowin](https://github.com/jlowin) in [#285](https://github.com/PrefectHQ/fastmcp/pull/285) +* Fix client docs for advanced features, add tests for logging by [@jlowin](https://github.com/jlowin) in [#284](https://github.com/PrefectHQ/fastmcp/pull/284) + +### Other Changes 🦾 + +* add testing doc by [@jlowin](https://github.com/jlowin) in [#264](https://github.com/PrefectHQ/fastmcp/pull/264) +* #267 Fix openapi template resource to support multiple path parameters by [@jeger-at](https://github.com/jeger-at) in [#278](https://github.com/PrefectHQ/fastmcp/pull/278) + +### New Contributors + +* [@sandipan1](https://github.com/sandipan1) made their first contribution in [#260](https://github.com/PrefectHQ/fastmcp/pull/260) +* [@jeger-at](https://github.com/jeger-at) made their first contribution in [#278](https://github.com/PrefectHQ/fastmcp/pull/278) + +**Full Changelog**: [v2.2.5...v2.2.6](https://github.com/PrefectHQ/fastmcp/compare/v2.2.5...v2.2.6) + + + + +## [v2.2.5: Context Switching](https://github.com/PrefectHQ/fastmcp/releases/tag/v2.2.5) + +### New Features 🎉 + +* Add tests for tool return types; improve serialization behavior by [@jlowin](https://github.com/jlowin) in [#262](https://github.com/PrefectHQ/fastmcp/pull/262) +* Support context injection in resources, templates, and prompts (like tools) by [@jlowin](https://github.com/jlowin) in [#263](https://github.com/PrefectHQ/fastmcp/pull/263) + +### Docs 📚 + +* Update wildcards to 2.2.4 by [@jlowin](https://github.com/jlowin) in [#257](https://github.com/PrefectHQ/fastmcp/pull/257) +* Update note in templates docs by [@jlowin](https://github.com/jlowin) in [#258](https://github.com/PrefectHQ/fastmcp/pull/258) +* Significant documentation and test expansion for tool input types by [@jlowin](https://github.com/jlowin) in [#261](https://github.com/PrefectHQ/fastmcp/pull/261) + +**Full Changelog**: [v2.2.4...v2.2.5](https://github.com/PrefectHQ/fastmcp/compare/v2.2.4...v2.2.5) + + + + +## [v2.2.4: The Wild Side, Actually](https://github.com/PrefectHQ/fastmcp/releases/tag/v2.2.4) + +The wildcard URI templates exposed in v2.2.3 were blocked by a server-level check which is removed in this release. + +### New Features 🎉 + +* Allow customization of inspector proxy port, ui port, and version by [@jlowin](https://github.com/jlowin) in [#253](https://github.com/PrefectHQ/fastmcp/pull/253) + +### Fixes 🐞 + +* fix: unintended type convert by [@cutekibry](https://github.com/cutekibry) in [#252](https://github.com/PrefectHQ/fastmcp/pull/252) +* Ensure openapi resources return valid responses by [@jlowin](https://github.com/jlowin) in [#254](https://github.com/PrefectHQ/fastmcp/pull/254) +* Ensure servers expose template wildcards by [@jlowin](https://github.com/jlowin) in [#256](https://github.com/PrefectHQ/fastmcp/pull/256) + +### Docs 📚 + +* Update README.md Grammar error by [@TechWithTy](https://github.com/TechWithTy) in [#249](https://github.com/PrefectHQ/fastmcp/pull/249) + +### Other Changes 🦾 + +* Add resource template tests by [@jlowin](https://github.com/jlowin) in [#255](https://github.com/PrefectHQ/fastmcp/pull/255) + +### New Contributors + +* [@TechWithTy](https://github.com/TechWithTy) made their first contribution in [#249](https://github.com/PrefectHQ/fastmcp/pull/249) +* [@cutekibry](https://github.com/cutekibry) made their first contribution in [#252](https://github.com/PrefectHQ/fastmcp/pull/252) + +**Full Changelog**: [v2.2.3...v2.2.4](https://github.com/PrefectHQ/fastmcp/compare/v2.2.3...v2.2.4) + + + + +## [v2.2.3: The Wild Side](https://github.com/PrefectHQ/fastmcp/releases/tag/v2.2.3) + +### New Features 🎉 + +* Add wildcard params for resource templates by [@jlowin](https://github.com/jlowin) in [#246](https://github.com/PrefectHQ/fastmcp/pull/246) + +### Docs 📚 + +* Indicate that Image class is for returns by [@jlowin](https://github.com/jlowin) in [#242](https://github.com/PrefectHQ/fastmcp/pull/242) +* Update mermaid diagram by [@jlowin](https://github.com/jlowin) in [#243](https://github.com/PrefectHQ/fastmcp/pull/243) + +### Other Changes 🦾 + +* update version badges by [@jlowin](https://github.com/jlowin) in [#248](https://github.com/PrefectHQ/fastmcp/pull/248) + +**Full Changelog**: [v2.2.2...v2.2.3](https://github.com/PrefectHQ/fastmcp/compare/v2.2.2...v2.2.3) + + + + +## [v2.2.2: Prompt and Circumstance](https://github.com/PrefectHQ/fastmcp/releases/tag/v2.2.2) + +### New Features 🎉 + +* Add prompt support by [@jlowin](https://github.com/jlowin) in [#235](https://github.com/PrefectHQ/fastmcp/pull/235) + +### Fixes 🐞 + +* Ensure that resource templates are properly exposed by [@jlowin](https://github.com/jlowin) in [#238](https://github.com/PrefectHQ/fastmcp/pull/238) + +### Docs 📚 + +* Update docs for prompts by [@jlowin](https://github.com/jlowin) in [#236](https://github.com/PrefectHQ/fastmcp/pull/236) + +### Other Changes 🦾 + +* Add prompt tests by [@jlowin](https://github.com/jlowin) in [#239](https://github.com/PrefectHQ/fastmcp/pull/239) + +**Full Changelog**: [v2.2.1...v2.2.2](https://github.com/PrefectHQ/fastmcp/compare/v2.2.1...v2.2.2) + + + + +## [v2.2.1: Template for Success](https://github.com/PrefectHQ/fastmcp/releases/tag/v2.2.1) + +### New Features 🎉 + +* Add resource templates by [@jlowin](https://github.com/jlowin) in [#230](https://github.com/PrefectHQ/fastmcp/pull/230) + +### Fixes 🐞 + +* Ensure that resource templates are properly exposed by [@jlowin](https://github.com/jlowin) in [#231](https://github.com/PrefectHQ/fastmcp/pull/231) + +### Docs 📚 + +* Update docs for resource templates by [@jlowin](https://github.com/jlowin) in [#232](https://github.com/PrefectHQ/fastmcp/pull/232) + +### Other Changes 🦾 + +* Add resource template tests by [@jlowin](https://github.com/jlowin) in [#233](https://github.com/PrefectHQ/fastmcp/pull/233) + +**Full Changelog**: [v2.2.0...v2.2.1](https://github.com/PrefectHQ/fastmcp/compare/v2.2.0...v2.2.1) + + + + +## [v2.2.0: Compose Yourself](https://github.com/PrefectHQ/fastmcp/releases/tag/v2.2.0) + +### New Features 🎉 + +* Add support for mounting FastMCP servers by [@jlowin](https://github.com/jlowin) in [#175](https://github.com/PrefectHQ/fastmcp/pull/175) +* Add support for duplicate behavior == ignore by [@jlowin](https://github.com/jlowin) in [#169](https://github.com/PrefectHQ/fastmcp/pull/169) + +### Breaking Changes 🛫 + +* Refactor MCP composition by [@jlowin](https://github.com/jlowin) in [#176](https://github.com/PrefectHQ/fastmcp/pull/176) + +### Docs 📚 + +* Improve integration documentation by [@jlowin](https://github.com/jlowin) in [#184](https://github.com/PrefectHQ/fastmcp/pull/184) +* Improve documentation by [@jlowin](https://github.com/jlowin) in [#185](https://github.com/PrefectHQ/fastmcp/pull/185) + +### Other Changes 🦾 + +* Add transport kwargs for mcp.run() and fastmcp run by [@jlowin](https://github.com/jlowin) in [#161](https://github.com/PrefectHQ/fastmcp/pull/161) +* Allow resource templates to have optional / excluded arguments by [@jlowin](https://github.com/jlowin) in [#164](https://github.com/PrefectHQ/fastmcp/pull/164) +* Update resources.mdx by [@jlowin](https://github.com/jlowin) in [#165](https://github.com/PrefectHQ/fastmcp/pull/165) + +### New Contributors + +* [@kongqi404](https://github.com/kongqi404) made their first contribution in [#181](https://github.com/PrefectHQ/fastmcp/pull/181) + +**Full Changelog**: [v2.1.2...v2.2.0](https://github.com/PrefectHQ/fastmcp/compare/v2.1.2...v2.2.0) + + + + +## [v2.1.2: Copy That, Good Buddy](https://github.com/PrefectHQ/fastmcp/releases/tag/v2.1.2) + +The main improvement in this release is a fix that allows FastAPI / OpenAPI-generated servers to be mounted as sub-servers. + +### Fixes 🐞 + +* Ensure objects are copied properly and test mounting fastapi by [@jlowin](https://github.com/jlowin) in [#153](https://github.com/PrefectHQ/fastmcp/pull/153) + +### Docs 📚 + +* Fix broken links in docs by [@jlowin](https://github.com/jlowin) in [#154](https://github.com/PrefectHQ/fastmcp/pull/154) + +### Other Changes 🦾 + +* Update README.md by [@jlowin](https://github.com/jlowin) in [#149](https://github.com/PrefectHQ/fastmcp/pull/149) +* Only apply log config to FastMCP loggers by [@jlowin](https://github.com/jlowin) in [#155](https://github.com/PrefectHQ/fastmcp/pull/155) +* Update pyproject.toml by [@jlowin](https://github.com/jlowin) in [#156](https://github.com/PrefectHQ/fastmcp/pull/156) + +**Full Changelog**: [v2.1.1...v2.1.2](https://github.com/PrefectHQ/fastmcp/compare/v2.1.1...v2.1.2) + + + + +## [v2.1.1: Doc Holiday](https://github.com/PrefectHQ/fastmcp/releases/tag/v2.1.1) + +FastMCP's docs are now available at gofastmcp.com. + +### Docs 📚 + +* Add docs by [@jlowin](https://github.com/jlowin) in [#136](https://github.com/PrefectHQ/fastmcp/pull/136) +* Add docs link to readme by [@jlowin](https://github.com/jlowin) in [#137](https://github.com/PrefectHQ/fastmcp/pull/137) +* Minor docs updates by [@jlowin](https://github.com/jlowin) in [#138](https://github.com/PrefectHQ/fastmcp/pull/138) + +### Fixes 🐞 + +* fix branch name in example by [@zzstoatzz](https://github.com/zzstoatzz) in [#140](https://github.com/PrefectHQ/fastmcp/pull/140) + +### Other Changes 🦾 + +* smart home example by [@zzstoatzz](https://github.com/zzstoatzz) in [#115](https://github.com/PrefectHQ/fastmcp/pull/115) +* Remove mac os tests by [@jlowin](https://github.com/jlowin) in [#142](https://github.com/PrefectHQ/fastmcp/pull/142) +* Expand support for various method interactions by [@jlowin](https://github.com/jlowin) in [#143](https://github.com/PrefectHQ/fastmcp/pull/143) +* Update docs and add\_resource\_fn by [@jlowin](https://github.com/jlowin) in [#144](https://github.com/PrefectHQ/fastmcp/pull/144) +* Update description by [@jlowin](https://github.com/jlowin) in [#145](https://github.com/PrefectHQ/fastmcp/pull/145) +* Support openapi 3.0 and 3.1 by [@jlowin](https://github.com/jlowin) in [#147](https://github.com/PrefectHQ/fastmcp/pull/147) + +**Full Changelog**: [v2.1.0...v2.1.1](https://github.com/PrefectHQ/fastmcp/compare/v2.1.0...v2.1.1) + + + + +## [v2.1.0: Tag, You're It](https://github.com/PrefectHQ/fastmcp/releases/tag/v2.1.0) + +The primary motivation for this release is the fix in #128 for Claude desktop compatibility, but the primary new feature of this release is per-object tags. Currently these are for bookkeeping only but will become useful in future releases. + +### New Features 🎉 + +* Add tags for all core MCP objects by [@jlowin](https://github.com/jlowin) in [#121](https://github.com/PrefectHQ/fastmcp/pull/121) +* Ensure that openapi tags are transferred to MCP objects by [@jlowin](https://github.com/jlowin) in [#124](https://github.com/PrefectHQ/fastmcp/pull/124) + +### Fixes 🐞 + +* Change default mounted tool separator from / to \_ by [@jlowin](https://github.com/jlowin) in [#128](https://github.com/PrefectHQ/fastmcp/pull/128) +* Enter mounted app lifespans by [@jlowin](https://github.com/jlowin) in [#129](https://github.com/PrefectHQ/fastmcp/pull/129) +* Fix CLI that called mcp instead of fastmcp by [@jlowin](https://github.com/jlowin) in [#128](https://github.com/PrefectHQ/fastmcp/pull/128) + +### Breaking Changes 🛫 + +* Changed configuration for duplicate resources/tools/prompts by [@jlowin](https://github.com/jlowin) in [#121](https://github.com/PrefectHQ/fastmcp/pull/121) +* Improve client return types by [@jlowin](https://github.com/jlowin) in [#123](https://github.com/PrefectHQ/fastmcp/pull/123) + +### Other Changes 🦾 + +* Add tests for tags in server decorators by [@jlowin](https://github.com/jlowin) in [#122](https://github.com/PrefectHQ/fastmcp/pull/122) +* Clean up server tests by [@jlowin](https://github.com/jlowin) in [#125](https://github.com/PrefectHQ/fastmcp/pull/125) + +**Full Changelog**: [v2.0.0...v2.1.0](https://github.com/PrefectHQ/fastmcp/compare/v2.0.0...v2.1.0) + + + + +## [v2.0.0: Second to None](https://github.com/PrefectHQ/fastmcp/releases/tag/v2.0.0) + +### New Features 🎉 + +* Support mounting FastMCP instances as sub-MCPs by [@jlowin](https://github.com/jlowin) in [#99](https://github.com/PrefectHQ/fastmcp/pull/99) +* Add in-memory client for calling FastMCP servers (and tests) by [@jlowin](https://github.com/jlowin) in [#100](https://github.com/PrefectHQ/fastmcp/pull/100) +* Add MCP proxy server by [@jlowin](https://github.com/jlowin) in [#105](https://github.com/PrefectHQ/fastmcp/pull/105) +* Update FastMCP for upstream changes by [@jlowin](https://github.com/jlowin) in [#107](https://github.com/PrefectHQ/fastmcp/pull/107) +* Generate FastMCP servers from OpenAPI specs and FastAPI by [@jlowin](https://github.com/jlowin) in [#110](https://github.com/PrefectHQ/fastmcp/pull/110) +* Reorganize all client / transports by [@jlowin](https://github.com/jlowin) in [#111](https://github.com/PrefectHQ/fastmcp/pull/111) +* Add sampling and roots by [@jlowin](https://github.com/jlowin) in [#117](https://github.com/PrefectHQ/fastmcp/pull/117) + +### Fixes 🐞 + +* Fix bug with tools that return lists by [@jlowin](https://github.com/jlowin) in [#116](https://github.com/PrefectHQ/fastmcp/pull/116) + +### Other Changes 🦾 + +* Add back FastMCP CLI by [@jlowin](https://github.com/jlowin) in [#108](https://github.com/PrefectHQ/fastmcp/pull/108) +* Update Readme for v2 by [@jlowin](https://github.com/jlowin) in [#112](https://github.com/PrefectHQ/fastmcp/pull/112) +* fix deprecation warnings by [@zzstoatzz](https://github.com/zzstoatzz) in [#113](https://github.com/PrefectHQ/fastmcp/pull/113) +* Readme by [@jlowin](https://github.com/jlowin) in [#118](https://github.com/PrefectHQ/fastmcp/pull/118) +* FastMCP 2.0 by [@jlowin](https://github.com/jlowin) in [#119](https://github.com/PrefectHQ/fastmcp/pull/119) + +**Full Changelog**: [v1.0...v2.0.0](https://github.com/PrefectHQ/fastmcp/compare/v1.0...v2.0.0) + + + + +## [v1.0: It's Official](https://github.com/PrefectHQ/fastmcp/releases/tag/v1.0) + +This release commemorates FastMCP 1.0, which is included in the official Model Context Protocol SDK: + +```python +from mcp.server.fastmcp import FastMCP +``` + +To the best of my knowledge, v1 is identical to the upstream version included with `mcp`. + +### Docs 📚 + +* Update readme to redirect to the official SDK by [@jlowin](https://github.com/jlowin) in [#79](https://github.com/PrefectHQ/fastmcp/pull/79) + +### Other Changes 🦾 + +* fix: use Mount instead of Route for SSE message handling by [@samihamine](https://github.com/samihamine) in [#77](https://github.com/PrefectHQ/fastmcp/pull/77) + +### New Contributors + +* [@samihamine](https://github.com/samihamine) made their first contribution in [#77](https://github.com/PrefectHQ/fastmcp/pull/77) + +**Full Changelog**: [v0.4.1...v1.0](https://github.com/PrefectHQ/fastmcp/compare/v0.4.1...v1.0) + + + + +## [v0.4.1: String Theory](https://github.com/PrefectHQ/fastmcp/releases/tag/v0.4.1) + +### Fixes 🐞 + +* fix: handle strings containing numbers correctly by [@sd2k](https://github.com/sd2k) in [#63](https://github.com/PrefectHQ/fastmcp/pull/63) + +### Docs 📚 + +* patch: Update pyproject.toml license by [@leonkozlowski](https://github.com/leonkozlowski) in [#67](https://github.com/PrefectHQ/fastmcp/pull/67) + +### Other Changes 🦾 + +* Avoid new try\_eval\_type unavailable with older pydantic by [@jurasofish](https://github.com/jurasofish) in [#57](https://github.com/PrefectHQ/fastmcp/pull/57) +* Decorator typing by [@jurasofish](https://github.com/jurasofish) in [#56](https://github.com/PrefectHQ/fastmcp/pull/56) + +### New Contributors + +* [@leonkozlowski](https://github.com/leonkozlowski) made their first contribution in [#67](https://github.com/PrefectHQ/fastmcp/pull/67) + +**Full Changelog**: [v0.4.0...v0.4.1](https://github.com/PrefectHQ/fastmcp/compare/v0.4.0...v0.4.1) + + + + +## [v0.4.0: Nice to MIT You](https://github.com/PrefectHQ/fastmcp/releases/tag/v0.4.0) + +This is a relatively small release in terms of features, but the version is bumped to 0.4 to reflect that the code is being relicensed from Apache 2.0 to MIT. This is to facilitate FastMCP's inclusion in the official MCP SDK. + +### New Features 🎉 + +* Add pyright + tests by [@jlowin](https://github.com/jlowin) in [#52](https://github.com/PrefectHQ/fastmcp/pull/52) +* add pgvector memory example by [@zzstoatzz](https://github.com/zzstoatzz) in [#49](https://github.com/PrefectHQ/fastmcp/pull/49) + +### Fixes 🐞 + +* fix: use stderr for logging by [@sd2k](https://github.com/sd2k) in [#51](https://github.com/PrefectHQ/fastmcp/pull/51) + +### Docs 📚 + +* Update ai-labeler.yml by [@jlowin](https://github.com/jlowin) in [#48](https://github.com/PrefectHQ/fastmcp/pull/48) +* Relicense from Apache 2.0 to MIT by [@jlowin](https://github.com/jlowin) in [#54](https://github.com/PrefectHQ/fastmcp/pull/54) + +### Other Changes 🦾 + +* fix warning and flake by [@zzstoatzz](https://github.com/zzstoatzz) in [#47](https://github.com/PrefectHQ/fastmcp/pull/47) + +### New Contributors + +* [@sd2k](https://github.com/sd2k) made their first contribution in [#51](https://github.com/PrefectHQ/fastmcp/pull/51) + +**Full Changelog**: [v0.3.5...v0.4.0](https://github.com/PrefectHQ/fastmcp/compare/v0.3.5...v0.4.0) + + + + +## [v0.3.5: Windows of Opportunity](https://github.com/PrefectHQ/fastmcp/releases/tag/v0.3.5) + +This release is highlighted by the ability to handle complex JSON objects as MCP inputs and improved Windows compatibility. + +### New Features 🎉 + +* Set up multiple os tests by [@jlowin](https://github.com/jlowin) in [#44](https://github.com/PrefectHQ/fastmcp/pull/44) +* Changes to accommodate windows users. by [@justjoehere](https://github.com/justjoehere) in [#42](https://github.com/PrefectHQ/fastmcp/pull/42) +* Handle complex inputs by [@jurasofish](https://github.com/jurasofish) in [#31](https://github.com/PrefectHQ/fastmcp/pull/31) + +### Docs 📚 + +* Make AI labeler more conservative by [@jlowin](https://github.com/jlowin) in [#46](https://github.com/PrefectHQ/fastmcp/pull/46) + +### Other Changes 🦾 + +* Additional Windows Fixes for Dev running and for importing modules in a server by [@justjoehere](https://github.com/justjoehere) in [#43](https://github.com/PrefectHQ/fastmcp/pull/43) + +### New Contributors + +* [@justjoehere](https://github.com/justjoehere) made their first contribution in [#42](https://github.com/PrefectHQ/fastmcp/pull/42) +* [@jurasofish](https://github.com/jurasofish) made their first contribution in [#31](https://github.com/PrefectHQ/fastmcp/pull/31) + +**Full Changelog**: [v0.3.4...v0.3.5](https://github.com/PrefectHQ/fastmcp/compare/v0.3.4...v0.3.5) + + + + +## [v0.3.4: URL's Well That Ends Well](https://github.com/PrefectHQ/fastmcp/releases/tag/v0.3.4) + +### Fixes 🐞 + +* Handle missing config file when installing by [@jlowin](https://github.com/jlowin) in [#37](https://github.com/PrefectHQ/fastmcp/pull/37) +* Remove BaseURL reference and use AnyURL by [@jlowin](https://github.com/jlowin) in [#40](https://github.com/PrefectHQ/fastmcp/pull/40) + +**Full Changelog**: [v0.3.3...v0.3.4](https://github.com/PrefectHQ/fastmcp/compare/v0.3.3...v0.3.4) + + + + +## [v0.3.3: Dependence Day](https://github.com/PrefectHQ/fastmcp/releases/tag/v0.3.3) + +### New Features 🎉 + +* Surge example by [@zzstoatzz](https://github.com/zzstoatzz) in [#29](https://github.com/PrefectHQ/fastmcp/pull/29) +* Support Python dependencies in Server by [@jlowin](https://github.com/jlowin) in [#34](https://github.com/PrefectHQ/fastmcp/pull/34) + +### Docs 📚 + +* add `Contributing` section to README by [@zzstoatzz](https://github.com/zzstoatzz) in [#32](https://github.com/PrefectHQ/fastmcp/pull/32) + +**Full Changelog**: [v0.3.2...v0.3.3](https://github.com/PrefectHQ/fastmcp/compare/v0.3.2...v0.3.3) + + + + +## [v0.3.2: Green with ENVy](https://github.com/PrefectHQ/fastmcp/releases/tag/v0.3.2) + +### New Features 🎉 + +* Support env vars when installing by [@jlowin](https://github.com/jlowin) in [#27](https://github.com/PrefectHQ/fastmcp/pull/27) + +### Docs 📚 + +* Remove top level env var by [@jlowin](https://github.com/jlowin) in [#28](https://github.com/PrefectHQ/fastmcp/pull/28) + +**Full Changelog**: [v0.3.1...v0.3.2](https://github.com/PrefectHQ/fastmcp/compare/v0.3.1...v0.3.2) + + + + +## [v0.3.1](https://github.com/PrefectHQ/fastmcp/releases/tag/v0.3.1) + +### New Features 🎉 + +* Update README.md by [@jlowin](https://github.com/jlowin) in [#23](https://github.com/PrefectHQ/fastmcp/pull/23) +* add rich handler and dotenv loading for settings by [@zzstoatzz](https://github.com/zzstoatzz) in [#22](https://github.com/PrefectHQ/fastmcp/pull/22) +* print exception when server can't start by [@jlowin](https://github.com/jlowin) in [#25](https://github.com/PrefectHQ/fastmcp/pull/25) + +### Docs 📚 + +* Update README.md by [@jlowin](https://github.com/jlowin) in [#24](https://github.com/PrefectHQ/fastmcp/pull/24) + +### Other Changes 🦾 + +* Remove log by [@jlowin](https://github.com/jlowin) in [#26](https://github.com/PrefectHQ/fastmcp/pull/26) + +**Full Changelog**: [v0.3.0...v0.3.1](https://github.com/PrefectHQ/fastmcp/compare/v0.3.0...v0.3.1) + + + + +## [v0.3.0: Prompt and Circumstance](https://github.com/PrefectHQ/fastmcp/releases/tag/v0.3.0) + +### New Features 🎉 + +* Update README by [@jlowin](https://github.com/jlowin) in [#3](https://github.com/PrefectHQ/fastmcp/pull/3) +* Make log levels strings by [@jlowin](https://github.com/jlowin) in [#4](https://github.com/PrefectHQ/fastmcp/pull/4) +* Make content method a function by [@jlowin](https://github.com/jlowin) in [#5](https://github.com/PrefectHQ/fastmcp/pull/5) +* Add template support by [@jlowin](https://github.com/jlowin) in [#6](https://github.com/PrefectHQ/fastmcp/pull/6) +* Refactor resources module by [@jlowin](https://github.com/jlowin) in [#7](https://github.com/PrefectHQ/fastmcp/pull/7) +* Clean up cli imports by [@jlowin](https://github.com/jlowin) in [#8](https://github.com/PrefectHQ/fastmcp/pull/8) +* Prepare to list templates by [@jlowin](https://github.com/jlowin) in [#11](https://github.com/PrefectHQ/fastmcp/pull/11) +* Move image to separate module by [@jlowin](https://github.com/jlowin) in [#9](https://github.com/PrefectHQ/fastmcp/pull/9) +* Add support for request context, progress, logging, etc. by [@jlowin](https://github.com/jlowin) in [#12](https://github.com/PrefectHQ/fastmcp/pull/12) +* Add context tests and better runtime loads by [@jlowin](https://github.com/jlowin) in [#13](https://github.com/PrefectHQ/fastmcp/pull/13) +* Refactor tools + resourcemanager by [@jlowin](https://github.com/jlowin) in [#14](https://github.com/PrefectHQ/fastmcp/pull/14) +* func → fn everywhere by [@jlowin](https://github.com/jlowin) in [#15](https://github.com/PrefectHQ/fastmcp/pull/15) +* Add support for prompts by [@jlowin](https://github.com/jlowin) in [#16](https://github.com/PrefectHQ/fastmcp/pull/16) +* Create LICENSE by [@jlowin](https://github.com/jlowin) in [#18](https://github.com/PrefectHQ/fastmcp/pull/18) +* Update cli file spec by [@jlowin](https://github.com/jlowin) in [#19](https://github.com/PrefectHQ/fastmcp/pull/19) +* Update readmeUpdate README by [@jlowin](https://github.com/jlowin) in [#20](https://github.com/PrefectHQ/fastmcp/pull/20) +* Use hatchling for version by [@jlowin](https://github.com/jlowin) in [#21](https://github.com/PrefectHQ/fastmcp/pull/21) + +### Other Changes 🦾 + +* Add echo server by [@jlowin](https://github.com/jlowin) in [#1](https://github.com/PrefectHQ/fastmcp/pull/1) +* Add github workflows by [@jlowin](https://github.com/jlowin) in [#2](https://github.com/PrefectHQ/fastmcp/pull/2) +* typing updates by [@zzstoatzz](https://github.com/zzstoatzz) in [#17](https://github.com/PrefectHQ/fastmcp/pull/17) + +### New Contributors + +* [@jlowin](https://github.com/jlowin) made their first contribution in [#1](https://github.com/PrefectHQ/fastmcp/pull/1) +* [@zzstoatzz](https://github.com/zzstoatzz) made their first contribution in [#17](https://github.com/PrefectHQ/fastmcp/pull/17) + +**Full Changelog**: [v0.2.0...v0.3.0](https://github.com/PrefectHQ/fastmcp/compare/v0.2.0...v0.3.0) + + + + +## [v0.2.0](https://github.com/PrefectHQ/fastmcp/releases/tag/v0.2.0) + +**Full Changelog**: [v0.1.0...v0.2.0](https://github.com/PrefectHQ/fastmcp/compare/v0.1.0...v0.2.0) + + + + +## [v0.1.0](https://github.com/PrefectHQ/fastmcp/releases/tag/v0.1.0) + +The very first release of FastMCP! 🎉 + +**Full Changelog**: [Initial commits](https://github.com/PrefectHQ/fastmcp/commits/v0.1.0) + \ No newline at end of file diff --git a/docs/cli/auth.mdx b/docs/cli/auth.mdx new file mode 100644 index 000000000..71b89e08a --- /dev/null +++ b/docs/cli/auth.mdx @@ -0,0 +1,85 @@ +--- +title: Auth Utilities +sidebarTitle: Auth +description: Create and validate CIMD documents for OAuth +icon: key +--- + +import { VersionBadge } from '/snippets/version-badge.mdx' + + + +The `fastmcp auth` commands help with CIMD (Client ID Metadata Document) management — part of MCP's OAuth authentication flow. A CIMD is a JSON document you host at an HTTPS URL to identify your client application to MCP servers. + +## Creating a CIMD + +`fastmcp auth cimd create` generates a CIMD document: + +```bash +fastmcp auth cimd create \ + --name "My App" \ + --redirect-uri "http://localhost:*/callback" +``` + +```json +{ + "client_id": "https://your-domain.com/oauth/client.json", + "client_name": "My App", + "redirect_uris": ["http://localhost:*/callback"], + "token_endpoint_auth_method": "none" +} +``` + +The generated document includes a placeholder `client_id` — update it to match the URL where you'll host the document before deploying. + +### Options + +| Option | Flag | Description | +| ------ | ---- | ----------- | +| Name | `--name` | **Required.** Human-readable client name | +| Redirect URI | `--redirect-uri` | **Required.** Allowed redirect URIs (repeatable) | +| Client URI | `--client-uri` | Client's home page URL | +| Logo URI | `--logo-uri` | Client's logo URL | +| Scope | `--scope` | Space-separated list of scopes | +| Output | `--output`, `-o` | Save to file (default: stdout) | +| Pretty | `--pretty` | Pretty-print JSON (default: true) | + +### Example + +```bash +fastmcp auth cimd create \ + --name "My Production App" \ + --redirect-uri "http://localhost:*/callback" \ + --redirect-uri "https://myapp.example.com/callback" \ + --client-uri "https://myapp.example.com" \ + --scope "read write" \ + --output client.json +``` + +## Validating a CIMD + +`fastmcp auth cimd validate` fetches a hosted CIMD and verifies it conforms to the spec: + +```bash +fastmcp auth cimd validate https://myapp.example.com/oauth/client.json +``` + +The validator checks that the URL is valid (HTTPS, non-root path), the document is valid JSON, the `client_id` matches the URL, and no shared-secret auth methods are used. + +On success: + +``` +→ Fetching https://myapp.example.com/oauth/client.json... +✓ Valid CIMD document + +Document details: + client_id: https://myapp.example.com/oauth/client.json + client_name: My App + token_endpoint_auth_method: none + redirect_uris: + • http://localhost:*/callback +``` + +| Option | Flag | Description | +| ------ | ---- | ----------- | +| Timeout | `--timeout`, `-t` | HTTP request timeout in seconds (default: 10) | diff --git a/docs/cli/client.mdx b/docs/cli/client.mdx new file mode 100644 index 000000000..bd72b163d --- /dev/null +++ b/docs/cli/client.mdx @@ -0,0 +1,140 @@ +--- +title: Client Commands +sidebarTitle: Client +description: List tools, call them, and discover configured servers +icon: satellite-dish +--- + +import { VersionBadge } from '/snippets/version-badge.mdx' + + + +The CLI can act as an MCP client — connecting to any server (local or remote) to list what it exposes and call its tools directly. This is useful for development, debugging, scripting, and giving shell-capable LLM agents access to MCP servers. + +## Listing Tools + +`fastmcp list` connects to a server and prints its tools as function signatures, showing parameter names, types, and descriptions at a glance: + +```bash +fastmcp list http://localhost:8000/mcp +fastmcp list server.py +fastmcp list weather # name-based resolution +``` + +When you need the full JSON Schema for a tool's inputs or outputs — for understanding nested objects, enum constraints, or complex types — opt in with `--input-schema` or `--output-schema`: + +```bash +fastmcp list server.py --input-schema +``` + +### Resources and Prompts + +By default, only tools are shown. Add `--resources` or `--prompts` to include those: + +```bash +fastmcp list server.py --resources --prompts +``` + +### Machine-Readable Output + +The `--json` flag switches to structured JSON with full schemas included. This is the format to use when feeding tool definitions to an LLM or building automation: + +```bash +fastmcp list server.py --json +``` + +### Options + +| Option | Flag | Description | +| ------ | ---- | ----------- | +| Command | `--command` | Connect via stdio (e.g., `'npx -y @mcp/server'`) | +| Transport | `--transport`, `-t` | Force `http` or `sse` for URL targets | +| Resources | `--resources` | Include resources in output | +| Prompts | `--prompts` | Include prompts in output | +| Input Schema | `--input-schema` | Show full input schemas | +| Output Schema | `--output-schema` | Show full output schemas | +| JSON | `--json` | Structured JSON output | +| Timeout | `--timeout` | Connection timeout in seconds | +| Auth | `--auth` | `oauth` (default for HTTP), a bearer token, or `none` | + +## Calling Tools + +`fastmcp call` invokes a single tool on a server. Pass arguments as `key=value` pairs — the CLI fetches the tool's schema and coerces your string values to the right types automatically: + +```bash +fastmcp call server.py greet name=World +fastmcp call http://localhost:8000/mcp search query=hello limit=5 +``` + +Type coercion is schema-driven: `"5"` becomes the integer `5` when the schema expects an integer. Booleans accept `true`/`false`, `yes`/`no`, and `1`/`0`. Arrays and objects are parsed as JSON. + +### Complex Arguments + +For tools with nested or structured parameters, `key=value` syntax gets awkward. Pass a single JSON object instead: + +```bash +fastmcp call server.py create_item '{"name": "Widget", "tags": ["sale"], "metadata": {"color": "blue"}}' +``` + +Or use `--input-json` to provide a base dictionary, then override individual keys with `key=value` pairs: + +```bash +fastmcp call server.py search --input-json '{"query": "hello", "limit": 5}' limit=10 +``` + +### Error Handling + +If you misspell a tool name, the CLI suggests corrections via fuzzy matching. Missing required arguments produce a clear message with the tool's signature as a reminder. Tool execution errors are printed with a non-zero exit code, making the CLI straightforward to use in scripts. + +### Structured Output + +`--json` emits the raw result including content blocks, error status, and structured content: + +```bash +fastmcp call server.py get_weather city=London --json +``` + +### Interactive Elicitation + +Some tools request additional input during execution through MCP's elicitation mechanism. When this happens, the CLI prompts you in the terminal — showing each field's name, type, and whether it's required. You can type `decline` to skip a question or `cancel` to abort the call entirely. + +### Options + +| Option | Flag | Description | +| ------ | ---- | ----------- | +| Command | `--command` | Connect via stdio | +| Transport | `--transport`, `-t` | Force `http` or `sse` | +| Input JSON | `--input-json` | Base arguments as JSON (merged with `key=value`) | +| JSON | `--json` | Raw JSON output | +| Timeout | `--timeout` | Connection timeout in seconds | +| Auth | `--auth` | `oauth`, a bearer token, or `none` | + +## Discovering Configured Servers + +`fastmcp discover` scans your machine for MCP servers configured in editors and tools. It checks: + +- **Claude Desktop** — `claude_desktop_config.json` +- **Claude Code** — `~/.claude.json` +- **Cursor** — `.cursor/mcp.json` (walks up from current directory) +- **Gemini CLI** — `~/.gemini/settings.json` +- **Goose** — `~/.config/goose/config.yaml` +- **Project** — `./mcp.json` in the current directory + +```bash +fastmcp discover +``` + +The output groups servers by source, showing each server's name and transport. Filter by source or get machine-readable output: + +```bash +fastmcp discover --source claude-code +fastmcp discover --source cursor --source gemini --json +``` + +Any server that appears here can be used by name with `list`, `call`, and other commands — so you can go from "I have a server in Claude Code" to querying it without copying URLs or paths. + +## LLM Agent Integration + +For LLM agents that can execute shell commands but don't have native MCP support, the CLI provides a clean bridge. The agent calls `fastmcp list --json` to discover available tools with full schemas, then `fastmcp call --json` to invoke them with structured results. + +Because the CLI handles connection management, transport selection, and type coercion internally, the agent doesn't need to understand MCP protocol details — it just reads JSON and constructs shell commands. diff --git a/docs/cli/generate-cli.mdx b/docs/cli/generate-cli.mdx new file mode 100644 index 000000000..2754d199a --- /dev/null +++ b/docs/cli/generate-cli.mdx @@ -0,0 +1,106 @@ +--- +title: Generate CLI +sidebarTitle: Generate CLI +description: Scaffold a standalone typed CLI from any MCP server +icon: wand-magic-sparkles +--- + +import { VersionBadge } from '/snippets/version-badge.mdx' + + + +`fastmcp list` and `fastmcp call` are general-purpose — you always specify the server, the tool name, and the arguments from scratch. `fastmcp generate-cli` goes further: it connects to a server, reads its tool schemas, and writes a standalone Python script where every tool is a proper subcommand with typed flags, help text, and tab completion. The result is a CLI that feels hand-written for that specific server. + +MCP tool schemas already contain everything a CLI framework needs — parameter names, types, descriptions, required/optional status, and defaults. `generate-cli` maps that into [cyclopts](https://cyclopts.readthedocs.io/) commands, so JSON Schema types become Python type annotations, descriptions become `--help` text, and required parameters become mandatory flags. + +## Generating a Script + +Point the command at any [server target](/cli/overview#server-targets) and it writes a CLI script: + +```bash +fastmcp generate-cli weather +fastmcp generate-cli http://localhost:8000/mcp +fastmcp generate-cli server.py my_weather_cli.py +``` + +The second positional argument sets the output path (defaults to `cli.py`). If the file already exists, pass `-f` to overwrite: + +```bash +fastmcp generate-cli weather -f +``` + +## What You Get + +The generated script is a regular Python file — executable, editable, and yours: + +``` +$ python cli.py call-tool --help +Usage: weather-cli call-tool COMMAND + +Call a tool on the server + +Commands: + get_forecast Get the weather forecast for a city. + search_city Search for a city by name. +``` + +Each tool has typed parameters with help text pulled directly from the server's schema: + +``` +$ python cli.py call-tool get_forecast --help +Usage: weather-cli call-tool get_forecast [OPTIONS] + +Get the weather forecast for a city. + +Options: + --city [str] City name (required) + --days [int] Number of forecast days (default: 3) +``` + +Beyond tool commands, the script includes generic MCP operations — `list-tools`, `list-resources`, `read-resource`, `list-prompts`, and `get-prompt` — that always reflect the server's current state, even if tools have changed since generation. + +## Parameter Handling + +Parameters are mapped based on their JSON Schema type: + +**Simple types** (`string`, `integer`, `number`, `boolean`) become typed flags: + +```bash +python cli.py call-tool get_forecast --city London --days 3 +``` + +**Arrays of simple types** become repeatable flags: + +```bash +python cli.py call-tool tag_items --tags python --tags fastapi --tags mcp +``` + +**Complex types** (objects, nested arrays, unions) accept JSON strings. The `--help` output shows the full schema so you know what structure to pass: + +```bash +python cli.py call-tool create_user \ + --name John \ + --metadata '{"role": "admin", "dept": "engineering"}' +``` + +## Agent Skill + +Alongside the CLI script, `generate-cli` writes a `SKILL.md` file — a [Claude Code agent skill](https://docs.anthropic.com/en/docs/agents-and-tools/claude-code/skills) that documents every tool's exact invocation syntax, parameter flags, types, and descriptions. An agent can pick up the CLI immediately without running `--help` or experimenting with flag names. + +To skip skill generation: + +```bash +fastmcp generate-cli weather --no-skill +``` + +## How It Works + +The generated script is a *client*, not a server — it connects to the server on every invocation rather than bundling it. A `CLIENT_SPEC` variable at the top holds the resolved transport (a URL string or `StdioTransport` with baked-in command and arguments). + +The most common edit is changing `CLIENT_SPEC` — for example, pointing a script generated from a dev server at production. Beyond that, the helper functions (`_call_tool`, `_print_tool_result`) are thin wrappers around `fastmcp.Client` that are easy to adapt. + +The script requires `fastmcp` as a dependency. If it lives outside a project that already has FastMCP installed: + +```bash +uv run --with fastmcp python cli.py call-tool get_forecast --city London +``` diff --git a/docs/cli/inspecting.mdx b/docs/cli/inspecting.mdx new file mode 100644 index 000000000..657921357 --- /dev/null +++ b/docs/cli/inspecting.mdx @@ -0,0 +1,72 @@ +--- +title: Inspecting Servers +sidebarTitle: Inspecting +description: View a server's components and metadata +icon: magnifying-glass +--- + +import { VersionBadge } from '/snippets/version-badge.mdx' + + + +`fastmcp inspect` loads a server and reports what it contains — its tools, resources, prompts, version, and metadata. The default output is a human-readable summary: + +```bash +fastmcp inspect server.py +``` + +``` +Server: MyServer +Instructions: A helpful MCP server +Version: 1.0.0 + +Components: + Tools: 5 + Prompts: 2 + Resources: 3 + Templates: 1 + +Environment: + FastMCP: 2.0.0 + MCP: 1.0.0 + +Use --format [fastmcp|mcp] for complete JSON output +``` + +## JSON Output + +For programmatic use, two JSON formats are available: + +**FastMCP format** (`--format fastmcp`) includes everything FastMCP knows about the server — tool tags, enabled status, output schemas, annotations, and custom metadata. Field names use `snake_case`. This is the format for debugging and introspecting FastMCP servers. + +**MCP protocol format** (`--format mcp`) shows exactly what MCP clients see through the protocol — only standard MCP fields, `camelCase` names, no FastMCP-specific extensions. This is the format for verifying client compatibility and debugging what clients actually receive. + +```bash +# Full FastMCP metadata to stdout +fastmcp inspect server.py --format fastmcp + +# MCP protocol view saved to file +fastmcp inspect server.py --format mcp -o manifest.json +``` + +## Options + +| Option | Flag | Description | +| ------ | ---- | ----------- | +| Format | `--format`, `-f` | `fastmcp` or `mcp` (required when using `-o`) | +| Output File | `--output`, `-o` | Save to file instead of stdout | + +## Entrypoints + +The `inspect` command supports the same local entrypoints as [`fastmcp run`](/cli/running): inferred instances, explicit entrypoints, factory functions, and `fastmcp.json` configs. + +```bash +fastmcp inspect server.py # inferred instance +fastmcp inspect server.py:my_server # explicit entrypoint +fastmcp inspect server.py:create_server # factory function +fastmcp inspect fastmcp.json # config file +``` + + +`inspect` only works with local files and `fastmcp.json` — it doesn't connect to remote URLs or standard MCP config files. + diff --git a/docs/cli/install-mcp.mdx b/docs/cli/install-mcp.mdx new file mode 100644 index 000000000..0171b7854 --- /dev/null +++ b/docs/cli/install-mcp.mdx @@ -0,0 +1,146 @@ +--- +title: Install MCP Servers +sidebarTitle: Install MCPs +description: Install MCP servers into Claude, Cursor, Gemini, and other clients +icon: download +--- + +import { VersionBadge } from '/snippets/version-badge.mdx' + + + +`fastmcp install` registers a server with an MCP client application so the client can launch it automatically. Each MCP client runs servers in its own isolated environment, which means dependencies need to be explicitly declared — you can't rely on whatever happens to be installed locally. + +```bash +fastmcp install claude-desktop server.py +fastmcp install claude-code server.py --with pandas --with matplotlib +fastmcp install cursor server.py -e . +``` + + +`uv` must be installed and available in your system PATH. Both Claude Desktop and Cursor run servers in isolated environments managed by `uv`. On macOS, install it globally with Homebrew for Claude Desktop compatibility: `brew install uv`. + + +## Supported Clients + +| Client | Install method | +| ------ | -------------- | +| `claude-code` | Claude Code's built-in MCP management | +| `claude-desktop` | Direct config file modification | +| `cursor` | Deeplink that opens Cursor for confirmation | +| `gemini-cli` | Gemini CLI's built-in MCP management | +| `goose` | Deeplink that opens Goose for confirmation (uses `uvx`) | +| `mcp-json` | Generates standard MCP JSON config for manual use | +| `stdio` | Outputs the shell command to run via stdio | + +## Declaring Dependencies + +Because MCP clients run servers in isolation, you need to tell the install command what your server needs. There are two approaches: + +**Command-line flags** let you specify dependencies directly: + +```bash +fastmcp install claude-desktop server.py --with pandas --with "sqlalchemy>=2.0" +fastmcp install cursor server.py -e . --with-requirements requirements.txt +``` + +**`fastmcp.json`** configuration files declare dependencies alongside the server definition. When you install from a config file, dependencies are picked up automatically: + +```bash +fastmcp install claude-desktop fastmcp.json +fastmcp install claude-desktop # auto-detects fastmcp.json in current directory +``` + +See [Server Configuration](/deployment/server-configuration) for the full config format. + +## Options + +| Option | Flag | Description | +| ------ | ---- | ----------- | +| Server Name | `--server-name`, `-n` | Custom name for the server | +| Editable Package | `--with-editable`, `-e` | Install a directory in editable mode | +| Extra Packages | `--with` | Additional packages (repeatable) | +| Environment Variables | `--env` | `KEY=VALUE` pairs (repeatable) | +| Environment File | `--env-file`, `-f` | Load env vars from a `.env` file | +| Python | `--python` | Python version (e.g., `3.11`) | +| Project | `--project` | Run within a uv project directory | +| Requirements | `--with-requirements` | Install from a requirements file | +| Config Path | `--config-path` | Custom path to Claude Desktop config directory (`claude-desktop` only) | + +## Examples + +```bash +# Basic install with auto-detected server instance +fastmcp install claude-desktop server.py + +# Install from fastmcp.json with auto-detection +fastmcp install claude-desktop + +# Explicit entrypoint with dependencies +fastmcp install claude-desktop server.py:my_server \ + --server-name "My Analysis Server" \ + --with pandas + +# With environment variables +fastmcp install claude-code server.py \ + --env API_KEY=secret \ + --env DEBUG=true + +# With env file +fastmcp install cursor server.py --env-file .env + +# Specific Python version and requirements file +fastmcp install claude-desktop server.py \ + --python 3.11 \ + --with-requirements requirements.txt + +# With custom config path (claude-desktop only) +fastmcp install claude-desktop server.py \ + --config-path "C:\Users\username\AppData\Local\Packages\Claude_xyz\LocalCache\Roaming\Claude" +``` + +## Generating MCP JSON + +The `mcp-json` target generates standard MCP configuration JSON instead of installing into a specific client. This is useful for clients that FastMCP doesn't directly support, for CI/CD environments, or for sharing server configs: + +```bash +fastmcp install mcp-json server.py +``` + +The output follows the standard format used by Claude Desktop, Cursor, and other MCP clients: + +```json +{ + "server-name": { + "command": "uv", + "args": ["run", "--with", "fastmcp", "fastmcp", "run", "/path/to/server.py"], + "env": { + "API_KEY": "value" + } + } +} +``` + +Use `--copy` to send it to your clipboard instead of stdout. + +## Generating Stdio Commands + +The `stdio` target outputs the shell command an MCP host would use to start your server over stdio: + +```bash +fastmcp install stdio server.py +# Output: uv run --with fastmcp fastmcp run /absolute/path/to/server.py +``` + +When installing from a `fastmcp.json`, dependencies from the config are included automatically: + +```bash +fastmcp install stdio fastmcp.json +# Output: uv run --with fastmcp --with pillow --with 'qrcode[pil]>=8.0' fastmcp run /path/to/server.py +``` + +Use `--copy` to copy to clipboard. + + +`fastmcp install` is designed for local server files with stdio transport. For remote servers running over HTTP, use your client's native configuration — FastMCP's value here is simplifying the complex local setup with `uv`, dependencies, and environment variables. + diff --git a/docs/cli/overview.mdx b/docs/cli/overview.mdx new file mode 100644 index 000000000..2cd4e145d --- /dev/null +++ b/docs/cli/overview.mdx @@ -0,0 +1,103 @@ +--- +title: CLI +sidebarTitle: Overview +description: The fastmcp command-line interface +icon: terminal +--- + +import { VersionBadge } from '/snippets/version-badge.mdx' + +The `fastmcp` CLI is installed automatically with FastMCP. It's the primary way to run, test, install, and interact with MCP servers from your terminal. + +```bash +fastmcp --help +``` + +## Commands at a Glance + +| Command | What it does | +| ------- | ------------ | +| [`run`](/cli/running) | Run a server (local file, factory function, remote URL, or config file) | +| [`dev inspector`](/cli/running#development-with-the-inspector) | Launch a server inside the MCP Inspector for interactive testing | +| [`install`](/cli/install-mcp) | Install a server into Claude Code, Claude Desktop, Cursor, Gemini CLI, or Goose | +| [`inspect`](/cli/inspecting) | Print a server's tools, resources, and prompts as a summary or JSON report | +| [`list`](/cli/client) | List a server's tools (and optionally resources and prompts) | +| [`call`](/cli/client#calling-tools) | Call a single tool with arguments | +| [`discover`](/cli/client#discovering-configured-servers) | Find MCP servers configured in your editors and tools | +| [`generate-cli`](/cli/generate-cli) | Scaffold a standalone typed CLI from a server's tool schemas | +| [`project prepare`](/cli/running#pre-building-environments) | Pre-install dependencies into a reusable uv project | +| [`auth cimd`](/cli/auth) | Create and validate CIMD documents for OAuth | +| `version` | Print version info (`--copy` to copy to clipboard) | + +## Server Targets + +Most commands need to know *which server* to talk to. You pass a "server spec" as the first argument, and FastMCP resolves the right transport automatically. + +**URLs** connect to a running HTTP server: + +```bash +fastmcp list http://localhost:8000/mcp +fastmcp call http://localhost:8000/mcp get_forecast city=London +``` + +**Python files** are loaded directly — no `mcp.run()` boilerplate needed. FastMCP finds a server instance named `mcp`, `server`, or `app` in the file, or you can specify one explicitly: + +```bash +fastmcp list server.py +fastmcp run server.py:my_custom_server +``` + +**Config files** work too — both FastMCP's own `fastmcp.json` format and standard MCP config files with an `mcpServers` key: + +```bash +fastmcp run fastmcp.json +fastmcp list mcp-config.json +``` + +**Stdio commands** connect to any MCP server that speaks over standard I/O. Use `--command` instead of a positional argument: + +```bash +fastmcp list --command 'npx -y @modelcontextprotocol/server-github' +``` + +### Name-Based Resolution + +If your servers are already configured in an editor or tool, you can refer to them by name. FastMCP scans configs from Claude Desktop, Claude Code, Cursor, Gemini CLI, and Goose: + +```bash +fastmcp list weather +fastmcp call weather get_forecast city=London +``` + +When the same name appears in multiple configs, use the `source:name` form to be specific: + +```bash +fastmcp list claude-code:my-server +fastmcp call cursor:weather get_forecast city=London +``` + +Run [`fastmcp discover`](/cli/client#discovering-configured-servers) to see what's available on your machine. + +## Authentication + +When targeting an HTTP URL, the CLI enables OAuth authentication by default. If the server requires it, you'll be guided through the flow (typically opening a browser). If it doesn't, the setup is a silent no-op. + +To skip authentication entirely — useful for local development servers — pass `--auth none`: + +```bash +fastmcp call http://localhost:8000/mcp my_tool --auth none +``` + +You can also pass a bearer token directly: + +```bash +fastmcp list http://localhost:8000/mcp --auth "Bearer sk-..." +``` + +## Transport Override + +FastMCP defaults to Streamable HTTP for URL targets. If the server only supports Server-Sent Events (SSE), force the older transport: + +```bash +fastmcp list http://localhost:8000 --transport sse +``` diff --git a/docs/cli/running.mdx b/docs/cli/running.mdx new file mode 100644 index 000000000..dd976d561 --- /dev/null +++ b/docs/cli/running.mdx @@ -0,0 +1,141 @@ +--- +title: Running Servers +sidebarTitle: Running +description: Start, develop, and configure servers from the command line +icon: play +--- + +import { VersionBadge } from '/snippets/version-badge.mdx' + +## Starting a Server + +`fastmcp run` starts a server. Point it at a Python file, a factory function, a remote URL, or a config file: + +```bash +fastmcp run server.py +fastmcp run server.py:create_server +fastmcp run https://example.com/mcp +fastmcp run fastmcp.json +``` + +By default, the server runs over **stdio** — the transport that MCP clients like Claude Desktop expect. To serve over HTTP instead, specify the transport: + +```bash +fastmcp run server.py --transport http +fastmcp run server.py --transport http --host 0.0.0.0 --port 9000 +``` + +### Entrypoints + +FastMCP supports several ways to locate and start your server: + +**Inferred instance** — FastMCP imports the file and looks for a variable named `mcp`, `server`, or `app`: + +```bash +fastmcp run server.py +``` + +**Explicit instance** — point at a specific variable: + +```bash +fastmcp run server.py:my_server +``` + +**Factory function** — FastMCP calls the function and uses the returned server. Useful when your server needs async setup or configuration that runs before startup: + +```bash +fastmcp run server.py:create_server +``` + +**Remote URL** — starts a local proxy that bridges to a remote server. Handy for local development against a deployed server, or for bridging a remote HTTP server to stdio: + +```bash +fastmcp run https://example.com/mcp +``` + +**FastMCP config** — uses a `fastmcp.json` file that declaratively specifies the server, its dependencies, and deployment settings. When you run `fastmcp run` with no arguments, it auto-detects `fastmcp.json` in the current directory: + +```bash +fastmcp run +fastmcp run my-config.fastmcp.json +``` + +See [Server Configuration](/deployment/server-configuration) for the full `fastmcp.json` format. + +**MCP config** — runs servers defined in a standard MCP configuration file (any `.json` with an `mcpServers` key): + +```bash +fastmcp run mcp.json +``` + + +`fastmcp run` completely ignores the `if __name__ == "__main__"` block. Any setup code in that block won't execute. If you need initialization logic to run, use a [factory function](/cli/overview#factory-functions). + + +### Options + +| Option | Flag | Description | +| ------ | ---- | ----------- | +| Transport | `--transport`, `-t` | `stdio` (default), `http`, or `sse` | +| Host | `--host` | Bind address for HTTP (default: `127.0.0.1`) | +| Port | `--port`, `-p` | Bind port for HTTP (default: `8000`) | +| Path | `--path` | URL path for HTTP (default: `/mcp/`) | +| Log Level | `--log-level`, `-l` | `DEBUG`, `INFO`, `WARNING`, `ERROR`, `CRITICAL` | +| No Banner | `--no-banner` | Suppress the startup banner | +| Auto-Reload | `--reload` / `--no-reload` | Watch for file changes and restart automatically | +| Reload Dirs | `--reload-dir` | Directories to watch (repeatable) | +| Skip Env | `--skip-env` | Don't set up a uv environment (use when already in one) | +| Python | `--python` | Python version to use (e.g., `3.11`) | +| Extra Packages | `--with` | Additional packages to install (repeatable) | +| Project | `--project` | Run within a specific uv project directory | +| Requirements | `--with-requirements` | Install from a requirements file | + +### Dependency Management + +By default, `fastmcp run` uses your current Python environment directly. When you pass `--python`, `--with`, `--project`, or `--with-requirements`, it switches to running via `uv run` in a subprocess, which handles dependency isolation automatically. + +The `--skip-env` flag is useful when you're already inside an activated venv, a Docker container with pre-installed dependencies, or a uv-managed project — it prevents uv from trying to set up another environment layer. + +## Development with the Inspector + +`fastmcp dev inspector` launches your server inside the [MCP Inspector](https://github.com/modelcontextprotocol/inspector), a browser-based tool for interactively testing MCP servers. Auto-reload is on by default, so your server restarts when you save changes. + +```bash +fastmcp dev inspector server.py +fastmcp dev inspector server.py -e . --with pandas +``` + + +The Inspector always runs your server via `uv run` in a subprocess — it never uses your local environment directly. Specify dependencies with `--with`, `--with-editable`, `--with-requirements`, or through a `fastmcp.json` file. + + + +The Inspector connects over **stdio only**. When it launches, you may need to select "STDIO" from the transport dropdown and click connect. To test a server over HTTP, start it separately with `fastmcp run server.py --transport http` and point the Inspector at the URL. + + +| Option | Flag | Description | +| ------ | ---- | ----------- | +| Editable Package | `--with-editable`, `-e` | Install a directory in editable mode | +| Extra Packages | `--with` | Additional packages (repeatable) | +| Inspector Version | `--inspector-version` | MCP Inspector version to use | +| UI Port | `--ui-port` | Port for the Inspector UI | +| Server Port | `--server-port` | Port for the Inspector proxy | +| Auto-Reload | `--reload` / `--no-reload` | File watching (default: on) | +| Reload Dirs | `--reload-dir` | Directories to watch (repeatable) | +| Python | `--python` | Python version | +| Project | `--project` | Run within a uv project directory | +| Requirements | `--with-requirements` | Install from a requirements file | + +## Pre-Building Environments + +`fastmcp project prepare` creates a persistent uv project from a `fastmcp.json` file, pre-installing all dependencies. This separates environment setup from server execution — install once, run many times. + +```bash +# Step 1: Build the environment (slow, does dependency resolution) +fastmcp project prepare fastmcp.json --output-dir ./env + +# Step 2: Run using the prepared environment (fast, no install step) +fastmcp run fastmcp.json --project ./env +``` + +The prepared directory contains a `pyproject.toml`, a `.venv` with all packages installed, and a `uv.lock` for reproducibility. This is particularly useful in deployment scenarios where you want deterministic, pre-built environments. diff --git a/docs/clients/auth/bearer.mdx b/docs/clients/auth/bearer.mdx new file mode 100644 index 000000000..2e12fbc13 --- /dev/null +++ b/docs/clients/auth/bearer.mdx @@ -0,0 +1,88 @@ +--- +title: Bearer Token Authentication +sidebarTitle: Bearer Auth +description: Authenticate your FastMCP client with a Bearer token. +icon: key +--- + +import { VersionBadge } from "/snippets/version-badge.mdx" + + + + +Bearer Token authentication is only relevant for HTTP-based transports. + + +You can configure your FastMCP client to use **bearer authentication** by supplying a valid access token. This is most appropriate for service accounts, long-lived API keys, CI/CD, applications where authentication is managed separately, or other non-interactive authentication methods. + +A Bearer token is a JSON Web Token (JWT) that is used to authenticate a request. It is most commonly used in the `Authorization` header of an HTTP request, using the `Bearer` scheme: + +```http +Authorization: Bearer +``` + + +## Client Usage + +The most straightforward way to use a pre-existing Bearer token is to provide it as a string to the `auth` parameter of the `fastmcp.Client` or transport instance. FastMCP will automatically format it correctly for the `Authorization` header and bearer scheme. + + +If you're using a string token, do not include the `Bearer` prefix. FastMCP will add it for you. + + +```python {5} +from fastmcp import Client + +async with Client( + "https://your-server.fastmcp.app/mcp", + auth="", +) as client: + await client.ping() +``` + +You can also supply a Bearer token to a transport instance, such as `StreamableHttpTransport` or `SSETransport`: + +```python {6} +from fastmcp import Client +from fastmcp.client.transports import StreamableHttpTransport + +transport = StreamableHttpTransport( + "http://your-server.fastmcp.app/mcp", + auth="", +) + +async with Client(transport) as client: + await client.ping() +``` + +## `BearerAuth` Helper + +If you prefer to be more explicit and not rely on FastMCP to transform your string token, you can use the `BearerAuth` class yourself, which implements the `httpx.Auth` interface. + +```python {6} +from fastmcp import Client +from fastmcp.client.auth import BearerAuth + +async with Client( + "https://your-server.fastmcp.app/mcp", + auth=BearerAuth(token=""), +) as client: + await client.ping() +``` + +## Custom Headers + +If the MCP server expects a custom header or token scheme, you can manually set the client's `headers` instead of using the `auth` parameter by setting them on your transport: + +```python {5} +from fastmcp import Client +from fastmcp.client.transports import StreamableHttpTransport + +async with Client( + transport=StreamableHttpTransport( + "https://your-server.fastmcp.app/mcp", + headers={"X-API-Key": ""}, + ), +) as client: + await client.ping() +``` diff --git a/docs/clients/auth/cimd.mdx b/docs/clients/auth/cimd.mdx new file mode 100644 index 000000000..c1f92d1c4 --- /dev/null +++ b/docs/clients/auth/cimd.mdx @@ -0,0 +1,138 @@ +--- +title: CIMD Authentication +sidebarTitle: CIMD +description: Use Client ID Metadata Documents for verifiable, domain-based client identity. +icon: id-badge +tag: NEW +--- + +import { VersionBadge } from "/snippets/version-badge.mdx" + + + + +CIMD authentication is only relevant for HTTP-based transports and requires a server that advertises CIMD support. + + +With standard OAuth, your client registers dynamically with every server it connects to, receiving a fresh `client_id` each time. This works, but the server has no way to verify *who* your client actually is — any client can claim any name during registration. + +CIMD (Client ID Metadata Documents) flips this around. You host a small JSON document at an HTTPS URL you control, and that URL becomes your `client_id`. When your client connects to a server, the server fetches your metadata document and can verify your identity through your domain ownership. Users see a verified domain badge in the consent screen instead of an unverified client name. + +## Client Usage + +Pass your CIMD document URL to the `client_metadata_url` parameter of `OAuth`: + +```python +from fastmcp import Client +from fastmcp.client.auth import OAuth + +async with Client( + "https://mcp-server.example.com/mcp", + auth=OAuth( + client_metadata_url="https://myapp.example.com/oauth/client.json", + ), +) as client: + await client.ping() +``` + +When the server supports CIMD, the client uses your metadata URL as its `client_id` instead of performing Dynamic Client Registration. The server fetches your document, validates it, and proceeds with the standard OAuth authorization flow. + + +You don't need to pass `mcp_url` when using `OAuth` with `Client(auth=...)` — the transport provides the server URL automatically. + + +## Creating a CIMD Document + +A CIMD document is a JSON file that describes your client. The most important field is `client_id`, which must exactly match the URL where you host the document. + +Use the FastMCP CLI to generate one: + +```bash +fastmcp auth cimd create \ + --name "My Application" \ + --redirect-uri "http://localhost:*/callback" \ + --client-id "https://myapp.example.com/oauth/client.json" +``` + +This produces: + +```json +{ + "client_id": "https://myapp.example.com/oauth/client.json", + "client_name": "My Application", + "redirect_uris": ["http://localhost:*/callback"], + "token_endpoint_auth_method": "none", + "grant_types": ["authorization_code"], + "response_types": ["code"] +} +``` + +If you omit `--client-id`, the CLI generates a placeholder value and reminds you to update it before hosting. + +### CLI Options + +The `create` command accepts these flags: + +| Flag | Description | +|------|-------------| +| `--name` | Human-readable client name (required) | +| `--redirect-uri`, `-r` | Allowed redirect URIs — can be specified multiple times (required) | +| `--client-id` | The URL where you'll host this document (sets `client_id` directly) | +| `--output`, `-o` | Write to a file instead of stdout | +| `--scope` | Space-separated list of scopes the client may request | +| `--client-uri` | URL of the client's home page | +| `--logo-uri` | URL of the client's logo image | +| `--no-pretty` | Output compact JSON | + +### Redirect URIs + +The `redirect_uris` field supports wildcard port matching for localhost. The pattern `http://localhost:*/callback` matches any port, which is useful for development clients that bind to random available ports (which is what FastMCP's `OAuth` helper does by default). + +## Hosting Requirements + +CIMD documents must be hosted at a publicly accessible HTTPS URL with a non-root path: + +- **HTTPS required** — HTTP URLs are rejected for security +- **Non-root path** — The URL must have a path component (e.g., `/oauth/client.json`, not just `/`) +- **Public accessibility** — The server must be able to fetch the document over the internet +- **Matching `client_id`** — The `client_id` field in the document must exactly match the hosting URL + +Common hosting options include static file hosting services like GitHub Pages, Cloudflare Pages, Vercel, or S3 — anywhere you can serve a JSON file over HTTPS. + +## Validating Your Document + +Before deploying, verify your hosted document passes validation: + +```bash +fastmcp auth cimd validate https://myapp.example.com/oauth/client.json +``` + +The validator fetches the document and checks that: +- The URL is valid (HTTPS, non-root path) +- The document is well-formed JSON conforming to the CIMD schema +- The `client_id` in the document matches the URL it was fetched from + +## How It Works + +When your client connects to a CIMD-enabled server, the flow works like this: + + + +Your client sends its `client_metadata_url` as the `client_id` in the OAuth authorization request. + + +The server sees that the `client_id` is an HTTPS URL with a path — the signature of a CIMD client — and skips Dynamic Client Registration. + + +The server fetches your JSON document from the URL, validates that `client_id` matches the URL, and extracts your client metadata (name, redirect URIs, scopes). + + +The standard OAuth flow continues: browser opens for user consent, authorization code exchange, token issuance. The consent screen shows your verified domain. + + + +The server caches your CIMD document according to HTTP cache headers, so subsequent requests don't require re-fetching. + +## Server Configuration + +CIMD is a server-side feature that your MCP server must support. FastMCP's OAuth proxy providers (GitHub, Google, Auth0, etc.) support CIMD by default. See the [OAuth Proxy CIMD documentation](/servers/auth/oauth-proxy#cimd-support) for server-side configuration, including private key JWT authentication and security details. diff --git a/docs/clients/auth/oauth.mdx b/docs/clients/auth/oauth.mdx new file mode 100644 index 000000000..84fbe2164 --- /dev/null +++ b/docs/clients/auth/oauth.mdx @@ -0,0 +1,186 @@ +--- +title: OAuth Authentication +sidebarTitle: OAuth +description: Authenticate your FastMCP client via OAuth 2.1. +icon: window +--- + +import { VersionBadge } from "/snippets/version-badge.mdx" + + + + +OAuth authentication is only relevant for HTTP-based transports and requires user interaction via a web browser. + + +When your FastMCP client needs to access an MCP server protected by OAuth 2.1, and the process requires user interaction (like logging in and granting consent), you should use the Authorization Code Flow. FastMCP provides the `fastmcp.client.auth.OAuth` helper to simplify this entire process. + +This flow is common for user-facing applications where the application acts on behalf of the user. + +## Client Usage + + +### Default Configuration + +The simplest way to use OAuth is to pass the string `"oauth"` to the `auth` parameter of the `Client` or transport instance. FastMCP will automatically configure the client to use OAuth with default settings: + +```python {4} +from fastmcp import Client + +# Uses default OAuth settings +async with Client("https://your-server.fastmcp.app/mcp", auth="oauth") as client: + await client.ping() +``` + + +### `OAuth` Helper + +To fully configure the OAuth flow, use the `OAuth` helper and pass it to the `auth` parameter of the `Client` or transport instance. `OAuth` manages the complexities of the OAuth 2.1 Authorization Code Grant with PKCE (Proof Key for Code Exchange) for enhanced security, and implements the full `httpx.Auth` interface. + +```python {2, 4, 6} +from fastmcp import Client +from fastmcp.client.auth import OAuth + +oauth = OAuth(scopes=["user"]) + +async with Client("https://your-server.fastmcp.app/mcp", auth=oauth) as client: + await client.ping() +``` + + +You don't need to pass `mcp_url` when using `OAuth` with `Client(auth=...)` — the transport provides the server URL automatically. + + +#### `OAuth` Parameters + +- **`scopes`** (`str | list[str]`, optional): OAuth scopes to request. Can be space-separated string or list of strings +- **`client_name`** (`str`, optional): Client name for dynamic registration. Defaults to `"FastMCP Client"` +- **`client_id`** (`str`, optional): Pre-registered OAuth client ID. When provided, skips Dynamic Client Registration entirely. See [Pre-Registered Clients](#pre-registered-clients) +- **`client_secret`** (`str`, optional): OAuth client secret for pre-registered clients. Optional — public clients that rely on PKCE can omit this +- **`client_metadata_url`** (`str`, optional): URL-based client identity (CIMD). See [CIMD Authentication](/clients/auth/cimd) for details +- **`token_storage`** (`AsyncKeyValue`, optional): Storage backend for persisting OAuth tokens. Defaults to in-memory storage (tokens lost on restart). See [Token Storage](#token-storage) for encrypted storage options +- **`additional_client_metadata`** (`dict[str, Any]`, optional): Extra metadata for client registration +- **`callback_port`** (`int`, optional): Fixed port for OAuth callback server. If not specified, uses a random available port +- **`httpx_client_factory`** (`McpHttpClientFactory`, optional): Factory for creating httpx clients + + +## OAuth Flow + +The OAuth flow is triggered when you use a FastMCP `Client` configured to use OAuth. + + + +The client first checks the configured `token_storage` backend for existing, valid tokens for the target server. If one is found, it will be used to authenticate the client. + + +If no valid tokens exist, the client attempts to discover the OAuth server's endpoints using a well-known URI (e.g., `/.well-known/oauth-authorization-server`) based on the `mcp_url`. + + +If a `client_id` is provided, the client uses those pre-registered credentials directly and skips this step entirely. Otherwise, if a `client_metadata_url` is configured and the server supports CIMD, the client uses its metadata URL as its identity. As a fallback, the client performs Dynamic Client Registration (RFC 7591) if the server supports it. + + +A temporary local HTTP server is started on an available port (or the port specified via `callback_port`). This server's address (e.g., `http://127.0.0.1:/callback`) acts as the `redirect_uri` for the OAuth flow. + + +The user's default web browser is automatically opened, directing them to the OAuth server's authorization endpoint. The user logs in and grants (or denies) the requested `scopes`. + + +Upon approval, the OAuth server redirects the user's browser to the local callback server with an `authorization_code`. The client captures this code and exchanges it with the OAuth server's token endpoint for an `access_token` (and often a `refresh_token`) using PKCE for security. + + +The obtained tokens are saved to the configured `token_storage` backend for future use, eliminating the need for repeated browser interactions. + + +The access token is automatically included in the `Authorization` header for requests to the MCP server. + + +If the access token expires, the client will automatically use the refresh token to get a new access token. + + + +## Token Storage + + + +By default, tokens are stored in memory and lost when your application restarts. For persistent storage, pass an `AsyncKeyValue`-compatible storage backend to the `token_storage` parameter. + + +**Security Consideration**: Use encrypted storage for production. MCP clients can accumulate OAuth credentials for many servers over time, and a compromised token store could expose access to multiple services. + + +```python +from fastmcp import Client +from fastmcp.client.auth import OAuth +from key_value.aio.stores.disk import DiskStore +from key_value.aio.wrappers.encryption import FernetEncryptionWrapper +from cryptography.fernet import Fernet +import os + +# Create encrypted disk storage +encrypted_storage = FernetEncryptionWrapper( + key_value=DiskStore(directory="~/.fastmcp/oauth-tokens"), + fernet=Fernet(os.environ["OAUTH_STORAGE_ENCRYPTION_KEY"]) +) + +oauth = OAuth(token_storage=encrypted_storage) + +async with Client("https://your-server.fastmcp.app/mcp", auth=oauth) as client: + await client.ping() +``` + +You can use any `AsyncKeyValue`-compatible backend from the [key-value library](https://github.com/strawgate/py-key-value) including Redis, DynamoDB, and more. Wrap your storage in `FernetEncryptionWrapper` for encryption. + + +When selecting a storage backend, review the [py-key-value documentation](https://github.com/strawgate/py-key-value) to understand the maturity level and limitations of your chosen backend. Some backends may be in preview or have constraints that affect production suitability. + + +## CIMD Authentication + + + +Client ID Metadata Documents (CIMD) provide an alternative to Dynamic Client Registration. Instead of registering with each server, your client hosts a static JSON document at an HTTPS URL. That URL becomes your client's identity, and servers can verify who you are through your domain ownership. + +```python +from fastmcp import Client +from fastmcp.client.auth import OAuth + +async with Client( + "https://mcp-server.example.com/mcp", + auth=OAuth( + client_metadata_url="https://myapp.example.com/oauth/client.json", + ), +) as client: + await client.ping() +``` + +See the [CIMD Authentication](/clients/auth/cimd) page for complete documentation on creating, hosting, and validating CIMD documents. + +## Pre-Registered Clients + + + +Some OAuth servers don't support Dynamic Client Registration — the MCP spec explicitly makes DCR optional. If your client has been pre-registered with the server (you already have a `client_id` and optionally a `client_secret`), you can provide them directly to skip DCR entirely. + +```python +from fastmcp import Client +from fastmcp.client.auth import OAuth + +async with Client( + "https://mcp-server.example.com/mcp", + auth=OAuth( + client_id="my-registered-client-id", + client_secret="my-client-secret", + ), +) as client: + await client.ping() +``` + +Public clients that rely on PKCE for security can omit `client_secret`: + +```python +oauth = OAuth(client_id="my-public-client-id") +``` + + +When using pre-registered credentials, the client will not attempt Dynamic Client Registration. If the server rejects the credentials, the error is surfaced immediately rather than falling back to DCR. + diff --git a/docs/clients/cli.mdx b/docs/clients/cli.mdx new file mode 100644 index 000000000..801c7632c --- /dev/null +++ b/docs/clients/cli.mdx @@ -0,0 +1,161 @@ +--- +title: Client CLI +sidebarTitle: CLI +description: Query and invoke MCP server tools directly from the terminal with fastmcp list and fastmcp call. +icon: terminal +--- + +import { VersionBadge } from '/snippets/version-badge.mdx' + + + +MCP servers are designed for programmatic consumption by AI assistants and applications. But during development, you often want to poke at a server directly: check what tools it exposes, call one with test arguments, or verify that a deployment is responding correctly. The FastMCP CLI gives you that direct access with two commands, `fastmcp list` and `fastmcp call`, so you can query and invoke any MCP server without writing a single line of Python. + +These commands are also valuable for LLM-based agents that lack native MCP support. An agent that can execute shell commands can use `fastmcp list --json` to discover available tools and `fastmcp call --json` to invoke them, with structured JSON output designed for programmatic consumption. + +## Server Targets + +Both commands need to know which server to talk to. You provide a "server spec" as the first argument, and FastMCP figures out the transport automatically. You can point at an HTTP URL for a running server, a Python file that defines one, a JSON configuration file that describes one, or a JavaScript file. The CLI resolves the right connection mechanism so you can focus on the query. + +```bash +fastmcp list http://localhost:8000/mcp +fastmcp list server.py +fastmcp list mcp-config.json +``` + +Python files are handled with particular care. Rather than requiring your script to call `mcp.run()` at the bottom, the CLI routes it through `fastmcp run` internally, which means any Python file that defines a FastMCP server object works as a target with no boilerplate. + +For servers that communicate over stdio (common with Node.js-based MCP servers), use the `--command` flag instead of a positional server spec. The string is shell-split into a command and arguments. + +```bash +fastmcp list --command 'npx -y @modelcontextprotocol/server-github' +``` + +### Name-Based Resolution + +If your MCP servers are already configured in an editor or tool, you can refer to them by name instead of spelling out URLs or file paths. The CLI scans config files from Claude Desktop, Claude Code, Cursor, Gemini CLI, and Goose, and matches the name you provide. + +```bash +fastmcp list weather +fastmcp call weather get_forecast city=London +``` + +You can also use the `source:name` form to target a specific source directly, which is useful when the same server name appears in multiple configs or when you want to be explicit about which config you mean. + +```bash +fastmcp list claude-code:my-server +fastmcp call cursor:weather get_forecast city=London +``` + +The available source names are `claude-desktop`, `claude-code`, `cursor`, `gemini`, `goose`, and `project` (for `./mcp.json`). Run `fastmcp discover` to see what's available. + +## Discovering Configured Servers + +`fastmcp discover` scans your local editor and project configurations for MCP server definitions. It checks Claude Desktop, Claude Code (`~/.claude.json`), Cursor workspace configs (walking up from the current directory), Gemini CLI (`~/.gemini/settings.json`), Goose (`~/.config/goose/config.yaml`), and `mcp.json` in the current directory. + +```bash +fastmcp discover +``` + +The output groups servers by source, showing each server's name and transport. Use `--source` to filter to specific sources, and `--json` for machine-readable output. + +```bash +fastmcp discover --source claude-code +fastmcp discover --source cursor --source gemini --json +``` + +Any server that appears here can be used by name (or `source:name`) with `fastmcp list` and `fastmcp call`, which means you can go from "I have a server configured in Claude Code" to querying it without copying any URLs or paths. + +## Discovering Tools + +`fastmcp list` connects to a server and prints every tool it exposes. The default output is compact: each tool appears as a function signature with its parameter names, types, and a description. + +```bash +fastmcp list http://localhost:8000/mcp +``` + +The output looks like a Python function signature, making it easy to see at a glance what a tool expects and what it returns. Required parameters appear with just their type annotation, while optional ones show their defaults. + +When you need the full JSON Schema for a tool's inputs or outputs -- useful for understanding nested object structures or enum constraints -- opt into them with `--input-schema` or `--output-schema`. These print the raw schema beneath each tool signature. + +### Beyond Tools + +MCP servers can expose resources and prompts alongside tools. By default, `fastmcp list` only shows tools because they are the most common interaction point. Add `--resources` or `--prompts` to include those in the output. + +```bash +fastmcp list server.py --resources --prompts +``` + +Resources appear with their URIs and descriptions. Prompts appear with their argument names so you can see what parameters they accept. + +### Machine-Readable Output + +The `--json` flag switches from human-friendly text to structured JSON. Each tool includes its name, description, and full input schema (and output schema when present). When combined with `--resources` or `--prompts`, those are included as additional top-level keys. + +```bash +fastmcp list server.py --json +``` + +This is the format to use when building automation around MCP servers or feeding tool definitions to an LLM agent that needs to decide which tool to call. + +## Calling Tools + +`fastmcp call` invokes a single tool on a server. You provide the server spec, the tool name, and arguments as `key=value` pairs. The CLI fetches the tool's schema, coerces your string values to the correct types (integers, floats, booleans, arrays, objects), and makes the call. + +```bash +fastmcp call http://localhost:8000/mcp search query=hello limit=5 +``` + +Type coercion is driven by the tool's JSON Schema. If a parameter is declared as an integer, the string `"5"` becomes the integer `5`. Booleans accept `true`/`false`, `yes`/`no`, and `1`/`0`. Array and object parameters are parsed as JSON. + +For tools with complex or deeply nested arguments, the `key=value` syntax gets unwieldy. You can pass a single JSON object as the argument instead, and the CLI treats it as the full input dictionary. + +```bash +fastmcp call server.py create_item '{"name": "Widget", "tags": ["sale", "new"], "metadata": {"color": "blue"}}' +``` + +Alternatively, `--input-json` provides the base argument dictionary. Any `key=value` pairs you add alongside it override keys from the JSON, which is useful for templating a complex call and varying one parameter at a time. + +### Error Handling + +The CLI validates your call before sending it. If you misspell a tool name, it uses fuzzy matching to suggest corrections. If you omit a required argument, it tells you which ones are missing and prints the tool's signature as a reminder. + +When a tool call itself returns an error (the server executed the tool but it failed), the error message is printed and the CLI exits with a non-zero status code, making it straightforward to use in scripts. + +### Structured Output + +Like `fastmcp list`, the `--json` flag on `fastmcp call` emits structured JSON instead of formatted text. The output includes the content blocks, error status, and structured content when the server provides it. Use this when you need to parse tool results programmatically. + +```bash +fastmcp call server.py get_weather city=London --json +``` + +## Authentication + +When the server target is an HTTP URL, the CLI automatically enables OAuth authentication. If the server requires it, you will be guided through the OAuth flow (typically opening a browser for authorization). If the server has no auth requirements, the OAuth setup is a silent no-op. + +To explicitly disable authentication -- for example, when connecting to a local development server where OAuth setup would just slow you down -- pass `--auth none`. + +```bash +fastmcp call http://localhost:8000/mcp my_tool --auth none +``` + +## Transport Override + +FastMCP defaults to Streamable HTTP for URL targets. If you are connecting to a server that only supports Server-Sent Events (SSE), use `--transport sse` to force the older transport. This appends `/sse` to the URL path automatically so the client picks the correct protocol. + +```bash +fastmcp list http://localhost:8000 --transport sse +``` + +## Interactive Elicitation + +Some MCP tools request additional input from the user during execution through a mechanism called elicitation. When a tool sends an elicitation request, the CLI prints the server's question to the terminal and prompts you to respond. Each field in the elicitation schema is presented with its name and expected type, and required fields are clearly marked. + +You can type `decline` to skip a question or `cancel` to abort the tool call entirely. This interactive behavior means the CLI works naturally with tools that have multi-step or conversational workflows. + +## LLM Agent Integration + +For LLM agents that can execute shell commands but lack built-in MCP support, the CLI provides a clean integration path. The agent calls `fastmcp list --json` to get a structured description of every available tool, including full input schemas, and then calls `fastmcp call --json` with the chosen tool and arguments. Both commands return well-formed JSON that is straightforward to parse. + +Because the CLI handles connection management, transport selection, and type coercion internally, the agent does not need to understand MCP protocol details. It just needs to read JSON and construct shell commands. diff --git a/docs/clients/client.mdx b/docs/clients/client.mdx new file mode 100644 index 000000000..fc5ddc263 --- /dev/null +++ b/docs/clients/client.mdx @@ -0,0 +1,237 @@ +--- +title: The FastMCP Client +sidebarTitle: Overview +description: Programmatic client for interacting with MCP servers through a well-typed, Pythonic interface. +icon: user-robot +--- + +import { VersionBadge } from '/snippets/version-badge.mdx' + + + +The `fastmcp.Client` class provides a programmatic interface for interacting with any MCP server. It handles protocol details and connection management automatically, letting you focus on the operations you want to perform. + +The FastMCP Client is designed for deterministic, controlled interactions rather than autonomous behavior, making it ideal for testing MCP servers during development, building deterministic applications that need reliable MCP interactions, and creating the foundation for agentic or LLM-based clients with structured, type-safe operations. + + +This is a programmatic client that requires explicit function calls and provides direct control over all MCP operations. Use it as a building block for higher-level systems. + + +## Creating a Client + +You provide a server source and the client automatically infers the appropriate transport mechanism. + +```python +import asyncio +from fastmcp import Client, FastMCP + +# In-memory server (ideal for testing) +server = FastMCP("TestServer") +client = Client(server) + +# HTTP server +client = Client("https://example.com/mcp") + +# Local Python script +client = Client("my_mcp_server.py") + +async def main(): + async with client: + # Basic server interaction + await client.ping() + + # List available operations + tools = await client.list_tools() + resources = await client.list_resources() + prompts = await client.list_prompts() + + # Execute operations + result = await client.call_tool("example_tool", {"param": "value"}) + print(result) + +asyncio.run(main()) +``` + +All client operations require using the `async with` context manager for proper connection lifecycle management. + +## Choosing a Transport + +The client automatically selects a transport based on what you pass to it, but different transports have different characteristics that matter for your use case. + +**In-memory transport** connects directly to a FastMCP server instance within the same Python process. Use this for testing and development where you want to eliminate subprocess and network complexity. The server shares your process's environment and memory space. + +```python +from fastmcp import Client, FastMCP + +server = FastMCP("TestServer") +client = Client(server) # In-memory, no network or subprocess +``` + +**STDIO transport** launches a server as a subprocess and communicates through stdin/stdout pipes. This is the standard mechanism used by desktop clients like Claude Desktop. The subprocess runs in an isolated environment, so you must explicitly pass any environment variables the server needs. + +```python +from fastmcp import Client + +# Simple inference from file path +client = Client("my_server.py") + +# With explicit environment configuration +client = Client("my_server.py", env={"API_KEY": "secret"}) +``` + +**HTTP transport** connects to servers running as web services. Use this for production deployments where the server runs independently and manages its own lifecycle. + +```python +from fastmcp import Client + +client = Client("https://api.example.com/mcp") +``` + +See [Transports](/clients/transports) for detailed configuration options including authentication headers, session persistence, and multi-server configurations. + +## Configuration-Based Clients + + + +Create clients from MCP configuration dictionaries, which can include multiple servers. While there is no official standard for MCP configuration format, FastMCP follows established conventions used by tools like Claude Desktop. + +```python +config = { + "mcpServers": { + "weather": { + "url": "https://weather-api.example.com/mcp" + }, + "assistant": { + "command": "python", + "args": ["./assistant_server.py"] + } + } +} + +client = Client(config) + +async with client: + # Tools are prefixed with server names + weather_data = await client.call_tool("weather_get_forecast", {"city": "London"}) + response = await client.call_tool("assistant_answer_question", {"question": "What's the capital of France?"}) + + # Resources use prefixed URIs + icons = await client.read_resource("weather://weather/icons/sunny") +``` + +## Connection Lifecycle + +The client uses context managers for connection management. When you enter the context, the client establishes a connection and performs an MCP initialization handshake with the server. This handshake exchanges capabilities, server metadata, and instructions. + +```python +from fastmcp import Client, FastMCP + +mcp = FastMCP(name="MyServer", instructions="Use the greet tool to say hello!") + +@mcp.tool +def greet(name: str) -> str: + """Greet a user by name.""" + return f"Hello, {name}!" + +async with Client(mcp) as client: + # Initialization already happened automatically + print(f"Server: {client.initialize_result.serverInfo.name}") + print(f"Instructions: {client.initialize_result.instructions}") + print(f"Capabilities: {client.initialize_result.capabilities.tools}") +``` + +For advanced scenarios where you need precise control over when initialization happens, disable automatic initialization and call `initialize()` manually: + +```python +from fastmcp import Client + +client = Client("my_mcp_server.py", auto_initialize=False) + +async with client: + # Connection established, but not initialized yet + print(f"Connected: {client.is_connected()}") + print(f"Initialized: {client.initialize_result is not None}") # False + + # Initialize manually with custom timeout + result = await client.initialize(timeout=10.0) + print(f"Server: {result.serverInfo.name}") + + # Now ready for operations + tools = await client.list_tools() +``` + +## Operations + +FastMCP clients interact with three types of server components. + +**Tools** are server-side functions that the client can execute with arguments. Call them with `call_tool()` and receive structured results. + +```python +async with client: + tools = await client.list_tools() + result = await client.call_tool("multiply", {"a": 5, "b": 3}) + print(result.data) # 15 +``` + +See [Tools](/clients/tools) for detailed documentation including version selection, error handling, and structured output. + +**Resources** are data sources that the client can read, either static or templated. Access them with `read_resource()` using URIs. + +```python +async with client: + resources = await client.list_resources() + content = await client.read_resource("file:///config/settings.json") + print(content[0].text) +``` + +See [Resources](/clients/resources) for detailed documentation including templates and binary content. + +**Prompts** are reusable message templates that can accept arguments. Retrieve rendered prompts with `get_prompt()`. + +```python +async with client: + prompts = await client.list_prompts() + messages = await client.get_prompt("analyze_data", {"data": [1, 2, 3]}) + print(messages.messages) +``` + +See [Prompts](/clients/prompts) for detailed documentation including argument serialization. + +## Callback Handlers + +The client supports callback handlers for advanced server interactions. These let you respond to server-initiated requests and receive notifications. + +```python +from fastmcp import Client +from fastmcp.client.logging import LogMessage + +async def log_handler(message: LogMessage): + print(f"Server log: {message.data}") + +async def progress_handler(progress: float, total: float | None, message: str | None): + print(f"Progress: {progress}/{total} - {message}") + +async def sampling_handler(messages, params, context): + # Integrate with your LLM service here + return "Generated response" + +client = Client( + "my_mcp_server.py", + log_handler=log_handler, + progress_handler=progress_handler, + sampling_handler=sampling_handler, + timeout=30.0 +) +``` + +Each handler type has its own documentation: + +- **[Sampling](/clients/sampling)** - Respond to server LLM requests +- **[Elicitation](/clients/elicitation)** - Handle server requests for user input +- **[Progress](/clients/progress)** - Monitor long-running operations +- **[Logging](/clients/logging)** - Handle server log messages +- **[Roots](/clients/roots)** - Provide local context to servers + + +The FastMCP Client is designed as a foundational tool. Use it directly for deterministic operations, or build higher-level agentic systems on top of its reliable, type-safe interface. + diff --git a/docs/clients/elicitation.mdx b/docs/clients/elicitation.mdx new file mode 100644 index 000000000..33adbb6d6 --- /dev/null +++ b/docs/clients/elicitation.mdx @@ -0,0 +1,138 @@ +--- +title: User Elicitation +sidebarTitle: Elicitation +description: Handle server requests for structured user input. +icon: message-question +--- + +import { VersionBadge } from "/snippets/version-badge.mdx"; + + + +Use this when you need to respond to server requests for user input during tool execution. + +Elicitation allows MCP servers to request structured input from users during operations. Instead of requiring all inputs upfront, servers can interactively ask for missing parameters, request clarification, or gather additional context. + +## Handler Template + +```python +from fastmcp import Client +from fastmcp.client.elicitation import ElicitResult, ElicitRequestParams, RequestContext + +async def elicitation_handler( + message: str, + response_type: type | None, + params: ElicitRequestParams, + context: RequestContext +) -> ElicitResult | object: + """ + Handle server requests for user input. + + Args: + message: The prompt to display to the user + response_type: Python dataclass type for the response (None if no data expected) + params: Original MCP elicitation parameters including raw JSON schema + context: Request context with metadata + + Returns: + - Data directly (implicitly accepts the elicitation) + - ElicitResult for explicit control over the action + """ + # Present the message and collect input + user_input = input(f"{message}: ") + + if not user_input: + return ElicitResult(action="decline") + + # Create response using the provided dataclass type + return response_type(value=user_input) + +client = Client( + "my_mcp_server.py", + elicitation_handler=elicitation_handler, +) +``` + +## How It Works + +When a server needs user input, it sends an elicitation request with a message prompt and a JSON schema describing the expected response structure. FastMCP automatically converts this schema into a Python dataclass type, making it easy to construct properly typed responses without manually parsing JSON schemas. + +The handler receives four parameters: + + + + The prompt message to display to the user + + + + A Python dataclass type that FastMCP created from the server's JSON schema. Use this to construct your response with proper typing. If the server requests an empty object, this will be `None`. + + + + The original MCP elicitation parameters, including the raw JSON schema in `params.requestedSchema` + + + + Request context containing metadata about the elicitation request + + + +## Response Actions + +You can return data directly, which implicitly accepts the elicitation: + +```python +async def elicitation_handler(message, response_type, params, context): + user_input = input(f"{message}: ") + return response_type(value=user_input) # Implicit accept +``` + +Or return an `ElicitResult` for explicit control over the action: + +```python +from fastmcp.client.elicitation import ElicitResult + +async def elicitation_handler(message, response_type, params, context): + user_input = input(f"{message}: ") + + if not user_input: + return ElicitResult(action="decline") # User declined + + if user_input == "cancel": + return ElicitResult(action="cancel") # Cancel entire operation + + return ElicitResult( + action="accept", + content=response_type(value=user_input) + ) +``` + +**Action types:** +- **`accept`**: User provided valid input. Include the data in the `content` field. +- **`decline`**: User chose not to provide the requested information. Omit `content`. +- **`cancel`**: User cancelled the entire operation. Omit `content`. + +## Example + +A file management tool might ask which directory to create: + +```python +from fastmcp import Client +from fastmcp.client.elicitation import ElicitResult + +async def elicitation_handler(message, response_type, params, context): + print(f"Server asks: {message}") + + user_response = input("Your response: ") + + if not user_response: + return ElicitResult(action="decline") + + # Use the response_type dataclass to create a properly structured response + return response_type(value=user_response) + +client = Client( + "my_mcp_server.py", + elicitation_handler=elicitation_handler +) +``` diff --git a/docs/clients/generate-cli.mdx b/docs/clients/generate-cli.mdx new file mode 100644 index 000000000..b0faaefb0 --- /dev/null +++ b/docs/clients/generate-cli.mdx @@ -0,0 +1,166 @@ +--- +title: Generate CLI +sidebarTitle: Generate CLI +description: Turn any MCP server into a standalone, typed command-line tool. +icon: wand-magic-sparkles +tag: NEW +--- + +import { VersionBadge } from '/snippets/version-badge.mdx' + + + +`fastmcp list` and `fastmcp call` let you poke at a server interactively, but they're developer tools — you always have to spell out the server spec, the tool name, and the arguments. `fastmcp generate-cli` takes the next step: it connects to a server, reads its schemas, and writes a standalone Python script where every tool is a proper subcommand with typed flags, help text, and tab completion. The result is a CLI that feels like it was hand-written for that specific server. + +The key insight is that MCP tool schemas already contain everything a CLI framework needs: parameter names, types, descriptions, required/optional status, and defaults. `generate-cli` maps that schema into [cyclopts](https://cyclopts.readthedocs.io/) commands, so JSON Schema types become Python type annotations, descriptions become `--help` text, and required parameters become mandatory flags. + +## Generating a Script + +Point the command at any server spec — URLs, Python files, discovered server names, MCPConfig JSON — and it writes a CLI script: + +```bash +fastmcp generate-cli weather +fastmcp generate-cli http://localhost:8000/mcp +fastmcp generate-cli server.py my_weather_cli.py +``` + +The second positional argument sets the output path. When omitted, it defaults to `cli.py`. If either the CLI file or its companion `SKILL.md` already exists, the command refuses to overwrite unless you pass `-f`: + +```bash +fastmcp generate-cli weather -f +fastmcp generate-cli weather my_cli.py -f +``` + +Name-based resolution works here too, so if you have a server configured in Claude Desktop, Cursor, or any other supported editor, you can reference it by name. Run [`fastmcp discover`](/clients/cli#discovering-configured-servers) to see what's available. + +```bash +fastmcp generate-cli claude-code:my-server output.py +``` + +The `--timeout` and `--auth` flags work the same way they do in `fastmcp list` and `fastmcp call`. + +## What You Get + +The generated script is a regular Python file — executable, editable, and yours. Here's what it looks like in practice: + +``` +$ python cli.py --help +Usage: weather-cli COMMAND + +CLI for weather MCP server + +Commands: + call-tool Call a tool on the server + list-tools List available tools. + list-resources List available resources. + read-resource Read a resource by URI. + list-prompts List available prompts. + get-prompt Get a prompt by name. Pass arguments as key=value pairs. +``` + +The `call-tool` subcommand is where the generated code lives. Each tool on the server becomes its own command: + +``` +$ python cli.py call-tool --help +Usage: weather-cli call-tool COMMAND + +Call a tool on the server + +Commands: + get_forecast Get the weather forecast for a city. + search_city Search for a city by name. +``` + +And each tool has typed parameters with help text pulled directly from the server's schema: + +``` +$ python cli.py call-tool get_forecast --help +Usage: weather-cli call-tool get_forecast [OPTIONS] + +Get the weather forecast for a city. + +Options: + --city [str] City name (required) + --days [int] Number of forecast days (default: 3) +``` + +Tool names are preserved exactly as the server defines them — underscores stay as underscores, so `call-tool get_forecast` matches what the server expects. + +## Agent Skill + +Alongside the CLI script, `generate-cli` also writes a `SKILL.md` file — a [Claude Code agent skill](https://docs.anthropic.com/en/docs/agents-and-tools/claude-code/skills) that documents the generated CLI. The skill includes every tool's exact invocation syntax, parameter flags with types and descriptions, and the utility commands, so an agent can use the CLI immediately without running `--help` or experimenting with flag names. + +The skill is written to the same directory as the CLI script. For a weather server, it looks something like: + +````markdown +--- +name: "weather-cli" +description: "CLI for the weather MCP server. Call tools, list resources, and get prompts." +--- + +# weather CLI + +## Tool Commands + +### get_forecast + +Get the weather forecast for a city. + +```bash +uv run --with fastmcp python cli.py call-tool get_forecast --city --days +``` + +| Flag | Type | Required | Description | +|------|------|----------|-------------| +| `--city` | string | yes | City name | +| `--days` | integer | no | Number of forecast days | +```` + +To skip skill generation, pass `--no-skill`: + +```bash +fastmcp generate-cli weather --no-skill +``` + +## How It Works + +The generated script is a client, not a server. It doesn't bundle or embed the MCP server — it connects to it on every invocation. For URL-based servers, the server needs to be running. For stdio-based servers, the command specified in `CLIENT_SPEC` must be available on the system's `PATH`. + +At the top of the generated file, a `CLIENT_SPEC` variable holds the resolved transport: either a URL string or a `StdioTransport` with the command and arguments baked in. Every invocation connects through this spec, so the script works without any external configuration. + +### Parameter Handling + +Parameters are mapped intelligently based on their complexity: + +**Simple types** (`string`, `integer`, `number`, `boolean`) become typed Python parameters with clean flags: +```bash +python cli.py call-tool get_forecast --city London --days 3 +``` + +**Arrays of simple types** (`array` with `string`/`integer`/`number`/`boolean` items) become `list[T]` parameters that accept multiple flags: +```bash +python cli.py call-tool tag_items --tags python --tags fastapi --tags mcp +``` + +**Complex types** (objects, nested arrays, or unions) accept JSON strings. The tool's `--help` displays the full JSON schema so you know exactly what structure to pass: +```bash +python cli.py call-tool create_user \ + --name John \ + --metadata '{"role": "admin", "dept": "engineering"}' +``` + +Required parameters are mandatory flags; optional ones default to their schema default or `None`. Empty values are filtered out before calling the server. + +Beyond tool commands, the script includes generic commands that work regardless of what the server exposes: `list-tools`, `list-resources`, `read-resource`, `list-prompts`, and `get-prompt`. These connect to the server at runtime, so they always reflect the server's current state even if the tools have changed since generation. + +## Editing the Output + +The most common edit is changing `CLIENT_SPEC`. If you generated from a local dev server and want to point at production, just change the string. If you generated from a discovered name and want to pin the transport, replace it with an explicit URL or `StdioTransport`. + +Beyond that, it's a regular Python file. You can add commands, change the output formatting, integrate it into a larger application, or strip out the parts you don't need. The helper functions (`_call_tool`, `_print_tool_result`) are thin wrappers around `fastmcp.Client` that are easy to adapt. + +The generated script requires `fastmcp` as a dependency. If the script lives outside a project that already has fastmcp installed, `uv run` is the easiest way to run it without permanent installation: + +```bash +uv run --with fastmcp python cli.py call-tool get_forecast --city London +``` diff --git a/docs/clients/logging.mdx b/docs/clients/logging.mdx new file mode 100644 index 000000000..eea9ff322 --- /dev/null +++ b/docs/clients/logging.mdx @@ -0,0 +1,92 @@ +--- +title: Server Logging +sidebarTitle: Logging +description: Receive and handle log messages from MCP servers. +icon: receipt +--- + +import { VersionBadge } from '/snippets/version-badge.mdx' + + + +Use this when you need to capture or process log messages sent by the server. + +MCP servers can emit log messages to clients. The client handles these through a log handler callback. + +## Log Handler + +Provide a `log_handler` function when creating the client: + +```python +import logging +from fastmcp import Client +from fastmcp.client.logging import LogMessage + +logging.basicConfig( + level=logging.INFO, + format='%(asctime)s - %(name)s - %(levelname)s - %(message)s' +) + +logger = logging.getLogger(__name__) +LOGGING_LEVEL_MAP = logging.getLevelNamesMapping() + +async def log_handler(message: LogMessage): + """Forward MCP server logs to Python's logging system.""" + msg = message.data.get('msg') + extra = message.data.get('extra') + + level = LOGGING_LEVEL_MAP.get(message.level.upper(), logging.INFO) + logger.log(level, msg, extra=extra) + +client = Client( + "my_mcp_server.py", + log_handler=log_handler, +) +``` + +The handler receives a `LogMessage` object: + + + + The log level + + + + The logger name (may be None) + + + + The log payload, containing `msg` and `extra` keys + + + +## Structured Logs + +The `message.data` attribute is a dictionary containing the log payload. This enables structured logging with rich contextual information. + +```python +async def detailed_log_handler(message: LogMessage): + msg = message.data.get('msg') + extra = message.data.get('extra') + + if message.level == "error": + print(f"ERROR: {msg} | Details: {extra}") + elif message.level == "warning": + print(f"WARNING: {msg} | Details: {extra}") + else: + print(f"{message.level.upper()}: {msg}") +``` + +This structure is preserved even when logs are forwarded through a FastMCP proxy, making it useful for debugging multi-server applications. + +## Default Behavior + +If you do not provide a custom `log_handler`, FastMCP's default handler routes server logs to Python's logging system at the appropriate severity level. The MCP levels map as follows: `notice` becomes INFO; `alert` and `emergency` become CRITICAL. + +```python +client = Client("my_mcp_server.py") + +async with client: + # Server logs are forwarded at proper severity automatically + await client.call_tool("some_tool") +``` diff --git a/docs/clients/notifications.mdx b/docs/clients/notifications.mdx new file mode 100644 index 000000000..5e1b447aa --- /dev/null +++ b/docs/clients/notifications.mdx @@ -0,0 +1,155 @@ +--- +title: Notifications +sidebarTitle: Notifications +description: Handle server-sent notifications for list changes and other events. +icon: envelope +--- + +import { VersionBadge } from "/snippets/version-badge.mdx"; + + + +Use this when you need to react to server-side changes like tool list updates or resource modifications. + +MCP servers can send notifications to inform clients about state changes. The message handler provides a unified way to process these notifications. + +## Handling Notifications + +The simplest approach is a function that receives all messages and filters for the notifications you care about: + +```python +from fastmcp import Client + +async def message_handler(message): + """Handle MCP notifications from the server.""" + if hasattr(message, 'root'): + method = message.root.method + + if method == "notifications/tools/list_changed": + print("Tools have changed - refresh tool cache") + elif method == "notifications/resources/list_changed": + print("Resources have changed") + elif method == "notifications/prompts/list_changed": + print("Prompts have changed") + +client = Client( + "my_mcp_server.py", + message_handler=message_handler, +) +``` + +## MessageHandler Class + +For fine-grained targeting, subclass `MessageHandler` to use specific hooks: + +```python +from fastmcp import Client +from fastmcp.client.messages import MessageHandler +import mcp.types + +class MyMessageHandler(MessageHandler): + async def on_tool_list_changed( + self, notification: mcp.types.ToolListChangedNotification + ) -> None: + """Handle tool list changes.""" + print("Tool list changed - refreshing available tools") + + async def on_resource_list_changed( + self, notification: mcp.types.ResourceListChangedNotification + ) -> None: + """Handle resource list changes.""" + print("Resource list changed") + + async def on_prompt_list_changed( + self, notification: mcp.types.PromptListChangedNotification + ) -> None: + """Handle prompt list changes.""" + print("Prompt list changed") + +client = Client( + "my_mcp_server.py", + message_handler=MyMessageHandler(), +) +``` + +### Handler Template + +```python +from fastmcp.client.messages import MessageHandler +import mcp.types + +class MyMessageHandler(MessageHandler): + async def on_message(self, message) -> None: + """Called for ALL messages (requests and notifications).""" + pass + + async def on_notification( + self, notification: mcp.types.ServerNotification + ) -> None: + """Called for notifications (fire-and-forget).""" + pass + + async def on_tool_list_changed( + self, notification: mcp.types.ToolListChangedNotification + ) -> None: + """Called when the server's tool list changes.""" + pass + + async def on_resource_list_changed( + self, notification: mcp.types.ResourceListChangedNotification + ) -> None: + """Called when the server's resource list changes.""" + pass + + async def on_prompt_list_changed( + self, notification: mcp.types.PromptListChangedNotification + ) -> None: + """Called when the server's prompt list changes.""" + pass + + async def on_progress( + self, notification: mcp.types.ProgressNotification + ) -> None: + """Called for progress updates during long-running operations.""" + pass + + async def on_logging_message( + self, notification: mcp.types.LoggingMessageNotification + ) -> None: + """Called for log messages from the server.""" + pass +``` + +## List Change Notifications + +A practical example of maintaining a tool cache that refreshes when tools change: + +```python +from fastmcp import Client +from fastmcp.client.messages import MessageHandler +import mcp.types + +class ToolCacheHandler(MessageHandler): + def __init__(self): + self.cached_tools = [] + + async def on_tool_list_changed( + self, notification: mcp.types.ToolListChangedNotification + ) -> None: + """Clear tool cache when tools change.""" + print("Tools changed - clearing cache") + self.cached_tools = [] # Force refresh on next access + +client = Client("server.py", message_handler=ToolCacheHandler()) +``` + +## Server Requests + +While the message handler receives server-initiated requests, you should use dedicated callback parameters for most interactive scenarios: + +- **Sampling requests**: Use [`sampling_handler`](/clients/sampling) +- **Elicitation requests**: Use [`elicitation_handler`](/clients/elicitation) +- **Progress updates**: Use [`progress_handler`](/clients/progress) +- **Log messages**: Use [`log_handler`](/clients/logging) + +The message handler is primarily for monitoring and handling notifications rather than responding to requests. diff --git a/docs/clients/progress.mdx b/docs/clients/progress.mdx new file mode 100644 index 000000000..707ab8dac --- /dev/null +++ b/docs/clients/progress.mdx @@ -0,0 +1,67 @@ +--- +title: Progress Monitoring +sidebarTitle: Progress +description: Handle progress notifications from long-running server operations. +icon: bars-progress +--- + +import { VersionBadge } from '/snippets/version-badge.mdx' + + + +Use this when you need to track progress of long-running operations. + +MCP servers can report progress during operations. The client receives these updates through a progress handler. + +## Progress Handler + +Set a handler when creating the client: + +```python +from fastmcp import Client + +async def progress_handler( + progress: float, + total: float | None, + message: str | None +) -> None: + if total is not None: + percentage = (progress / total) * 100 + print(f"Progress: {percentage:.1f}% - {message or ''}") + else: + print(f"Progress: {progress} - {message or ''}") + +client = Client( + "my_mcp_server.py", + progress_handler=progress_handler +) +``` + +The handler receives three parameters: + + + + Current progress value + + + + Expected total value (may be None if unknown) + + + + Optional status message + + + +## Per-Call Handler + +Override the client-level handler for specific tool calls: + +```python +async with client: + result = await client.call_tool( + "long_running_task", + {"param": "value"}, + progress_handler=my_progress_handler + ) +``` diff --git a/docs/clients/prompts.mdx b/docs/clients/prompts.mdx new file mode 100644 index 000000000..bb50d475f --- /dev/null +++ b/docs/clients/prompts.mdx @@ -0,0 +1,147 @@ +--- +title: Getting Prompts +sidebarTitle: Prompts +description: Retrieve rendered message templates with automatic argument serialization. +icon: message-lines +--- + +import { VersionBadge } from '/snippets/version-badge.mdx' + + + +Use this when you need to retrieve server-defined message templates for LLM interactions. + +Prompts are reusable message templates exposed by MCP servers. They can accept arguments to generate personalized message sequences for LLM interactions. + +## Basic Usage + +Request a rendered prompt with `get_prompt()`: + +```python +async with client: + # Simple prompt without arguments + result = await client.get_prompt("welcome_message") + # result -> mcp.types.GetPromptResult + + # Access the generated messages + for message in result.messages: + print(f"Role: {message.role}") + print(f"Content: {message.content}") +``` + +Pass arguments to customize the prompt: + +```python +async with client: + result = await client.get_prompt("user_greeting", { + "name": "Alice", + "role": "administrator" + }) + + for message in result.messages: + print(f"Generated message: {message.content}") +``` + +## Argument Serialization + + + +FastMCP automatically serializes complex arguments to JSON strings as required by the MCP specification. You can pass typed objects directly: + +```python +from dataclasses import dataclass + +@dataclass +class UserData: + name: str + age: int + +async with client: + result = await client.get_prompt("analyze_user", { + "user": UserData(name="Alice", age=30), # Automatically serialized + "preferences": {"theme": "dark"}, # Dict serialized + "scores": [85, 92, 78], # List serialized + "simple_name": "Bob" # Strings unchanged + }) +``` + +The client handles serialization using `pydantic_core.to_json()` for consistent formatting. FastMCP servers automatically deserialize these JSON strings back to the expected types. + +## Working with Results + +The `get_prompt()` method returns a `GetPromptResult` containing a list of messages: + +```python +async with client: + result = await client.get_prompt("conversation_starter", {"topic": "climate"}) + + for i, message in enumerate(result.messages): + print(f"Message {i + 1}:") + print(f" Role: {message.role}") + print(f" Content: {message.content.text if hasattr(message.content, 'text') else message.content}") +``` + +Prompts can generate different message types. System messages configure LLM behavior: + +```python +async with client: + result = await client.get_prompt("system_configuration", { + "role": "helpful assistant", + "expertise": "python programming" + }) + + # Access the returned messages + message = result.messages[0] + print(f"Prompt: {message.content}") +``` + +Conversation templates generate multi-turn flows: + +```python +async with client: + result = await client.get_prompt("interview_template", { + "candidate_name": "Alice", + "position": "Senior Developer" + }) + + # Multiple messages for a conversation flow + for message in result.messages: + print(f"{message.role}: {message.content}") +``` + +## Version Selection + + + +When a server exposes multiple versions of a prompt, you can request a specific version: + +```python +async with client: + # Get the highest version (default) + result = await client.get_prompt("summarize", {"text": "..."}) + + # Get a specific version + result_v1 = await client.get_prompt("summarize", {"text": "..."}, version="1.0") +``` + +See [Metadata](/servers/versioning#version-discovery) for how to discover available versions. + +## Multi-Server Clients + +When using multi-server clients, prompts are accessible directly without prefixing: + +```python +async with client: # Multi-server client + result1 = await client.get_prompt("weather_prompt", {"city": "London"}) + result2 = await client.get_prompt("assistant_prompt", {"query": "help"}) +``` + +## Raw Protocol Access + +For complete control, use `get_prompt_mcp()` which returns the full MCP protocol object: + +```python +async with client: + result = await client.get_prompt_mcp("example_prompt", {"arg": "value"}) + # result -> mcp.types.GetPromptResult +``` diff --git a/docs/clients/resources.mdx b/docs/clients/resources.mdx new file mode 100644 index 000000000..a3e9300da --- /dev/null +++ b/docs/clients/resources.mdx @@ -0,0 +1,110 @@ +--- +title: Reading Resources +sidebarTitle: Resources +description: Access static and templated data sources from MCP servers. +icon: folder-open +--- + +import { VersionBadge } from '/snippets/version-badge.mdx' + + + +Use this when you need to read data from server-exposed resources like configuration files, generated content, or external data sources. + +Resources are data sources exposed by MCP servers. They can be static files with fixed content, or dynamic templates that generate content based on parameters in the URI. + +## Reading Resources + +Read a resource using its URI: + +```python +async with client: + content = await client.read_resource("file:///path/to/README.md") + # content -> list[TextResourceContents | BlobResourceContents] + + # Access text content + if hasattr(content[0], 'text'): + print(content[0].text) + + # Access binary content + if hasattr(content[0], 'blob'): + print(f"Binary data: {len(content[0].blob)} bytes") +``` + +Resource templates generate content based on URI parameters. The template defines a pattern like `weather://{{city}}/current`, and you fill in the parameters when reading: + +```python +async with client: + # Read from a resource template + weather_content = await client.read_resource("weather://london/current") + print(weather_content[0].text) +``` + +## Content Types + +Resources return different content types depending on what they expose. + +Text resources include configuration files, JSON data, and other human-readable content: + +```python +async with client: + content = await client.read_resource("resource://config/settings.json") + + for item in content: + if hasattr(item, 'text'): + print(f"Text content: {item.text}") + print(f"MIME type: {item.mimeType}") +``` + +Binary resources include images, PDFs, and other non-text data: + +```python +async with client: + content = await client.read_resource("resource://images/logo.png") + + for item in content: + if hasattr(item, 'blob'): + print(f"Binary content: {len(item.blob)} bytes") + print(f"MIME type: {item.mimeType}") + + # Save to file + with open("downloaded_logo.png", "wb") as f: + f.write(item.blob) +``` + +## Multi-Server Clients + +When using multi-server clients, resource URIs are prefixed with the server name: + +```python +async with client: # Multi-server client + weather_icons = await client.read_resource("weather://weather/icons/sunny") + templates = await client.read_resource("resource://assistant/templates/list") +``` + +## Version Selection + + + +When a server exposes multiple versions of a resource, you can request a specific version: + +```python +async with client: + # Read the highest version (default) + content = await client.read_resource("data://config") + + # Read a specific version + content_v1 = await client.read_resource("data://config", version="1.0") +``` + +See [Metadata](/servers/versioning#version-discovery) for how to discover available versions. + +## Raw Protocol Access + +For complete control, use `read_resource_mcp()` which returns the full MCP protocol object: + +```python +async with client: + result = await client.read_resource_mcp("resource://example") + # result -> mcp.types.ReadResourceResult +``` diff --git a/docs/clients/roots.mdx b/docs/clients/roots.mdx new file mode 100644 index 000000000..0370c119a --- /dev/null +++ b/docs/clients/roots.mdx @@ -0,0 +1,45 @@ +--- +title: Client Roots +sidebarTitle: Roots +description: Provide local context and resource boundaries to MCP servers. +icon: folder-tree +--- + +import { VersionBadge } from '/snippets/version-badge.mdx' + + + +Use this when you need to tell servers what local resources the client has access to. + +Roots inform servers about resources the client can provide. Servers can use this information to adjust behavior or provide more relevant responses. + +## Static Roots + +Provide a list of roots when creating the client: + +```python +from fastmcp import Client + +client = Client( + "my_mcp_server.py", + roots=["/path/to/root1", "/path/to/root2"] +) +``` + +## Dynamic Roots + +Use a callback to compute roots dynamically when the server requests them: + +```python +from fastmcp import Client +from fastmcp.client.roots import RequestContext + +async def roots_callback(context: RequestContext) -> list[str]: + print(f"Server requested roots (Request ID: {context.request_id})") + return ["/path/to/root1", "/path/to/root2"] + +client = Client( + "my_mcp_server.py", + roots=roots_callback +) +``` diff --git a/docs/clients/sampling.mdx b/docs/clients/sampling.mdx new file mode 100644 index 000000000..a2e0e9942 --- /dev/null +++ b/docs/clients/sampling.mdx @@ -0,0 +1,190 @@ +--- +title: LLM Sampling +sidebarTitle: Sampling +description: Handle server-initiated LLM completion requests. +icon: robot +--- + +import { VersionBadge } from "/snippets/version-badge.mdx"; + + + +Use this when you need to respond to server requests for LLM completions. + +MCP servers can request LLM completions from clients during tool execution. This enables servers to delegate AI reasoning to the client, which controls which LLM is used and how requests are made. + +## Handler Template + +```python +from fastmcp import Client +from fastmcp.client.sampling import SamplingMessage, SamplingParams, RequestContext + +async def sampling_handler( + messages: list[SamplingMessage], + params: SamplingParams, + context: RequestContext +) -> str: + """ + Handle server requests for LLM completions. + + Args: + messages: Conversation messages to send to the LLM + params: Sampling parameters (temperature, max_tokens, etc.) + context: Request context with metadata + + Returns: + Generated text response from your LLM + """ + # Extract message content + conversation = [] + for message in messages: + content = message.content.text if hasattr(message.content, 'text') else str(message.content) + conversation.append(f"{message.role}: {content}") + + # Use the system prompt if provided + system_prompt = params.systemPrompt or "You are a helpful assistant." + + # Integrate with your LLM service here + return "Generated response based on the messages" + +client = Client( + "my_mcp_server.py", + sampling_handler=sampling_handler, +) +``` + +## Handler Parameters + + + + The role of the message + + + + The content of the message. TextContent has a `.text` attribute. + + + + + + Optional system prompt the server wants to use + + + + Server preferences for model selection (hints, cost/speed/intelligence priorities) + + + + Sampling temperature + + + + Maximum tokens to generate + + + + Stop sequences for sampling + + + + Tools the LLM can use during sampling + + + + Tool usage behavior (`auto`, `required`, or `none`) + + + +## Built-in Handlers + +FastMCP provides built-in handlers for OpenAI, Anthropic, and Google Gemini APIs that support the full sampling API including tool use. + +### OpenAI Handler + + + +```python +from fastmcp import Client +from fastmcp.client.sampling.handlers.openai import OpenAISamplingHandler + +client = Client( + "my_mcp_server.py", + sampling_handler=OpenAISamplingHandler(default_model="gpt-4o"), +) +``` + +For OpenAI-compatible APIs (like local models): + +```python +from openai import AsyncOpenAI + +client = Client( + "my_mcp_server.py", + sampling_handler=OpenAISamplingHandler( + default_model="llama-3.1-70b", + client=AsyncOpenAI(base_url="http://localhost:8000/v1"), + ), +) +``` + + +Install the OpenAI handler with `pip install fastmcp[openai]`. + + +### Anthropic Handler + + + +```python +from fastmcp import Client +from fastmcp.client.sampling.handlers.anthropic import AnthropicSamplingHandler + +client = Client( + "my_mcp_server.py", + sampling_handler=AnthropicSamplingHandler(default_model="claude-sonnet-4-5"), +) +``` + + +Install the Anthropic handler with `pip install fastmcp[anthropic]`. + + +### Google Gemini Handler + + + +```python +from fastmcp import Client +from fastmcp.client.sampling.handlers.google_genai import GoogleGenAISamplingHandler + +client = Client( + "my_mcp_server.py", + sampling_handler=GoogleGenAISamplingHandler(default_model="gemini-2.0-flash"), +) +``` + + +Install the Google Gemini handler with `pip install fastmcp[gemini]`. + + +## Sampling Capabilities + +When you provide a `sampling_handler`, FastMCP automatically advertises full sampling capabilities to the server, including tool support. To disable tool support for simpler handlers: + +```python +from mcp.types import SamplingCapability + +client = Client( + "my_mcp_server.py", + sampling_handler=basic_handler, + sampling_capabilities=SamplingCapability(), # No tool support +) +``` + +## Tool Execution + +Tool execution happens on the server side. The client's role is to pass tools to the LLM and return the LLM's response (which may include tool use requests). The server then executes the tools and may send follow-up sampling requests with tool results. + + +To implement a custom sampling handler, see the [handler source code](https://github.com/PrefectHQ/fastmcp/tree/main/src/fastmcp/client/sampling/handlers) as a reference. + diff --git a/docs/clients/tasks.mdx b/docs/clients/tasks.mdx new file mode 100644 index 000000000..ce27520e4 --- /dev/null +++ b/docs/clients/tasks.mdx @@ -0,0 +1,182 @@ +--- +title: Background Tasks +sidebarTitle: Tasks +description: Execute operations asynchronously and track their progress. +icon: clock +tag: "NEW" +--- + +import { VersionBadge } from "/snippets/version-badge.mdx" + + + +Use this when you need to run long operations asynchronously while doing other work. + +The MCP task protocol lets you request operations to run in the background. The call returns a Task object immediately, letting you track progress, cancel operations, or await results. + +## Requesting Background Execution + +Pass `task=True` to run an operation as a background task: + +```python +from fastmcp import Client + +async with Client(server) as client: + # Start a background task + task = await client.call_tool("slow_computation", {"duration": 10}, task=True) + + print(f"Task started: {task.task_id}") + + # Do other work while it runs... + + # Get the result when ready + result = await task.result() +``` + +This works with tools, resources, and prompts: + +```python +tool_task = await client.call_tool("my_tool", args, task=True) +resource_task = await client.read_resource("file://large.txt", task=True) +prompt_task = await client.get_prompt("my_prompt", args, task=True) +``` + +## Task API + +All task types share a common interface. + +### Getting Results + +Call `await task.result()` or simply `await task` to block until the task completes: + +```python +task = await client.call_tool("analyze", {"text": "hello"}, task=True) + +# Wait for result (blocking) +result = await task.result() +# or: result = await task +``` + +### Checking Status + +Check the current status without blocking: + +```python +status = await task.status() +print(f"{status.status}: {status.statusMessage}") +# status.status is "working", "completed", "failed", or "cancelled" +``` + +### Waiting with Control + +Use `task.wait()` for more control over waiting: + +```python +# Wait up to 30 seconds for completion +status = await task.wait(timeout=30.0) + +# Wait for a specific state +status = await task.wait(state="completed", timeout=30.0) +``` + +### Cancellation + +Cancel a running task: + +```python +await task.cancel() +``` + +## Status Updates + +Register callbacks to receive real-time status updates as the server reports progress: + +```python +def on_status_change(status): + print(f"Task {status.taskId}: {status.status} - {status.statusMessage}") + +task.on_status_change(on_status_change) + +# Async callbacks work too +async def on_status_async(status): + await log_status(status) + +task.on_status_change(on_status_async) +``` + +### Handler Template + +```python +from fastmcp import Client + +def status_handler(status): + """ + Handle task status updates. + + Args: + status: Task status object with: + - taskId: Unique task identifier + - status: "working", "completed", "failed", or "cancelled" + - statusMessage: Optional progress message from server + """ + if status.status == "working": + print(f"Progress: {status.statusMessage}") + elif status.status == "completed": + print("Task completed") + elif status.status == "failed": + print(f"Task failed: {status.statusMessage}") + +task.on_status_change(status_handler) +``` + +## Graceful Degradation + +You can always pass `task=True` regardless of whether the server supports background tasks. Per the MCP specification, servers without task support execute the operation immediately and return the result inline. + +```python +task = await client.call_tool("my_tool", args, task=True) + +if task.returned_immediately: + print("Server executed immediately (no background support)") +else: + print("Running in background") + +# Either way, this works +result = await task.result() +``` + +This lets you write task-aware client code without worrying about server capabilities. + +## Example + +```python +import asyncio +from fastmcp import Client + +async def main(): + async with Client(server) as client: + # Start background task + task = await client.call_tool( + "slow_computation", + {"duration": 10}, + task=True, + ) + + # Subscribe to updates + def on_update(status): + print(f"Progress: {status.statusMessage}") + + task.on_status_change(on_update) + + # Do other work while task runs + print("Doing other work...") + await asyncio.sleep(2) + + # Wait for completion and get result + result = await task.result() + print(f"Result: {result.content}") + +asyncio.run(main()) +``` + +See [Server Background Tasks](/servers/tasks) for how to enable background task support on the server side. diff --git a/docs/clients/tools.mdx b/docs/clients/tools.mdx new file mode 100644 index 000000000..1541f593e --- /dev/null +++ b/docs/clients/tools.mdx @@ -0,0 +1,183 @@ +--- +title: Calling Tools +sidebarTitle: Tools +description: Execute server-side tools and handle structured results. +icon: wrench +--- + +import { VersionBadge } from '/snippets/version-badge.mdx' + + + +Use this when you need to execute server-side functions and process their results. + +Tools are executable functions exposed by MCP servers. The client's `call_tool()` method executes a tool by name with arguments and returns structured results. + +## Basic Execution + +```python +async with client: + result = await client.call_tool("add", {"a": 5, "b": 3}) + # result -> CallToolResult with structured and unstructured data + + # Access structured data (automatically deserialized) + print(result.data) # 8 + + # Access traditional content blocks + print(result.content[0].text) # "8" +``` + +Arguments are passed as a dictionary. For multi-server clients, tool names are automatically prefixed with the server name (e.g., `weather_get_forecast` for a tool named `get_forecast` on the `weather` server). + +## Execution Options + +The `call_tool()` method supports timeout control and progress monitoring: + +```python +async with client: + # With timeout (aborts if execution takes longer than 2 seconds) + result = await client.call_tool( + "long_running_task", + {"param": "value"}, + timeout=2.0 + ) + + # With progress handler + result = await client.call_tool( + "long_running_task", + {"param": "value"}, + progress_handler=my_progress_handler + ) +``` + +## Structured Results + + + +Tool execution returns a `CallToolResult` object. The `.data` property provides fully hydrated Python objects including complex types like datetimes and UUIDs, reconstructed from the server's output schema. + +```python +from datetime import datetime +from uuid import UUID + +async with client: + result = await client.call_tool("get_weather", {"city": "London"}) + + # FastMCP reconstructs complete Python objects + weather = result.data + print(f"Temperature: {weather.temperature}C at {weather.timestamp}") + + # Complex types are properly deserialized + assert isinstance(weather.timestamp, datetime) + assert isinstance(weather.station_id, UUID) + + # Raw structured JSON is also available + print(f"Raw JSON: {result.structured_content}") +``` + + + + Fully hydrated Python objects with complex type support (datetimes, UUIDs, custom classes). FastMCP exclusive. + + + + Standard MCP content blocks (`TextContent`, `ImageContent`, `AudioContent`, etc.). + + + + Standard MCP structured JSON data as sent by the server. + + + + Boolean indicating if the tool execution failed. + + + +For tools without output schemas or when deserialization fails, `.data` will be `None`. Fall back to content blocks in that case: + +```python +async with client: + result = await client.call_tool("legacy_tool", {"param": "value"}) + + if result.data is not None: + print(f"Structured: {result.data}") + else: + for content in result.content: + if hasattr(content, 'text'): + print(f"Text result: {content.text}") +``` + + +FastMCP servers automatically wrap primitive results (like `int`, `str`, `bool`) in a `{"result": value}` structure. FastMCP clients automatically unwrap this, so you get the original value in `.data`. + + +## Error Handling + +By default, `call_tool()` raises a `ToolError` if the tool execution fails: + +```python +from fastmcp.exceptions import ToolError + +async with client: + try: + result = await client.call_tool("potentially_failing_tool", {"param": "value"}) + print("Tool succeeded:", result.data) + except ToolError as e: + print(f"Tool failed: {e}") +``` + +To handle errors manually instead of catching exceptions, disable automatic error raising: + +```python +async with client: + result = await client.call_tool( + "potentially_failing_tool", + {"param": "value"}, + raise_on_error=False + ) + + if result.is_error: + print(f"Tool failed: {result.content[0].text}") + else: + print(f"Tool succeeded: {result.data}") +``` + +## Sending Metadata + + + +The `meta` parameter sends ancillary information alongside tool calls for observability, debugging, or client identification: + +```python +async with client: + result = await client.call_tool( + name="send_email", + arguments={ + "to": "user@example.com", + "subject": "Hello", + "body": "Welcome!" + }, + meta={ + "trace_id": "abc-123", + "request_source": "mobile_app" + } + ) +``` + +See [Client Metadata](/servers/context#client-metadata) to learn how servers access this data. + +## Raw Protocol Access + +For complete control, use `call_tool_mcp()` which returns the raw MCP protocol object: + +```python +async with client: + result = await client.call_tool_mcp("my_tool", {"param": "value"}) + # result -> mcp.types.CallToolResult + + if result.isError: + print(f"Tool failed: {result.content}") + else: + print(f"Tool succeeded: {result.content}") + # Note: No automatic deserialization with call_tool_mcp() +``` diff --git a/docs/clients/transports.mdx b/docs/clients/transports.mdx new file mode 100644 index 000000000..7e3eb03db --- /dev/null +++ b/docs/clients/transports.mdx @@ -0,0 +1,235 @@ +--- +title: Client Transports +sidebarTitle: Transports +description: Configure how clients connect to and communicate with MCP servers. +icon: link +--- + +import { VersionBadge } from "/snippets/version-badge.mdx" + + + +Transports handle the underlying connection between your client and MCP servers. While the client can automatically select a transport based on what you pass to it, instantiating transports explicitly gives you full control over configuration. + +## STDIO Transport + +STDIO transport communicates with MCP servers through subprocess pipes. When using STDIO, your client launches and manages the server process, controlling its lifecycle and environment. + + +STDIO servers run in isolated environments by default. They do not inherit your shell's environment variables. You must explicitly pass any configuration the server needs. + + +```python +from fastmcp import Client +from fastmcp.client.transports import StdioTransport + +transport = StdioTransport( + command="python", + args=["my_server.py", "--verbose"], + env={"API_KEY": "secret", "LOG_LEVEL": "DEBUG"}, + cwd="/path/to/server" +) +client = Client(transport) +``` + +For convenience, the client can infer STDIO transport from file paths, though this limits configuration options: + +```python +from fastmcp import Client + +client = Client("my_server.py") # Limited - no configuration options +``` + +### Environment Variables + +Since STDIO servers do not inherit your environment, you need strategies for passing configuration. + +**Selective forwarding** passes only the variables your server needs: + +```python +import os +from fastmcp.client.transports import StdioTransport + +required_vars = ["API_KEY", "DATABASE_URL", "REDIS_HOST"] +env = {var: os.environ[var] for var in required_vars if var in os.environ} + +transport = StdioTransport(command="python", args=["server.py"], env=env) +client = Client(transport) +``` + +**Loading from .env files** keeps configuration separate from code: + +```python +from dotenv import dotenv_values +from fastmcp.client.transports import StdioTransport + +env = dotenv_values(".env") +transport = StdioTransport(command="python", args=["server.py"], env=env) +client = Client(transport) +``` + +### Session Persistence + +STDIO transports maintain sessions across multiple client contexts by default (`keep_alive=True`). This reuses the same subprocess for multiple connections, improving performance. + +```python +from fastmcp.client.transports import StdioTransport + +transport = StdioTransport(command="python", args=["server.py"]) +client = Client(transport) + +async def efficient_multiple_operations(): + async with client: + await client.ping() + + async with client: # Reuses the same subprocess + await client.call_tool("process_data", {"file": "data.csv"}) +``` + +For complete isolation between connections, disable session persistence: + +```python +transport = StdioTransport(command="python", args=["server.py"], keep_alive=False) +``` + +## HTTP Transport + + + +HTTP transport connects to MCP servers running as web services. This is the recommended transport for production deployments. + +```python +from fastmcp import Client +from fastmcp.client.transports import StreamableHttpTransport + +transport = StreamableHttpTransport( + url="https://api.example.com/mcp", + headers={ + "Authorization": "Bearer your-token-here", + "X-Custom-Header": "value" + } +) +client = Client(transport) +``` + +FastMCP also provides authentication helpers: + +```python +from fastmcp import Client +from fastmcp.client.auth import BearerAuth + +client = Client( + "https://api.example.com/mcp", + auth=BearerAuth("your-token-here") +) +``` + +### SSE Transport + +Server-Sent Events transport is maintained for backward compatibility. Use Streamable HTTP for new deployments unless you have specific infrastructure requirements. + +```python +from fastmcp.client.transports import SSETransport + +transport = SSETransport( + url="https://api.example.com/sse", + headers={"Authorization": "Bearer token"} +) +client = Client(transport) +``` + +## In-Memory Transport + +In-memory transport connects directly to a FastMCP server instance within the same Python process. This eliminates both subprocess management and network overhead, making it ideal for testing. + +```python +from fastmcp import FastMCP, Client +import os + +mcp = FastMCP("TestServer") + +@mcp.tool +def greet(name: str) -> str: + prefix = os.environ.get("GREETING_PREFIX", "Hello") + return f"{prefix}, {name}!" + +client = Client(mcp) + +async with client: + result = await client.call_tool("greet", {"name": "World"}) +``` + + +Unlike STDIO transports, in-memory servers share the same memory space and environment variables as your client code. + + +## Multi-Server Configuration + + + +Connect to multiple servers defined in a configuration dictionary: + +```python +from fastmcp import Client + +config = { + "mcpServers": { + "weather": { + "url": "https://weather.example.com/mcp", + "transport": "http" + }, + "assistant": { + "command": "python", + "args": ["./assistant.py"], + "env": {"LOG_LEVEL": "INFO"} + } + } +} + +client = Client(config) + +async with client: + # Tools are namespaced by server + weather = await client.call_tool("weather_get_forecast", {"city": "NYC"}) + answer = await client.call_tool("assistant_ask", {"question": "What?"}) +``` + +### Tool Transformations + +FastMCP supports tool transformations within the configuration. You can change names, descriptions, tags, and arguments for tools from a server. + +```python +config = { + "mcpServers": { + "weather": { + "url": "https://weather.example.com/mcp", + "transport": "http", + "tools": { + "weather_get_forecast": { + "name": "miami_weather", + "description": "Get the weather for Miami", + "arguments": { + "city": { + "default": "Miami", + "hide": True, + } + } + } + } + } + } +} +``` + +To filter tools by tag, use `include_tags` or `exclude_tags` at the server level: + +```python +config = { + "mcpServers": { + "weather": { + "url": "https://weather.example.com/mcp", + "include_tags": ["forecast"] # Only tools with this tag + } + } +} +``` diff --git a/docs/community/README.md b/docs/community/README.md new file mode 100644 index 000000000..b61f5cf6d --- /dev/null +++ b/docs/community/README.md @@ -0,0 +1,22 @@ +# Community Section + +This directory contains community-contributed content and showcases for FastMCP. + +## Structure + +- `showcase.mdx` - Main community showcase page featuring high-quality projects and examples + +## Adding Content + +To add new community content: +1. Create a new MDX file in this directory +2. Update `docs.json` to include it in the navigation +3. Follow the existing format for consistency + +## Guidelines + +Community content should: +- Demonstrate best practices +- Provide educational value +- Include proper documentation +- Be maintained and up-to-date \ No newline at end of file diff --git a/docs/community/showcase.mdx b/docs/community/showcase.mdx new file mode 100644 index 000000000..9ba4c6877 --- /dev/null +++ b/docs/community/showcase.mdx @@ -0,0 +1,65 @@ +--- +title: 'Community Showcase' +description: 'High-quality projects and examples from the FastMCP community' +icon: 'users' +--- + +import { YouTubeEmbed } from '/snippets/youtube-embed.mdx' + +## Join the Community + + + Connect with other FastMCP developers, share your projects, and discuss ideas. + + +## Featured Projects + +Discover exemplary MCP servers and implementations created by our community. These projects demonstrate best practices and innovative uses of FastMCP. + +### Learning Resources + + + A comprehensive educational example demonstrating FastMCP best practices with professional dual-transport server implementation, interactive test client, and detailed documentation. + + +#### Video Tutorials + +**Build Remote MCP Servers w/ Python & FastMCP** - Claude Integrations Tutorial by Greg + Code + + + +**FastMCP — the best way to build an MCP server with Python** - Tutorial by ZazenCodes + + + +**Speedrun a MCP server for Claude Desktop (fastmcp)** - Tutorial by Nate from Prefect + + + +### Community Examples + +Have you built something interesting with FastMCP? We'd love to feature high-quality examples here! Start a [discussion on GitHub](https://github.com/PrefectHQ/fastmcp/discussions) to share your project. + +## Contributing + +To get your project featured: + +1. Ensure your project demonstrates best practices +2. Include comprehensive documentation +3. Add clear usage examples +4. Open a discussion in our [GitHub Discussions](https://github.com/PrefectHQ/fastmcp/discussions) + +We review submissions regularly and feature projects that provide value to the FastMCP community. + +## Further Reading + +- [Contrib Modules](/patterns/contrib) - Community-contributed modules that are distributed with FastMCP itself \ No newline at end of file diff --git a/docs/css/banner.css b/docs/css/banner.css new file mode 100644 index 000000000..f9c6384b2 --- /dev/null +++ b/docs/css/banner.css @@ -0,0 +1,74 @@ +/* Banner styling -- improve readability with better contrast */ +#banner { + background: #f1f5f9 !important; + color: #1e293b !important; + font-size: 0.95rem !important; + font-weight: 600 !important; + padding-top: 12px !important; + padding-bottom: 12px !important; + overflow: hidden !important; +} + +#banner::before { + content: ""; + position: absolute; + top: 0; + left: 0; + width: 100%; + height: 100%; + background: linear-gradient( + 90deg, + rgba(6, 182, 212, 0.25) 0%, + rgba(6, 182, 212, 0.05) 25%, + rgba(6, 182, 212, 0.35) 50%, + rgba(6, 182, 212, 0.08) 75%, + rgba(6, 182, 212, 0.28) 100% + ); + background-size: 300% 100%; + animation: colorWave 14s ease-in-out infinite alternate; + pointer-events: none; +} + +.dark #banner { + background: #475569 !important; + color: #f1f5f9 !important; +} + +.dark #banner::before { + background: linear-gradient( + 90deg, + rgba(247, 37, 133, 0.35) 0%, + rgba(247, 37, 133, 0.08) 25%, + rgba(247, 37, 133, 0.45) 50%, + rgba(247, 37, 133, 0.12) 75%, + rgba(247, 37, 133, 0.38) 100% + ); + background-size: 300% 100%; +} + +@keyframes colorWave { + 0% { + background-position: 0% 0%; + } + 100% { + background-position: 100% 0%; + } +} + +#banner * { + color: #1e293b !important; + margin: 0 !important; +} + +.dark #banner * { + color: #f1f5f9 !important; +} + +@media (max-width: 767px) { + #banner { + font-size: 0.8rem !important; + padding-top: 8px !important; + padding-bottom: 8px !important; + } +} + diff --git a/docs/css/python-sdk.css b/docs/css/python-sdk.css new file mode 100644 index 000000000..72a64c21a --- /dev/null +++ b/docs/css/python-sdk.css @@ -0,0 +1,3 @@ +a:has(svg.icon) { + border: none !important; +} \ No newline at end of file diff --git a/docs/css/style.css b/docs/css/style.css new file mode 100644 index 000000000..99844f692 --- /dev/null +++ b/docs/css/style.css @@ -0,0 +1,63 @@ +html:not([data-page-mode="wide"]) #content-area { + max-width: 44rem !important; +} + +img.nav-logo { + max-width: 200px; +} + +/* Code highlighting -- target only inline code elements, not code blocks */ +p code:not(pre code), +table code:not(pre code), +.prose code:not(pre code), +li code:not(pre code), +h1 code:not(pre code), +h2 code:not(pre code), +h3 code:not(pre code), +h4 code:not(pre code), +h5 code:not(pre code), +h6 code:not(pre code) { + color: #f72585 !important; + background-color: rgba(247, 37, 133, 0.09); +} + +/* V2 banner - inside content-container, breaks out of padding with negative margins */ +#v2-banner { + display: block; + background: linear-gradient(135deg, #4cc9f0 0%, #2d00f7 100%); + color: white; + text-align: center; + padding: 10px 16px; + font-size: 0.875rem; + font-weight: 600; + box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1); + margin: -2rem -2rem 1.5rem -2rem; + width: calc(100% + 4rem); + border-radius: 8px 8px 0 0; +} + +#v2-banner a { + color: white; + text-decoration: underline; + font-weight: 700; +} + +#v2-banner a:hover { + opacity: 0.9; +} + +@media (min-width: 1024px) { + #v2-banner { + margin: -3rem -4rem 1.5rem -4rem; + width: calc(100% + 8rem); + } +} + +.dark #v2-banner { + background: linear-gradient(135deg, #2d00f7 0%, #4cc9f0 100%); +} + + + + + diff --git a/docs/css/version-badge.css b/docs/css/version-badge.css new file mode 100644 index 000000000..20aa16809 --- /dev/null +++ b/docs/css/version-badge.css @@ -0,0 +1,23 @@ +/* Version badge -- display a badge with the current version of the documentation */ +.version-badge { + --color-text: #ff5400 !important; + --color-bg: #fef2f2 !important; + color: #ff5400 !important; + background: #fef2f2 !important; + border: 1px solid rgba(220, 38, 38, 0.3) !important; + transition: box-shadow 0.2s, transform 0.15s; +} + +.version-badge:hover { + box-shadow: 0 2px 8px 0 rgba(160, 132, 252, 0.1); + transform: translateY(-1px) scale(1.03); +} + +.dark .version-badge { + --color-text: #f1f5f9 !important; + --color-bg: #334155 !important; + color: #f1f5f9 !important; + background: #334155 !important; + border: 1px solid #64748b !important; +} + diff --git a/docs/deployment/http.mdx b/docs/deployment/http.mdx new file mode 100644 index 000000000..e961de9d1 --- /dev/null +++ b/docs/deployment/http.mdx @@ -0,0 +1,870 @@ +--- +title: HTTP Deployment +sidebarTitle: HTTP Deployment +description: Deploy your FastMCP server over HTTP for remote access +icon: server +--- + +import { VersionBadge } from "/snippets/version-badge.mdx"; + + +STDIO transport is perfect for local development and desktop applications. But to unlock the full potential of MCP—centralized services, multi-client access, and network availability—you need remote HTTP deployment. + + +This guide walks you through deploying your FastMCP server as a remote MCP service that's accessible via a URL. Once deployed, your MCP server will be available over the network, allowing multiple clients to connect simultaneously and enabling integration with cloud-based LLM applications. This guide focuses specifically on remote MCP deployment, not local STDIO servers. + +## Choosing Your Approach + +FastMCP provides two ways to deploy your server as an HTTP service. Understanding the trade-offs helps you choose the right approach for your needs. + +The **direct HTTP server** approach is simpler and perfect for getting started quickly. You modify your server's `run()` method to use HTTP transport, and FastMCP handles all the web server configuration. This approach works well for standalone deployments where you want your MCP server to be the only service running on a port. + +The **ASGI application** approach gives you more control and flexibility. Instead of running the server directly, you create an ASGI application that can be served by Uvicorn. This approach is better when you need advanced server features like multiple workers, custom middleware, or when you're integrating with existing web applications. + +### Direct HTTP Server + +The simplest way to get your MCP server online is to use the built-in `run()` method with HTTP transport. This approach handles all the server configuration for you and is ideal when you want a standalone MCP server without additional complexity. + +```python server.py +from fastmcp import FastMCP + +mcp = FastMCP("My Server") + +@mcp.tool +def process_data(input: str) -> str: + """Process data on the server""" + return f"Processed: {input}" + +if __name__ == "__main__": + mcp.run(transport="http", host="0.0.0.0", port=8000) +``` + +Run your server with a simple Python command: +```bash +python server.py +``` + +Your server is now accessible at `http://localhost:8000/mcp` (or use your server's actual IP address for remote access). + +This approach is ideal when you want to get online quickly with minimal configuration. It's perfect for internal tools, development environments, or simple deployments where you don't need advanced server features. The built-in server handles all the HTTP details, letting you focus on your MCP implementation. + +### ASGI Application + +For production deployments, you'll often want more control over how your server runs. FastMCP can create a standard ASGI application that works with any ASGI server like Uvicorn, Gunicorn, or Hypercorn. This approach is particularly useful when you need to configure advanced server options, run multiple workers, or integrate with existing infrastructure. + +```python app.py +from fastmcp import FastMCP + +mcp = FastMCP("My Server") + +@mcp.tool +def process_data(input: str) -> str: + """Process data on the server""" + return f"Processed: {input}" + +# Create ASGI application +app = mcp.http_app() +``` + +Run with any ASGI server - here's an example with Uvicorn: +```bash +uvicorn app:app --host 0.0.0.0 --port 8000 +``` + +Your server is accessible at the same URL: `http://localhost:8000/mcp` (or use your server's actual IP address for remote access). + +The ASGI approach shines in production environments where you need reliability and performance. You can run multiple worker processes to handle concurrent requests, add custom middleware for logging or monitoring, integrate with existing deployment pipelines, or mount your MCP server as part of a larger application. + +## Configuring Your Server + +### Custom Path + +By default, your MCP server is accessible at `/mcp/` on your domain. You can customize this path to fit your URL structure or avoid conflicts with existing endpoints. This is particularly useful when integrating MCP into an existing application or following specific API conventions. + +```python +# Option 1: With mcp.run() +mcp.run(transport="http", host="0.0.0.0", port=8000, path="/api/mcp/") + +# Option 2: With ASGI app +app = mcp.http_app(path="/api/mcp/") +``` + +Now your server is accessible at `http://localhost:8000/api/mcp/`. + +### Authentication + + +Authentication is **highly recommended** for remote MCP servers. Some LLM clients require authentication for remote servers and will refuse to connect without it. + + +FastMCP supports multiple authentication methods to secure your remote server. See the [Authentication Overview](/servers/auth/authentication) for complete configuration options including Bearer tokens, JWT, and OAuth. + +If you're mounting an authenticated server under a path prefix, see [Mounting Authenticated Servers](#mounting-authenticated-servers) below for important routing considerations. + +### Health Checks + +Health check endpoints are essential for monitoring your deployed server and ensuring it's responding correctly. FastMCP allows you to add custom routes alongside your MCP endpoints, making it easy to implement health checks that work with both deployment approaches. + +```python +from starlette.responses import JSONResponse + +@mcp.custom_route("/health", methods=["GET"]) +async def health_check(request): + return JSONResponse({"status": "healthy", "service": "mcp-server"}) +``` + +This health endpoint will be available at `http://localhost:8000/health` and can be used by load balancers, monitoring systems, or deployment platforms to verify your server is running. + +### Custom Middleware + + + + +Add custom Starlette middleware to your FastMCP ASGI apps: + +```python +from fastmcp import FastMCP +from starlette.middleware import Middleware +from starlette.middleware.cors import CORSMiddleware + +# Create your FastMCP server +mcp = FastMCP("MyServer") + +# Define middleware +middleware = [ + Middleware( + CORSMiddleware, + allow_origins=["*"], + allow_methods=["*"], + allow_headers=["*"], + ) +] + +# Create ASGI app with middleware +http_app = mcp.http_app(middleware=middleware) +``` + +### CORS for Browser-Based Clients + + +Most MCP clients, including those that you access through a browser like ChatGPT or Claude, don't need CORS configuration. Only enable CORS if you're working with an MCP client that connects directly from a browser, such as debugging tools or inspectors. + + +CORS (Cross-Origin Resource Sharing) is needed when JavaScript running in a web browser connects directly to your MCP server. This is different from using an LLM through a browser—in that case, the browser connects to the LLM service, and the LLM service connects to your MCP server (no CORS needed). + +Browser-based MCP clients that need CORS include: + +- **MCP Inspector** - Browser-based debugging tool for testing MCP servers +- **Custom browser-based MCP clients** - If you're building a web app that directly connects to MCP servers + +For these scenarios, add CORS middleware with the specific headers required for MCP protocol: + +```python +from fastmcp import FastMCP +from starlette.middleware import Middleware +from starlette.middleware.cors import CORSMiddleware + +mcp = FastMCP("MyServer") + +# Configure CORS for browser-based clients +middleware = [ + Middleware( + CORSMiddleware, + allow_origins=["*"], # Allow all origins; use specific origins for security + allow_methods=["GET", "POST", "DELETE", "OPTIONS"], + allow_headers=[ + "mcp-protocol-version", + "mcp-session-id", + "Authorization", + "Content-Type", + ], + expose_headers=["mcp-session-id"], + ) +] + +app = mcp.http_app(middleware=middleware) +``` + +**Key configuration details:** + +- **`allow_origins`**: Specify exact origins (e.g., `["http://localhost:3000"]`) rather than `["*"]` for production deployments +- **`allow_headers`**: Must include `mcp-protocol-version`, `mcp-session-id`, and `Authorization` (for authenticated servers) +- **`expose_headers`**: Must include `mcp-session-id` so JavaScript can read the session ID from responses and send it in subsequent requests + +Without `expose_headers=["mcp-session-id"]`, browsers will receive the session ID but JavaScript won't be able to access it, causing session management to fail. + + +**Production Security**: Never use `allow_origins=["*"]` in production. Specify the exact origins of your browser-based clients. Using wildcards exposes your server to unauthorized access from any website. + + +### SSE Polling for Long-Running Operations + + + + +This feature only applies to the **StreamableHTTP transport** (the default for `http_app()`). It does not apply to the legacy SSE transport (`transport="sse"`). + + +When running tools that take a long time to complete, you may encounter issues with load balancers or proxies terminating connections that stay idle too long. [SEP-1699](https://github.com/modelcontextprotocol/modelcontextprotocol/issues/1699) introduces SSE polling to solve this by allowing the server to gracefully close connections and have clients automatically reconnect. + +To enable SSE polling, configure an `EventStore` when creating your HTTP application: + +```python +from fastmcp import FastMCP, Context +from fastmcp.server.event_store import EventStore + +mcp = FastMCP("My Server") + +@mcp.tool +async def long_running_task(ctx: Context) -> str: + """A task that takes several minutes to complete.""" + for i in range(100): + await ctx.report_progress(i, 100) + + # Periodically close the connection to avoid load balancer timeouts + # Client will automatically reconnect and resume receiving progress + if i % 30 == 0 and i > 0: + await ctx.close_sse_stream() + + await do_expensive_work() + + return "Done!" + +# Configure with EventStore for resumability +event_store = EventStore() +app = mcp.http_app( + event_store=event_store, + retry_interval=2000, # Client reconnects after 2 seconds +) +``` + +**How it works:** + +1. When `event_store` is configured, the server stores all events (progress updates, results) with unique IDs +2. Calling `ctx.close_sse_stream()` gracefully closes the HTTP connection +3. The client automatically reconnects with a `Last-Event-ID` header +4. The server replays any events the client missed during the disconnection + +The `retry_interval` parameter (in milliseconds) controls how long clients wait before reconnecting. Choose a value that balances responsiveness with server load. + + +`close_sse_stream()` is a no-op if called without an `EventStore` configured, so you can safely include it in tools that may run in different deployment configurations. + + +#### Custom Storage Backends + +By default, `EventStore` uses in-memory storage. For production deployments with multiple server instances, you can provide a custom storage backend using the `key_value` package: + +```python +from fastmcp.server.event_store import EventStore +from key_value.aio.stores.redis import RedisStore + +# Use Redis for distributed deployments +redis_store = RedisStore(url="redis://localhost:6379") +event_store = EventStore( + storage=redis_store, + max_events_per_stream=100, # Keep last 100 events per stream + ttl=3600, # Events expire after 1 hour +) + +app = mcp.http_app(event_store=event_store) +``` + +## Integration with Web Frameworks + +If you already have a web application running, you can add MCP capabilities by mounting a FastMCP server as a sub-application. This allows you to expose MCP tools alongside your existing API endpoints, sharing the same domain and infrastructure. The MCP server becomes just another route in your application, making it easy to manage and deploy. + +### Mounting in Starlette + +Mount your FastMCP server in a Starlette application: + +```python +from fastmcp import FastMCP +from starlette.applications import Starlette +from starlette.routing import Mount + +# Create your FastMCP server +mcp = FastMCP("MyServer") + +@mcp.tool +def analyze(data: str) -> dict: + return {"result": f"Analyzed: {data}"} + +# Create the ASGI app +mcp_app = mcp.http_app(path='/mcp') + +# Create a Starlette app and mount the MCP server +app = Starlette( + routes=[ + Mount("/mcp-server", app=mcp_app), + # Add other routes as needed + ], + lifespan=mcp_app.lifespan, +) +``` + +The MCP endpoint will be available at `/mcp-server/mcp/` of the resulting Starlette app. + + +For Streamable HTTP transport, you **must** pass the lifespan context from the FastMCP app to the resulting Starlette app, as nested lifespans are not recognized. Otherwise, the FastMCP server's session manager will not be properly initialized. + + +#### Nested Mounts + +You can create complex routing structures by nesting mounts: + +```python +from fastmcp import FastMCP +from starlette.applications import Starlette +from starlette.routing import Mount + +# Create your FastMCP server +mcp = FastMCP("MyServer") + +# Create the ASGI app +mcp_app = mcp.http_app(path='/mcp') + +# Create nested application structure +inner_app = Starlette(routes=[Mount("/inner", app=mcp_app)]) +app = Starlette( + routes=[Mount("/outer", app=inner_app)], + lifespan=mcp_app.lifespan, +) +``` + +In this setup, the MCP server is accessible at the `/outer/inner/mcp/` path. + +### FastAPI Integration + +For FastAPI-specific integration patterns including both mounting MCP servers into FastAPI apps and generating MCP servers from FastAPI apps, see the [FastAPI Integration guide](/integrations/fastapi). + +Here's a quick example showing how to add MCP to an existing FastAPI application: + +```python +from fastapi import FastAPI +from fastmcp import FastMCP + +# Create your MCP server +mcp = FastMCP("API Tools") + +@mcp.tool +def query_database(query: str) -> dict: + """Run a database query""" + return {"result": "data"} + +# Create the MCP ASGI app with path="/" since we'll mount at /mcp +mcp_app = mcp.http_app(path="/") + +# Create FastAPI app with MCP lifespan (required for session management) +api = FastAPI(lifespan=mcp_app.lifespan) + +@api.get("/api/status") +def status(): + return {"status": "ok"} + +# Mount MCP at /mcp +api.mount("/mcp", mcp_app) + +# Run with: uvicorn app:api --host 0.0.0.0 --port 8000 +``` + +Your existing API remains at `http://localhost:8000/api` while MCP is available at `http://localhost:8000/mcp`. + + +Just like with Starlette, you **must** pass the lifespan from the MCP app to FastAPI. Without this, the session manager won't initialize properly and requests will fail. + + +## Mounting Authenticated Servers + + + + +This section only applies if you're **mounting an OAuth-protected FastMCP server under a path prefix** (like `/api`) inside another application using `Mount()`. + +If you're deploying your FastMCP server at root level without any `Mount()` prefix, the well-known routes are automatically included in `mcp.http_app()` and you don't need to do anything special. + + +OAuth specifications (RFC 8414 and RFC 9728) require discovery metadata to be accessible at well-known paths under the root level of your domain. When you mount an OAuth-protected FastMCP server under a path prefix like `/api`, this creates a routing challenge: your operational OAuth endpoints move under the prefix, but discovery endpoints must remain at the root. + + +**Common Mistakes to Avoid:** + +1. **Forgetting to mount `.well-known` routes at root** - FastMCP cannot do this automatically when your server is mounted under a path prefix. You must explicitly mount well-known routes at the root level. + +2. **Including mount prefix in both base_url AND mcp_path** - The mount prefix (like `/api`) should only be in `base_url`, not in `mcp_path`. Otherwise you'll get double paths. + + ✅ **Correct:** + ```python + base_url = "http://localhost:8000/api" + mcp_path = "/mcp" + # Result: /api/mcp + ``` + + ❌ **Wrong:** + ```python + base_url = "http://localhost:8000/api" + mcp_path = "/api/mcp" + # Result: /api/api/mcp (double prefix!) + ``` + +Follow the configuration instructions below to set up mounting correctly. + + + +**CORS Middleware Conflicts:** + +If you're integrating FastMCP into an existing application with its own CORS middleware, be aware that layering CORS middleware can cause conflicts (such as 404 errors on `.well-known` routes or OPTIONS requests). + +FastMCP and the MCP SDK already handle CORS for OAuth routes. If you need CORS on your own application routes, consider using the sub-app pattern: mount FastMCP and your routes as separate apps, each with their own middleware, rather than adding application-wide CORS middleware. + + +### Route Types + +OAuth-protected MCP servers expose two categories of routes: + +**Operational routes** handle the OAuth flow and MCP protocol: +- `/authorize` - OAuth authorization endpoint +- `/token` - Token exchange endpoint +- `/auth/callback` - OAuth callback handler +- `/mcp` - MCP protocol endpoint + +**Discovery routes** provide metadata for OAuth clients: +- `/.well-known/oauth-authorization-server` - Authorization server metadata +- `/.well-known/oauth-protected-resource/*` - Protected resource metadata + +When you mount your MCP app under a prefix, operational routes move with it, but discovery routes must stay at root level for RFC compliance. + +### Configuration Parameters + +Three parameters control where routes are located and how they combine: + +**`base_url`** tells clients where to find operational endpoints. This includes any Starlette `Mount()` path prefix (e.g., `/api`): + +```python +base_url="http://localhost:8000/api" # Includes mount prefix +``` + +**`mcp_path`** is the internal FastMCP endpoint path, which gets appended to `base_url`: + +```python +mcp_path="/mcp" # Internal MCP path, NOT the mount prefix +``` + +**`issuer_url`** (optional) controls the authorization server identity for OAuth discovery. Defaults to `base_url`. + +```python +# Usually not needed - just set base_url and it works +issuer_url="http://localhost:8000" # Only if you want root-level discovery +``` + +When `issuer_url` has a path (either explicitly or by defaulting from `base_url`), FastMCP creates path-aware discovery routes per RFC 8414. For example, if `base_url` is `http://localhost:8000/api`, the authorization server metadata will be at `/.well-known/oauth-authorization-server/api`. + +**Key Invariant:** `base_url + mcp_path = actual externally-accessible MCP URL` + +Example: +- `base_url`: `http://localhost:8000/api` (mount prefix `/api`) +- `mcp_path`: `/mcp` (internal path) +- Result: `http://localhost:8000/api/mcp` (final MCP endpoint) + +Note that the mount prefix (`/api` from `Mount("/api", ...)`) goes in `base_url`, while `mcp_path` is just the internal MCP route. Don't include the mount prefix in both places or you'll get `/api/api/mcp`. + +### Mounting Strategy + +When mounting an OAuth-protected server under a path prefix, declare your URLs upfront to make the relationships clear: + +```python +from fastmcp import FastMCP +from fastmcp.server.auth.providers.github import GitHubProvider +from starlette.applications import Starlette +from starlette.routing import Mount + +# Define the routing structure +ROOT_URL = "http://localhost:8000" +MOUNT_PREFIX = "/api" +MCP_PATH = "/mcp" +``` + +Create the auth provider with `base_url`: + +```python +auth = GitHubProvider( + client_id="your-client-id", + client_secret="your-client-secret", + base_url=f"{ROOT_URL}{MOUNT_PREFIX}", # Operational endpoints under prefix + # issuer_url defaults to base_url - path-aware discovery works automatically +) +``` + +Create the MCP app, which generates operational routes at the specified path: + +```python +mcp = FastMCP("Protected Server", auth=auth) +mcp_app = mcp.http_app(path=MCP_PATH) +``` + +Retrieve the discovery routes from the auth provider. The `mcp_path` argument should match the path used when creating the MCP app: + +```python +well_known_routes = auth.get_well_known_routes(mcp_path=MCP_PATH) +``` + +Finally, mount everything in the Starlette app with discovery routes at root and the MCP app under the prefix: + +```python +app = Starlette( + routes=[ + *well_known_routes, # Discovery routes at root level + Mount(MOUNT_PREFIX, app=mcp_app), # Operational routes under prefix + ], + lifespan=mcp_app.lifespan, +) +``` + +This configuration produces the following URL structure: + +- MCP endpoint: `http://localhost:8000/api/mcp` +- OAuth authorization: `http://localhost:8000/api/authorize` +- OAuth callback: `http://localhost:8000/api/auth/callback` +- Authorization server metadata: `http://localhost:8000/.well-known/oauth-authorization-server/api` +- Protected resource metadata: `http://localhost:8000/.well-known/oauth-protected-resource/api/mcp` + +Both discovery endpoints use path-aware URLs per RFC 8414 and RFC 9728, matching the `base_url` path. + +### Complete Example + +Here's a complete working example showing all the pieces together: + +```python +from fastmcp import FastMCP +from fastmcp.server.auth.providers.github import GitHubProvider +from starlette.applications import Starlette +from starlette.routing import Mount +import uvicorn + +# Define routing structure +ROOT_URL = "http://localhost:8000" +MOUNT_PREFIX = "/api" +MCP_PATH = "/mcp" + +# Create OAuth provider +auth = GitHubProvider( + client_id="your-client-id", + client_secret="your-client-secret", + base_url=f"{ROOT_URL}{MOUNT_PREFIX}", + # issuer_url defaults to base_url - path-aware discovery works automatically +) + +# Create MCP server +mcp = FastMCP("Protected Server", auth=auth) + +@mcp.tool +def analyze(data: str) -> dict: + return {"result": f"Analyzed: {data}"} + +# Create MCP app +mcp_app = mcp.http_app(path=MCP_PATH) + +# Get discovery routes for root level +well_known_routes = auth.get_well_known_routes(mcp_path=MCP_PATH) + +# Assemble the application +app = Starlette( + routes=[ + *well_known_routes, + Mount(MOUNT_PREFIX, app=mcp_app), + ], + lifespan=mcp_app.lifespan, +) + +if __name__ == "__main__": + uvicorn.run(app, host="0.0.0.0", port=8000) +``` + +For more details on OAuth authentication, see the [Authentication guide](/servers/auth). + +## Production Deployment + +### Running with Uvicorn + +When deploying to production, you'll want to optimize your server for performance and reliability. Uvicorn provides several options to improve your server's capabilities: + +```bash +# Run with basic configuration +uvicorn app:app --host 0.0.0.0 --port 8000 + +# Run with multiple workers for production (requires stateless mode - see below) +uvicorn app:app --host 0.0.0.0 --port 8000 --workers 4 +``` + +### Horizontal Scaling + + + +When deploying FastMCP behind a load balancer or running multiple server instances, you need to understand how the HTTP transport handles sessions and configure your server appropriately. + +#### Understanding Sessions + +By default, FastMCP's Streamable HTTP transport maintains server-side sessions. Sessions enable stateful MCP features like [elicitation](/servers/elicitation) and [sampling](/servers/sampling), where the server needs to maintain context across multiple requests from the same client. + +This works perfectly for single-instance deployments. However, sessions are stored in memory on each server instance, which creates challenges when scaling horizontally. + +#### Without Stateless Mode + +When running multiple server instances behind a load balancer (Traefik, nginx, HAProxy, Kubernetes, etc.), requests from the same client may be routed to different instances: + +1. Client connects to Instance A → session created on Instance A +2. Next request routes to Instance B → session doesn't exist → **request fails** + +You might expect sticky sessions (session affinity) to solve this, but they don't work reliably with MCP clients. + + +**Why sticky sessions don't work:** Most MCP clients—including Cursor and Claude Code—use `fetch()` internally and don't properly forward `Set-Cookie` headers. Without cookies, load balancers can't identify which instance should handle subsequent requests. This is a limitation in how these clients implement HTTP, not something you can fix with load balancer configuration. + + +#### Enabling Stateless Mode + +For horizontally scaled deployments, enable stateless HTTP mode. In stateless mode, each request creates a fresh transport context, eliminating the need for session affinity entirely. + +**Option 1: Via constructor** + +```python +from fastmcp import FastMCP + +mcp = FastMCP("My Server", stateless_http=True) + +@mcp.tool +def process(data: str) -> str: + return f"Processed: {data}" + +app = mcp.http_app() +``` + +**Option 2: Via `run()`** + +```python +if __name__ == "__main__": + mcp.run(transport="http", stateless_http=True) +``` + +**Option 3: Via environment variable** + +```bash +FASTMCP_STATELESS_HTTP=true uvicorn app:app --host 0.0.0.0 --port 8000 --workers 4 +``` + +### Environment Variables + +Production deployments should never hardcode sensitive information like API keys or authentication tokens. Instead, use environment variables to configure your server at runtime. This keeps your code secure and makes it easy to deploy the same code to different environments with different configurations. + +Here's an example using bearer token authentication (though OAuth is recommended for production): + +```python +import os +from fastmcp import FastMCP +from fastmcp.server.auth import BearerTokenAuth + +# Read configuration from environment +auth_token = os.environ.get("MCP_AUTH_TOKEN") +if auth_token: + auth = BearerTokenAuth(token=auth_token) + mcp = FastMCP("Production Server", auth=auth) +else: + mcp = FastMCP("Production Server") + +app = mcp.http_app() +``` + +Deploy with your secrets safely stored in environment variables: +```bash +MCP_AUTH_TOKEN=secret uvicorn app:app --host 0.0.0.0 --port 8000 +``` + +### OAuth Token Security + + + +If you're using the [OAuth Proxy](/servers/auth/oauth-proxy), FastMCP issues its own JWT tokens to clients instead of forwarding upstream provider tokens. This maintains proper OAuth 2.0 token boundaries. + +**Default Behavior (Development Only):** + +By default, FastMCP automatically manages cryptographic keys: +- **Mac/Windows**: Keys are generated and stored in your system keyring, surviving server restarts. Suitable **only** for development and local testing. +- **Linux**: Keys are ephemeral (random salt at startup), so tokens are invalidated on restart. + +This automatic approach is convenient for development but not suitable for production deployments. + +**For Production:** + +Production requires explicit key management to ensure tokens survive restarts and can be shared across multiple server instances. This requires the following two things working together: + +1. **Explicit JWT signing key** for signing tokens issued to clients +3. **Persistent network-accessible storage** for upstream tokens (wrapped in `FernetEncryptionWrapper` to encrypt sensitive data at rest) + +**Configuration:** + +Add two parameters to your auth provider: + +```python {8-12} +from key_value.aio.stores.redis import RedisStore +from key_value.aio.wrappers.encryption import FernetEncryptionWrapper +from cryptography.fernet import Fernet + +auth = GitHubProvider( + client_id=os.environ["GITHUB_CLIENT_ID"], + client_secret=os.environ["GITHUB_CLIENT_SECRET"], + jwt_signing_key=os.environ["JWT_SIGNING_KEY"], + client_storage=FernetEncryptionWrapper( + key_value=RedisStore(host="redis.example.com", port=6379), + fernet=Fernet(os.environ["STORAGE_ENCRYPTION_KEY"]) + ), + base_url="https://your-server.com" # use HTTPS +) +``` + +Both parameters are required for production. Without an explicit signing key, keys are signed using a key derived from the client_secret, which will cause invalidation upon rotation of the client secret. Without persistent storage, tokens are local to the server and won't be trusted across hosts. **Wrap your storage backend in `FernetEncryptionWrapper` to encrypt sensitive OAuth tokens at rest** - without encryption, tokens are stored in plaintext. + +For more details on the token architecture and key management, see [OAuth Proxy Key and Storage Management](/servers/auth/oauth-proxy#key-and-storage-management). + +## Reverse Proxy (nginx) + +In production, you'll typically run your FastMCP server behind a reverse proxy like nginx. A reverse proxy provides TLS termination, domain-based routing, static file serving, and an additional layer of security between the internet and your application. + +### Running FastMCP as a Linux Service + +Before configuring nginx, you need your FastMCP server running as a background service. A systemd unit file ensures your server starts automatically and restarts on failure. + +Create a file at `/etc/systemd/system/fastmcp.service`: + +```ini +[Unit] +Description=FastMCP Server +After=network.target + +[Service] +User=www-data +Group=www-data +WorkingDirectory=/opt/fastmcp +ExecStart=/opt/fastmcp/.venv/bin/uvicorn app:app --host 127.0.0.1 --port 8000 +Restart=always +RestartSec=5 +Environment="PATH=/opt/fastmcp/.venv/bin" + +[Install] +WantedBy=multi-user.target +``` + +Enable and start the service: + +```bash +sudo systemctl daemon-reload +sudo systemctl enable fastmcp +sudo systemctl start fastmcp +``` + +This assumes your ASGI application is in `/opt/fastmcp/app.py` with a virtual environment at `/opt/fastmcp/.venv`. Adjust paths to match your deployment layout. + +### nginx Configuration + +FastMCP's Streamable HTTP transport uses Server-Sent Events (SSE) for streaming responses. This requires specific nginx settings to prevent buffering from breaking the event stream. + +Create a site configuration at `/etc/nginx/sites-available/fastmcp`: + +```nginx +server { + listen 80; + server_name mcp.example.com; + + # Redirect HTTP to HTTPS + return 301 https://$host$request_uri; +} + +server { + listen 443 ssl; + server_name mcp.example.com; + + ssl_certificate /etc/letsencrypt/live/mcp.example.com/fullchain.pem; + ssl_certificate_key /etc/letsencrypt/live/mcp.example.com/privkey.pem; + + location / { + proxy_pass http://127.0.0.1:8000; + proxy_http_version 1.1; + proxy_set_header Connection ''; + proxy_set_header Host $host; + proxy_set_header X-Real-IP $remote_addr; + proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for; + proxy_set_header X-Forwarded-Proto $scheme; + + # Required for SSE (Server-Sent Events) streaming + proxy_buffering off; + proxy_cache off; + + # Allow long-lived connections for streaming responses + proxy_read_timeout 300s; + proxy_send_timeout 300s; + } +} +``` + +Enable the site and reload nginx: + +```bash +sudo ln -s /etc/nginx/sites-available/fastmcp /etc/nginx/sites-enabled/ +sudo nginx -t +sudo systemctl reload nginx +``` + +Your FastMCP server is now accessible at `https://mcp.example.com/mcp`. + + +**SSE buffering is the most common issue.** If clients connect but never receive streaming responses (progress updates, tool results), verify that `proxy_buffering off` is set. Without it, nginx buffers the entire SSE stream and delivers it only when the connection closes, which breaks real-time communication. + + +### Key Considerations + +When deploying FastMCP behind a reverse proxy, keep these points in mind: + +- **Disable buffering**: SSE requires `proxy_buffering off` so events reach clients immediately. This is the single most important setting. +- **Increase timeouts**: The default nginx `proxy_read_timeout` is 60 seconds. Long-running MCP tools will cause the connection to drop. Set timeouts to at least 300 seconds, or higher if your tools run longer. For tools that may exceed any timeout, use [SSE Polling](#sse-polling-for-long-running-operations) to gracefully handle proxy disconnections. +- **Use HTTP/1.1**: Set `proxy_http_version 1.1` and `proxy_set_header Connection ''` to enable keep-alive connections between nginx and your server. Clearing the `Connection` header prevents clients from sending `Connection: close` to your upstream, which would break SSE streams. Both settings are required for proper SSE support. +- **Forward headers**: Pass `X-Forwarded-For` and `X-Forwarded-Proto` so your FastMCP server can determine the real client IP and protocol. This is important for logging and for OAuth redirect URLs. +- **TLS termination**: Let nginx handle TLS certificates (e.g., via Let's Encrypt with Certbot). Your FastMCP server can then run on plain HTTP internally. + +### Mounting Under a Path Prefix + +If you want your MCP server available at a subpath like `https://example.com/api/mcp` instead of at the root domain, adjust the nginx `location` block: + +```nginx +location /api/ { + proxy_pass http://127.0.0.1:8000/; + proxy_http_version 1.1; + proxy_set_header Connection ''; + proxy_set_header Host $host; + proxy_set_header X-Real-IP $remote_addr; + proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for; + proxy_set_header X-Forwarded-Proto $scheme; + + # Required for SSE streaming + proxy_buffering off; + proxy_cache off; + proxy_read_timeout 300s; + proxy_send_timeout 300s; +} +``` + +Note the trailing `/` on both `location /api/` and `proxy_pass http://127.0.0.1:8000/` — this ensures nginx strips the `/api` prefix before forwarding to your server. If you're using OAuth authentication with a mount prefix, see [Mounting Authenticated Servers](#mounting-authenticated-servers) for additional configuration. + +## Testing Your Deployment + +Once your server is deployed, you'll need to verify it's accessible and functioning correctly. For comprehensive testing strategies including connectivity tests, client testing, and authentication testing, see the [Testing Your Server](/development/tests) guide. + +## Hosting Your Server + +This guide has shown you how to create an HTTP-accessible MCP server, but you'll still need a hosting provider to make it available on the internet. Your FastMCP server can run anywhere that supports Python web applications: + +- **Cloud VMs** (AWS EC2, Google Compute Engine, Azure VMs) +- **Container platforms** (Cloud Run, Container Instances, ECS) +- **Platform-as-a-Service** (Railway, Render, Vercel) +- **Edge platforms** (Cloudflare Workers) +- **Kubernetes clusters** (self-managed or managed) + +The key requirements are Python 3.10+ support and the ability to expose an HTTP port. Most providers will require you to package your server (requirements.txt, Dockerfile, etc.) according to their deployment format. For managed, zero-configuration deployment, see [Prefect Horizon](/deployment/prefect-horizon). diff --git a/docs/deployment/prefect-horizon.mdx b/docs/deployment/prefect-horizon.mdx new file mode 100644 index 000000000..a7d053813 --- /dev/null +++ b/docs/deployment/prefect-horizon.mdx @@ -0,0 +1,120 @@ +--- +title: Prefect Horizon +sidebarTitle: Prefect Horizon +description: The MCP platform from the FastMCP team +icon: cloud +--- + +[Prefect Horizon](https://www.prefect.io/horizon) is a platform for deploying and managing MCP servers. Built by the FastMCP team at [Prefect](https://www.prefect.io), Horizon provides managed hosting, authentication, access control, and a registry of MCP capabilities. + +Horizon includes a **free personal tier for FastMCP users**, making it the fastest way to get a secure, production-ready server URL with built-in OAuth authentication. + + +Horizon is free for personal projects. Enterprise governance features are available for teams deploying to thousands of users. + + +## The Platform + +Horizon is organized into four integrated pillars: + +- **Deploy**: Managed hosting with CI/CD, scaling, monitoring, and rollbacks. Push code and get a live, governed endpoint in 60 seconds. +- **Registry**: A central catalog of MCP servers across your organization—first-party, third-party, and curated remix servers composed from multiple sources. +- **Gateway**: Role-based access control, authentication, and audit logs. Define what agents can see and do at the tool level. +- **Agents**: A permissioned chat interface for interacting with any MCP server or curated combination of servers. + +This guide focuses on **Horizon Deploy**, the managed hosting layer that gives you the fastest path from a FastMCP server to a production URL. + +## Prerequisites + +To use Horizon, you'll need a [GitHub](https://github.com) account and a GitHub repo containing a FastMCP server. If you don't have one yet, Horizon can create a starter repo for you during onboarding. + +Your repo can be public or private, but must include at least a Python file containing a FastMCP server instance. + + +To verify your file is compatible with Horizon, run `fastmcp inspect ` to see what Horizon will see when it runs your server. + + +If you have a `requirements.txt` or `pyproject.toml` in the repo, Horizon will automatically detect your server's dependencies and install them. Your file *can* have an `if __name__ == "__main__"` block, but it will be ignored by Horizon. + +For example, a minimal server file might look like: + +```python +from fastmcp import FastMCP + +mcp = FastMCP("MyServer") + +@mcp.tool +def hello(name: str) -> str: + return f"Hello, {name}!" +``` + +## Getting Started + +There are just three steps to deploying a server to Horizon: + +### Step 1: Select a Repository + +Visit [horizon.prefect.io](https://horizon.prefect.io) and sign in with your GitHub account. Connect your GitHub account to grant Horizon access to your repositories, then select the repo you want to deploy. + +Horizon repository selection + +### Step 2: Configure Your Server + +Next, you'll configure how Horizon should build and deploy your server. + +Horizon server configuration + +The configuration screen lets you specify: +- **Server name**: A unique name for your server. This determines your server's URL. +- **Description**: A brief description of what your server does. +- **Entrypoint**: The Python file containing your FastMCP server (e.g., `main.py`). This field has the same syntax as the `fastmcp run` command—use `main.py:mcp` to specify a specific object in the file. +- **Authentication**: When enabled, only authenticated users in your organization can connect. Horizon handles all the OAuth complexity for you. + +Horizon will automatically detect your server's Python dependencies from either a `requirements.txt` or `pyproject.toml` file. + +### Step 3: Deploy and Connect + +Click **Deploy Server** and Horizon will clone your repository, build your server, and deploy it to a unique URL—typically in under 60 seconds. + +Horizon deployment view showing live server + +Once deployed, your server is accessible at a URL like: + +``` +https://your-server-name.fastmcp.app/mcp +``` + +Horizon monitors your repo and redeploys automatically whenever you push to `main`. It also builds preview deployments for every PR, so you can test changes before they go live. + +## Testing Your Server + +Horizon provides two ways to verify your server is working before connecting external clients. + +### Inspector + +The Inspector gives you a structured view of everything your server exposes—tools, resources, and prompts. You can click any tool, fill in the inputs, execute it, and see the output. This is useful for systematically validating each capability and debugging specific behaviors. + +### ChatMCP + +For quick end-to-end testing, ChatMCP lets you interact with your server conversationally. It uses a fast model optimized for rapid iteration—you can verify the server works, test tool calls in context, and confirm the overall behavior before sharing it with others. + +Horizon ChatMCP interface + +ChatMCP is designed for testing, not as a daily work environment. Once you've confirmed your server works, you can copy connection snippets for Claude Desktop, Cursor, Claude Code, and other MCP clients—or use the FastMCP client library to connect programmatically. + +## Horizon Agents + +Beyond testing individual servers, Horizon lets you create **Agents**—chat interfaces backed by one or more MCP servers. While ChatMCP tests a single server, Agents let you compose capabilities from multiple servers into a unified experience. + +Horizon Agent configuration + +To create an agent: +1. Navigate to **Agents** in the sidebar +2. Click **Create Agent** and give it a name and description +3. Add MCP servers to the agent—these can be servers you've deployed to Horizon or external servers in the registry + +Once configured, you can chat with your agent directly in Horizon: + +Chatting with a Horizon Agent + +Agents are useful for creating purpose-built interfaces that combine tools from different servers. For example, you might create an agent that has access to both your company's internal data server and a general-purpose utilities server. diff --git a/docs/deployment/running-server.mdx b/docs/deployment/running-server.mdx new file mode 100644 index 000000000..c10855345 --- /dev/null +++ b/docs/deployment/running-server.mdx @@ -0,0 +1,286 @@ +--- +title: Running Your Server +sidebarTitle: Running Your Server +description: Learn how to run your FastMCP server locally for development and testing +icon: circle-play +--- + +import { VersionBadge } from '/snippets/version-badge.mdx' + +FastMCP servers can be run in different ways depending on your needs. This guide focuses on running servers locally for development and testing. For production deployment to a URL, see the [HTTP Deployment](/deployment/http) guide. + +## The `run()` Method + +Every FastMCP server needs to be started to accept connections. The simplest way to run a server is by calling the `run()` method on your FastMCP instance. This method starts the server and blocks until it's stopped, handling all the connection management for you. + + +For maximum compatibility, it's best practice to place the `run()` call within an `if __name__ == "__main__":` block. This ensures the server starts only when the script is executed directly, not when imported as a module. + + +```python {9-10} my_server.py +from fastmcp import FastMCP + +mcp = FastMCP(name="MyServer") + +@mcp.tool +def hello(name: str) -> str: + return f"Hello, {name}!" + +if __name__ == "__main__": + mcp.run() +``` + +You can now run this MCP server by executing `python my_server.py`. + +## Transport Protocols + +MCP servers communicate with clients through different transport protocols. Think of transports as the "language" your server speaks to communicate with clients. FastMCP supports three main transport protocols, each designed for specific use cases and deployment scenarios. + +The choice of transport determines how clients connect to your server, what network capabilities are available, and how many clients can connect simultaneously. Understanding these transports helps you choose the right approach for your application. + +### STDIO Transport (Default) + +STDIO (Standard Input/Output) is the default transport for FastMCP servers. When you call `run()` without arguments, your server uses STDIO transport. This transport communicates through standard input and output streams, making it perfect for command-line tools and desktop applications like Claude Desktop. + +With STDIO transport, the client spawns a new server process for each session and manages its lifecycle. The server reads MCP messages from stdin and writes responses to stdout. This is why STDIO servers don't stay running - they're started on-demand by the client. + +```python +from fastmcp import FastMCP + +mcp = FastMCP("MyServer") + +@mcp.tool +def hello(name: str) -> str: + return f"Hello, {name}!" + +if __name__ == "__main__": + mcp.run() # Uses STDIO transport by default +``` + +STDIO is ideal for: +- Local development and testing +- Claude Desktop integration +- Command-line tools +- Single-user applications + +### HTTP Transport (Streamable) + +HTTP transport turns your MCP server into a web service accessible via a URL. This transport uses the Streamable HTTP protocol, which allows clients to connect over the network. Unlike STDIO where each client gets its own process, an HTTP server can handle multiple clients simultaneously. + +The Streamable HTTP protocol provides full bidirectional communication between client and server, supporting all MCP operations including streaming responses. This makes it the recommended choice for network-based deployments. + +To use HTTP transport, specify it in the `run()` method along with networking options: + +```python +from fastmcp import FastMCP + +mcp = FastMCP("MyServer") + +@mcp.tool +def hello(name: str) -> str: + return f"Hello, {name}!" + +if __name__ == "__main__": + # Start an HTTP server on port 8000 + mcp.run(transport="http", host="127.0.0.1", port=8000) +``` + +Your server is now accessible at `http://localhost:8000/mcp`. This URL is the MCP endpoint that clients will connect to. HTTP transport enables: +- Network accessibility +- Multiple concurrent clients +- Integration with web infrastructure +- Remote deployment capabilities + +For production HTTP deployment with authentication and advanced configuration, see the [HTTP Deployment](/deployment/http) guide. + +### SSE Transport (Legacy) + +Server-Sent Events (SSE) transport was the original HTTP-based transport for MCP. While still supported for backward compatibility, it has limitations compared to the newer Streamable HTTP transport. SSE only supports server-to-client streaming, making it less efficient for bidirectional communication. + +```python +if __name__ == "__main__": + # SSE transport - use HTTP instead for new projects + mcp.run(transport="sse", host="127.0.0.1", port=8000) +``` + +We recommend using HTTP transport instead of SSE for all new projects. SSE remains available only for compatibility with older clients that haven't upgraded to Streamable HTTP. + +### Choosing the Right Transport + +Each transport serves different needs. STDIO is perfect when you need simple, local execution - it's what Claude Desktop and most command-line tools expect. HTTP transport is essential when you need network access, want to serve multiple clients, or plan to deploy your server remotely. SSE exists only for backward compatibility and shouldn't be used in new projects. + +Consider your deployment scenario: Are you building a tool for local use? STDIO is your best choice. Need a centralized service that multiple clients can access? HTTP transport is the way to go. + +## The FastMCP CLI + +FastMCP provides a powerful command-line interface for running servers without modifying the source code. The CLI can automatically find and run your server with different transports, manage dependencies, and handle development workflows: + +```bash +fastmcp run server.py +``` + +The CLI automatically finds a FastMCP instance in your file (named `mcp`, `server`, or `app`) and runs it with the specified options. This is particularly useful for testing different transports or configurations without changing your code. + +### Dependency Management + +The CLI integrates with `uv` to manage Python environments and dependencies: + +```bash +# Run with a specific Python version +fastmcp run server.py --python 3.11 + +# Run with additional packages +fastmcp run server.py --with pandas --with numpy + +# Run with dependencies from a requirements file +fastmcp run server.py --with-requirements requirements.txt + +# Combine multiple options +fastmcp run server.py --python 3.10 --with httpx --transport http + +# Run within a specific project directory +fastmcp run server.py --project /path/to/project +``` + + +When using `--python`, `--with`, `--project`, or `--with-requirements`, the server runs via `uv run` subprocess instead of using your local environment. + + +### Passing Arguments to Servers + +When servers accept command line arguments (using argparse, click, or other libraries), you can pass them after `--`: + +```bash +fastmcp run config_server.py -- --config config.json +fastmcp run database_server.py -- --database-path /tmp/db.sqlite --debug +``` + +This is useful for servers that need configuration files, database paths, API keys, or other runtime options. + +For more CLI features including development mode with the MCP Inspector, see the [CLI documentation](/cli/running). + +### Auto-Reload for Development + + + +During development, you can use the `--reload` flag to automatically restart your server when source files change: + +```bash +fastmcp run server.py --reload +``` + +The server watches for changes to Python files in the current directory and restarts automatically when you save changes. This provides a fast feedback loop during development without manually stopping and starting the server. + +```bash +# Watch specific directories for changes +fastmcp run server.py --reload --reload-dir ./src --reload-dir ./lib + +# Combine with other options +fastmcp run server.py --reload --transport http --port 8080 +``` + + +Auto-reload uses stateless mode to enable seamless restarts. For stdio transport, this is fully featured. For HTTP transport, some bidirectional features like elicitation are not available during reload mode. + + +SSE transport does not support auto-reload due to session limitations. Use HTTP transport instead if you need both network access and auto-reload. + +### Async Usage + +FastMCP servers are built on async Python, but the framework provides both synchronous and asynchronous APIs to fit your application's needs. The `run()` method we've been using is actually a synchronous wrapper around the async server implementation. + +For applications that are already running in an async context, FastMCP provides the `run_async()` method: + +```python {10-12} +from fastmcp import FastMCP +import asyncio + +mcp = FastMCP(name="MyServer") + +@mcp.tool +def hello(name: str) -> str: + return f"Hello, {name}!" + +async def main(): + # Use run_async() in async contexts + await mcp.run_async(transport="http", port=8000) + +if __name__ == "__main__": + asyncio.run(main()) +``` + + +The `run()` method cannot be called from inside an async function because it creates its own async event loop internally. If you attempt to call `run()` from inside an async function, you'll get an error about the event loop already running. + +Always use `run_async()` inside async functions and `run()` in synchronous contexts. + + +Both `run()` and `run_async()` accept the same transport arguments, so all the examples above apply to both methods. + +## Custom Routes + +When using HTTP transport, you might want to add custom web endpoints alongside your MCP server. This is useful for health checks, status pages, or simple APIs. FastMCP lets you add custom routes using the `@custom_route` decorator: + +```python +from fastmcp import FastMCP +from starlette.requests import Request +from starlette.responses import PlainTextResponse + +mcp = FastMCP("MyServer") + +@mcp.custom_route("/health", methods=["GET"]) +async def health_check(request: Request) -> PlainTextResponse: + return PlainTextResponse("OK") + +@mcp.tool +def process(data: str) -> str: + return f"Processed: {data}" + +if __name__ == "__main__": + mcp.run(transport="http") # Health check at http://localhost:8000/health +``` + +Custom routes are served by the same web server as your MCP endpoint. They're available at the root of your domain while the MCP endpoint is at `/mcp/`. For more complex web applications, consider [mounting your MCP server into a FastAPI or Starlette app](/deployment/http#integration-with-web-frameworks). + +## Alternative Initialization Patterns + +The `if __name__ == "__main__"` pattern works well for standalone scripts, but some deployment scenarios require different approaches. FastMCP handles these cases automatically. + +### CLI-Only Servers + +When using the FastMCP CLI, you don't need the `if __name__` block at all. The CLI will find your FastMCP instance and run it: + +```python +# server.py +from fastmcp import FastMCP + +mcp = FastMCP("MyServer") # CLI looks for 'mcp', 'server', or 'app' + +@mcp.tool +def process(data: str) -> str: + return f"Processed: {data}" + +# No if __name__ block needed - CLI will find and run 'mcp' +``` + +### ASGI Applications + +For ASGI deployment (running with Uvicorn or similar), you'll want to create an ASGI application object. This approach is common in production deployments where you need more control over the server configuration: + +```python +# app.py +from fastmcp import FastMCP + +def create_app(): + mcp = FastMCP("MyServer") + + @mcp.tool + def process(data: str) -> str: + return f"Processed: {data}" + + return mcp.http_app() + +app = create_app() # Uvicorn will use this +``` + +See the [HTTP Deployment](/deployment/http) guide for more ASGI deployment patterns. \ No newline at end of file diff --git a/docs/deployment/server-configuration.mdx b/docs/deployment/server-configuration.mdx new file mode 100644 index 000000000..f9b0e4781 --- /dev/null +++ b/docs/deployment/server-configuration.mdx @@ -0,0 +1,640 @@ +--- +title: "Project Configuration" +sidebarTitle: "Project Configuration" +description: Use fastmcp.json for portable, declarative project configuration +icon: file-code +--- + +import { VersionBadge } from "/snippets/version-badge.mdx" + + + +FastMCP supports declarative configuration through `fastmcp.json` files. This is the canonical and preferred way to configure FastMCP projects, providing a single source of truth for server settings, dependencies, and deployment options that replaces complex command-line arguments. + +The `fastmcp.json` file is designed to be a portable description of your server configuration that can be shared across environments and teams. When running from a `fastmcp.json` file, you can override any configuration values using CLI arguments. + +## Overview + +The `fastmcp.json` configuration file allows you to define all aspects of your FastMCP server in a structured, shareable format. Instead of remembering command-line arguments or writing shell scripts, you declare your server's configuration once and use it everywhere. + +When you have a `fastmcp.json` file, running your server becomes as simple as: + +```bash +# Run the server using the configuration +fastmcp run fastmcp.json + +# Or if fastmcp.json exists in the current directory +fastmcp run +``` + +This configuration approach ensures reproducible deployments across different environments, from local development to production servers. It works seamlessly with Claude Desktop, VS Code extensions, and any MCP-compatible client. + +## File Structure + +The `fastmcp.json` configuration answers three fundamental questions about your server: + +- **Source** = WHERE does your server code live? +- **Environment** = WHAT environment setup does it require? +- **Deployment** = HOW should the server run? + +This conceptual model helps you understand the purpose of each configuration section and organize your settings effectively. The configuration file maps directly to these three concerns: + +```json +{ + "$schema": "https://gofastmcp.com/public/schemas/fastmcp.json/v1.json", + "source": { + // WHERE: Location of your server code + "type": "filesystem", // Optional, defaults to "filesystem" + "path": "server.py", + "entrypoint": "mcp" + }, + "environment": { + // WHAT: Environment setup and dependencies + "type": "uv", // Optional, defaults to "uv" + "python": ">=3.10", + "dependencies": ["pandas", "numpy"] + }, + "deployment": { + // HOW: Runtime configuration + "transport": "stdio", + "log_level": "INFO" + } +} +``` + +Only the `source` field is required. The `environment` and `deployment` sections are optional and provide additional configuration when needed. + +### JSON Schema Support + +FastMCP provides JSON schemas for IDE autocomplete and validation. Add the schema reference to your `fastmcp.json` for enhanced developer experience: + +```json +{ + "$schema": "https://gofastmcp.com/public/schemas/fastmcp.json/v1.json", + "source": { + "path": "server.py", + "entrypoint": "mcp" + } +} +``` + +Two schema URLs are available: +- **Version-specific**: `https://gofastmcp.com/public/schemas/fastmcp.json/v1.json` +- **Latest version**: `https://gofastmcp.com/public/schemas/fastmcp.json/latest.json` + +Modern IDEs like VS Code will automatically provide autocomplete suggestions, validation, and inline documentation when the schema is specified. + +### Source Configuration + +The source configuration determines **WHERE** your server code lives. It tells FastMCP how to find and load your server, whether it's a local Python file, a remote repository, or hosted in the cloud. This section is required and forms the foundation of your configuration. + + + + The server source configuration that determines where your server code lives. + + + The source type identifier that determines which implementation to use. Currently supports `"filesystem"` for local files. Future releases will add support for `"git"` and `"cloud"` source types. + + + + When `type` is `"filesystem"` (or omitted), the source points to a local Python file containing your FastMCP server: + + + Path to the Python file containing your FastMCP server. + + + + Name of the server instance or factory function within the module: + - Can be a FastMCP server instance (e.g., `mcp = FastMCP("MyServer")`) + - Can be a function with no arguments that returns a FastMCP server + - If not specified, FastMCP searches for common names: `mcp`, `server`, or `app` + + + **Example:** + ```json + "source": { + "type": "filesystem", + "path": "src/server.py", + "entrypoint": "mcp" + } + ``` + + Note: File paths are resolved relative to the configuration file's location. + + + + + +**Future Source Types** + +Future releases will support additional source types: +- **Git repositories** (`type: "git"`) for loading server code directly from version control +- **Prefect Horizon** (`type: "cloud"`) for hosted servers with automatic scaling and management + + +### Environment Configuration + +The environment configuration determines **WHAT** environment setup your server requires. It controls the build-time setup of your Python environment, ensuring your server runs with the exact Python version and dependencies it requires. This section creates isolated, reproducible environments across different systems. + +FastMCP uses an extensible environment system with a base `Environment` class that can be implemented by different environment providers. Currently, FastMCP supports the `UVEnvironment` for Python environment management using `uv`'s powerful dependency resolver. + + + + Optional environment configuration. When specified, FastMCP uses the appropriate environment implementation to set up your server's runtime. + + + The environment type identifier that determines which implementation to use. Currently supports `"uv"` for Python environments managed by uv. If omitted, defaults to `"uv"`. + + + + When `type` is `"uv"` (or omitted), the environment uses uv to manage Python dependencies: + + + Python version constraint. Examples: + - Exact version: `"3.12"` + - Minimum version: `">=3.10"` + - Version range: `">=3.10,<3.13"` + + + + List of pip packages with optional version specifiers (PEP 508 format). + ```json + "dependencies": ["pandas>=2.0", "requests", "httpx"] + ``` + + + + Path to a requirements.txt file, resolved relative to the config file location. + ```json + "requirements": "requirements.txt" + ``` + + + + Path to a project directory containing pyproject.toml for uv project management. + ```json + "project": "." + ``` + + + + List of paths to packages to install in editable/development mode. Useful for local development when you want changes to be reflected immediately. Supports multiple packages for monorepo setups or shared libraries. + ```json + "editable": ["."] + ``` + Or with multiple packages: + ```json + "editable": [".", "../shared-lib", "/path/to/another-package"] + ``` + + + **Example:** + ```json + "environment": { + "type": "uv", + "python": ">=3.10", + "dependencies": ["pandas", "numpy"], + "editable": ["."] + } + ``` + + Note: When any UVEnvironment field is specified, FastMCP automatically creates an isolated environment using `uv` before running your server. + + + + +When environment configuration is provided, FastMCP: +1. Detects the environment type (defaults to `"uv"` if not specified) +2. Creates an isolated environment using the appropriate provider +3. Installs the specified dependencies +4. Runs your server in this clean environment + +This build-time setup ensures your server always has the dependencies it needs, without polluting your system Python or conflicting with other projects. + + +**Future Environment Types** + +Similar to source types, future releases may support additional environment types for different runtime requirements, such as Docker containers or language-specific environments beyond Python. + + +### Deployment Configuration + +The deployment configuration controls **HOW** your server runs. It defines the runtime behavior including network settings, environment variables, and execution context. These settings determine how your server operates when it executes, from transport protocols to logging levels. + +Environment variables are included in this section because they're runtime configuration that affects how your server behaves when it executes, not how its environment is built. The deployment configuration is applied every time your server starts, controlling its operational characteristics. + + + + Optional runtime configuration for the server. + + + + Protocol for client communication: + - `"stdio"`: Standard input/output for desktop clients + - `"http"`: Network-accessible HTTP server + - `"sse"`: Server-sent events + + + + Network interface to bind (HTTP transport only): + - `"127.0.0.1"`: Local connections only + - `"0.0.0.0"`: All network interfaces + + + + Port number for HTTP transport. + + + + URL path for the MCP endpoint when using HTTP transport. + + + + Server logging verbosity. Options: + - `"DEBUG"`: Detailed debugging information + - `"INFO"`: General informational messages + - `"WARNING"`: Warning messages + - `"ERROR"`: Error messages only + - `"CRITICAL"`: Critical errors only + + + + Environment variables to set when running the server. Supports `${VAR_NAME}` syntax for runtime interpolation. + ```json + "env": { + "API_KEY": "secret-key", + "DATABASE_URL": "postgres://${DB_USER}@${DB_HOST}/mydb" + } + ``` + + + + Working directory for the server process. Relative paths are resolved from the config file location. + + + + Command-line arguments to pass to the server, passed after `--` to the server's argument parser. + ```json + "args": ["--config", "server-config.json"] + ``` + + + + + +#### Environment Variable Interpolation + +The `env` field in deployment configuration supports runtime interpolation of environment variables using `${VAR_NAME}` syntax. This enables dynamic configuration based on your deployment environment: + +```json +{ + "deployment": { + "env": { + "API_URL": "https://api.${ENVIRONMENT}.example.com", + "DATABASE_URL": "postgres://${DB_USER}:${DB_PASS}@${DB_HOST}/myapp", + "CACHE_KEY": "myapp_${ENVIRONMENT}_${VERSION}" + } + } +} +``` + +When the server starts, FastMCP replaces `${ENVIRONMENT}`, `${DB_USER}`, etc. with values from your system's environment variables. If a variable doesn't exist, the placeholder is preserved as-is. + +**Example**: If your system has `ENVIRONMENT=production` and `DB_HOST=db.example.com`: +```json +// Configuration +{ + "deployment": { + "env": { + "API_URL": "https://api.${ENVIRONMENT}.example.com", + "DB_HOST": "${DB_HOST}" + } + } +} + +// Result at runtime +{ + "API_URL": "https://api.production.example.com", + "DB_HOST": "db.example.com" +} +``` + +This feature is particularly useful for: +- Deploying the same configuration across development, staging, and production +- Keeping sensitive values out of configuration files +- Building dynamic URLs and connection strings +- Creating environment-specific prefixes or suffixes + +## Usage with CLI Commands + +FastMCP automatically detects and uses a file specifically named `fastmcp.json` in the current directory, making server execution simple and consistent. Files with FastMCP configuration format but different names are not auto-detected and must be specified explicitly: + +```bash +# Auto-detect fastmcp.json in current directory +cd my-project +fastmcp run # No arguments needed! + +# Or specify a configuration file explicitly +fastmcp run prod.fastmcp.json + +# Skip environment setup when already in a uv environment +fastmcp run fastmcp.json --skip-env + +# Skip source preparation when source is already prepared +fastmcp run fastmcp.json --skip-source + +# Skip both environment and source preparation +fastmcp run fastmcp.json --skip-env --skip-source +``` + +### Pre-building Environments + +You can use `fastmcp project prepare` to create a persistent uv project with all dependencies pre-installed: + +```bash +# Create a persistent environment +fastmcp project prepare fastmcp.json --output-dir ./env + +# Use the pre-built environment to run the server +fastmcp run fastmcp.json --project ./env +``` + +This pattern separates environment setup (slow) from server execution (fast), useful for deployment scenarios. + +### Using an Existing Environment + +By default, FastMCP creates an isolated environment with `uv` based on your configuration. When you already have a suitable Python environment, use the `--skip-env` flag to skip environment creation: + +```bash +fastmcp run fastmcp.json --skip-env +``` + +**When you already have an environment:** +- You're in an activated virtual environment with all dependencies installed +- You're inside a Docker container with pre-installed dependencies +- You're in a CI/CD pipeline that pre-builds the environment +- You're using a system-wide installation with all required packages +- You're in a uv-managed environment (prevents infinite recursion) + +This flag tells FastMCP: "I already have everything installed, just run the server." + +### Using an Existing Source + +When working with source types that require preparation (future support for git repositories or cloud sources), use the `--skip-source` flag when you already have the source code available: + +```bash +fastmcp run fastmcp.json --skip-source +``` + +**When you already have the source:** +- You've previously cloned a git repository and don't need to re-fetch +- You have a cached copy of a cloud-hosted server +- You're in a CI/CD pipeline where source checkout is a separate step +- You're iterating locally on already-downloaded code + +This flag tells FastMCP: "I already have the source code, skip any download/clone steps." + +Note: For filesystem sources (local Python files), this flag has no effect since they don't require preparation. + +The configuration file works with all FastMCP commands: +- **`run`** - Start the server in production mode +- **`dev`** - Launch with the Inspector UI for development +- **`inspect`** - View server capabilities and configuration +- **`install`** - Install to Claude Desktop, Cursor, or other MCP clients + +When no file argument is provided, FastMCP searches the current directory for `fastmcp.json`. This means you can simply navigate to your project directory and run `fastmcp run` to start your server with all its configured settings. + +### CLI Override Behavior + +Command-line arguments take precedence over configuration file values, allowing ad-hoc adjustments without modifying the file: + +```bash +# Config specifies port 3000, CLI overrides to 8080 +fastmcp run fastmcp.json --port 8080 + +# Config specifies stdio, CLI overrides to HTTP +fastmcp run fastmcp.json --transport http + +# Add extra dependencies not in config +fastmcp run fastmcp.json --with requests --with httpx +``` + +This precedence order enables: +- Quick testing of different settings +- Environment-specific overrides in deployment scripts +- Debugging with increased log levels +- Temporary configuration changes + +### Custom Naming Patterns + +You can use different configuration files for different environments: + +- `fastmcp.json` - Default configuration +- `dev.fastmcp.json` - Development settings +- `prod.fastmcp.json` - Production settings +- `test_fastmcp.json` - Test configuration + +Any file with "fastmcp.json" in the name is recognized as a configuration file. + +## Examples + + + + +A minimal configuration for a simple server: + +```json +{ + "$schema": "https://gofastmcp.com/public/schemas/fastmcp.json/v1.json", + "source": { + "path": "server.py", + "entrypoint": "mcp" + } +} +``` +This configuration explicitly specifies the server entrypoint (`mcp`), making it clear which server instance or factory function to use. Uses all defaults: STDIO transport, no special dependencies, standard logging. + + + +A configuration optimized for local development: + +```json +{ + "$schema": "https://gofastmcp.com/public/schemas/fastmcp.json/v1.json", + // WHERE does the server live? + "source": { + "path": "src/server.py", + "entrypoint": "app" + }, + // WHAT dependencies does it need? + "environment": { + "type": "uv", + "python": "3.12", + "dependencies": ["fastmcp[dev]"], + "editable": "." + }, + // HOW should it run? + "deployment": { + "transport": "http", + "host": "127.0.0.1", + "port": 8000, + "log_level": "DEBUG", + "env": { + "DEBUG": "true", + "ENV": "development" + } + } +} +``` + + + +A production-ready configuration with full dependency management: + +```json +{ + "$schema": "https://gofastmcp.com/public/schemas/fastmcp.json/v1.json", + // WHERE does the server live? + "source": { + "path": "app/main.py", + "entrypoint": "mcp_server" + }, + // WHAT dependencies does it need? + "environment": { + "python": "3.11", + "requirements": "requirements/production.txt", + "project": "." + }, + // HOW should it run? + "deployment": { + "transport": "http", + "host": "0.0.0.0", + "port": 3000, + "path": "/api/mcp/", + "log_level": "INFO", + "env": { + "ENV": "production", + "API_BASE_URL": "https://api.example.com", + "DATABASE_URL": "postgresql://user:pass@db.example.com/prod" + }, + "cwd": "/app", + "args": ["--workers", "4"] + } +} +``` + + + +Configuration for a data analysis server with scientific packages: + +```json +{ + "$schema": "https://gofastmcp.com/public/schemas/fastmcp.json/v1.json", + "source": { + "path": "analysis_server.py", + "entrypoint": "mcp" + }, + "environment": { + "python": "3.11", + "dependencies": [ + "pandas>=2.0", + "numpy", + "scikit-learn", + "matplotlib", + "jupyterlab" + ] + }, + "deployment": { + "transport": "stdio", + "env": { + "MATPLOTLIB_BACKEND": "Agg", + "DATA_PATH": "./datasets" + } + } +} +``` + + + +You can maintain multiple configuration files for different environments: + +**dev.fastmcp.json**: +```json +{ + "$schema": "https://gofastmcp.com/public/schemas/fastmcp.json/v1.json", + "source": { + "path": "server.py", + "entrypoint": "mcp" + }, + "deployment": { + "transport": "http", + "log_level": "DEBUG" + } +} +``` + +**prod.fastmcp.json**: +```json +{ + "$schema": "https://gofastmcp.com/public/schemas/fastmcp.json/v1.json", + "source": { + "path": "server.py", + "entrypoint": "mcp" + }, + "environment": { + "requirements": "requirements/production.txt" + }, + "deployment": { + "transport": "http", + "host": "0.0.0.0", + "log_level": "WARNING" + } +} +``` + +Run different configurations: +```bash +fastmcp run dev.fastmcp.json # Development +fastmcp run prod.fastmcp.json # Production +``` + + + +## Migrating from CLI Arguments + +If you're currently using command-line arguments or shell scripts, migrating to `fastmcp.json` simplifies your workflow. Here's how common CLI patterns map to configuration: + +**CLI Command**: +```bash +uv run --with pandas --with requests \ + fastmcp run server.py \ + --transport http \ + --port 8000 \ + --log-level INFO +``` + +**Equivalent fastmcp.json**: +```json +{ + "$schema": "https://gofastmcp.com/public/schemas/fastmcp.json/v1.json", + "source": { + "path": "server.py", + "entrypoint": "mcp" + }, + "environment": { + "dependencies": ["pandas", "requests"] + }, + "deployment": { + "transport": "http", + "port": 8000, + "log_level": "INFO" + } +} +``` + +Now simply run: +```bash +fastmcp run # Automatically finds and uses fastmcp.json +``` + +The configuration file approach provides better documentation, easier sharing, and consistent execution across different environments while maintaining the flexibility to override settings when needed. \ No newline at end of file diff --git a/docs/development/contributing.mdx b/docs/development/contributing.mdx new file mode 100644 index 000000000..c8772765a --- /dev/null +++ b/docs/development/contributing.mdx @@ -0,0 +1,198 @@ +--- +title: "Contributing" +description: "Development workflow for FastMCP contributors" +icon: code-pull-request +--- + +Contributing to FastMCP means joining a community that values clean, maintainable code and thoughtful API design. All contributions are valued - from fixing typos in documentation to implementing major features. + +## Design Principles + +Every contribution should advance these principles: + +- 🚀 **Fast** — High-level interfaces mean less code and faster development +- 🍀 **Simple** — Minimal boilerplate; the obvious way should be the right way +- 🐍 **Pythonic** — Feels natural to Python developers; no surprising patterns +- 🔍 **Complete** — Everything needed for production: auth, testing, deployment, observability + +PRs are evaluated against these principles. Code that makes FastMCP slower, harder to reason about, less Pythonic, or less complete will be rejected. + +## Issues + +### Issue First, Code Second + +**Every pull request requires a corresponding issue - no exceptions.** This requirement creates a collaborative space where approach, scope, and alignment are established before code is written. Issues serve as design documents where maintainers and contributors discuss implementation strategy, identify potential conflicts with existing patterns, and ensure proposed changes advance FastMCP's vision. + +**FastMCP is an opinionated framework, not a kitchen sink.** The maintainers have strong beliefs about what FastMCP should and shouldn't do. Just because something takes N lines of code and you want it in fewer lines doesn't mean FastMCP should take on the maintenance burden or endorse that pattern. This is judged at the maintainers' discretion. + +Use issues to understand scope BEFORE opening PRs. The issue discussion determines whether a feature belongs in core, contrib, or not at all. + +### Writing Good Issues + +FastMCP is an extremely highly-trafficked repository maintained by a very small team. Issues that appear to transfer burden to maintainers without any effort to validate the problem will be closed. Please help the maintainers help you by always providing a minimal reproducible example and clearly describing the problem. + +**LLM-generated issues will be closed immediately.** Issues that contain paragraphs of unnecessary explanation, verbose problem descriptions, or obvious LLM authorship patterns obfuscate the actual problem and transfer burden to maintainers. + +Write clear, concise issues that: +- State the problem directly +- Provide a minimal reproducible example +- Skip unnecessary background or context +- Take responsibility for clear communication + +Issues may be labeled "Invalid" simply due to confusion caused by verbosity or not adhering to the guidelines outlined here. + +## Pull Requests + +PRs that deviate from FastMCP's core principles will be rejected regardless of implementation quality. **PRs are NOT for iterating on ideas** - they should only be opened for ideas that already have a bias toward acceptance based on issue discussion. + + +### Development Environment + +#### Installation + +To contribute to FastMCP, you'll need to set up a development environment with all necessary tools and dependencies. + +```bash +# Clone the repository +git clone https://github.com/PrefectHQ/fastmcp.git +cd fastmcp + +# Install all dependencies including dev tools +uv sync + +# Install prek hooks +uv run prek install +``` + +In addition, some development commands require [just](https://github.com/casey/just) to be installed. + +Prek hooks will run automatically on every commit to catch issues before they reach CI. If you see failures, fix them before committing - never commit broken code expecting to fix it later. + +### Development Standards + +#### Scope + +Large pull requests create review bottlenecks and quality risks. Unless you're fixing a discrete bug or making an incredibly well-scoped change, keep PRs small and focused. + +A PR that changes 50 lines across 3 files can be thoroughly reviewed in minutes. A PR that changes 500 lines across 20 files requires hours of careful analysis and often hides subtle issues. + +Breaking large features into smaller PRs: +- Creates better review experiences +- Makes git history clear +- Simplifies debugging with bisect +- Reduces merge conflicts +- Gets your code merged faster + +#### Code Quality + +FastMCP values clarity over cleverness. Every line you write will be maintained by someone else - possibly years from now, possibly without context about your decisions. + +**PRs can be rejected for two opposing reasons:** +1. **Insufficient quality** - Code that doesn't meet our standards for clarity, maintainability, or idiomaticity +2. **Overengineering** - Code that is overbearing, unnecessarily complex, or tries to be too clever + +The focus is on idiomatic, high-quality Python. FastMCP uses patterns like `NotSet` type as an alternative to `None` in certain situations - follow existing patterns. + +#### Required Practices + +**Full type annotations** on all functions and methods. They catch bugs before runtime and serve as inline documentation. + +**Async/await patterns** for all I/O operations. Even if your specific use case doesn't need concurrency, consistency means users can compose features without worrying about blocking operations. + +**Descriptive names** make code self-documenting. `auth_token` is clear; `tok` requires mental translation. + +**Specific exception types** make error handling predictable. Catching `ValueError` tells readers exactly what error you expect. Never use bare `except` clauses. + +#### Anti-Patterns to Avoid + +**Complex one-liners** are hard to debug and modify. Break operations into clear steps. + +**Mutable default arguments** cause subtle bugs. Use `None` as the default and create the mutable object inside the function. + +**Breaking established patterns** confuses readers. If you must deviate, discuss in the issue first. + +### Prek Checks + +```bash +# Runs automatically on commit, or manually: +uv run prek run --all-files +``` + +This runs three critical tools: +- **Ruff**: Linting and formatting +- **Prettier**: Code formatting +- **ty**: Static type checking + +Pytest runs separately as a distinct workflow step after prek checks pass. CI will reject PRs that fail these checks. Always run them locally first. + +### Testing + +Tests are documentation that shows how features work. Good tests give reviewers confidence and help future maintainers understand intent. + +```bash +# Run specific test directory +uv run pytest tests/server/ -v + +# Run all tests before submitting PR +uv run pytest +``` + +Every new feature needs tests. See the [Testing Guide](/development/tests) for patterns and requirements. + +### Documentation + +A feature doesn't exist unless it's documented. Note that FastMCP's hosted documentation always tracks the main branch - users who want historical documentation can clone the repo, checkout a specific tag, and host it themselves. + +```bash +# Preview documentation locally +just docs +``` + +Documentation requirements: +- **Explain concepts in prose first** - Code without context is just syntax +- **Complete, runnable examples** - Every code block should be copy-pasteable +- **Register in docs.json** - Makes pages appear in navigation +- **Version badges** - Mark when features were added using `` + +#### SDK Documentation + +FastMCP's SDK documentation is auto-generated from the source code docstrings and type annotations. It is automatically updated on every merge to main by a GitHub Actions workflow, so users are *not* responsible for keeping the documentation up to date. However, to generate it proactively, you can use the following command: + +```bash +just api-ref-all +``` + +### Submitting Your PR + +#### Before Submitting + +1. **Run all checks**: `uv run prek run --all-files && uv run pytest` +2. **Keep scope small**: One feature or fix per PR +3. **Write clear description**: Your PR description becomes permanent documentation +4. **Update docs**: Include documentation for API changes + +#### PR Description + +Write PR descriptions that explain: +- What problem you're solving +- Why you chose this approach +- Any trade-offs or alternatives considered +- Migration path for breaking changes + +Focus on the "why" - the code shows the "what". Keep it concise but complete. + +#### What We Look For + +**Framework Philosophy**: FastMCP is NOT trying to do all things or provide all shortcuts. Features are rejected when they don't align with the framework's vision, even if perfectly implemented. The burden of proof is on the PR to demonstrate value. + +**Code Quality**: We verify code follows existing patterns. Consistency reduces cognitive load. When every module works similarly, developers understand new code quickly. + +**Test Coverage**: Not every line needs testing, but every behavior does. Tests document intent and protect against regressions. + +**Breaking Changes**: May be acceptable in minor versions but must be clearly documented. See the [versioning policy](/development/releases#versioning-policy). + +## Special Modules + +**`contrib`**: Community-maintained patterns and utilities. Original authors maintain their contributions. Not representative of the core framework. + +**`experimental`**: Maintainer-developed features that may preview future functionality. Can break or be deleted at any time without notice. Pin your FastMCP version when using these features. \ No newline at end of file diff --git a/docs/development/releases.mdx b/docs/development/releases.mdx new file mode 100644 index 000000000..346462736 --- /dev/null +++ b/docs/development/releases.mdx @@ -0,0 +1,79 @@ +--- +title: "Releases" +description: "FastMCP versioning and release process" +icon: "truck-fast" +--- + +FastMCP releases frequently to deliver features quickly in the rapidly evolving MCP ecosystem. We use semantic versioning pragmatically - the Model Context Protocol is young, patterns are still emerging, and waiting for perfect stability would mean missing opportunities to empower developers with better tools. + +## Versioning Policy + +### Semantic Versioning + +**Major (x.0.0)**: Complete API redesigns + +Major versions represent fundamental shifts. FastMCP 2.x is entirely different from 1.x in both implementation and design philosophy. + +**Minor (2.x.0)**: New features and evolution + + +Unlike traditional semantic versioning, minor versions **may** include [breaking changes](#breaking-changes) when necessary for the ecosystem's evolution. This flexibility is essential in a young ecosystem where perfect backwards compatibility would prevent important improvements. + + +FastMCP always targets the most current MCP Protocol version. Breaking changes in the MCP spec or MCP SDK automatically flow through to FastMCP - we prioritize staying current with the latest features and conventions over maintaining compatibility with older protocol versions. + +**Patch (2.0.x)**: Bug fixes and refinements + +Patch versions contain only bug fixes without breaking changes. These are safe updates you can apply with confidence. + +### Breaking Changes + +We permit breaking changes in minor versions because the MCP ecosystem is rapidly evolving. Refusing to break problematic APIs would accumulate design debt that eventually makes the framework unusable. Each breaking change represents a deliberate decision to keep FastMCP aligned with the ecosystem's evolution. + +When breaking changes occur: +- They only happen in minor versions (e.g., 2.3.x to 2.4.0) +- Release notes explain what changed and how to migrate +- We provide deprecation warnings at least 1 minor version in advance when possible +- Changes must substantially benefit users to justify disruption + +The public API is what's covered by our compatibility guarantees - these are the parts of FastMCP you can rely on to remain stable within a minor version. The public API consists of: +- `FastMCP` server class, `Client` class, and FastMCP `Context` +- Core MCP components: `Tool`, `Prompt`, `Resource`, `ResourceTemplate`, and transports +- Their public methods and documented behaviors + +Everything else (utilities, private methods, internal modules) may change without notice. This boundary lets us refactor internals and improve implementation details without breaking your code. For production stability, pin to specific versions. + + +The `fastmcp.server.auth` module was introduced in 2.12.0 and is exempted from this policy temporarily, meaning it is *expected* to have breaking changes even on patch versions. This is because auth is a rapidly evolving part of the MCP spec and it would be dangerous to be beholden to old decisions. Please pin your FastMCP version if using authentication in production. + +We expect this exemption to last through at least the 2.12.x and 2.13.x release series. + + +### Production Use + +Pin to exact versions: +``` +fastmcp==2.11.0 # Good +fastmcp>=2.11.0 # Bad - will install breaking changes +``` + +## Creating Releases + +Our release process is intentionally simple: + +1. Create GitHub release with tag `vMAJOR.MINOR.PATCH` (e.g., `v2.11.0`) +2. Generate release notes automatically, and curate or add additional editorial information as needed +3. GitHub releases automatically trigger PyPI deployments + +This automation lets maintainers focus on code quality rather than release mechanics. + +### Release Cadence + +We follow a feature-driven release cadence rather than a fixed schedule. Minor versions ship approximately every 3-4 weeks when significant functionality is ready. + +Patch releases ship promptly for: +- Critical bug fixes +- Security updates (immediate release) +- Regression fixes + +This approach means you get improvements as soon as they're ready rather than waiting for arbitrary release dates. diff --git a/docs/development/tests.mdx b/docs/development/tests.mdx new file mode 100644 index 000000000..6a9973fe8 --- /dev/null +++ b/docs/development/tests.mdx @@ -0,0 +1,396 @@ +--- +title: "Tests" +description: "Testing patterns and requirements for FastMCP" +icon: vial +--- + +import { VersionBadge } from "/snippets/version-badge.mdx" + +Good tests are the foundation of reliable software. In FastMCP, we treat tests as first-class documentation that demonstrates how features work while protecting against regressions. Every new capability needs comprehensive tests that demonstrate correctness. + +## FastMCP Tests + +### Running Tests + +```bash +# Run all tests +uv run pytest + +# Run specific test file +uv run pytest tests/server/test_auth.py + +# Run with coverage +uv run pytest --cov=fastmcp + +# Skip integration tests for faster runs +uv run pytest -m "not integration" + +# Skip tests that spawn processes +uv run pytest -m "not integration and not client_process" +``` + +Tests should complete in under 1 second unless marked as integration tests. This speed encourages running them frequently, catching issues early. + +### Test Organization + +Our test organization mirrors the `src/` directory structure, creating a predictable mapping between code and tests. When you're working on `src/fastmcp/server/auth.py`, you'll find its tests in `tests/server/test_auth.py`. In rare cases tests are split further - for example, the OpenAPI tests are so comprehensive they're split across multiple files. + +### Test Markers + +We use pytest markers to categorize tests that require special resources or take longer to run: + +```python +@pytest.mark.integration +async def test_github_api_integration(): + """Test GitHub API integration with real service.""" + token = os.getenv("FASTMCP_GITHUB_TOKEN") + if not token: + pytest.skip("FASTMCP_GITHUB_TOKEN not available") + + # Test against real GitHub API + client = GitHubClient(token) + repos = await client.list_repos("prefecthq") + assert "fastmcp" in [repo.name for repo in repos] + +@pytest.mark.client_process +async def test_stdio_transport(): + """Test STDIO transport with separate process.""" + # This spawns a subprocess + async with Client("python examples/simple_echo.py") as client: + result = await client.call_tool("echo", {"message": "test"}) + assert result.content[0].text == "test" +``` + +## Writing Tests + + +### Test Requirements + +Following these practices creates maintainable, debuggable test suites that serve as both documentation and regression protection. + +#### Single Behavior Per Test + +Each test should verify exactly one behavior. When it fails, you need to know immediately what broke. A test that checks five things gives you five potential failure points to investigate. A test that checks one thing points directly to the problem. + + + +```python Good: Atomic Test +async def test_tool_registration(): + """Test that tools are properly registered with the server.""" + mcp = FastMCP("test-server") + + @mcp.tool + def add(a: int, b: int) -> int: + return a + b + + tools = mcp.list_tools() + assert len(tools) == 1 + assert tools[0].name == "add" +``` + +```python Bad: Multi-Behavior Test +async def test_server_functionality(): + """Test multiple server features at once.""" + mcp = FastMCP("test-server") + + # Tool registration + @mcp.tool + def add(a: int, b: int) -> int: + return a + b + + # Resource creation + @mcp.resource("config://app") + def get_config(): + return {"version": "1.0"} + + # Authentication setup + mcp.auth = BearerTokenProvider({"token": "user"}) + + # What exactly are we testing? If this fails, what broke? + assert mcp.list_tools() + assert mcp.list_resources() + assert mcp.auth is not None +``` + + + +#### Self-Contained Setup + +Every test must create its own setup. Tests should be runnable in any order, in parallel, or in isolation. When a test fails, you should be able to run just that test to reproduce the issue. + + + +```python Good: Self-Contained +async def test_tool_execution_with_error(): + """Test that tool errors are properly handled.""" + mcp = FastMCP("test-server") + + @mcp.tool + def divide(a: int, b: int) -> float: + if b == 0: + raise ValueError("Cannot divide by zero") + return a / b + + async with Client(mcp) as client: + with pytest.raises(Exception): + await client.call_tool("divide", {"a": 10, "b": 0}) +``` + +```python Bad: Test Dependencies +# Global state that tests depend on +test_server = None + +def test_setup_server(): + """Setup for other tests.""" + global test_server + test_server = FastMCP("shared-server") + +def test_server_works(): + """Test server functionality.""" + # Depends on test_setup_server running first + assert test_server is not None +``` + + + +#### Clear Intent + +Test names and assertions should make the verified behavior obvious. A developer reading your test should understand what feature it validates and how that feature should behave. + +```python +async def test_authenticated_tool_requires_valid_token(): + """Test that authenticated users can access protected tools.""" + mcp = FastMCP("test-server") + mcp.auth = BearerTokenProvider({"secret-token": "test-user"}) + + @mcp.tool + def protected_action() -> str: + return "success" + + async with Client(mcp, auth=BearerAuth("secret-token")) as client: + result = await client.call_tool("protected_action", {}) + assert result.content[0].text == "success" +``` + +#### Using Fixtures + +Use fixtures to create reusable data, server configurations, or other resources for your tests. Note that you should **not** open FastMCP clients in your fixtures as it can create hard-to-diagnose issues with event loops. + +```python +import pytest +from fastmcp import FastMCP, Client + +@pytest.fixture +def weather_server(): + server = FastMCP("WeatherServer") + + @server.tool + def get_temperature(city: str) -> dict: + temps = {"NYC": 72, "LA": 85, "Chicago": 68} + return {"city": city, "temp": temps.get(city, 70)} + + return server + +async def test_temperature_tool(weather_server): + async with Client(weather_server) as client: + result = await client.call_tool("get_temperature", {"city": "LA"}) + assert result.data == {"city": "LA", "temp": 85} +``` + +#### Effective Assertions + +Assertions should be specific and provide context on failure. When a test fails during CI, the assertion message should tell you exactly what went wrong. + +```python +# Basic assertion - minimal context on failure +assert result.status == "success" + +# Better - explains what was expected +assert result.status == "success", f"Expected successful operation, got {result.status}: {result.error}" +``` + +Try not to have too many assertions in a single test unless you truly need to check various aspects of the same behavior. In general, assertions of different behaviors should be in separate tests. + +#### Inline Snapshots + +FastMCP uses `inline-snapshot` for testing complex data structures. On first run of `pytest --inline-snapshot=create` with an empty `snapshot()`, pytest will auto-populate the expected value. To update snapshots after intentional changes, run `pytest --inline-snapshot=fix`. This is particularly useful for testing JSON schemas and API responses. + +```python +from inline_snapshot import snapshot + +async def test_tool_schema_generation(): + """Test that tool schemas are generated correctly.""" + mcp = FastMCP("test-server") + + @mcp.tool + def calculate_tax(amount: float, rate: float = 0.1) -> dict: + """Calculate tax on an amount.""" + return {"amount": amount, "tax": amount * rate, "total": amount * (1 + rate)} + + tools = mcp.list_tools() + schema = tools[0].inputSchema + + # First run: snapshot() is empty, gets auto-populated + # Subsequent runs: compares against stored snapshot + assert schema == snapshot({ + "type": "object", + "properties": { + "amount": {"type": "number"}, + "rate": {"type": "number", "default": 0.1} + }, + "required": ["amount"] + }) +``` + +### In-Memory Testing + +FastMCP uses in-memory transport for testing, where servers and clients communicate directly. The majority of functionality can be tested in a deterministic fashion this way. We use more complex setups only when testing transports themselves. + +The in-memory transport runs the real MCP protocol implementation without network overhead. Instead of deploying your server or managing network connections, you pass your server instance directly to the client. Everything runs in the same Python process - you can set breakpoints anywhere and step through with your debugger. + +```python +from fastmcp import FastMCP, Client + +# Create your server +server = FastMCP("WeatherServer") + +@server.tool +def get_temperature(city: str) -> dict: + """Get current temperature for a city""" + temps = {"NYC": 72, "LA": 85, "Chicago": 68} + return {"city": city, "temp": temps.get(city, 70)} + +async def test_weather_operations(): + # Pass server directly - no deployment needed + async with Client(server) as client: + result = await client.call_tool("get_temperature", {"city": "NYC"}) + assert result.data == {"city": "NYC", "temp": 72} +``` + +This pattern makes tests deterministic and fast - typically completing in milliseconds rather than seconds. + +### Mocking External Dependencies + +FastMCP servers are standard Python objects, so you can mock external dependencies using your preferred approach: + +```python +from unittest.mock import AsyncMock + +async def test_database_tool(): + server = FastMCP("DataServer") + + # Mock the database + mock_db = AsyncMock() + mock_db.fetch_users.return_value = [ + {"id": 1, "name": "Alice"}, + {"id": 2, "name": "Bob"} + ] + + @server.tool + async def list_users() -> list: + return await mock_db.fetch_users() + + async with Client(server) as client: + result = await client.call_tool("list_users", {}) + assert len(result.data) == 2 + assert result.data[0]["name"] == "Alice" + mock_db.fetch_users.assert_called_once() +``` + +### Testing Network Transports + +While in-memory testing covers most unit testing needs, you'll occasionally need to test actual network transports like HTTP or SSE. FastMCP provides two approaches: in-process async servers (preferred), and separate subprocess servers (for special cases). + +#### In-Process Network Testing (Preferred) + + + +For most network transport tests, use `run_server_async` as an async context manager. This runs the server as a task in the same process, providing fast, deterministic tests with full debugger support: + +```python +import pytest +from fastmcp import FastMCP, Client +from fastmcp.client.transports import StreamableHttpTransport +from fastmcp.utilities.tests import run_server_async + +def create_test_server() -> FastMCP: + """Create a test server instance.""" + server = FastMCP("TestServer") + + @server.tool + def greet(name: str) -> str: + return f"Hello, {name}!" + + return server + +@pytest.fixture +async def http_server() -> str: + """Start server in-process for testing.""" + server = create_test_server() + async with run_server_async(server) as url: + yield url + +async def test_http_transport(http_server: str): + """Test actual HTTP transport behavior.""" + async with Client( + transport=StreamableHttpTransport(http_server) + ) as client: + result = await client.ping() + assert result is True + + greeting = await client.call_tool("greet", {"name": "World"}) + assert greeting.data == "Hello, World!" +``` + +The `run_server_async` context manager automatically handles server lifecycle and cleanup. This approach is faster than subprocess-based testing and provides better error messages. + +#### Subprocess Testing (Special Cases) + +For tests that require complete process isolation (like STDIO transport or testing subprocess behavior), use `run_server_in_process`: + +```python +import pytest +from fastmcp.utilities.tests import run_server_in_process +from fastmcp import FastMCP, Client +from fastmcp.client.transports import StreamableHttpTransport + +def run_server(host: str, port: int) -> None: + """Function to run in subprocess.""" + server = FastMCP("TestServer") + + @server.tool + def greet(name: str) -> str: + return f"Hello, {name}!" + + server.run(host=host, port=port) + +@pytest.fixture +async def http_server(): + """Fixture that runs server in subprocess.""" + with run_server_in_process(run_server, transport="http") as url: + yield f"{url}/mcp" + +async def test_http_transport(http_server: str): + """Test actual HTTP transport behavior.""" + async with Client( + transport=StreamableHttpTransport(http_server) + ) as client: + result = await client.ping() + assert result is True +``` + +The `run_server_in_process` utility handles server lifecycle, port allocation, and cleanup automatically. Use this only when subprocess isolation is truly necessary, as it's slower and harder to debug than in-process testing. FastMCP uses the `client_process` marker to isolate these tests in CI. + +### Documentation Testing + +Documentation requires the same validation as code. The `just docs` command launches a local Mintlify server that renders your documentation exactly as users will see it: + +```bash +# Start local documentation server with hot reload +just docs + +# Or run Mintlify directly +mintlify dev +``` + +The local server watches for changes and automatically refreshes. This preview catches formatting issues and helps you see documentation as users will experience it. \ No newline at end of file diff --git a/docs/development/v3-notes/auth-provider-env-vars.mdx b/docs/development/v3-notes/auth-provider-env-vars.mdx new file mode 100644 index 000000000..c61f61cbe --- /dev/null +++ b/docs/development/v3-notes/auth-provider-env-vars.mdx @@ -0,0 +1,73 @@ +--- +title: Auth Provider Environment Variables +--- + +## Decision: Remove automatic environment variable loading from auth providers + +You can still use environment variables for configuration - you just read them yourself with `os.environ` instead of relying on FastMCP's automatic loading. + +**Status:** Implemented in v3.0.0 + +### Background + +Auth providers in v2.x used `pydantic-settings` to automatically load configuration from environment variables with a `FASTMCP_SERVER_AUTH__` prefix. For example, `GitHubProvider` would read from: + +- `FASTMCP_SERVER_AUTH_GITHUB_CLIENT_ID` +- `FASTMCP_SERVER_AUTH_GITHUB_CLIENT_SECRET` +- `FASTMCP_SERVER_AUTH_GITHUB_BASE_URL` +- etc. + +This was implemented via a `*ProviderSettings(BaseSettings)` class in each provider, combined with a `NotSet` sentinel pattern to distinguish between "not provided" and `None`. + +### Why remove it + +1. **Maintenance burden**: Every new provider needed to implement the settings class, validators, and the `NotSet` merging logic. This was ~50-100 lines of boilerplate per provider. + +2. **Documentation complexity**: Each provider needed documentation explaining both the parameter and the corresponding environment variable. This doubled the surface area to document and maintain. + +3. **Contributor friction**: New contributors adding providers had to understand and replicate this pattern, which was a source of inconsistency and bugs. + +4. **Marginal user value**: Python developers are comfortable with `os.environ["VAR"]` or `os.environ.get("VAR", default)`. The automatic loading saved a single line of code per parameter while adding significant complexity. + +5. **Implicit behavior**: Magic environment variable loading makes it harder to understand where values come from. Explicit `os.environ` calls are more traceable. + +### Migration path + +The migration is trivial - users add explicit environment variable reads: + +```python +# Before (v2.x) +auth = GitHubProvider() # Relied on env vars + +# After (v3.0) +import os + +auth = GitHubProvider( + client_id=os.environ["GITHUB_CLIENT_ID"], + client_secret=os.environ["GITHUB_CLIENT_SECRET"], + base_url=os.environ["MY_BASE_URL"], +) +``` + +Users can also use `os.environ.get()` with defaults, or any other configuration library they prefer (dotenv, dynaconf, etc.). + +### Backwards compatibility + +We chose not to provide backwards compatibility because: + +1. This is a major version bump (v3.0), which is the appropriate time for breaking changes +2. The migration is straightforward (add `os.environ` calls) +3. Maintaining compatibility would require keeping all the boilerplate we're trying to remove +4. The pattern was likely not heavily used - most production deployments pass secrets explicitly rather than relying on magic prefixes + +### What was removed + +- `*ProviderSettings(BaseSettings)` classes from all auth providers +- `NotSet` sentinel usage in provider constructors +- `pydantic-settings` dependency for auth providers +- Environment variable documentation from provider docs +- Related test cases for env var loading + +### Result + +Provider constructors are now simple and explicit. Required parameters are actually required (Python raises `TypeError` if missing), and optional parameters have clear defaults. The code is more readable and easier to maintain. diff --git a/docs/development/v3-notes/v3-features.mdx b/docs/development/v3-notes/v3-features.mdx new file mode 100644 index 000000000..da9fc87db --- /dev/null +++ b/docs/development/v3-notes/v3-features.mdx @@ -0,0 +1,1482 @@ +--- +title: v3.0 Feature Tracking +--- + +This document tracks major features in FastMCP v3.0 for release notes preparation. + +## 3.0.0rc1 + +### SamplingTool Conversion Helpers + +Server tools (FunctionTool and TransformedTool) can now be passed directly to sampling methods via `SamplingTool.from_callable_tool()` ([#3062](https://github.com/PrefectHQ/fastmcp/pull/3062)). Previously, tools defined with `@mcp.tool` had to be recreated as functions for use in `ctx.sample()`. Now `ctx.sample()` and `ctx.sample_step()` accept these tool instances directly. + +```python +@mcp.tool +def search(query: str) -> str: + """Search the web.""" + return do_search(query) + +# Use tool directly in sampling +result = await ctx.sample( + "Research Python frameworks", + tools=[search] # FunctionTool works directly! +) +``` + +### Google GenAI Sampling Handler + +FastMCP now includes a sampling handler for Google's Gemini models ([#2977](https://github.com/jlowin/fastmcp/pull/2977)). This enables MCP clients to use Google's GenAI models with the sampling protocol, including full tool calling support. + +```python +from fastmcp import Client +from fastmcp.client.sampling.handlers import GoogleGenaiSamplingHandler +from google.genai import Client as GoogleGenaiClient + +# Initialize the handler +handler = GoogleGenaiSamplingHandler( + default_model="gemini-2.0-flash-exp", + client=GoogleGenaiClient(), # Optional - creates one if not provided +) + +# Use with MCP sampling (handler is configured at Client construction) +async with Client("http://server/mcp", sampling_handler=handler) as client: + result = await client.sample( + messages=[...], + tools=[...], + ) +``` + +Key features: +- Converts MCP tool schemas to Google's function calling format +- Supports all Google GenAI models that implement function calling +- Handles nullable types, nested objects, and arrays in tool schemas +- Properly maps tool choices (`auto`, `required`, `none`) to Google's configuration +- Preserves model preferences from MCP sampling parameters + +The handler joins the existing Anthropic and OpenAI handlers, providing a consistent interface for model-agnostic sampling across providers. + +### Concurrent Tool Execution in Sampling + +When an LLM returns multiple tool calls in a single sampling response, they can now be executed concurrently ([#3022](https://github.com/PrefectHQ/fastmcp/pull/3022)). Default behavior remains sequential; opt in with `tool_concurrency`. Tools can declare `sequential=True` to force sequential execution even when concurrency is enabled. + +```python +result = await context.sample( + messages="Fetch weather for NYC and LA", + tools=[fetch_weather], + tool_concurrency=0, # Unlimited parallel execution +) +``` + +### OpenAPI `validate_output` Option + +`OpenAPIProvider` and `FastMCP.from_openapi()` now accept `validate_output=False` to skip output schema validation ([#3134](https://github.com/PrefectHQ/fastmcp/pull/3134)). Useful when backends don't conform to their own OpenAPI response schemas — structured JSON still flows through, only the strict schema checking is disabled. + +```python +mcp = FastMCP.from_openapi( + openapi_spec=spec, + client=client, + validate_output=False, +) +``` + +### Auth Token Injection and Azure OBO Dependencies + +New dependency injection for accessing the authenticated user's token directly in tool parameters ([#2918](https://github.com/PrefectHQ/fastmcp/pull/2918)). Works with any auth provider. + +```python +from fastmcp.server.dependencies import CurrentAccessToken, TokenClaim +from fastmcp.server.auth import AccessToken + +@mcp.tool() +async def my_tool( + token: AccessToken = CurrentAccessToken, + user_id: str = TokenClaim("oid"), +): ... +``` + +For Azure/Entra, the new `fastmcp[azure]` extra adds `EntraOBOToken`, which handles the On-Behalf-Of token exchange declaratively: + +```python +from fastmcp.server.auth.providers.azure import EntraOBOToken + +@mcp.tool() +async def get_emails( + graph_token: str = EntraOBOToken(["https://graph.microsoft.com/Mail.Read"]), +): + # graph_token is ready — OBO exchange happened automatically + ... +``` + +### `generate-cli` Agent Skill Generation + +`fastmcp generate-cli` now produces a `SKILL.md` alongside the CLI script ([#3115](https://github.com/PrefectHQ/fastmcp/pull/3115)) — a Claude Code agent skill with pre-computed invocation syntax for every tool. Agents reading the skill can call tools immediately without running `--help`. On by default; pass `--no-skill` to opt out. + +### Background Task Notification Queue + +Background tasks now use a distributed Redis notification queue for reliable delivery ([#2906](https://github.com/PrefectHQ/fastmcp/pull/2906)). Elicitation switches from polling to BLPOP (single blocking call instead of ~7,200 round-trips/hour), and notification delivery retries up to 3x with TTL-based expiration. + +### Async Auth Checks + +Auth check functions can now be `async`, enabling authorization decisions that depend on asynchronous operations like reading server state via `Context.get_state` or calling external services ([#3150](https://github.com/PrefectHQ/fastmcp/issues/3150)). Sync and async checks can be freely mixed. Previously, passing an async function as an auth check would silently pass (coroutine objects are truthy). + +### Optional `$ref` Dereferencing in Schemas + +Schema `$ref` dereferencing — which inlines all `$defs` for compatibility with MCP clients that don't handle `$ref` — is now controlled by the `dereference_schemas` constructor kwarg ([#3141](https://github.com/PrefectHQ/fastmcp/issues/3141)). Default is `True` (dereference on) because the non-compliant clients are popular and the failure mode is silent breakage that server authors can't diagnose. Opt out when you know your clients handle `$ref` and want smaller schemas: + +```python +mcp = FastMCP("my-server", dereference_schemas=False) +``` + +Dereferencing is implemented as middleware (`DereferenceRefsMiddleware`) that runs at serve-time, so schemas are stored with `$ref` intact and only inlined when sent to clients. + +### Breaking: Deprecated `FastMCP()` Constructor Kwargs Removed + +Sixteen deprecated keyword arguments have been removed from `FastMCP.__init__`. Passing any of them now raises `TypeError` with a migration hint. Environment variables (e.g., `FASTMCP_HOST`) continue to work — only the constructor kwargs moved. + +**Transport/server settings** (`host`, `port`, `log_level`, `debug`, `sse_path`, `message_path`, `streamable_http_path`, `json_response`, `stateless_http`): Pass to `run()`, `run_http_async()`, or `http_app()` as appropriate, or set via environment variables. + +```python +# Before +mcp = FastMCP("server", host="0.0.0.0", port=8080) +mcp.run() + +# After +mcp = FastMCP("server") +mcp.run(transport="http", host="0.0.0.0", port=8080) +``` + +**Duplicate handling** (`on_duplicate_tools`, `on_duplicate_resources`, `on_duplicate_prompts`): Use the unified `on_duplicate=` parameter. + +**Tag filtering** (`include_tags`, `exclude_tags`): Use `server.enable(tags=..., only=True)` and `server.disable(tags=...)` after construction. + +**Tool serializer** (`tool_serializer`): Return `ToolResult` from tools instead. + +**Tool transformations** (`tool_transformations`): Use `server.add_transform(ToolTransform(...))` after construction. + +The `_deprecated_settings` attribute and `.settings` property are also removed. `ExperimentalSettings` has been deleted (dead code). + +### Breaking: `ui=` Renamed to `app=` + +The MCP Apps decorator parameter has been renamed from `ui=ToolUI(...)` / `ui=ResourceUI(...)` to `app=AppConfig(...)` ([#3117](https://github.com/PrefectHQ/fastmcp/pull/3117)). `ToolUI` and `ResourceUI` are consolidated into a single `AppConfig` class. Wire format is unchanged. See the MCP Apps section under beta2 for full details. +## 3.0.0beta2 + +### CLI: `fastmcp list` and `fastmcp call` + +New client-side CLI commands for querying and invoking tools on any MCP server — remote URLs, local Python files, MCPConfig JSON, or arbitrary stdio commands. Especially useful for giving LLMs that don't have built-in MCP support access to MCP tools via shell commands. + +```bash +# Discover tools on a server +fastmcp list http://localhost:8000/mcp +fastmcp list server.py +fastmcp list --command 'npx -y @modelcontextprotocol/server-github' + +# Call a tool +fastmcp call server.py greet name=World +fastmcp call http://localhost:8000/mcp search query=hello limit=5 +fastmcp call server.py create_item '{"name": "Widget", "tags": ["a", "b"]}' +``` + +Key features: +- Tool arguments are auto-coerced using the tool's JSON schema (`limit=5` → int) +- Single JSON objects work as positional args alongside `key=value` and `--input-json` +- `--input-schema` / `--output-schema` for full JSON schemas, `--json` for machine-readable output +- `--transport sse` for SSE servers, `--command` for stdio servers +- Auto OAuth for HTTP targets (no-ops if server doesn't require auth) +- Fuzzy tool name matching suggests alternatives on typos +- Interactive terminal elicitation for tools that request user input mid-execution + +Documentation: [CLI Querying](/cli/client) + +### CLI: `fastmcp discover` and name-based resolution + +`fastmcp discover` scans editor configs (Claude Desktop, Claude Code, Cursor, Gemini CLI, Goose) and project-level `mcp.json` files for MCP server definitions. Discovered servers can be referenced by name — or `source:name` for precision — in `fastmcp list` and `fastmcp call`. + +```bash +# See all configured servers +fastmcp discover + +# Use a server by name +fastmcp list weather +fastmcp call weather get_forecast city=London + +# Target a specific source with source:name +fastmcp list claude-code:my-server +fastmcp call cursor:weather get_forecast city=London + +# Filter discovery to specific sources +fastmcp discover --source claude-code --source cursor +``` + +Documentation: [CLI Querying](/cli/client) + +### CLI: Expanded Reload File Watching + +The `--reload` flag now watches a comprehensive set of file types, making it suitable for MCP apps with frontend bundles ([#3028](https://github.com/PrefectHQ/fastmcp/pull/3028)). Previously limited to `.py` files, it now watches JavaScript, TypeScript, HTML, CSS, config files, and media assets. + +### CLI: fastmcp install stdio + +The new `fastmcp install stdio` command generates full `uv run` commands for running FastMCP servers over stdio ([#3032](https://github.com/PrefectHQ/fastmcp/pull/3032)). + +```bash +# Generate command for a server +fastmcp install stdio server.py + +# Outputs: +# uv run --directory /path/to/project fastmcp run server.py +``` + +The command automatically detects the project directory and generates the appropriate `uv run` invocation, making it easy to integrate FastMCP servers with MCP clients. + +### CIMD (Client ID Metadata Documents) + +CIMD provides an alternative to Dynamic Client Registration for OAuth-authenticated MCP servers. Instead of registering with each server dynamically, clients host a static JSON document at an HTTPS URL. That URL becomes the client's `client_id`, and servers verify identity through domain ownership. + +**Client usage:** + +```python +from fastmcp import Client +from fastmcp.client.auth import OAuth + +async with Client( + "https://mcp-server.example.com/mcp", + auth=OAuth( + client_metadata_url="https://myapp.example.com/oauth/client.json", + ), +) as client: + await client.ping() +``` + +The `OAuth` helper now supports deferred binding — `mcp_url` is optional when using `OAuth` with `Client(auth=...)`, since the transport provides the server URL automatically. + +**CLI tools for document management:** + +```bash +# Generate a CIMD document +fastmcp auth cimd create --name "My App" \ + --redirect-uri "http://localhost:*/callback" \ + --client-id "https://myapp.example.com/oauth/client.json" \ + --output client.json + +# Validate a hosted document +fastmcp auth cimd validate https://myapp.example.com/oauth/client.json +``` + +**Server-side support:** + +CIMD is enabled by default on `OAuthProxy` and its provider subclasses (GitHub, Google, etc.). The server-side implementation includes SSRF-hardened document fetching with DNS pinning, dual redirect URI validation (both CIMD document patterns and proxy patterns must match), HTTP cache-aware revalidation, and `private_key_jwt` assertion validation for clients that need stronger authentication than public client auth. + +Key details: +- CIMD URLs must be HTTPS with a non-root path +- `token_endpoint_auth_method` limited to `none` or `private_key_jwt` (no shared secrets) +- `redirect_uris` in CIMD documents support wildcard port patterns (`http://localhost:*/callback`) +- Servers fetch and cache documents with standard HTTP caching (ETag, Last-Modified, Cache-Control) +- CIMD is a protocol-level feature — any auth provider implementing the spec can support it + +Documentation: [CIMD Authentication](/clients/auth/cimd), [OAuth Proxy CIMD config](/servers/auth/oauth-proxy#cimd-support) + +### Pre-Registered OAuth Clients + +The `OAuth` client helper now accepts `client_id` and `client_secret` parameters for servers where the client is already registered ([#3086](https://github.com/PrefectHQ/fastmcp/pull/3086)). This bypasses Dynamic Client Registration entirely — useful when DCR is disabled, or when the server has pre-provisioned credentials for your application. + +```python +from fastmcp import Client +from fastmcp.client.auth import OAuth + +async with Client( + "https://mcp-server.example.com/mcp", + auth=OAuth( + client_id="my-registered-app", + client_secret="my-secret", + scopes=["read", "write"], + ), +) as client: + await client.ping() +``` + +The static credentials are injected before the OAuth flow begins, so the client never attempts DCR. If the server rejects the credentials, the error surfaces immediately rather than retrying with fresh registration (which can't help for fixed credentials). Public clients can omit `client_secret`. + +Documentation: [Pre-Registered Clients](/clients/auth/oauth#pre-registered-clients) + +### CLI: `fastmcp generate-cli` + +`fastmcp generate-cli` connects to any MCP server, reads its tool schemas, and writes a standalone Python CLI script where every tool becomes a typed subcommand with flags, help text, and tab completion ([#3065](https://github.com/PrefectHQ/fastmcp/pull/3065)). The insight is that MCP tool schemas already contain everything a CLI framework needs — parameter names, types, descriptions, required/optional status — so the generator maps JSON Schema directly into [cyclopts](https://cyclopts.readthedocs.io/) commands. + +```bash +# Generate from any server spec +fastmcp generate-cli weather +fastmcp generate-cli http://localhost:8000/mcp +fastmcp generate-cli server.py my_weather_cli.py + +# Use the generated script +python my_weather_cli.py call-tool get_forecast --city London --days 3 +python my_weather_cli.py list-tools +python my_weather_cli.py read-resource docs://readme +``` + +The generated script embeds the resolved transport (URL or stdio command), so it's self-contained — users don't need to know about MCP or FastMCP to use it. Supports `-f` to overwrite existing files, and name-based resolution via `fastmcp discover`. + +Documentation: [Generate CLI](/cli/generate-cli) + +### CLI: Goose Integration + +New `fastmcp install goose` command that generates a `goose://extension?...` deeplink URL and opens it, prompting Goose to install the server as a STDIO extension ([#3040](https://github.com/PrefectHQ/fastmcp/pull/3040)). Goose requires `uvx` rather than `uv run`, so the command builds the appropriate invocation automatically. + +```bash +fastmcp install goose server.py +fastmcp install goose server.py --with pandas --python 3.11 +``` + +Also adds a full integration guide at [Goose Integration](/integrations/goose). + +### ResponseLimitingMiddleware + +New middleware for controlling tool response sizes, preventing large outputs from overwhelming LLM context windows ([#3072](https://github.com/PrefectHQ/fastmcp/pull/3072)). Text responses are truncated at UTF-8 character boundaries; structured responses (tools with `output_schema`) raise `ToolError` since truncation would corrupt the schema. + +```python +from fastmcp.server.middleware.response_limiting import ResponseLimitingMiddleware + +# Limit all tool responses to 500KB +mcp.add_middleware(ResponseLimitingMiddleware(max_size=500_000)) + +# Limit only specific tools, raise errors instead of truncating +mcp.add_middleware(ResponseLimitingMiddleware( + max_size=100_000, + tools=["search", "fetch_data"], + raise_on_unstructured=True, +)) +``` + +Key features: +- Configurable size limit (default 1MB) +- Tool-specific filtering via `tools` parameter +- Size metadata added to result's `meta` field for monitoring +- Configurable `raise_on_structured` and `raise_on_unstructured` behavior + +Documentation: [Middleware](/servers/middleware) + +### Background Task Context (SEP-1686) + +`Context` now works transparently in background tasks running in Docket workers ([#2905](https://github.com/PrefectHQ/fastmcp/pull/2905)). Previously, tools running as background tasks couldn't use `ctx.elicit()` because there was no active request context. Now, when a tool executes in a Docket worker, `Context` detects this via its `task_id` and routes elicitation through Redis-based coordination: the task sets its status to `input_required`, sends a `notifications/tasks/updated` notification with elicitation metadata, and waits for the client to respond via `tasks/sendInput`. + +```python +@mcp.tool(task=True) +async def interactive_task(ctx: Context) -> str: + # Works transparently in both foreground and background task modes + result = await ctx.elicit("Please provide additional input", str) + + if isinstance(result, AcceptedElicitation): + return f"You provided: {result.data}" + else: + return "Elicitation was declined or cancelled" +``` + +`ctx.is_background_task` and `ctx.task_id` are available for tools that need to branch on execution mode. + +### `require_auth` Removed + +The `require_auth` authorization check introduced in beta1 has been removed in favor of scope-based authorization via `require_scopes` ([#3103](https://github.com/PrefectHQ/fastmcp/pull/3103)). Since configuring an `AuthProvider` already rejects unauthenticated requests at the transport level, `require_auth` was redundant — `require_scopes` provides the same guarantee with better granularity. The beta1 Component Authorization section has been updated to reflect this. + +### MCP Apps (SDK Compatibility) + +Support for [MCP Apps](https://modelcontextprotocol.io/specification/2025-06-18/server/apps) — the spec extension that lets MCP servers deliver interactive UIs via sandboxed iframes. Extension negotiation, typed UI metadata on tools and resources, and the `ui://` resource scheme. No component DSL, renderer, or `FastMCPApp` class yet — those are future phases. + +**Breaking change from beta 2:** The `ui=` parameter on `@mcp.tool()` and `@mcp.resource()` has been renamed to `app=`, and the `ToolUI`/`ResourceUI` classes have been consolidated into a single `AppConfig` class. This follows the established `task=True`/`TaskConfig` pattern. The wire format (`meta["ui"]`, `_meta.ui`) is unchanged. + +**Registering tools with app metadata:** + +```python +from fastmcp import FastMCP +from fastmcp.server.apps import AppConfig, ResourceCSP, ResourcePermissions + +mcp = FastMCP("My Server") + +# Register the HTML bundle as a ui:// resource with CSP +@mcp.resource( + "ui://my-app/view.html", + app=AppConfig( + csp=ResourceCSP(resource_domains=["https://unpkg.com"]), + permissions=ResourcePermissions(clipboard_write={}), + ), +) +def app_html() -> str: + from pathlib import Path + return Path("./dist/index.html").read_text() + +# Tool with UI — clients render an iframe alongside the result +@mcp.tool(app=AppConfig(resource_uri="ui://my-app/view.html")) +async def list_users() -> list[dict]: + return [{"id": "1", "name": "Alice"}] + +# App-only tool — visible to the UI but hidden from the model +@mcp.tool(app=AppConfig(resource_uri="ui://my-app/view.html", visibility=["app"])) +async def delete_user(id: str) -> dict: + return {"deleted": True} +``` + +The `app=` parameter accepts `True` (enable with defaults), an `AppConfig` instance, or a raw dict for forward compatibility. It merges into `meta["ui"]` — alongside any other metadata you set. + +**`ui://` resources** automatically get the correct MIME type (`text/html;profile=mcp-app`) unless you override it explicitly. + +**Extension negotiation**: The server advertises `io.modelcontextprotocol/ui` in `capabilities.extensions`. UI metadata (`_meta.ui`) always flows through to clients — the MCP Apps spec assigns visibility enforcement to the host, not the server. Tools can check whether the connected client supports a given extension at runtime via `ctx.client_supports_extension()`: + +```python +from fastmcp import Context +from fastmcp.server.apps import AppConfig, UI_EXTENSION_ID + +@mcp.tool(app=AppConfig(resource_uri="ui://dashboard")) +async def dashboard(ctx: Context) -> dict: + data = compute_dashboard() + if ctx.client_supports_extension(UI_EXTENSION_ID): + return data + return {"summary": format_text(data)} +``` + +**Key details:** +- `AppConfig` fields: `resource_uri`, `visibility`, `csp`, `permissions`, `domain`, `prefers_border` (all optional). On resources, `resource_uri` and `visibility` are validated as not-applicable and will raise `ValueError` if set. +- `csp` accepts a `ResourceCSP` model with structured domain lists: `connect_domains`, `resource_domains`, `frame_domains`, `base_uri_domains` +- `permissions` accepts a `ResourcePermissions` model: `camera`, `microphone`, `geolocation`, `clipboard_write` (each set to `{}` to request) +- `AppConfig` uses `extra="allow"` for forward compatibility with future spec additions +- Models use Pydantic aliases for wire format (`resourceUri`, `prefersBorder`, `connectDomains`, `clipboardWrite`) +- Resource metadata (including CSP/permissions) is propagated to `resources/read` response content items so hosts can read it when rendering the iframe +- `ctx.client_supports_extension(id)` is a general-purpose method — works for any extension, not just MCP Apps +- `structuredContent` in tool results already works via `ToolResult` — MCP Apps clients use this to pass data into the iframe +- The server does not strip `_meta.ui` for non-UI clients; per the spec, visibility enforcement is the host's responsibility + +**Future phases** will add a component DSL for building UIs declaratively, an in-repo renderer, and a `FastMCPApp` class. + +Implementation: `src/fastmcp/server/apps.py` (models and constants), with integration points in `server.py` (decorator parameters), `low_level.py` (extension advertisement), and `context.py` (`client_supports_extension` method). + +--- + +## 3.0.0beta1 + +### Provider-Based Architecture + +v3.0 introduces a provider-based component system that replaces v2's static-only registration ([#2622](https://github.com/PrefectHQ/fastmcp/pull/2622)). Providers dynamically source tools, resources, templates, and prompts at runtime. + +**Core abstraction** (`src/fastmcp/server/providers/base.py`): +```python +class Provider: + async def list_tools(self) -> Sequence[Tool]: ... + async def get_tool(self, name: str) -> Tool | None: ... + async def list_resources(self) -> Sequence[Resource]: ... + async def get_resource(self, uri: str) -> Resource | None: ... + async def list_resource_templates(self) -> Sequence[ResourceTemplate]: ... + async def get_resource_template(self, uri: str) -> ResourceTemplate | None: ... + async def list_prompts(self) -> Sequence[Prompt]: ... + async def get_prompt(self, name: str) -> Prompt | None: ... +``` + +Providers support: +- **Lifecycle management**: `async def lifespan()` for setup/teardown +- **Visibility control**: `enable()` / `disable()` with name, version, tags, components, and allowlist mode +- **Transform stacking**: `provider.add_transform(Namespace(...))`, `provider.add_transform(ToolTransform(...))` + +### LocalProvider + +`LocalProvider` (`src/fastmcp/server/providers/local_provider.py`) manages components registered via decorators. Can be used standalone and attached to multiple servers: + +```python +from fastmcp.server.providers import LocalProvider + +provider = LocalProvider() + +@provider.tool +def greet(name: str) -> str: + return f"Hello, {name}!" + +# Attach to multiple servers +server1 = FastMCP("Server1", providers=[provider]) +server2 = FastMCP("Server2", providers=[provider]) +``` + +### ProxyProvider + +`ProxyProvider` (`src/fastmcp/server/providers/proxy.py`) proxies components from remote MCP servers via a client factory. Used by `create_proxy()` and `FastMCP.mount()` for remote server integration. + +```python +from fastmcp.server import create_proxy + +# Create proxy to remote server +server = create_proxy("http://remote-server/mcp") +``` + +### OpenAPIProvider + +`OpenAPIProvider` (`src/fastmcp/server/providers/openapi/provider.py`) creates MCP components from OpenAPI specifications. Routes map HTTP operations to tools, resources, or templates based on configurable rules. + +```python +from fastmcp.server.providers.openapi import OpenAPIProvider +import httpx + +client = httpx.AsyncClient(base_url="https://api.example.com") +provider = OpenAPIProvider(openapi_spec=spec, client=client) + +mcp = FastMCP("API Server", providers=[provider]) +``` + +Features: +- Automatic route-to-component mapping (GET → resource, POST/PUT/DELETE → tool) +- Custom route mappings via `route_maps` or `route_map_fn` +- Component customization via `mcp_component_fn` +- Name collision detection and handling + +### FastMCPProvider + +`FastMCPProvider` (`src/fastmcp/server/providers/fastmcp_provider.py`) wraps a FastMCP server to enable mounting one server onto another. Components delegate execution through the wrapped server's middleware chain. + +```python +from fastmcp import FastMCP +from fastmcp.server.providers import FastMCPProvider +from fastmcp.server.transforms import Namespace + +main = FastMCP("Main") +sub = FastMCP("Sub") + +@sub.tool +def greet(name: str) -> str: + return f"Hello, {name}!" + +# Mount with namespace +provider = FastMCPProvider(sub) +provider.add_transform(Namespace("sub")) +main.add_provider(provider) +# Tool accessible as "sub_greet" +``` + +### Transforms + +Transforms modify components (tools, resources, prompts) as they flow from providers to clients ([#2836](https://github.com/PrefectHQ/fastmcp/pull/2836)). They use a middleware pattern where each transform receives a `call_next` callable to continue the chain. + +**Built-in transforms** (`src/fastmcp/server/transforms/`): + +- `Namespace` - adds prefixes to names (`tool` → `api_tool`) and path segments to URIs (`data://x` → `data://api/x`) +- `ToolTransform` - modifies tool schemas (rename, description, tags, argument transforms) +- `Visibility` - sets visibility state on components by key or tag (backs `enable()`/`disable()` API) +- `VersionFilter` - filters components by version range (`version_gte`, `version_lt`) +- `ResourcesAsTools` - exposes resources as tools for tool-only clients +- `PromptsAsTools` - exposes prompts as tools for tool-only clients + +```python +from fastmcp.server.transforms import Namespace, ToolTransform +from fastmcp.tools.tool_transform import ToolTransformConfig + +provider = SomeProvider() +provider.add_transform(Namespace("api")) +provider.add_transform(ToolTransform({ + "api_verbose_tool_name": ToolTransformConfig(name="short") +})) + +# Stacking composes transformations +# "foo" → "api_foo" (namespace) → "short" (rename) +``` + +**Custom transforms** subclass `Transform` and override needed methods: + +```python +from collections.abc import Sequence +from fastmcp.server.transforms import Transform, ListToolsNext, GetToolNext +from fastmcp.tools import Tool + +class TagFilter(Transform): + def __init__(self, required_tags: set[str]): + self.required_tags = required_tags + + async def list_tools(self, call_next: ListToolsNext) -> Sequence[Tool]: + tools = await call_next() # Get tools from downstream + return [t for t in tools if t.tags & self.required_tags] + + async def get_tool(self, name: str, call_next: GetToolNext) -> Tool | None: + tool = await call_next(name) + return tool if tool and tool.tags & self.required_tags else None +``` + +Transforms apply at two levels: +- **Provider-level**: `provider.add_transform()` - affects only that provider's components +- **Server-level**: `server.add_transform()` - affects all components from all providers + +Documentation: `docs/servers/transforms/transforms.mdx`, `docs/servers/visibility.mdx` + +### ResourcesAsTools and PromptsAsTools + +These transforms expose resources and prompts as tools for clients that only support the tools protocol. Each transform generates two tools that provide listing and access functionality. + +**ResourcesAsTools** generates `list_resources` and `read_resource` tools: + +```python +from fastmcp import FastMCP +from fastmcp.server.transforms import ResourcesAsTools + +mcp = FastMCP("Server") + +@mcp.resource("data://config") +def get_config() -> dict: + return {"setting": "value"} + +mcp.add_transform(ResourcesAsTools(mcp)) +# Now has list_resources and read_resource tools +``` + +The `list_resources` tool returns JSON with resource metadata. The `read_resource` tool accepts a URI and returns the resource content, preserving both text and binary data through base64 encoding. + +**PromptsAsTools** generates `list_prompts` and `get_prompt` tools: + +```python +from fastmcp import FastMCP +from fastmcp.server.transforms import PromptsAsTools + +mcp = FastMCP("Server") + +@mcp.prompt +def analyze_code(code: str, language: str = "python") -> str: + return f"Analyze this {language} code:\n{code}" + +mcp.add_transform(PromptsAsTools(mcp)) +# Now has list_prompts and get_prompt tools +``` + +The `list_prompts` tool returns JSON with prompt metadata including argument information. The `get_prompt` tool accepts a prompt name and optional arguments dict, returning the rendered prompt as a messages array. Non-text content (like embedded resources) is preserved as structured JSON. + +Both transforms: +- Capture a provider reference at construction for deferred querying +- Route through `FastMCP.read_resource()` / `FastMCP.render_prompt()` when the provider is FastMCP, ensuring middleware chains execute +- Fall back to direct provider methods for plain providers +- Return JSON for easy parsing by tool-only clients + +Documentation: `docs/servers/transforms/resources-as-tools.mdx`, `docs/servers/transforms/prompts-as-tools.mdx` + +--- + +### Session-Scoped State + +v3.0 changes context state from request-scoped to session-scoped. State now persists across multiple tool calls within the same MCP session. + +```python +@mcp.tool +async def increment_counter(ctx: Context) -> int: + count = await ctx.get_state("counter") or 0 + await ctx.set_state("counter", count + 1) + return count + 1 +``` + +State is automatically keyed by session ID, ensuring isolation between different clients. The implementation uses [pykeyvalue](https://github.com/strawgate/py-key-value) for pluggable storage backends: + +```python +from key_value.aio.stores.redis import RedisStore + +# Use Redis for distributed deployments +mcp = FastMCP("server", session_state_store=RedisStore(...)) +``` + +**Key details:** +- Methods are now async: `await ctx.get_state()`, `await ctx.set_state()`, `await ctx.delete_state()` +- State expires after 1 day (TTL) to prevent unbounded memory growth +- Works during `on_initialize` middleware when using the same session object +- For distributed HTTP, session identity comes from the `mcp-session-id` header + +Documentation: `docs/servers/context.mdx` + +--- + +### Visibility System + +Components can be enabled/disabled using the visibility system. Each `enable()` or `disable()` call adds a stateless Visibility transform that marks components via internal metadata. Later transforms override earlier ones. + +```python +mcp = FastMCP("Server") + +# Disable by name and component type +mcp.disable(names={"dangerous_tool"}, components=["tool"]) + +# Disable by tag +mcp.disable(tags={"admin"}) + +# Disable by version +mcp.disable(names={"old_tool"}, version="1.0", components=["tool"]) + +# Allowlist mode - only show components with these tags +mcp.enable(tags={"public"}, only=True) + +# Enable overrides earlier disable (later transform wins) +mcp.disable(tags={"internal"}) +mcp.enable(names={"safe_tool"}) # safe_tool is visible despite internal tag +``` + +Works at both server and provider level. Supports: +- **Blocklist mode** (default): All components visible except explicitly disabled +- **Allowlist mode** (`only=True`): Only explicitly enabled components visible +- **Tag-based filtering**: Enable/disable groups of components by tag +- **Override semantics**: Later transforms override earlier marks (enable after disable = enabled) +- **Transform ordering**: Visibility transforms are injected at the point you call them, so component state is known + +#### Per-Session Visibility + +Server-level visibility changes affect all connected clients. For per-session control, use `Context` methods that apply rules only to the current session ([#2917](https://github.com/PrefectHQ/fastmcp/pull/2917)): + +```python +from fastmcp import FastMCP +from fastmcp.server.context import Context + +mcp = FastMCP("Server") + +@mcp.tool(tags={"premium"}) +def premium_analysis(data: str) -> str: + return f"Premium analysis of: {data}" + +@mcp.tool +async def unlock_premium(ctx: Context) -> str: + """Unlock premium features for this session only.""" + await ctx.enable_components(tags={"premium"}) + return "Premium features unlocked" + +@mcp.tool +async def reset_features(ctx: Context) -> str: + """Reset to default feature set.""" + await ctx.reset_visibility() + return "Features reset to defaults" + +# Globally disabled - sessions unlock individually +mcp.disable(tags={"premium"}) +``` + +Session visibility methods: +- `await ctx.enable_components(...)`: Enable components for this session +- `await ctx.disable_components(...)`: Disable components for this session +- `await ctx.reset_visibility()`: Clear session rules, return to global defaults + +Session rules override global transforms. FastMCP automatically sends `ToolListChangedNotification` (and resource/prompt equivalents) to affected sessions when visibility changes. + +Documentation: `docs/servers/visibility.mdx` + +--- + +### Component Versioning + +v3.0 introduces versioning support for tools, resources, and prompts. Components can declare a version, and when multiple versions of the same component exist, the highest version is automatically exposed to clients. + +**Declaring versions:** + +```python +@mcp.tool(version="1.0") +def add(x: int, y: int) -> int: + return x + y + +@mcp.tool(version="2.0") +def add(x: int, y: int, z: int = 0) -> int: + return x + y + z + +# Only v2.0 is exposed to clients via list_tools() +# Calling "add" invokes the v2.0 implementation +``` + +**Version comparison:** +- Uses PEP 440 semantic versioning (1.10 > 1.9 > 1.2) +- Falls back to string comparison for non-PEP 440 versions (dates like `2025-01-15` work) +- Unversioned components sort lower than any versioned component +- The `v` prefix is normalized (`v1.0` equals `1.0`) + +**Version visibility in meta:** + +List operations expose all available versions in the component's `meta` field: + +```python +tools = await client.list_tools() +# Each tool's meta includes: +# - meta["fastmcp"]["version"]: the version of this component ("2.0") +# - meta["fastmcp"]["versions"]: all available versions ["2.0", "1.0"] +``` + +**Retrieving and calling specific versions:** + +```python +# Get the highest version (default) +tool = await server.get_tool("add") + +# Get a specific version +tool_v1 = await server.get_tool("add", version="1.0") + +# Call a specific version +result = await server.call_tool("add", {"x": 1, "y": 2}, version="1.0") +``` + +**Client version requests:** + +The FastMCP client supports version selection: + +```python +async with Client(server) as client: + # Call specific tool version + result = await client.call_tool("add", {"x": 1, "y": 2}, version="1.0") + + # Get specific prompt version + prompt = await client.get_prompt("my_prompt", {"text": "..."}, version="2.0") +``` + +For generic MCP clients, pass version via `_meta` in arguments: + +```json +{ + "x": 1, + "y": 2, + "_meta": { + "fastmcp": { + "version": "1.0" + } + } +} +``` + +**VersionFilter transform:** + +The `VersionFilter` transform enables serving different API versions from a single codebase: + +```python +from fastmcp import FastMCP +from fastmcp.server.providers import LocalProvider +from fastmcp.server.transforms import VersionFilter + +# Define components on a shared provider +components = LocalProvider() + +@components.tool(version="1.0") +def calculate(x: int, y: int) -> int: + return x + y + +@components.tool(version="2.0") +def calculate(x: int, y: int, z: int = 0) -> int: + return x + y + z + +# Create servers that share the provider with different filters +api_v1 = FastMCP("API v1", providers=[components]) +api_v1.add_transform(VersionFilter(version_lt="2.0")) + +api_v2 = FastMCP("API v2", providers=[components]) +api_v2.add_transform(VersionFilter(version_gte="2.0")) +``` + +Parameters mirror comparison operators: +- `version_gte`: Versions >= this value pass through +- `version_lt`: Versions < this value pass through + +**Key format:** + +Component keys now include a version suffix using `@` as a delimiter: +- Versioned: `tool:add@1.0`, `resource:data://config@2.0` +- Unversioned: `tool:add@`, `resource:data://config@` + +The `@` is always present (even for unversioned components) to enable unambiguous parsing of URIs that may contain `@`. + +--- + +### Type-Safe Canonical Results + +v3.0 introduces type-safe result classes that provide explicit control over component responses while supporting MCP runtime metadata: `ToolResult` ([#2736](https://github.com/PrefectHQ/fastmcp/pull/2736)), `ResourceResult` ([#2734](https://github.com/PrefectHQ/fastmcp/pull/2734)), and `PromptResult` ([#2738](https://github.com/PrefectHQ/fastmcp/pull/2738)). + +#### ToolResult + +`ToolResult` (`src/fastmcp/tools/tool.py:79`) provides structured tool responses: + +```python +from fastmcp.tools import ToolResult + +@mcp.tool +def process(data: str) -> ToolResult: + return ToolResult( + content=[TextContent(type="text", text="Done")], + structured_content={"status": "success", "count": 42}, + meta={"processing_time_ms": 150} + ) +``` + +Fields: +- `content`: List of MCP ContentBlocks (text, images, etc.) +- `structured_content`: Dict matching tool's output schema +- `meta`: Runtime metadata passed to MCP as `_meta` + +#### ResourceResult + +`ResourceResult` (`src/fastmcp/resources/resource.py:117`) provides structured resource responses: + +```python +from fastmcp.resources import ResourceResult, ResourceContent + +@mcp.resource("data://items") +def get_items() -> ResourceResult: + return ResourceResult( + contents=[ + ResourceContent({"key": "value"}), # auto-serialized to JSON + ResourceContent(b"binary data"), + ], + meta={"count": 2} + ) +``` + +Accepts strings, bytes, or `list[ResourceContent]` for flexible content handling. + +#### PromptResult + +`PromptResult` (`src/fastmcp/prompts/prompt.py:109`) provides structured prompt responses: + +```python +from fastmcp.prompts import PromptResult, Message + +@mcp.prompt +def conversation() -> PromptResult: + return PromptResult( + messages=[ + Message("What's the weather?"), + Message("It's sunny today.", role="assistant"), + ], + meta={"generated_at": "2024-01-01"} + ) +``` + +--- + +### Background Tasks (SEP-1686) + +v3.0 implements MCP SEP-1686 for background task execution via Docket integration. + +**Configuration** (`src/fastmcp/server/tasks/config.py`): + +```python +from fastmcp.server.tasks import TaskConfig + +@mcp.tool(task=TaskConfig(mode="required")) +async def long_running_task(): + # Must be executed as background task + ... + +@mcp.tool(task=TaskConfig(mode="optional")) +async def flexible_task(): + # Supports both sync and task execution + ... + +@mcp.tool(task=True) # Shorthand for mode="optional" +async def simple_task(): + ... +``` + +Task modes: +- `"forbidden"`: Component does not support task execution (default) +- `"optional"`: Supports both synchronous and task execution +- `"required"`: Must be executed as background task + +Requires Docket server for task scheduling and result polling. + +--- + +### Decorators Return Functions + +v3.0 changes what decorators (`@tool`, `@resource`, `@prompt`) return ([#2856](https://github.com/PrefectHQ/fastmcp/pull/2856)). Decorators now return the original function unchanged, rather than transforming it into a component object. + +**v3 behavior (default):** +```python +@mcp.tool +def greet(name: str) -> str: + return f"Hello, {name}!" + +# greet is still your function - call it directly +greet("World") # "Hello, World!" +``` + +**Why this matters:** +- Functions stay callable - useful for testing and reuse +- Instance methods just work: `mcp.add_tool(obj.method)` +- Matches how Flask, FastAPI, and Typer decorators behave + +**For v2 compatibility:** + +```python +import fastmcp + +# v2 behavior: decorators return FunctionTool/FunctionResource/FunctionPrompt objects +fastmcp.settings.decorator_mode = "object" +``` + +Environment variable: `FASTMCP_DECORATOR_MODE=object` + +--- + +### CLI Auto-Reload + +The `--reload` flag enables file watching with automatic server restarts for development ([#2816](https://github.com/PrefectHQ/fastmcp/pull/2816)). + +```bash +# Watch for changes and restart +fastmcp run server.py --reload + +# Watch specific directories +fastmcp run server.py --reload --reload-dir ./src --reload-dir ./lib + +# Works with any transport +fastmcp run server.py --reload --transport http --port 8080 +``` + +Implementation (`src/fastmcp/cli/run.py`): +- Uses `watchfiles` for efficient file monitoring +- Runs server as subprocess for clean restarts +- Stateless mode for seamless reconnection after restart +- stdio: Full MCP features including elicitation +- HTTP: Limited bidirectional features during reload + +Also available with `fastmcp dev inspector`: +```bash +fastmcp dev inspector server.py # Includes --reload by default +``` + +--- + +### Component Authorization + +v3.0 introduces callable-based authorization for tools, resources, and prompts ([#2855](https://github.com/PrefectHQ/fastmcp/pull/2855)). + +**Component-level auth**: + +```python +from fastmcp import FastMCP +from fastmcp.server.auth import require_scopes + +mcp = FastMCP() + +@mcp.tool(auth=require_scopes("write")) +def protected_tool(): ... + +@mcp.resource("data://secret", auth=require_scopes("read")) +def secret_data(): ... + +@mcp.prompt(auth=require_scopes("admin")) +def admin_prompt(): ... +``` + +**Server-wide auth via middleware**: + +```python +from fastmcp.server.middleware import AuthMiddleware +from fastmcp.server.auth import require_scopes, restrict_tag + +# Require specific scope for all components +mcp = FastMCP(middleware=[AuthMiddleware(auth=require_scopes("api"))]) + +# Tag-based restrictions +mcp = FastMCP(middleware=[ + AuthMiddleware(auth=restrict_tag("admin", scopes=["admin"])) +]) +``` + +Built-in checks: +- `require_scopes(*scopes)`: Requires specific OAuth scopes +- `restrict_tag(tag, scopes)`: Requires scopes only for tagged components + +Custom checks receive `AuthContext` with `token` and `component`: + +```python +def custom_check(ctx: AuthContext) -> bool: + return ctx.token is not None and "admin" in ctx.token.scopes +``` + +STDIO transport bypasses all auth checks (no OAuth concept). + +--- + +### FileSystemProvider + +v3.0 introduces `FileSystemProvider`, a fundamentally different approach to organizing MCP servers. Instead of importing a server instance and decorating functions with `@server.tool`, you use standalone decorators in separate files and let the provider discover them. + +**The problem it solves**: Traditional servers require coordination between files—either tool files import the server (creating coupling) or the server imports all tool modules (creating a registry bottleneck). FileSystemProvider removes this coupling entirely. + +**Usage** ([#2823](https://github.com/PrefectHQ/fastmcp/pull/2823)): + +```python +from fastmcp import FastMCP +from fastmcp.server.providers import FileSystemProvider + +# Scans mcp/ directory for decorated functions +mcp = FastMCP("server", providers=[FileSystemProvider("mcp/")]) +``` + +**Tool files are self-contained**: + +```python +# mcp/tools/greet.py +from fastmcp.tools import tool + +@tool +def greet(name: str) -> str: + """Greet someone by name.""" + return f"Hello, {name}!" +``` + +Features: +- **Standalone decorators**: `@tool`, `@resource`, `@prompt` from `fastmcp.tools`, `fastmcp.resources`, `fastmcp.prompts` ([#2832](https://github.com/PrefectHQ/fastmcp/pull/2832)) +- **Reload mode**: `FileSystemProvider("mcp/", reload=True)` re-scans on every request for development +- **Package support**: Directories with `__init__.py` support relative imports +- **Warning deduplication**: Broken imports warn once per file modification + +Documentation: [FileSystemProvider](/servers/providers/filesystem) + +--- + +### SkillsProvider + +v3.0 introduces `SkillsProvider` for exposing agent skills as MCP resources ([#2944](https://github.com/PrefectHQ/fastmcp/pull/2944)). Skills are directories containing instructions and supporting files that teach AI assistants how to perform tasks—used by Claude Code, Cursor, VS Code Copilot, and other AI coding tools. + +**Usage**: + +```python +from pathlib import Path +from fastmcp import FastMCP +from fastmcp.server.providers.skills import SkillsDirectoryProvider + +mcp = FastMCP("Skills Server") +mcp.add_provider(SkillsDirectoryProvider(roots=Path.home() / ".claude" / "skills")) +``` + +Each subdirectory with a `SKILL.md` file becomes a discoverable skill. Clients see: +- `skill://{name}/SKILL.md` - Main instruction file +- `skill://{name}/_manifest` - JSON listing of all files with sizes and hashes +- `skill://{name}/{path}` - Supporting files (via template or resources) + +**Two-layer architecture**: +- `SkillProvider` - Handles a single skill folder +- `SkillsDirectoryProvider` - Scans directories, creates a `SkillProvider` per valid skill + +**Vendor providers** with locked default paths: + +| Provider | Directory | +|----------|-----------| +| `ClaudeSkillsProvider` | `~/.claude/skills/` | +| `CursorSkillsProvider` | `~/.cursor/skills/` | +| `VSCodeSkillsProvider` | `~/.copilot/skills/` | +| `CodexSkillsProvider` | `/etc/codex/skills/`, `~/.codex/skills/` | +| `GeminiSkillsProvider` | `~/.gemini/skills/` | +| `GooseSkillsProvider` | `~/.config/agents/skills/` | +| `CopilotSkillsProvider` | `~/.copilot/skills/` | +| `OpenCodeSkillsProvider` | `~/.config/opencode/skills/` | + +**Progressive disclosure**: By default, supporting files are hidden from `list_resources()` and accessed via template. Set `supporting_files="resources"` for full enumeration. + +Documentation: [Skills Provider](/servers/providers/skills) + +--- + +### OpenTelemetry Tracing + +v3.0 adds OpenTelemetry instrumentation for observability into server and client operations ([#2869](https://github.com/PrefectHQ/fastmcp/pull/2869)). + +**Server spans**: Created for tool calls, resource reads, and prompt renders with attributes including component key, provider type, session ID, and auth context. + +**Client spans**: Wrap outgoing calls with W3C trace context propagation via request meta. + +```python +# Tracing is passive - configure an OTel SDK to export spans +from opentelemetry import trace +from opentelemetry.sdk.trace import TracerProvider +from opentelemetry.sdk.trace.export import BatchSpanProcessor +from opentelemetry.exporter.otlp.proto.grpc.trace_exporter import OTLPSpanExporter + +provider = TracerProvider() +provider.add_span_processor(BatchSpanProcessor(OTLPSpanExporter())) +trace.set_tracer_provider(provider) + +# Use fastmcp normally - spans export to your configured backend +``` + +Components provide their own span attributes through a `get_span_attributes()` method that subclasses override—this lets LocalProvider, FastMCPProvider, and ProxyProvider each include relevant context (original names, backend URIs, etc.). + +Documentation: [Telemetry](/servers/telemetry) + +--- + +### Pagination + +v3.0 adds pagination support for list operations when servers expose many components ([#2903](https://github.com/PrefectHQ/fastmcp/pull/2903)). + +```python +from fastmcp import FastMCP + +# Enable pagination with 50 items per page +server = FastMCP("ComponentRegistry", list_page_size=50) +``` + +When `list_page_size` is set, `tools/list`, `resources/list`, `resources/templates/list`, and `prompts/list` paginate responses with `nextCursor` for subsequent pages. + +**Client behavior**: The FastMCP Client fetches all pages automatically—`list_tools()` and similar methods return the complete list. For manual pagination (memory constraints, progress reporting), use `_mcp` variants: + +```python +async with Client(server) as client: + result = await client.list_tools_mcp() + while result.nextCursor: + result = await client.list_tools_mcp(cursor=result.nextCursor) +``` + +Documentation: [Pagination](/servers/pagination) + +--- + +### Composable Lifespans + +Lifespans can be combined with the `|` operator for modular setup/teardown ([#2828](https://github.com/PrefectHQ/fastmcp/pull/2828)): + +```python +from fastmcp import FastMCP +from fastmcp.server.lifespan import lifespan + +@lifespan +async def db_lifespan(server): + db = await connect_db() + try: + yield {"db": db} + finally: + await db.close() + +@lifespan +async def cache_lifespan(server): + cache = await connect_cache() + try: + yield {"cache": cache} + finally: + await cache.close() + +mcp = FastMCP("server", lifespan=db_lifespan | cache_lifespan) +``` + +Both enter lifespans in order and exit in reverse (LIFO). Context dicts are merged. + +Also adds `combine_lifespans()` utility for FastAPI integration: + +```python +from fastmcp.utilities.lifespan import combine_lifespans + +app = FastAPI(lifespan=combine_lifespans(app_lifespan, mcp_app.lifespan)) +``` + +Documentation: [Lifespan](/servers/lifespan) + +--- + +### Tool Timeout + +Tools can limit foreground execution time with a `timeout` parameter ([#2872](https://github.com/PrefectHQ/fastmcp/pull/2872)): + +```python +@mcp.tool(timeout=30.0) +async def fetch_data(url: str) -> dict: + """Fetch with 30-second timeout.""" + ... +``` + +When exceeded, clients receive MCP error code `-32000`. Both sync and async tools are supported—sync functions run in thread pools so the timeout applies regardless of execution model. + +Note: This timeout applies to foreground execution only. Background tasks (`task=True`) execute in Docket workers where this timeout isn't enforced. + +--- + +### PingMiddleware + +Sends periodic server-to-client pings to keep long-lived connections alive ([#2838](https://github.com/PrefectHQ/fastmcp/pull/2838)): + +```python +from fastmcp import FastMCP +from fastmcp.server.middleware import PingMiddleware + +mcp = FastMCP("server") +mcp.add_middleware(PingMiddleware(interval_ms=5000)) +``` + +The middleware starts a background ping task on first message from each session, using the session's existing task group for automatic cleanup when the session ends. + +--- + +### Context.transport Property + +Tools can detect which transport is active ([#2850](https://github.com/PrefectHQ/fastmcp/pull/2850)): + +```python +from fastmcp import FastMCP, Context + +mcp = FastMCP("example") + +@mcp.tool +def my_tool(ctx: Context) -> str: + if ctx.transport == "stdio": + return "short response" + return "detailed response with more context" +``` + +Returns `Literal["stdio", "sse", "streamable-http"]` when running, or `None` outside a server context. + +--- + +### Automatic Threadpool for Sync Functions + +Synchronous tools, resources, and prompts now automatically run in a threadpool, preventing event loop blocking during concurrent requests ([#2865](https://github.com/PrefectHQ/fastmcp/pull/2865)): + +```python +import time + +@mcp.tool +def slow_tool(): + time.sleep(10) # No longer blocks other requests + return "done" +``` + +Three concurrent calls now execute in parallel (~10s) rather than sequentially (30s). Uses `anyio.to_thread.run_sync()` which properly propagates contextvars, so `Context` and `Depends` continue to work. + +--- + +### CLI Update Notifications + +The CLI notifies users when a newer FastMCP version is available on PyPI ([#2840](https://github.com/PrefectHQ/fastmcp/pull/2840)). + +**Setting**: `FASTMCP_CHECK_FOR_UPDATES` +- `"stable"` - Check for stable releases (default) +- `"prerelease"` - Include alpha/beta/rc versions +- `"off"` - Disable + +12-hour cache, 2-second timeout, fails silently on network errors. + +--- + +### Deprecated Features + +These emit deprecation warnings but continue to work. + +#### Mount Prefix Parameter + +The `prefix` parameter for `mount()` renamed to `namespace`: + +```python +# Deprecated +main.mount(subserver, prefix="api") + +# New +main.mount(subserver, namespace="api") +``` + +#### Tag Filtering, Tool Serializer, Tool Transformations Init Parameters + +These constructor parameters have been **removed** (not just deprecated) as of rc1. See "Breaking: Deprecated `FastMCP()` Constructor Kwargs Removed" in the rc1 section above. The `add_tool_transformation()` and `remove_tool_transformation()` methods remain as deprecated shims. + +--- + +### Breaking Changes + +#### WSTransport Removed + +The deprecated `WSTransport` client transport has been removed ([#2826](https://github.com/PrefectHQ/fastmcp/pull/2826)). Use `StreamableHttpTransport` instead. + +#### Decorators Return Functions + +Decorators (`@tool`, `@resource`, `@prompt`) now return the original function instead of component objects. Code that treats the decorated function as a `FunctionTool`, `FunctionResource`, or `FunctionPrompt` will break. + +```python +# v2.x +@mcp.tool +def greet(name: str) -> str: + return f"Hello, {name}!" + +isinstance(greet, FunctionTool) # True + +# v3.0 +@mcp.tool +def greet(name: str) -> str: + return f"Hello, {name}!" + +isinstance(greet, FunctionTool) # False +callable(greet) # True - it's still your function +greet("World") # "Hello, World!" +``` + +Set `FASTMCP_DECORATOR_MODE=object` or `fastmcp.settings.decorator_mode = "object"` for v2 behavior. + +#### Component Enable/Disable Moved to Server/Provider + +The `enabled` field and `enable()`/`disable()` methods removed from component objects: + +```python +# v2.x +tool = await server.get_tool("my_tool") +tool.disable() + +# v3.0 +server.disable(names={"my_tool"}, components=["tool"]) +``` + +#### Component Lookup Methods + +Server lookup and listing methods have updated signatures: + +- Parameter names: `get_tool(name=...)`, `get_resource(uri=...)`, etc. (was `key`) +- Plural listing methods renamed: `get_tools()` → `list_tools()`, `get_resources()` → `list_resources()`, etc. +- Return types: `list_tools()`, `list_resources()`, etc. return lists instead of dicts + +```python +# v2.x +tools = await server.get_tools() +tool = tools["my_tool"] + +# v3.0 +tools = await server.list_tools() +tool = next((t for t in tools if t.name == "my_tool"), None) +``` + +#### Prompt Return Types + +Prompt functions now use `Message` instead of `mcp.types.PromptMessage`: + +```python +# v2.x +from mcp.types import PromptMessage, TextContent + +@mcp.prompt +def my_prompt() -> PromptMessage: + return PromptMessage(role="user", content=TextContent(type="text", text="Hello")) + +# v3.0 +from fastmcp.prompts import Message + +@mcp.prompt +def my_prompt() -> Message: + return Message("Hello") # role defaults to "user" +``` + +#### Auth Provider Environment Variables Removed + +Auth providers no longer auto-load from environment variables ([#2752](https://github.com/PrefectHQ/fastmcp/pull/2752)): + +```python +# v2.x - auto-loaded from FASTMCP_SERVER_AUTH_GITHUB_* +auth = GitHubProvider() + +# v3.0 - explicit configuration +import os +auth = GitHubProvider( + client_id=os.environ["GITHUB_CLIENT_ID"], + client_secret=os.environ["GITHUB_CLIENT_SECRET"], +) +``` + +See `docs/development/v3-notes/auth-provider-env-vars.mdx` for rationale. + +#### Server Banner Environment Variable + +`FASTMCP_SHOW_CLI_BANNER` → `FASTMCP_SHOW_SERVER_BANNER` ([#2771](https://github.com/PrefectHQ/fastmcp/pull/2771)) + +Now applies to all server startup methods, not just the CLI. + +#### Context State Methods Are Async + +`ctx.set_state()` and `ctx.get_state()` are now async and session-scoped: + +```python +# v2.x +ctx.set_state("key", "value") +value = ctx.get_state("key") + +# v3.0 +await ctx.set_state("key", "value") +value = await ctx.get_state("key") +``` + +State now persists across requests within a session. 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"/getting-started/upgrading/from-low-level-sdk", + "source": "/getting-started/low-level-sdk" + } + ], + "search": { + "prompt": "Search the docs..." + }, + "styling": { + "codeblocks": { + "theme": { + "dark": "dark-plus", + "light": "snazzy-light" + } + } + }, + "theme": "almond", + "thumbnails": { + "appearance": "light", + "background": "/assets/brand/thumbnail-background-4.jpeg" + } +} \ No newline at end of file diff --git a/docs/getting-started/installation.mdx b/docs/getting-started/installation.mdx new file mode 100644 index 000000000..20443337b --- /dev/null +++ b/docs/getting-started/installation.mdx @@ -0,0 +1,97 @@ +--- +title: Installation +description: Install FastMCP and verify your setup +icon: arrow-down-to-line +--- +## Install FastMCP + +We recommend using [uv](https://docs.astral.sh/uv/getting-started/installation/) to install and manage FastMCP. + +```bash +pip install fastmcp +``` + +Or with uv: + +```bash +uv add fastmcp +``` + +### Optional Dependencies + +FastMCP provides optional extras for specific features. For example, to install the background tasks extra: + +```bash +pip install "fastmcp[tasks]" +``` + +See [Background Tasks](/servers/tasks) for details on the task system. + +### Verify Installation + +To verify that FastMCP is installed correctly, you can run the following command: + +```bash +fastmcp version +``` + +You should see output like the following: + +```bash +$ fastmcp version + +FastMCP version: 3.0.0 +MCP version: 1.25.0 +Python version: 3.12.2 +Platform: macOS-15.3.1-arm64-arm-64bit +FastMCP root path: ~/Developer/fastmcp +``` + +### Dependency Licensing + + +FastMCP depends on Cyclopts for CLI functionality. Cyclopts v4 includes docutils as a transitive dependency, which has complex licensing that may trigger compliance reviews in some organizations. + +If this is a concern, you can install Cyclopts v5 alpha which removes this dependency: + +```bash +pip install "cyclopts>=5.0.0a1" +``` + +Alternatively, wait for the stable v5 release. See [this issue](https://github.com/BrianPugh/cyclopts/issues/672) for details. + +## Upgrading + +### From FastMCP 2.0 + +See the [Upgrade Guide](/getting-started/upgrading/from-fastmcp-2) for a complete list of breaking changes and migration steps. + +### From the MCP SDK + +#### From FastMCP 1.0 + +If you're using FastMCP 1.0 via the `mcp` package (meaning you import FastMCP as `from mcp.server.fastmcp import FastMCP`), upgrading is straightforward — for most servers, it's a single import change. See the [full upgrade guide](/getting-started/upgrading/from-mcp-sdk) for details. + +#### From the Low-Level Server API + +If you built your server directly on the `mcp` package's `Server` class — with `list_tools()`/`call_tool()` handlers and hand-written JSON Schema — see the [migration guide](/getting-started/upgrading/from-low-level-sdk) for a full walkthrough. + +## Versioning Policy + +FastMCP follows semantic versioning with pragmatic adaptations for the rapidly evolving MCP ecosystem. Breaking changes may occur in minor versions (e.g., 2.3.x to 2.4.0) when necessary to stay current with the MCP Protocol. + +For production use, always pin to exact versions: +``` +fastmcp==3.0.0 # Good +fastmcp>=3.0.0 # Bad - may install breaking changes +``` + +See the full [versioning and release policy](/development/releases#versioning-policy) for details on our public API, deprecation practices, and breaking change philosophy. + +## Contributing to FastMCP + +Interested in contributing to FastMCP? See the [Contributing Guide](/development/contributing) for details on: +- Setting up your development environment +- Running tests and pre-commit hooks +- Submitting issues and pull requests +- Code standards and review process diff --git a/docs/getting-started/quickstart.mdx b/docs/getting-started/quickstart.mdx new file mode 100644 index 000000000..3f240cec1 --- /dev/null +++ b/docs/getting-started/quickstart.mdx @@ -0,0 +1,136 @@ +--- +title: Quickstart +icon: rocket-launch +--- + +Welcome! This guide will help you quickly set up FastMCP, run your first MCP server, and deploy a server to Prefect Horizon. + +If you haven't already installed FastMCP, follow the [installation instructions](/getting-started/installation). + +## Create a FastMCP Server + +A FastMCP server is a collection of tools, resources, and other MCP components. To create a server, start by instantiating the `FastMCP` class. + +Create a new file called `my_server.py` and add the following code: + +```python my_server.py +from fastmcp import FastMCP + +mcp = FastMCP("My MCP Server") +``` + + +That's it! You've created a FastMCP server, albeit a very boring one. Let's add a tool to make it more interesting. + + +## Add a Tool + +To add a tool that returns a simple greeting, write a function and decorate it with `@mcp.tool` to register it with the server: + +```python my_server.py {5-7} +from fastmcp import FastMCP + +mcp = FastMCP("My MCP Server") + +@mcp.tool +def greet(name: str) -> str: + return f"Hello, {name}!" +``` + + +## Run the Server + +The simplest way to run your FastMCP server is to call its `run()` method. You can choose between different transports, like `stdio` for local servers, or `http` for remote access: + + + +```python my_server.py (stdio) {9, 10} +from fastmcp import FastMCP + +mcp = FastMCP("My MCP Server") + +@mcp.tool +def greet(name: str) -> str: + return f"Hello, {name}!" + +if __name__ == "__main__": + mcp.run() +``` + +```python my_server.py (HTTP) {9, 10} +from fastmcp import FastMCP + +mcp = FastMCP("My MCP Server") + +@mcp.tool +def greet(name: str) -> str: + return f"Hello, {name}!" + +if __name__ == "__main__": + mcp.run(transport="http", port=8000) +``` + + + +This lets us run the server with `python my_server.py`. The stdio transport is the traditional way to connect MCP servers to clients, while the HTTP transport enables remote connections. + + +Why do we need the `if __name__ == "__main__":` block? + +The `__main__` block is recommended for consistency and compatibility, ensuring your server works with all MCP clients that execute your server file as a script. Users who will exclusively run their server with the FastMCP CLI can omit it, as the CLI imports the server object directly. + + +### Using the FastMCP CLI + +You can also use the `fastmcp run` command to start your server. Note that the FastMCP CLI **does not** execute the `__main__` block of your server file. Instead, it imports your server object and runs it with whatever transport and options you provide. + +For example, to run this server with the default stdio transport (no matter how you called `mcp.run()`), you can use the following command: +```bash +fastmcp run my_server.py:mcp +``` + +To run this server with the HTTP transport, you can use the following command: +```bash +fastmcp run my_server.py:mcp --transport http --port 8000 +``` + +## Call Your Server + +Once your server is running with HTTP transport, you can connect to it with a FastMCP client or any LLM client that supports the MCP protocol: + +```python my_client.py +import asyncio +from fastmcp import Client + +client = Client("http://localhost:8000/mcp") + +async def call_tool(name: str): + async with client: + result = await client.call_tool("greet", {"name": name}) + print(result) + +asyncio.run(call_tool("Ford")) +``` + +Note that: +- FastMCP clients are asynchronous, so we need to use `asyncio.run` to run the client +- We must enter a client context (`async with client:`) before using the client +- You can make multiple client calls within the same context + +## Deploy to Prefect Horizon + +[Prefect Horizon](https://horizon.prefect.io) is the enterprise MCP platform built by the FastMCP team at [Prefect](https://www.prefect.io). It provides managed hosting, authentication, access control, and observability for MCP servers. + + +Horizon is **free for personal projects** and offers enterprise governance for teams. + + +To deploy your server, you'll need a [GitHub account](https://github.com). Once you have one, you can deploy your server in three steps: + +1. Push your `my_server.py` file to a GitHub repository +2. Sign in to [Prefect Horizon](https://horizon.prefect.io) with your GitHub account +3. Create a new project from your repository and enter `my_server.py:mcp` as the server entrypoint + +That's it! Horizon will build and deploy your server, making it available at a URL like `https://your-project.fastmcp.app/mcp`. You can chat with it to test its functionality, or connect to it from any LLM client that supports the MCP protocol. + +For more details, see the [Prefect Horizon guide](/deployment/prefect-horizon). diff --git a/docs/getting-started/upgrading/from-fastmcp-2.mdx b/docs/getting-started/upgrading/from-fastmcp-2.mdx new file mode 100644 index 000000000..47baa5655 --- /dev/null +++ b/docs/getting-started/upgrading/from-fastmcp-2.mdx @@ -0,0 +1,440 @@ +--- +title: Upgrading from FastMCP 2 +sidebarTitle: "From FastMCP 2" +description: Migration instructions for upgrading between FastMCP versions +icon: up +--- + +This guide covers breaking changes and migration steps when upgrading FastMCP. + +## v3.0.0 + +For most servers, upgrading to v3 is straightforward. The breaking changes below affect deprecated constructor kwargs, sync-to-async shifts, a few renamed methods, and some less commonly used features. + +### Install + +Since you already have `fastmcp` installed, you need to explicitly request the new version — `pip install fastmcp` won't upgrade an existing installation: + +```bash +pip install --upgrade fastmcp +# or +uv add --upgrade fastmcp +``` + +If you pin versions in a requirements file or `pyproject.toml`, update your pin to `fastmcp>=3.0.0,<4`. + + +**New repository home.** As part of the v3 release, FastMCP's GitHub repository has moved from `jlowin/fastmcp` to [`PrefectHQ/fastmcp`](https://github.com/PrefectHQ/fastmcp) under [Prefect](https://prefect.io)'s stewardship. GitHub automatically redirects existing clones and bookmarks, so nothing breaks — but you can update your local remote whenever convenient: + +```bash +git remote set-url origin https://github.com/PrefectHQ/fastmcp.git +``` + +If you reference the repository URL in dependency specifications (e.g., `git+https://github.com/jlowin/fastmcp.git`), update those to the new location. + + + +You are upgrading a FastMCP v2 server to FastMCP v3.0. Analyze the provided code and identify every change needed. The full upgrade guide is at https://gofastmcp.com/getting-started/upgrading/from-fastmcp-2 and the complete FastMCP documentation is at https://gofastmcp.com — fetch these for complete context. + +BREAKING CHANGES (will crash at import or runtime): + +1. CONSTRUCTOR KWARGS REMOVED: FastMCP() no longer accepts these kwargs (raises TypeError): + - Transport settings: host, port, log_level, debug, sse_path, streamable_http_path, json_response, stateless_http + Fix: pass to run() or run_http_async() instead, e.g. mcp.run(transport="http", host="0.0.0.0", port=8080) + - message_path: set via environment variable FASTMCP_MESSAGE_PATH only (not a run() kwarg) + - Duplicate handling: on_duplicate_tools, on_duplicate_resources, on_duplicate_prompts + Fix: use unified on_duplicate= parameter + - Tool settings: tool_serializer, include_tags, exclude_tags, tool_transformations + Fix: use ToolResult returns, server.enable()/disable(), server.add_transform() + +2. COMPONENT METHODS REMOVED: + - tool.enable()/disable() raises NotImplementedError + Fix: server.disable(names={"tool_name"}, components={"tool"}) or server.disable(tags={"tag"}) + - get_tools()/get_resources()/get_prompts()/get_resource_templates() removed + Fix: use list_tools()/list_resources()/list_prompts()/list_resource_templates() — these return lists, not dicts + +3. ASYNC STATE: ctx.set_state() and ctx.get_state() are now async (must be awaited). + State values must be JSON-serializable unless serializable=False is passed. + Each FastMCP instance has its own state store, so serializable state set by parent middleware isn't visible to mounted tools by default. + Fix: pass the same session_state_store to both servers, or use serializable=False (request-scoped state is always shared). + +4. PROMPTS: mcp.types.PromptMessage replaced by fastmcp.prompts.Message. + Before: PromptMessage(role="user", content=TextContent(type="text", text="Hello")) + After: Message("Hello") # role defaults to "user", accepts plain strings + Also: if prompts return raw dicts like `{"role": "user", "content": "..."}`, these must become Message objects. + v2 silently coerced dicts; v3 requires typed Message objects or plain strings. + +5. AUTH PROVIDERS: No longer auto-load from env vars. Pass client_id, client_secret explicitly via os.environ. + +6. WSTRANSPORT: Removed. Use StreamableHttpTransport. + +7. OPENAPI: timeout parameter removed from OpenAPIProvider. Set timeout on the httpx.AsyncClient instead. + +8. METADATA: Namespace changed from "_fastmcp" to "fastmcp" in tool.meta. The include_fastmcp_meta parameter is removed (always included). + +9. ENV VAR: FASTMCP_SHOW_CLI_BANNER renamed to FASTMCP_SHOW_SERVER_BANNER. + +10. DECORATORS: @mcp.tool, @mcp.resource, @mcp.prompt now return the original function, not a component object. Code that accesses .name, .description, or other component attributes on the decorated result will crash with AttributeError. + Fix: set FASTMCP_DECORATOR_MODE=object for v2 compat (itself deprecated). + +11. OAUTH STORAGE: Default OAuth client storage changed from DiskStore to FileTreeStore due to pickle deserialization vulnerability in diskcache (CVE-2025-69872). Clients using default storage will re-register automatically on first connection. If using DiskStore explicitly, switch to FileTreeStore or add pip install 'py-key-value-aio[disk]'. + +12. REPO MOVE: GitHub repository moved from jlowin/fastmcp to PrefectHQ/fastmcp. Update git remotes and dependency URLs that reference the old location. + +13. BACKGROUND TASKS: FastMCP's background task system (SEP-1686) is now an optional dependency. If the code uses task=True or TaskConfig, add pip install "fastmcp[tasks]". + +DEPRECATIONS (still work but emit warnings): + +- mount(prefix="x") -> mount(namespace="x") +- import_server(sub) -> mount(sub) +- FastMCP.as_proxy(url) -> from fastmcp.server import create_proxy; create_proxy(url) +- from fastmcp.server.proxy -> from fastmcp.server.providers.proxy +- from fastmcp.server.openapi import FastMCPOpenAPI -> from fastmcp.server.providers.openapi import OpenAPIProvider; use FastMCP("name", providers=[OpenAPIProvider(...)]) +- mcp.add_tool_transformation(name, cfg) -> from fastmcp.server.transforms import ToolTransform; mcp.add_transform(ToolTransform(...)) + +For each issue found, show the original line, explain why it breaks, and provide the corrected code. + + +### Breaking Changes + +**Transport and server settings removed from constructor** + +In v2, you could configure transport settings directly in the `FastMCP()` constructor. In v3, `FastMCP()` is purely about your server's identity and behavior — transport configuration happens when you actually start serving. Passing any of the old kwargs now raises `TypeError` with a migration hint. + +```python +# Before +mcp = FastMCP("server", host="0.0.0.0", port=8080) +mcp.run() + +# After +mcp = FastMCP("server") +mcp.run(transport="http", host="0.0.0.0", port=8080) +``` + +The full list of removed kwargs and their replacements: + +- `host`, `port`, `log_level`, `debug`, `sse_path`, `streamable_http_path`, `json_response`, `stateless_http` — pass to `run()`, `run_http_async()`, or `http_app()`, or set via environment variables (e.g. `FASTMCP_HOST`) +- `message_path` — set via environment variable `FASTMCP_MESSAGE_PATH` only (not a `run()` kwarg) +- `on_duplicate_tools`, `on_duplicate_resources`, `on_duplicate_prompts` — consolidated into a single `on_duplicate=` parameter +- `tool_serializer` — return [`ToolResult`](/servers/tools#custom-serialization) from your tools instead +- `include_tags` / `exclude_tags` — use `server.enable(tags=..., only=True)` / `server.disable(tags=...)` after construction +- `tool_transformations` — use `server.add_transform(ToolTransform(...))` after construction + +**OAuth storage backend changed (diskcache CVE)** + +The default OAuth client storage has moved from `DiskStore` to `FileTreeStore` to address a pickle deserialization vulnerability in diskcache ([CVE-2025-69872](https://github.com/PrefectHQ/fastmcp/issues/3166)). + +If you were using the default storage (i.e., not passing an explicit `client_storage`), clients will need to re-register on their first connection after upgrading. This happens automatically — no user action required, and it's the same flow that already occurs whenever a server restarts with in-memory storage. + +If you were passing a `DiskStore` explicitly, you can either [switch to `FileTreeStore`](/servers/storage-backends) (recommended) or keep using `DiskStore` by adding the dependency yourself: + + +Keeping `DiskStore` requires `pip install 'py-key-value-aio[disk]'`, which re-introduces the vulnerable `diskcache` package into your dependency tree. + + +**Component enable()/disable() moved to server** + +In v2, you could enable or disable individual components by calling methods on the component object itself. In v3, visibility is controlled through the server (or provider), which lets you target components by name, tag, or type without needing a reference to the object: + +```python +# Before +tool = await server.get_tool("my_tool") +tool.disable() + +# After +server.disable(names={"my_tool"}, components={"tool"}) +``` + +Calling `.enable()` or `.disable()` on a component object now raises `NotImplementedError`. See [Visibility](/servers/visibility) for the full API, including tag-based filtering and per-session visibility. + +**Listing methods renamed and return lists** + +The `get_tools()`, `get_resources()`, `get_prompts()`, and `get_resource_templates()` methods have been renamed to `list_tools()`, `list_resources()`, `list_prompts()`, and `list_resource_templates()`. More importantly, they now return lists instead of dicts — so code that indexes by name needs to change: + +```python +# Before +tools = await server.get_tools() +tool = tools["my_tool"] + +# After +tools = await server.list_tools() +tool = next((t for t in tools if t.name == "my_tool"), None) +``` + +**Prompts use Message class** + +Prompt functions now use FastMCP's `Message` class instead of `mcp.types.PromptMessage`. The new class is simpler — it accepts a plain string and defaults to `role="user"`, so most prompts become one-liners: + +```python +# Before +from mcp.types import PromptMessage, TextContent + +@mcp.prompt +def my_prompt() -> PromptMessage: + return PromptMessage(role="user", content=TextContent(type="text", text="Hello")) + +# After +from fastmcp.prompts import Message + +@mcp.prompt +def my_prompt() -> Message: + return Message("Hello") +``` + +If your prompt functions return raw dicts with `role` and `content` keys, those also need to change. v2 silently coerced dicts into prompt messages, but v3 requires typed `Message` objects (or plain strings for single user messages): + +```python +# Before (v2 accepted this) +@mcp.prompt +def my_prompt(): + return [ + {"role": "user", "content": "Hello"}, + {"role": "assistant", "content": "How can I help?"}, + ] + +# After +from fastmcp.prompts import Message + +@mcp.prompt +def my_prompt() -> list[Message]: + return [ + Message("Hello"), + Message("How can I help?", role="assistant"), + ] +``` + +**Context state methods are async** + +`ctx.set_state()` and `ctx.get_state()` are now async because state in v3 is session-scoped and backed by a pluggable storage backend (rather than a simple dict). This means state persists across multiple tool calls within the same session: + +```python +# Before +ctx.set_state("key", "value") +value = ctx.get_state("key") + +# After +await ctx.set_state("key", "value") +value = await ctx.get_state("key") +``` + +State values must also be JSON-serializable by default (dicts, lists, strings, numbers, etc.). If you need to store non-serializable values like an HTTP client, pass `serializable=False` — these values are request-scoped and only available during the current tool call: + +```python +await ctx.set_state("client", my_http_client, serializable=False) +``` + +**Mounted servers have isolated state stores** + +Each `FastMCP` instance has its own state store. In v2 this wasn't noticeable because mounted tools ran in the parent's context, but in v3's provider architecture each server is isolated. Non-serializable state (`serializable=False`) is request-scoped and automatically shared across mount boundaries. For serializable state, pass the same `session_state_store` to both servers: + +```python +from fastmcp import FastMCP +from key_value.aio.stores.memory import MemoryStore + +store = MemoryStore() +parent = FastMCP("Parent", session_state_store=store) +child = FastMCP("Child", session_state_store=store) +parent.mount(child, namespace="child") +``` + +**Auth provider environment variables removed** + +In v2, auth providers like `GitHubProvider` could auto-load configuration from environment variables with a `FASTMCP_SERVER_AUTH_*` prefix. This magic has been removed — pass values explicitly: + +```python +# Before (v2) — client_id and client_secret loaded automatically +# from FASTMCP_SERVER_AUTH_GITHUB_CLIENT_ID, etc. +auth = GitHubProvider() + +# After (v3) — pass values explicitly +import os +from fastmcp.server.auth.providers.github import GitHubProvider + +auth = GitHubProvider( + client_id=os.environ["GITHUB_CLIENT_ID"], + client_secret=os.environ["GITHUB_CLIENT_SECRET"], +) +``` + +**WSTransport removed** + +The deprecated WebSocket client transport has been removed. Use `StreamableHttpTransport` instead: + +```python +# Before +from fastmcp.client.transports import WSTransport +transport = WSTransport("ws://localhost:8000/ws") + +# After +from fastmcp.client.transports import StreamableHttpTransport +transport = StreamableHttpTransport("http://localhost:8000/mcp") +``` + +**OpenAPI `timeout` parameter removed** + +`OpenAPIProvider` no longer accepts a `timeout` parameter. Configure timeout on the httpx client directly. The `client` parameter is also now optional — when omitted, a default client is created from the spec's `servers` URL with a 30-second timeout: + +```python +# Before +provider = OpenAPIProvider(spec, client, timeout=60) + +# After +client = httpx.AsyncClient(base_url="https://api.example.com", timeout=60) +provider = OpenAPIProvider(spec, client) +``` + +**Metadata namespace renamed** + +The FastMCP metadata key in component `meta` dicts changed from `_fastmcp` to `fastmcp`. If you read metadata from tool or resource objects, update the key: + +```python +# Before +tags = tool.meta.get("_fastmcp", {}).get("tags", []) + +# After +tags = tool.meta.get("fastmcp", {}).get("tags", []) +``` + +Metadata is now always included — the `include_fastmcp_meta` parameter has been removed from `FastMCP()` and `to_mcp_tool()`, so there is no way to suppress it. + +**Server banner environment variable renamed** + +`FASTMCP_SHOW_CLI_BANNER` is now `FASTMCP_SHOW_SERVER_BANNER`. + +**Decorators return functions** + +In v2, `@mcp.tool` transformed your function into a `FunctionTool` object. In v3, decorators return your original function unchanged — which means decorated functions stay callable for testing, reuse, and composition: + +```python +@mcp.tool +def greet(name: str) -> str: + return f"Hello, {name}!" + +greet("World") # Works! Returns "Hello, World!" +``` + +If you have code that treats the decorated result as a `FunctionTool` (e.g., accessing `.name` or `.description`), set `FASTMCP_DECORATOR_MODE=object` for v2 compatibility. This escape hatch is itself deprecated and will be removed in a future release. + +**Background tasks require optional dependency** + +FastMCP's background task system (SEP-1686) is now behind an optional extra. If your server uses background tasks, install with: + +```bash +pip install "fastmcp[tasks]" +``` + +Without the extra, configuring a tool with `task=True` or `TaskConfig` will raise an import error at runtime. See [Background Tasks](/servers/tasks) for details. + +### Deprecated Features + +These still work but emit warnings. Update when convenient. + +**mount() prefix → namespace** + +```python +# Deprecated +main.mount(subserver, prefix="api") + +# New +main.mount(subserver, namespace="api") +``` + +**import_server() → mount()** + +```python +# Deprecated +main.import_server(subserver) + +# New +main.mount(subserver) +``` + +**Module import paths for proxy and OpenAPI** + +The proxy and OpenAPI modules have moved under `providers` to reflect v3's provider-based architecture: + +```python +# Deprecated +from fastmcp.server.proxy import FastMCPProxy +from fastmcp.server.openapi import FastMCPOpenAPI + +# New +from fastmcp.server.providers.proxy import FastMCPProxy +from fastmcp.server.providers.openapi import OpenAPIProvider +``` + +`FastMCPOpenAPI` itself is deprecated — use `FastMCP` with an `OpenAPIProvider` instead: + +```python +# Deprecated +from fastmcp.server.openapi import FastMCPOpenAPI +server = FastMCPOpenAPI(spec, client) + +# New +from fastmcp import FastMCP +from fastmcp.server.providers.openapi import OpenAPIProvider +server = FastMCP("my_api", providers=[OpenAPIProvider(spec, client)]) +``` + +**add_tool_transformation() → add_transform()** + +```python +# Deprecated +mcp.add_tool_transformation("name", config) + +# New +from fastmcp.server.transforms import ToolTransform +mcp.add_transform(ToolTransform({"name": config})) +``` + +**FastMCP.as_proxy() → create_proxy()** + +```python +# Deprecated +proxy = FastMCP.as_proxy("http://example.com/mcp") + +# New +from fastmcp.server import create_proxy +proxy = create_proxy("http://example.com/mcp") +``` + +## v2.14.0 + +### OpenAPI Parser Promotion + +The experimental OpenAPI parser is now standard. Update imports: + +```python +# Before +from fastmcp.experimental.server.openapi import FastMCPOpenAPI + +# After +from fastmcp.server.openapi import FastMCPOpenAPI +``` + +### Removed Deprecated Features + +- `BearerAuthProvider` → use `JWTVerifier` +- `Context.get_http_request()` → use `get_http_request()` from dependencies +- `from fastmcp import Image` → use `from fastmcp.utilities.types import Image` +- `FastMCP(dependencies=[...])` → use `fastmcp.json` configuration +- `FastMCPProxy(client=...)` → use `client_factory=lambda: ...` +- `output_schema=False` → use `output_schema=None` + +## v2.13.0 + +### OAuth Token Key Management + +The OAuth proxy now issues its own JWT tokens. For production, provide explicit keys: + +```python +auth = GitHubProvider( + client_id=os.environ["GITHUB_CLIENT_ID"], + client_secret=os.environ["GITHUB_CLIENT_SECRET"], + base_url="https://your-server.com", + jwt_signing_key=os.environ["JWT_SIGNING_KEY"], + client_storage=RedisStore(host="redis.example.com"), +) +``` + +See [OAuth Token Security](/deployment/http#oauth-token-security) for details. diff --git a/docs/getting-started/upgrading/from-low-level-sdk.mdx b/docs/getting-started/upgrading/from-low-level-sdk.mdx new file mode 100644 index 000000000..ce4ddea75 --- /dev/null +++ b/docs/getting-started/upgrading/from-low-level-sdk.mdx @@ -0,0 +1,592 @@ +--- +title: Upgrading from the MCP Low-Level SDK +sidebarTitle: "From MCP Low-Level SDK" +description: Upgrade your MCP server from the low-level Python SDK's Server class to FastMCP +icon: up +--- + +If you've been building MCP servers directly on the `mcp` package's `Server` class — writing `list_tools()` and `call_tool()` handlers, hand-crafting JSON Schema dicts, and wiring up transport boilerplate — this guide is for you. FastMCP replaces all of that machinery with a declarative, Pythonic API where your functions *are* the protocol surface. + +The core idea: instead of telling the SDK what your tools look like and then separately implementing them, you write ordinary Python functions and let FastMCP derive the protocol layer from your code. Type hints become JSON Schema. Docstrings become descriptions. Return values are serialized automatically. The plumbing you wrote to satisfy the protocol just disappears. + + +This guide covers upgrading from **v1** of the `mcp` package. We'll provide a separate guide when v2 ships. + + + +Already using FastMCP 1.0 via `from mcp.server.fastmcp import FastMCP`? Your upgrade is simpler — see the [FastMCP 1.0 upgrade guide](/getting-started/upgrading/from-mcp-sdk) instead. + + + +You are upgrading an MCP server from the `mcp` package's low-level Server class (v1) to FastMCP 3.0. The server currently uses `mcp.server.Server` (or `mcp.server.lowlevel.server.Server`) with manual handler registration. Analyze the provided code and rewrite it using FastMCP's high-level API. The full guide is at https://gofastmcp.com/getting-started/upgrading/from-low-level-sdk and the complete FastMCP documentation is at https://gofastmcp.com — fetch these for complete context. + +UPGRADE RULES: + +1. IMPORTS: Replace all `mcp.*` imports with FastMCP equivalents. + - `from mcp.server import Server` or `from mcp.server.lowlevel.server import Server` → `from fastmcp import FastMCP` + - `import mcp.types as types` → remove (not needed for most code) + - `from mcp.server.stdio import stdio_server` → remove (handled by mcp.run()) + - `from mcp.server.sse import SseServerTransport` → remove (handled by mcp.run()) + +2. SERVER: Replace `Server("name")` with `FastMCP("name")`. + +3. TOOLS: Replace the list_tools + call_tool handler pair with individual @mcp.tool decorators. + - Delete the `@server.list_tools()` handler entirely + - Delete the `@server.call_tool()` handler entirely + - For each tool that was listed in list_tools and dispatched in call_tool, create a new function: + - Decorate it with `@mcp.tool` + - Use the tool name as the function name (or pass name= to the decorator) + - Use the docstring for the description (or pass description= to the decorator) + - Convert the inputSchema JSON Schema into typed Python parameters (e.g., `{"type": "integer"}` → `int`, `{"type": "string"}` → `str`, `{"type": "array", "items": {"type": "string"}}` → `list[str]`) + - Return plain Python values (`str`, `int`, `dict`, etc.) instead of `list[types.TextContent(...)]` + - If the tool returned `types.ImageContent` or `types.EmbeddedResource`, use `from fastmcp.utilities.types import Image` or return the appropriate type + +4. RESOURCES: Replace the list_resources + list_resource_templates + read_resource handler trio with individual @mcp.resource decorators. + - Delete all three handlers + - For each static resource, create a function decorated with `@mcp.resource("uri://...")` + - For each resource template, use `@mcp.resource("uri://{param}/path")` with `{param}` in the URI and a matching function parameter + - Return str for text content, bytes for binary content + - Set `mime_type=` in the decorator if needed + +5. PROMPTS: Replace the list_prompts + get_prompt handler pair with individual @mcp.prompt decorators. + - Delete both handlers + - For each prompt, create a function decorated with `@mcp.prompt` + - Convert PromptArgument definitions into typed function parameters + - Return str for simple single-message prompts (auto-wrapped as user message) + - Return `list[Message]` for multi-message prompts: `from fastmcp.prompts import Message` + - `Message("text")` defaults to `role="user"`; use `Message("text", role="assistant")` for assistant messages + +6. TRANSPORT: Replace all transport boilerplate with mcp.run(). + - `async with stdio_server() as (r, w): await server.run(r, w, ...)` → `mcp.run()` (`stdio` is the default) + - SSE/Starlette setup → `mcp.run(transport="sse", host="...", port=...)` + - Streamable HTTP setup → `mcp.run(transport="http", host="...", port=...)` + - Delete asyncio.run(main()) boilerplate — use `if __name__ == "__main__": mcp.run()` + +7. CONTEXT: Replace `server.request_context` with FastMCP's Context parameter. + - Add `from fastmcp import Context` and add a `ctx: Context` parameter to any tool that needs it + - `server.request_context.session.send_log_message(...)` → `await ctx.info("message")` or `await ctx.warning("message")` + - Progress reporting → `await ctx.report_progress(current, total)` + +For each change, show the original code, explain what it did, and provide the FastMCP equivalent. + + +## Install + +```bash +pip install --upgrade fastmcp +# or +uv add fastmcp +``` + +FastMCP includes the `mcp` package as a transitive dependency, so you don't lose access to anything. + +## Server and Transport + +The `Server` class requires you to choose a transport, connect streams, build initialization options, and run an event loop. FastMCP collapses all of that into a constructor and a `run()` call. + + + +```python Before +import asyncio +from mcp.server import Server +from mcp.server.stdio import stdio_server + +server = Server("my-server") + +# ... register handlers ... + +async def main(): + async with stdio_server() as (read_stream, write_stream): + await server.run( + read_stream, + write_stream, + server.create_initialization_options(), + ) + +asyncio.run(main()) +``` + +```python After +from fastmcp import FastMCP + +mcp = FastMCP("my-server") + +# ... register tools, resources, prompts ... + +if __name__ == "__main__": + mcp.run() +``` + + + +Need HTTP instead of stdio? With the `Server` class, you'd wire up Starlette routes and `SseServerTransport` or `StreamableHTTPSessionManager`. With FastMCP: + +```python +mcp.run(transport="http", host="0.0.0.0", port=8000) +``` + +## Tools + +This is where the difference is most dramatic. The `Server` class requires two handlers — one to describe your tools (with hand-written JSON Schema) and another to dispatch calls by name. FastMCP eliminates both by deriving everything from your function signature. + + + +```python Before +import mcp.types as types +from mcp.server import Server + +server = Server("math") + +@server.list_tools() +async def list_tools() -> list[types.Tool]: + return [ + types.Tool( + name="add", + description="Add two numbers", + inputSchema={ + "type": "object", + "properties": { + "a": {"type": "number"}, + "b": {"type": "number"}, + }, + "required": ["a", "b"], + }, + ), + types.Tool( + name="multiply", + description="Multiply two numbers", + inputSchema={ + "type": "object", + "properties": { + "a": {"type": "number"}, + "b": {"type": "number"}, + }, + "required": ["a", "b"], + }, + ), + ] + +@server.call_tool() +async def call_tool( + name: str, arguments: dict +) -> list[types.TextContent]: + if name == "add": + result = arguments["a"] + arguments["b"] + return [types.TextContent(type="text", text=str(result))] + elif name == "multiply": + result = arguments["a"] * arguments["b"] + return [types.TextContent(type="text", text=str(result))] + raise ValueError(f"Unknown tool: {name}") +``` + +```python After +from fastmcp import FastMCP + +mcp = FastMCP("math") + +@mcp.tool +def add(a: float, b: float) -> float: + """Add two numbers""" + return a + b + +@mcp.tool +def multiply(a: float, b: float) -> float: + """Multiply two numbers""" + return a * b +``` + + + +Each `@mcp.tool` function is self-contained: its name becomes the tool name, its docstring becomes the description, its type annotations become the JSON Schema, and its return value is serialized automatically. No routing. No schema dictionaries. No content-type wrappers. + +### Type Mapping + +When converting your `inputSchema` to Python type hints: + +| JSON Schema | Python Type | +|---|---| +| `{"type": "string"}` | `str` | +| `{"type": "number"}` | `float` | +| `{"type": "integer"}` | `int` | +| `{"type": "boolean"}` | `bool` | +| `{"type": "array", "items": {"type": "string"}}` | `list[str]` | +| `{"type": "object"}` | `dict` | +| Optional property (not in `required`) | `param: str \| None = None` | + +### Return Values + +With the `Server` class, tools return `list[types.TextContent | types.ImageContent | ...]`. In FastMCP, return plain Python values — strings, numbers, dicts, lists, dataclasses, Pydantic models — and serialization is handled for you. + +For images or other non-text content, FastMCP provides helpers: + +```python +from fastmcp import FastMCP +from fastmcp.utilities.types import Image + +mcp = FastMCP("media") + +@mcp.tool +def create_chart(data: list[float]) -> Image: + """Generate a chart from data.""" + png_bytes = generate_chart(data) # your logic + return Image(data=png_bytes, format="png") +``` + +## Resources + +The `Server` class uses three handlers for resources: `list_resources()` to enumerate them, `list_resource_templates()` for URI templates, and `read_resource()` to serve content — all with manual routing by URI. FastMCP replaces all three with per-resource decorators. + + + +```python Before +import json +import mcp.types as types +from mcp.server import Server +from pydantic import AnyUrl + +server = Server("data") + +@server.list_resources() +async def list_resources() -> list[types.Resource]: + return [ + types.Resource( + uri=AnyUrl("config://app"), + name="app_config", + description="Application configuration", + mimeType="application/json", + ), + types.Resource( + uri=AnyUrl("config://features"), + name="feature_flags", + description="Active feature flags", + mimeType="application/json", + ), + ] + +@server.list_resource_templates() +async def list_resource_templates() -> list[types.ResourceTemplate]: + return [ + types.ResourceTemplate( + uriTemplate="users://{user_id}/profile", + name="user_profile", + description="User profile by ID", + ), + types.ResourceTemplate( + uriTemplate="projects://{project_id}/status", + name="project_status", + description="Project status by ID", + ), + ] + +@server.read_resource() +async def read_resource(uri: AnyUrl) -> str: + uri_str = str(uri) + if uri_str == "config://app": + return json.dumps({"debug": False, "version": "1.0"}) + if uri_str == "config://features": + return json.dumps({"dark_mode": True, "beta": False}) + if uri_str.startswith("users://"): + user_id = uri_str.split("/")[2] + return json.dumps({"id": user_id, "name": f"User {user_id}"}) + if uri_str.startswith("projects://"): + project_id = uri_str.split("/")[2] + return json.dumps({"id": project_id, "status": "active"}) + raise ValueError(f"Unknown resource: {uri}") +``` + +```python After +import json +from fastmcp import FastMCP + +mcp = FastMCP("data") + +@mcp.resource("config://app", mime_type="application/json") +def app_config() -> str: + """Application configuration""" + return json.dumps({"debug": False, "version": "1.0"}) + +@mcp.resource("config://features", mime_type="application/json") +def feature_flags() -> str: + """Active feature flags""" + return json.dumps({"dark_mode": True, "beta": False}) + +@mcp.resource("users://{user_id}/profile") +def user_profile(user_id: str) -> str: + """User profile by ID""" + return json.dumps({"id": user_id, "name": f"User {user_id}"}) + +@mcp.resource("projects://{project_id}/status") +def project_status(project_id: str) -> str: + """Project status by ID""" + return json.dumps({"id": project_id, "status": "active"}) +``` + + + +Static resources and URI templates use the same `@mcp.resource` decorator — FastMCP detects `{placeholders}` in the URI and automatically registers a template. The function parameter `user_id` maps directly to the `{user_id}` placeholder. + +## Prompts + +Same pattern: the `Server` class uses `list_prompts()` and `get_prompt()` with manual routing. FastMCP uses one decorator per prompt. + + + +```python Before +import mcp.types as types +from mcp.server import Server + +server = Server("prompts") + +@server.list_prompts() +async def list_prompts() -> list[types.Prompt]: + return [ + types.Prompt( + name="review_code", + description="Review code for issues", + arguments=[ + types.PromptArgument( + name="code", + description="The code to review", + required=True, + ), + types.PromptArgument( + name="language", + description="Programming language", + required=False, + ), + ], + ) + ] + +@server.get_prompt() +async def get_prompt( + name: str, arguments: dict[str, str] | None +) -> types.GetPromptResult: + if name == "review_code": + code = (arguments or {}).get("code", "") + language = (arguments or {}).get("language", "") + lang_note = f" (written in {language})" if language else "" + return types.GetPromptResult( + description="Code review prompt", + messages=[ + types.PromptMessage( + role="user", + content=types.TextContent( + type="text", + text=f"Please review this code{lang_note}:\n\n{code}", + ), + ) + ], + ) + raise ValueError(f"Unknown prompt: {name}") +``` + +```python After +from fastmcp import FastMCP + +mcp = FastMCP("prompts") + +@mcp.prompt +def review_code(code: str, language: str | None = None) -> str: + """Review code for issues""" + lang_note = f" (written in {language})" if language else "" + return f"Please review this code{lang_note}:\n\n{code}" +``` + + + +Returning a `str` from a prompt function automatically wraps it as a user message. For multi-turn prompts, return a `list[Message]`: + +```python +from fastmcp import FastMCP +from fastmcp.prompts import Message + +mcp = FastMCP("prompts") + +@mcp.prompt +def debug_session(error: str) -> list[Message]: + """Start a debugging conversation""" + return [ + Message(f"I'm seeing this error:\n\n{error}"), + Message("I'll help you debug that. Can you share the relevant code?", role="assistant"), + ] +``` + +## Request Context + +The `Server` class exposes request context through `server.request_context`, which gives you the raw `ServerSession` for sending notifications. FastMCP replaces this with a typed `Context` object injected into any function that declares it. + + + +```python Before +import mcp.types as types +from mcp.server import Server + +server = Server("worker") + +@server.call_tool() +async def call_tool(name: str, arguments: dict): + if name == "process_data": + ctx = server.request_context + await ctx.session.send_log_message( + level="info", data="Starting processing..." + ) + # ... do work ... + await ctx.session.send_log_message( + level="info", data="Done!" + ) + return [types.TextContent(type="text", text="Processed")] +``` + +```python After +from fastmcp import FastMCP, Context + +mcp = FastMCP("worker") + +@mcp.tool +async def process_data(ctx: Context) -> str: + """Process data with progress logging""" + await ctx.info("Starting processing...") + # ... do work ... + await ctx.info("Done!") + return "Processed" +``` + + + +The `Context` object provides logging (`ctx.debug()`, `ctx.info()`, `ctx.warning()`, `ctx.error()`), progress reporting (`ctx.report_progress()`), resource subscriptions, session state, and more. See [Context](/servers/context) for the full API. + +## Complete Example + +A full server upgrade, showing how all the pieces fit together: + + + +```python Before expandable +import asyncio +import json +import mcp.types as types +from mcp.server import Server +from mcp.server.stdio import stdio_server +from pydantic import AnyUrl + +server = Server("demo") + +@server.list_tools() +async def list_tools() -> list[types.Tool]: + return [ + types.Tool( + name="greet", + description="Greet someone by name", + inputSchema={ + "type": "object", + "properties": { + "name": {"type": "string"}, + }, + "required": ["name"], + }, + ) + ] + +@server.call_tool() +async def call_tool(name: str, arguments: dict) -> list[types.TextContent]: + if name == "greet": + return [types.TextContent(type="text", text=f"Hello, {arguments['name']}!")] + raise ValueError(f"Unknown tool: {name}") + +@server.list_resources() +async def list_resources() -> list[types.Resource]: + return [ + types.Resource( + uri=AnyUrl("info://version"), + name="version", + description="Server version", + ) + ] + +@server.read_resource() +async def read_resource(uri: AnyUrl) -> str: + if str(uri) == "info://version": + return json.dumps({"version": "1.0.0"}) + raise ValueError(f"Unknown resource: {uri}") + +@server.list_prompts() +async def list_prompts() -> list[types.Prompt]: + return [ + types.Prompt( + name="summarize", + description="Summarize text", + arguments=[ + types.PromptArgument(name="text", required=True) + ], + ) + ] + +@server.get_prompt() +async def get_prompt( + name: str, arguments: dict[str, str] | None +) -> types.GetPromptResult: + if name == "summarize": + return types.GetPromptResult( + description="Summarize text", + messages=[ + types.PromptMessage( + role="user", + content=types.TextContent( + type="text", + text=f"Summarize:\n\n{(arguments or {}).get('text', '')}", + ), + ) + ], + ) + raise ValueError(f"Unknown prompt: {name}") + +async def main(): + async with stdio_server() as (read_stream, write_stream): + await server.run( + read_stream, write_stream, + server.create_initialization_options(), + ) + +asyncio.run(main()) +``` + +```python After +import json +from fastmcp import FastMCP + +mcp = FastMCP("demo") + +@mcp.tool +def greet(name: str) -> str: + """Greet someone by name""" + return f"Hello, {name}!" + +@mcp.resource("info://version") +def version() -> str: + """Server version""" + return json.dumps({"version": "1.0.0"}) + +@mcp.prompt +def summarize(text: str) -> str: + """Summarize text""" + return f"Summarize:\n\n{text}" + +if __name__ == "__main__": + mcp.run() +``` + + + +## What's Next + +Once you've upgraded, you have access to everything FastMCP provides beyond the basics: + +- **[Server composition](/servers/composition)** — Mount sub-servers to build modular applications +- **[Middleware](/servers/middleware)** — Add logging, rate limiting, error handling, and caching +- **[Proxy servers](/servers/providers/proxy)** — Create a proxy to any existing MCP server +- **[OpenAPI integration](/integrations/openapi)** — Generate an MCP server from an OpenAPI spec +- **[Authentication](/servers/auth/authentication)** — Built-in OAuth and token verification +- **[Testing](/servers/testing)** — Test your server directly in Python without running a subprocess + +Explore the full documentation at [gofastmcp.com](https://gofastmcp.com). diff --git a/docs/getting-started/upgrading/from-mcp-sdk.mdx b/docs/getting-started/upgrading/from-mcp-sdk.mdx new file mode 100644 index 000000000..494d06bdc --- /dev/null +++ b/docs/getting-started/upgrading/from-mcp-sdk.mdx @@ -0,0 +1,166 @@ +--- +title: Upgrading from the MCP SDK +sidebarTitle: "From MCP SDK" +description: Upgrade from FastMCP in the MCP Python SDK to the standalone FastMCP framework +icon: up +--- + +If your server starts with `from mcp.server.fastmcp import FastMCP`, you're using FastMCP 1.0 — the version bundled with v1 of the `mcp` package. Upgrading to the standalone FastMCP framework is easy. **For most servers, it's a single import change.** + +```python +# Before +from mcp.server.fastmcp import FastMCP + +# After +from fastmcp import FastMCP +``` + +That's it. Your `@mcp.tool`, `@mcp.resource`, and `@mcp.prompt` decorators, your `mcp.run()` call, and the rest of your server code all work as-is. + + +**Why upgrade?** FastMCP 1.0 pioneered the Pythonic MCP server experience, and we're proud it was bundled into the `mcp` package. The standalone FastMCP project has since grown into a full framework for taking MCP servers from prototype to production — with composition, middleware, proxy servers, authentication, and much more. Upgrading gives you access to all of that, plus ongoing updates and fixes. + + +## Install + +```bash +pip install --upgrade fastmcp +# or +uv add fastmcp +``` + +FastMCP includes the `mcp` package as a dependency, so you don't lose access to anything. Update your import, run your server, and if your tools work, you're done. + + +You are upgrading an MCP server from FastMCP 1.0 (bundled in the `mcp` package v1) to standalone FastMCP 3.0. Analyze the provided code and identify every change needed. The full upgrade guide is at https://gofastmcp.com/getting-started/upgrading/from-mcp-sdk and the complete FastMCP documentation is at https://gofastmcp.com — fetch these for complete context. + +STEP 1 — IMPORT (required for all servers): +Change "from mcp.server.fastmcp import FastMCP" to "from fastmcp import FastMCP". + +STEP 2 — CONSTRUCTOR KWARGS (only if FastMCP() receives transport settings): +FastMCP() no longer accepts: host, port, log_level, debug, sse_path, streamable_http_path, json_response, stateless_http. +Fix: pass these to run() instead. +Before: `mcp = FastMCP("server", host="0.0.0.0", port=8080); mcp.run()` +After: `mcp = FastMCP("server"); mcp.run(transport="http", host="0.0.0.0", port=8080)` + +STEP 3 — PROMPTS (only if using PromptMessage directly or returning dicts): +mcp.types.PromptMessage is replaced by fastmcp.prompts.Message. +Before: `PromptMessage(role="user", content=TextContent(type="text", text="Hello"))` +After: `Message("Hello")` — role defaults to "user", accepts plain strings. +Also: if prompts return raw dicts like `{"role": "user", "content": "..."}`, these must become Message objects or plain strings. +The MCP SDK's FastMCP 1.0 silently coerced dicts; standalone FastMCP requires typed returns. + +STEP 4 — OTHER MCP IMPORTS (only if importing from mcp.* directly): +Direct imports from the `mcp` package (e.g., `import mcp.types`, `from mcp.server.stdio import stdio_server`) still work because FastMCP includes `mcp` as a dependency. However, prefer FastMCP's own APIs where equivalents exist: +- mcp.types.TextContent for tool returns → just return plain Python values (str, int, dict, etc.) +- mcp.types.ImageContent → fastmcp.utilities.types.Image +- from mcp.server.stdio import stdio_server → not needed, mcp.run() handles transport + +STEP 5 — DECORATORS (only if treating decorated functions as objects): +@mcp.tool, @mcp.resource, @mcp.prompt now return the original function, not a component object. Code that accesses .name or .description on the decorated result needs updating. Set FASTMCP_DECORATOR_MODE=object temporarily to restore v1 behavior (this compat setting is itself deprecated). + +For each issue found, show the original line, explain what changed, and provide the corrected code. + + +## What Might Need Updating + +Most servers need nothing beyond the import change. Skim the sections below to see if any apply. + +### Constructor Settings + +If you passed transport settings like `host` or `port` directly to `FastMCP()`, those now belong on `run()`. This keeps your server definition independent of how it's deployed: + +```python +# Before +mcp = FastMCP("my-server", host="0.0.0.0", port=8080) +mcp.run() + +# After +mcp = FastMCP("my-server") +mcp.run(transport="http", host="0.0.0.0", port=8080) +``` + +If you pass the old kwargs, you'll get a clear `TypeError` with a migration hint. + +### Prompts + +If your prompt functions return `mcp.types.PromptMessage` objects or raw dicts with `role`/`content` keys, you'll need to upgrade to FastMCP's `Message` class. Or just return a plain string — it's automatically wrapped as a user message. The MCP SDK's bundled FastMCP 1.0 silently coerced dicts into messages; standalone FastMCP requires typed `Message` objects or strings. + +```python +from fastmcp import FastMCP + +mcp = FastMCP("prompts") + +@mcp.prompt +def review(code: str) -> str: + """Review code for issues""" + return f"Please review this code:\n\n{code}" +``` + +For multi-turn prompts: + +```python +from fastmcp.prompts import Message + +@mcp.prompt +def debug(error: str) -> list[Message]: + """Start a debugging session""" + return [ + Message(f"I'm seeing this error:\n\n{error}"), + Message("I'll help debug that. Can you share the relevant code?", role="assistant"), + ] +``` + +### Other `mcp.*` Imports + +If your server imports directly from the `mcp` package — like `import mcp.types` or `from mcp.server.stdio import stdio_server` — those still work. FastMCP includes `mcp` as a dependency, so nothing breaks. + +Where FastMCP provides its own API for the same thing, it's worth switching over: + +| mcp Package | FastMCP Equivalent | +|---|---| +| `mcp.types.TextContent(type="text", text=str(x))` | Just return `x` from your tool | +| `mcp.types.ImageContent(...)` | `from fastmcp.utilities.types import Image` | +| `mcp.types.PromptMessage(...)` | `from fastmcp.prompts import Message` | +| `from mcp.server.stdio import stdio_server` | Not needed — `mcp.run()` handles transport | + +For anything without a FastMCP equivalent (e.g., specific protocol types you use directly), the `mcp.*` import is fine to keep. + +### Decorated Functions + +In FastMCP 1.0, `@mcp.tool` returned a `FunctionTool` object. Now decorators return your original function unchanged — so decorated functions stay callable for testing, reuse, and composition: + +```python +@mcp.tool +def greet(name: str) -> str: + """Greet someone""" + return f"Hello, {name}!" + +# This works now — the function is still a regular function +assert greet("World") == "Hello, World!" +``` + +If you have code that accesses `.name`, `.description`, or other attributes on the decorated result, that will need updating. This is uncommon — most servers don't interact with the tool object directly. If you need the old behavior temporarily, set `FASTMCP_DECORATOR_MODE=object` to restore it (this compatibility setting is itself deprecated and will be removed in a future release). + +## Verify the Upgrade + +```bash +# Install +pip install --upgrade fastmcp + +# Check version +fastmcp version + +# Run your server +python my_server.py +``` + +You can also inspect your server's registered components with the FastMCP CLI: + +```bash +fastmcp inspect my_server.py +``` + +## Looking Ahead + +The MCP ecosystem is evolving fast. Part of FastMCP's job is to absorb that complexity on your behalf — as the protocol and its tooling grow, we do the work so your server code doesn't have to change. diff --git a/docs/getting-started/welcome.mdx b/docs/getting-started/welcome.mdx new file mode 100644 index 000000000..28932284f --- /dev/null +++ b/docs/getting-started/welcome.mdx @@ -0,0 +1,124 @@ +--- +title: "Welcome to FastMCP" +sidebarTitle: "Welcome!" +description: The fast, Pythonic way to build MCP servers, clients, and applications. +icon: hand-wave +mode: center +--- +{/* 'F' logo on a watercolor background + 'F' logo on a watercolor background + + + */} + + + + +**FastMCP is the standard framework for building MCP applications.** The [Model Context Protocol](https://modelcontextprotocol.io/) (MCP) connects LLMs to tools and data. FastMCP gives you everything you need to go from prototype to production — build servers that expose capabilities, connect clients to any MCP service, and give your tools interactive UIs: + +```python {1} +from fastmcp import FastMCP + +mcp = FastMCP("Demo 🚀") + +@mcp.tool +def add(a: int, b: int) -> int: + """Add two numbers""" + return a + b + +if __name__ == "__main__": + mcp.run() +``` + + +## Move Fast and Make Things + +The [Model Context Protocol](https://modelcontextprotocol.io/) (MCP) lets you give agents access to your tools and data. But building an effective MCP application is harder than it looks. + +FastMCP handles all of it. Declare a tool with a Python function, and the schema, validation, and documentation are generated automatically. Connect to a server with a URL, and transport negotiation, authentication, and protocol lifecycle are managed for you. You focus on your logic, and the MCP part just works: **with FastMCP, best practices are built in.** + +**That's why FastMCP is the standard framework for working with MCP.** FastMCP 1.0 was incorporated into the official MCP Python SDK in 2024. Today, the actively maintained standalone project is downloaded a million times a day, and some version of FastMCP powers 70% of MCP servers across all languages. + +FastMCP has three pillars: + + + + Expose tools, resources, and prompts to LLMs. + + + Give your tools interactive UIs rendered directly in the conversation. + + + Connect to any MCP server — local or remote, programmatic or CLI. + + + +**[Servers](/servers/server)** wrap your Python functions into MCP-compliant tools, resources, and prompts. **[Clients](/clients/client)** connect to any server with full protocol support. And **[Apps](/apps/overview)** give your tools interactive UIs rendered directly in the conversation. + +Ready to build? Start with the [installation guide](/getting-started/installation) or jump straight to the [quickstart](/getting-started/quickstart). When you're ready to deploy, [Prefect Horizon](https://www.prefect.io/horizon) offers free hosting for FastMCP users. + +FastMCP is made with 💙 by [Prefect](https://www.prefect.io/). + + +**This documentation reflects FastMCP's `main` branch**, meaning it always reflects the latest development version. Features are generally marked with version badges (e.g. `New in version: 3.0.0`) to indicate when they were introduced. Note that this may include features that are not yet released. + + +## LLM-Friendly Docs + +The FastMCP documentation is available in multiple LLM-friendly formats: + +### MCP Server + +The FastMCP docs are accessible via MCP! The server URL is `https://gofastmcp.com/mcp`. + +In fact, you can use FastMCP to search the FastMCP docs: + +```python +import asyncio +from fastmcp import Client + +async def main(): + async with Client("https://gofastmcp.com/mcp") as client: + result = await client.call_tool( + name="SearchFastMcp", + arguments={"query": "deploy a FastMCP server"} + ) + print(result) + +asyncio.run(main()) +``` + +### Text Formats + +The docs are also available in [llms.txt format](https://llmstxt.org/): +- [llms.txt](https://gofastmcp.com/llms.txt) - A sitemap listing all documentation pages +- [llms-full.txt](https://gofastmcp.com/llms-full.txt) - The entire documentation in one file (may exceed context windows) + +Any page can be accessed as markdown by appending `.md` to the URL. For example, this page becomes `https://gofastmcp.com/getting-started/welcome.md`. + +You can also copy any page as markdown by pressing "Cmd+C" (or "Ctrl+C" on Windows) on your keyboard. diff --git a/docs/integrations/anthropic.mdx b/docs/integrations/anthropic.mdx new file mode 100644 index 000000000..b8156ac95 --- /dev/null +++ b/docs/integrations/anthropic.mdx @@ -0,0 +1,228 @@ +--- +title: Anthropic API 🤝 FastMCP +sidebarTitle: Anthropic API +description: Connect FastMCP servers to the Anthropic API +icon: message-code +--- + +import { VersionBadge } from "/snippets/version-badge.mdx" + + +Anthropic's [Messages API](https://docs.anthropic.com/en/api/messages) supports MCP servers as remote tool sources. This tutorial will show you how to create a FastMCP server and deploy it to a public URL, then how to call it from the Messages API. + + +Currently, the MCP connector only accesses **tools** from MCP servers—it queries the `list_tools` endpoint and exposes those functions to Claude. Other MCP features like resources and prompts are not currently supported. You can read more about the MCP connector in the [Anthropic documentation](https://docs.anthropic.com/en/docs/agents-and-tools/mcp-connector). + + +## Create a Server + +First, create a FastMCP server with the tools you want to expose. For this example, we'll create a server with a single tool that rolls dice. + +```python server.py +import random +from fastmcp import FastMCP + +mcp = FastMCP(name="Dice Roller") + +@mcp.tool +def roll_dice(n_dice: int) -> list[int]: + """Roll `n_dice` 6-sided dice and return the results.""" + return [random.randint(1, 6) for _ in range(n_dice)] + +if __name__ == "__main__": + mcp.run(transport="http", port=8000) +``` + +## Deploy the Server + +Your server must be deployed to a public URL in order for Anthropic to access it. The MCP connector supports both SSE and Streamable HTTP transports. + +For development, you can use tools like `ngrok` to temporarily expose a locally-running server to the internet. We'll do that for this example (you may need to install `ngrok` and create a free account), but you can use any other method to deploy your server. + +Assuming you saved the above code as `server.py`, you can run the following two commands in two separate terminals to deploy your server and expose it to the internet: + + +```bash FastMCP server +python server.py +``` + +```bash ngrok +ngrok http 8000 +``` + + + +This exposes your unauthenticated server to the internet. Only run this command in a safe environment if you understand the risks. + + +## Call the Server + +To use the Messages API with MCP servers, you'll need to install the Anthropic Python SDK (not included with FastMCP): + +```bash +pip install anthropic +``` + +You'll also need to authenticate with Anthropic. You can do this by setting the `ANTHROPIC_API_KEY` environment variable. Consult the Anthropic SDK documentation for more information. + +```bash +export ANTHROPIC_API_KEY="your-api-key" +``` + +Here is an example of how to call your server from Python. Note that you'll need to replace `https://your-server-url.com` with the actual URL of your server. In addition, we use `/mcp/` as the endpoint because we deployed a streamable-HTTP server with the default path; you may need to use a different endpoint if you customized your server's deployment. **At this time you must also include the `extra_headers` parameter with the `anthropic-beta` header.** + +```python {5, 13-22} +import anthropic +from rich import print + +# Your server URL (replace with your actual URL) +url = 'https://your-server-url.com' + +client = anthropic.Anthropic() + +response = client.beta.messages.create( + model="claude-sonnet-4-20250514", + max_tokens=1000, + messages=[{"role": "user", "content": "Roll a few dice!"}], + mcp_servers=[ + { + "type": "url", + "url": f"{url}/mcp/", + "name": "dice-server", + } + ], + extra_headers={ + "anthropic-beta": "mcp-client-2025-04-04" + } +) + +print(response.content) +``` + +If you run this code, you'll see something like the following output: + +```text +I'll roll some dice for you! Let me use the dice rolling tool. + +I rolled 3 dice and got: 4, 2, 6 + +The results were 4, 2, and 6. Would you like me to roll again or roll a different number of dice? +``` + + +## Authentication + + + +The MCP connector supports OAuth authentication through authorization tokens, which means you can secure your server while still allowing Anthropic to access it. + +### Server Authentication + +The simplest way to add authentication to the server is to use a bearer token scheme. + +For this example, we'll quickly generate our own tokens with FastMCP's `RSAKeyPair` utility, but this may not be appropriate for production use. For more details, see the complete server-side [Token Verification](/servers/auth/token-verification) documentation. + +We'll start by creating an RSA key pair to sign and verify tokens. + +```python +from fastmcp.server.auth.providers.jwt import RSAKeyPair + +key_pair = RSAKeyPair.generate() +access_token = key_pair.create_token(audience="dice-server") +``` + + +FastMCP's `RSAKeyPair` utility is for development and testing only. + + +Next, we'll create a `JWTVerifier` to authenticate the server. + +```python +from fastmcp import FastMCP +from fastmcp.server.auth import JWTVerifier + +auth = JWTVerifier( + public_key=key_pair.public_key, + audience="dice-server", +) + +mcp = FastMCP(name="Dice Roller", auth=auth) +``` + +Here is a complete example that you can copy/paste. For simplicity and the purposes of this example only, it will print the token to the console. **Do NOT do this in production!** + +```python server.py [expandable] +from fastmcp import FastMCP +from fastmcp.server.auth import JWTVerifier +from fastmcp.server.auth.providers.jwt import RSAKeyPair +import random + +key_pair = RSAKeyPair.generate() +access_token = key_pair.create_token(audience="dice-server") + +auth = JWTVerifier( + public_key=key_pair.public_key, + audience="dice-server", +) + +mcp = FastMCP(name="Dice Roller", auth=auth) + +@mcp.tool +def roll_dice(n_dice: int) -> list[int]: + """Roll `n_dice` 6-sided dice and return the results.""" + return [random.randint(1, 6) for _ in range(n_dice)] + +if __name__ == "__main__": + print(f"\n---\n\n🔑 Dice Roller access token:\n\n{access_token}\n\n---\n") + mcp.run(transport="http", port=8000) +``` + +### Client Authentication + +If you try to call the authenticated server with the same Anthropic code we wrote earlier, you'll get an error indicating that the server rejected the request because it's not authenticated. + +```python +Error code: 400 - { + "type": "error", + "error": { + "type": "invalid_request_error", + "message": "MCP server 'dice-server' requires authentication. Please provide an authorization_token.", + }, +} +``` + +To authenticate the client, you can pass the token using the `authorization_token` parameter in your MCP server configuration: + +```python {8, 21} +import anthropic +from rich import print + +# Your server URL (replace with your actual URL) +url = 'https://your-server-url.com' + +# Your access token (replace with your actual token) +access_token = 'your-access-token' + +client = anthropic.Anthropic() + +response = client.beta.messages.create( + model="claude-sonnet-4-20250514", + max_tokens=1000, + messages=[{"role": "user", "content": "Roll a few dice!"}], + mcp_servers=[ + { + "type": "url", + "url": f"{url}/mcp/", + "name": "dice-server", + "authorization_token": access_token + } + ], + extra_headers={ + "anthropic-beta": "mcp-client-2025-04-04" + } +) + +print(response.content) +``` + +You should now see the dice roll results in the output. diff --git a/docs/integrations/auth0.mdx b/docs/integrations/auth0.mdx new file mode 100644 index 000000000..65f9d3873 --- /dev/null +++ b/docs/integrations/auth0.mdx @@ -0,0 +1,195 @@ +--- +title: Auth0 OAuth 🤝 FastMCP +sidebarTitle: Auth0 +description: Secure your FastMCP server with Auth0 OAuth +icon: shield-check +--- + +import { VersionBadge } from "/snippets/version-badge.mdx" + + + +This guide shows you how to secure your FastMCP server using **Auth0 OAuth**. While Auth0 does have support for Dynamic Client Registration, it is not enabled by default so this integration uses the [**OIDC Proxy**](/servers/auth/oidc-proxy) pattern to bridge Auth0's dynamic OIDC configuration with MCP's authentication requirements. + +## Configuration + +### Prerequisites + +Before you begin, you will need: +1. An **[Auth0 Account](https://auth0.com/)** with access to create Applications +2. Your FastMCP server's URL (can be localhost for development, e.g., `http://localhost:8000`) + +### Step 1: Create an Auth0 Application + +Create an Application in your Auth0 settings to get the credentials needed for authentication: + + + + Go to **Applications → Applications** in your Auth0 account. + + Click **"+ Create Application"** to create a new application. + + + + - **Name**: Choose a name users will recognize (e.g., "My FastMCP Server") + - **Choose an application type**: Choose "Single Page Web Applications" + - Click **Create** to create the application + + + + Select the "Settings" tab for your application, then find the "Application URIs" section. + + - **Allowed Callback URLs**: Your server URL + `/auth/callback` (e.g., `http://localhost:8000/auth/callback`) + - Click **Save** to save your changes + + + The callback URL must match exactly. The default path is `/auth/callback`, but you can customize it using the `redirect_path` parameter. + + + + If you want to use a custom callback path (e.g., `/auth/auth0/callback`), make sure to set the same path in both your Auth0 Application settings and the `redirect_path` parameter when configuring the Auth0Provider. + + + + + After creating the app, in the "Basic Information" section you'll see: + + - **Client ID**: A public identifier like `tv2ObNgaZAWWhhycr7Bz1LU2mxlnsmsB` + - **Client Secret**: A private hidden value that should always be stored securely + + + Store these credentials securely. Never commit them to version control. Use environment variables or a secrets manager in production. + + + + + Go to **Applications → APIs** in your Auth0 account. + + - Find the API that you want to use for your application + - **API Audience**: A URL that uniquely identifies the API + + + Store this along with of the credentials above. Never commit this to version control. Use environment variables or a secrets manager in production. + + + + +### Step 2: FastMCP Configuration + +Create your FastMCP server using the `Auth0Provider`. + +```python server.py +from fastmcp import FastMCP +from fastmcp.server.auth.providers.auth0 import Auth0Provider + +# The Auth0Provider utilizes Auth0 OIDC configuration +auth_provider = Auth0Provider( + config_url="https://.../.well-known/openid-configuration", # Your Auth0 configuration URL + client_id="tv2ObNgaZAWWhhycr7Bz1LU2mxlnsmsB", # Your Auth0 application Client ID + client_secret="vPYqbjemq...", # Your Auth0 application Client Secret + audience="https://...", # Your Auth0 API audience + base_url="http://localhost:8000", # Must match your application configuration + # redirect_path="/auth/callback" # Default value, customize if needed +) + +mcp = FastMCP(name="Auth0 Secured App", auth=auth_provider) + +# Add a protected tool to test authentication +@mcp.tool +async def get_token_info() -> dict: + """Returns information about the Auth0 token.""" + from fastmcp.server.dependencies import get_access_token + + token = get_access_token() + + return { + "issuer": token.claims.get("iss"), + "audience": token.claims.get("aud"), + "scope": token.claims.get("scope") + } +``` + +## Testing + +### Running the Server + +Start your FastMCP server with HTTP transport to enable OAuth flows: + +```bash +fastmcp run server.py --transport http --port 8000 +``` + +Your server is now running and protected by Auth0 authentication. + +### Testing with a Client + +Create a test client that authenticates with your Auth0-protected server: + +```python test_client.py +from fastmcp import Client +import asyncio + +async def main(): + # The client will automatically handle Auth0 OAuth flows + async with Client("http://localhost:8000/mcp", auth="oauth") as client: + # First-time connection will open Auth0 login in your browser + print("✓ Authenticated with Auth0!") + + # Test the protected tool + result = await client.call_tool("get_token_info") + print(f"Auth0 audience: {result['audience']}") + +if __name__ == "__main__": + asyncio.run(main()) +``` + +When you run the client for the first time: +1. Your browser will open to Auth0's authorization page +2. After you authorize the app, you'll be redirected back +3. The client receives the token and can make authenticated requests + +## Production Configuration + + + +For production deployments with persistent token management across server restarts, configure `jwt_signing_key`, and `client_storage`: + +```python server.py +import os +from fastmcp import FastMCP +from fastmcp.server.auth.providers.auth0 import Auth0Provider +from key_value.aio.stores.redis import RedisStore +from key_value.aio.wrappers.encryption import FernetEncryptionWrapper +from cryptography.fernet import Fernet + +# Production setup with encrypted persistent token storage +auth_provider = Auth0Provider( + config_url="https://.../.well-known/openid-configuration", + client_id="tv2ObNgaZAWWhhycr7Bz1LU2mxlnsmsB", + client_secret="vPYqbjemq...", + audience="https://...", + base_url="https://your-production-domain.com", + + # Production token management + jwt_signing_key=os.environ["JWT_SIGNING_KEY"], + client_storage=FernetEncryptionWrapper( + key_value=RedisStore( + host=os.environ["REDIS_HOST"], + port=int(os.environ["REDIS_PORT"]) + ), + fernet=Fernet(os.environ["STORAGE_ENCRYPTION_KEY"]) + ) +) + +mcp = FastMCP(name="Production Auth0 App", auth=auth_provider) +``` + + +Parameters (`jwt_signing_key` and `client_storage`) work together to ensure tokens and client registrations survive server restarts. **Wrap your storage in `FernetEncryptionWrapper` to encrypt sensitive OAuth tokens at rest** - without it, tokens are stored in plaintext. Store secrets in environment variables and use a persistent storage backend like Redis for distributed deployments. + +For complete details on these parameters, see the [OAuth Proxy documentation](/servers/auth/oauth-proxy#configuration-parameters). + + + +The client caches tokens locally, so you won't need to re-authenticate for subsequent runs unless the token expires or you explicitly clear the cache. + diff --git a/docs/integrations/authkit.mdx b/docs/integrations/authkit.mdx new file mode 100644 index 000000000..e99f78351 --- /dev/null +++ b/docs/integrations/authkit.mdx @@ -0,0 +1,101 @@ +--- +title: AuthKit 🤝 FastMCP +sidebarTitle: AuthKit +description: Secure your FastMCP server with AuthKit by WorkOS +icon: shield-check +--- + +import { VersionBadge } from "/snippets/version-badge.mdx" + + + +This guide shows you how to secure your FastMCP server using WorkOS's **AuthKit**, a complete authentication and user management solution. This integration uses the [**Remote OAuth**](/servers/auth/remote-oauth) pattern, where AuthKit handles user login and your FastMCP server validates the tokens. + + +AuthKit does not currently support [RFC 8707](https://www.rfc-editor.org/rfc/rfc8707.html) resource indicators, so FastMCP cannot validate that tokens were issued for the specific resource server. If you need resource-specific audience validation, consider using [WorkOSProvider](/integrations/workos) (OAuth proxy pattern) instead. + + +## Configuration +### Prerequisites + +Before you begin, you will need: +1. A **[WorkOS Account](https://workos.com/)** and a new **Project**. +2. An **[AuthKit](https://www.authkit.com/)** instance configured within your WorkOS project. +3. Your FastMCP server's URL (can be localhost for development, e.g., `http://localhost:8000`). + +### Step 1: AuthKit Configuration + +In your WorkOS Dashboard, enable AuthKit and configure the following settings: + + + + Go to **Applications → Configuration** and enable **Dynamic Client Registration**. This allows MCP clients register with your application automatically. + + ![Enable Dynamic Client Registration](./images/authkit/enable_dcr.png) + + + + Find your **AuthKit Domain** on the configuration page. It will look like `https://your-project-12345.authkit.app`. You'll need this for your FastMCP server configuration. + + + +### Step 2: FastMCP Configuration + +Create your FastMCP server file and use the `AuthKitProvider` to handle all the OAuth integration automatically: + +```python server.py +from fastmcp import FastMCP +from fastmcp.server.auth.providers.workos import AuthKitProvider + +# The AuthKitProvider automatically discovers WorkOS endpoints +# and configures JWT token validation +auth_provider = AuthKitProvider( + authkit_domain="https://your-project-12345.authkit.app", + base_url="http://localhost:8000" # Use your actual server URL +) + +mcp = FastMCP(name="AuthKit Secured App", auth=auth_provider) +``` + +## Testing + +To test your server, you can use the `fastmcp` CLI to run it locally. Assuming you've saved the above code to `server.py` (after replacing the `authkit_domain` and `base_url` with your actual values!), you can run the following command: + +```bash +fastmcp run server.py --transport http --port 8000 +``` + +AuthKit defaults DCR clients to `client_secret_basic` for token exchange, which conflicts with how some MCP clients send credentials. To avoid token exchange errors, register as a public client by setting `token_endpoint_auth_method` to `"none"`: + +```python client.py +from fastmcp import Client +from fastmcp.client.auth import OAuth +import asyncio + +auth = OAuth(additional_client_metadata={"token_endpoint_auth_method": "none"}) + +async def main(): + async with Client("http://localhost:8000/mcp", auth=auth) as client: + assert await client.ping() + +if __name__ == "__main__": + asyncio.run(main()) +``` + +## Production Configuration + +For production deployments, load sensitive configuration from environment variables: + +```python server.py +import os +from fastmcp import FastMCP +from fastmcp.server.auth.providers.workos import AuthKitProvider + +# Load configuration from environment variables +auth = AuthKitProvider( + authkit_domain=os.environ.get("AUTHKIT_DOMAIN"), + base_url=os.environ.get("BASE_URL", "https://your-server.com") +) + +mcp = FastMCP(name="AuthKit Secured App", auth=auth) +``` diff --git a/docs/integrations/aws-cognito.mdx b/docs/integrations/aws-cognito.mdx new file mode 100644 index 000000000..b7df29222 --- /dev/null +++ b/docs/integrations/aws-cognito.mdx @@ -0,0 +1,278 @@ +--- +title: AWS Cognito OAuth 🤝 FastMCP +sidebarTitle: AWS Cognito +description: Secure your FastMCP server with AWS Cognito user pools +icon: aws +--- + +import { VersionBadge } from "/snippets/version-badge.mdx" + + + +This guide shows you how to secure your FastMCP server using **AWS Cognito user pools**. Since AWS Cognito doesn't support Dynamic Client Registration, this integration uses the [**OAuth Proxy**](/servers/auth/oauth-proxy) pattern to bridge AWS Cognito's traditional OAuth with MCP's authentication requirements. It also includes robust JWT token validation, ensuring enterprise-grade authentication. + +## Configuration + +### Prerequisites + +Before you begin, you will need: +1. An **[AWS Account](https://aws.amazon.com/)** with access to create AWS Cognito user pools +2. Basic familiarity with AWS Cognito concepts (user pools, app clients) +3. Your FastMCP server's URL (can be localhost for development, e.g., `http://localhost:8000`) + +### Step 1: Create an AWS Cognito User Pool and App Client + +Set up AWS Cognito user pool with an app client to get the credentials needed for authentication: + + + + Go to the **[AWS Cognito Console](https://console.aws.amazon.com/cognito/)** and ensure you're in your desired AWS region. + + Select **"User pools"** from the side navigation (click on the hamburger icon at the top left in case you don't see any), and click **"Create user pool"** to create a new user pool. + + + + AWS Cognito now provides a streamlined setup experience: + + 1. **Application type**: Select **"Traditional web application"** (this is the correct choice for FastMCP server-side authentication) + 2. **Name your application**: Enter a descriptive name (e.g., `FastMCP Server`) + + The traditional web application type automatically configures: + - Server-side authentication with client secrets + - Authorization code grant flow + - Appropriate security settings for confidential clients + + + Choose "Traditional web application" rather than SPA, Mobile app, or Machine-to-machine options. This ensures proper OAuth 2.0 configuration for FastMCP. + + + + + AWS will guide you through configuration options: + + - **Sign-in identifiers**: Choose how users will sign in (email, username, or phone) + - **Required attributes**: Select any additional user information you need + - **Return URL**: Add your callback URL (e.g., `http://localhost:8000/auth/callback` for development) + + + The simplified interface handles most OAuth security settings automatically based on your application type selection. + + + + + Review your configuration and click **"Create user pool"**. + + After creation, you'll see your user pool details. Save these important values: + - **User pool ID** (format: `eu-central-1_XXXXXXXXX`) + - **Client ID** (found under → "Applications" → "App clients" in the side navigation → \ → "App client information") + - **Client Secret** (found under → "Applications" → "App clients" in the side navigation → \ → "App client information") + + + The user pool ID and app client credentials are all you need for FastMCP configuration. + + + + + Under "Login pages" in your app client's settings, you can double check and adjust the OAuth configuration: + + - **Allowed callback URLs**: Add your server URL + `/auth/callback` (e.g., `http://localhost:8000/auth/callback`) + - **Allowed sign-out URLs**: Optional, for logout functionality + - **OAuth 2.0 grant types**: Ensure "Authorization code grant" is selected + - **OpenID Connect scopes**: Select scopes your application needs (e.g., `openid`, `email`, `profile`) + + + For local development, you can use `http://localhost` URLs. For production, you must use HTTPS. + + + + + AWS Cognito requires a resource server entry to support OAuth with protected resources. Without this, token exchange will fail with an `invalid_grant` error. + + Navigate to **"Branding" → "Domain"** in the side navigation, then: + + 1. Click **"Create resource server"** + 2. **Resource server name**: Enter a descriptive name (e.g., `My MCP Server`) + 3. **Resource server identifier**: Enter your MCP endpoint URL exactly as it will be accessed (e.g., `http://localhost:8000/mcp` for development, or `https://your-server.com/mcp` for production) + 4. Click **"Create resource server"** + + + The resource server identifier must exactly match your `base_url + mcp_path`. For the default configuration with `base_url="http://localhost:8000"` and `path="/mcp"`, use `http://localhost:8000/mcp`. + + + + + After setup, you'll have: + + - **User Pool ID**: Format like `eu-central-1_XXXXXXXXX` + - **Client ID**: Your application's client identifier + - **Client Secret**: Generated client secret (keep secure) + - **AWS Region**: Where Your AWS Cognito user pool is located + + + Store these credentials securely. Never commit them to version control. Use environment variables or AWS Secrets Manager in production. + + + + +### Step 2: FastMCP Configuration + +Create your FastMCP server using the `AWSCognitoProvider`, which handles AWS Cognito's JWT tokens and user claims automatically: + +```python server.py +from fastmcp import FastMCP +from fastmcp.server.auth.providers.aws import AWSCognitoProvider +from fastmcp.server.dependencies import get_access_token + +# The AWSCognitoProvider handles JWT validation and user claims +auth_provider = AWSCognitoProvider( + user_pool_id="eu-central-1_XXXXXXXXX", # Your AWS Cognito user pool ID + aws_region="eu-central-1", # AWS region (defaults to eu-central-1) + client_id="your-app-client-id", # Your app client ID + client_secret="your-app-client-secret", # Your app client Secret + base_url="http://localhost:8000", # Must match your callback URL + # redirect_path="/auth/callback" # Default value, customize if needed +) + +mcp = FastMCP(name="AWS Cognito Secured App", auth=auth_provider) + +# Add a protected tool to test authentication +@mcp.tool +async def get_access_token_claims() -> dict: + """Get the authenticated user's access token claims.""" + token = get_access_token() + return { + "sub": token.claims.get("sub"), + "username": token.claims.get("username"), + "cognito:groups": token.claims.get("cognito:groups", []), + } +``` + +## Testing + +### Running the Server + +Start your FastMCP server with HTTP transport to enable OAuth flows: + +```bash +fastmcp run server.py --transport http --port 8000 +``` + +Your server is now running and protected by AWS Cognito OAuth authentication. + +### Testing with a Client + +Create a test client that authenticates with Your AWS Cognito-protected server: + +```python test_client.py +from fastmcp import Client +import asyncio + +async def main(): + # The client will automatically handle AWS Cognito OAuth + async with Client("http://localhost:8000/mcp", auth="oauth") as client: + # First-time connection will open AWS Cognito login in your browser + print("✓ Authenticated with AWS Cognito!") + + # Test the protected tool + print("Calling protected tool: get_access_token_claims") + result = await client.call_tool("get_access_token_claims") + user_data = result.data + print("Available access token claims:") + print(f"- sub: {user_data.get('sub', 'N/A')}") + print(f"- username: {user_data.get('username', 'N/A')}") + print(f"- cognito:groups: {user_data.get('cognito:groups', [])}") + +if __name__ == "__main__": + asyncio.run(main()) +``` + +When you run the client for the first time: +1. Your browser will open to AWS Cognito's hosted UI login page +2. After you sign in (or sign up), you'll be redirected back to your MCP server +3. The client receives the JWT token and can make authenticated requests + + +The client caches tokens locally, so you won't need to re-authenticate for subsequent runs unless the token expires or you explicitly clear the cache. + + +## Production Configuration + + + +For production deployments with persistent token management across server restarts, configure `jwt_signing_key`, and `client_storage`: + +```python server.py +import os +from fastmcp import FastMCP +from fastmcp.server.auth.providers.aws import AWSCognitoProvider +from key_value.aio.stores.redis import RedisStore +from key_value.aio.wrappers.encryption import FernetEncryptionWrapper +from cryptography.fernet import Fernet + +# Production setup with encrypted persistent token storage +auth_provider = AWSCognitoProvider( + user_pool_id="eu-central-1_XXXXXXXXX", + aws_region="eu-central-1", + client_id="your-app-client-id", + client_secret="your-app-client-secret", + base_url="https://your-production-domain.com", + + # Production token management + jwt_signing_key=os.environ["JWT_SIGNING_KEY"], + client_storage=FernetEncryptionWrapper( + key_value=RedisStore( + host=os.environ["REDIS_HOST"], + port=int(os.environ["REDIS_PORT"]) + ), + fernet=Fernet(os.environ["STORAGE_ENCRYPTION_KEY"]) + ) +) + +mcp = FastMCP(name="Production AWS Cognito App", auth=auth_provider) +``` + + +Parameters (`jwt_signing_key` and `client_storage`) work together to ensure tokens and client registrations survive server restarts. **Wrap your storage in `FernetEncryptionWrapper` to encrypt sensitive OAuth tokens at rest** - without it, tokens are stored in plaintext. Store secrets in environment variables and use a persistent storage backend like Redis for distributed deployments. + +For complete details on these parameters, see the [OAuth Proxy documentation](/servers/auth/oauth-proxy#configuration-parameters). + + +## Features + +### JWT Token Validation + +The AWS Cognito provider includes robust JWT token validation: + +- **Signature Verification**: Validates tokens against AWS Cognito's public keys (JWKS) +- **Expiration Checking**: Automatically rejects expired tokens +- **Issuer Validation**: Ensures tokens come from your specific AWS Cognito user pool +- **Scope Enforcement**: Verifies required OAuth scopes are present + +### User Claims and Groups + +Access rich user information from AWS Cognito JWT tokens: + +```python +from fastmcp.server.dependencies import get_access_token + +@mcp.tool +async def admin_only_tool() -> str: + """A tool only available to admin users.""" + token = get_access_token() + user_groups = token.claims.get("cognito:groups", []) + + if "admin" not in user_groups: + raise ValueError("This tool requires admin access") + + return "Admin access granted!" +``` + +### Enterprise Integration + +Perfect for enterprise environments with: + +- **Single Sign-On (SSO)**: Integrate with corporate identity providers +- **Multi-Factor Authentication (MFA)**: Leverage AWS Cognito's built-in MFA +- **User Groups**: Role-based access control through AWS Cognito groups +- **Custom Attributes**: Access custom user attributes defined in your AWS Cognito user pool +- **Compliance**: Meet enterprise security and compliance requirements \ No newline at end of file diff --git a/docs/integrations/azure.mdx b/docs/integrations/azure.mdx new file mode 100644 index 000000000..4376a38ce --- /dev/null +++ b/docs/integrations/azure.mdx @@ -0,0 +1,460 @@ +--- +title: Azure (Microsoft Entra ID) OAuth 🤝 FastMCP +sidebarTitle: Azure (Entra ID) +description: Secure your FastMCP server with Azure/Microsoft Entra OAuth +icon: microsoft +--- + +import { VersionBadge } from "/snippets/version-badge.mdx" + + + +This guide shows you how to secure your FastMCP server using **Azure OAuth** (Microsoft Entra ID). Since Azure doesn't support Dynamic Client Registration, this integration uses the [**OAuth Proxy**](/servers/auth/oauth-proxy) pattern to bridge Azure's traditional OAuth with MCP's authentication requirements. FastMCP validates Azure JWTs against your application's client_id. + +## Configuration + +### Prerequisites + +Before you begin, you will need: +1. An **[Azure Account](https://portal.azure.com/)** with access to create App registrations +2. Your FastMCP server's URL (can be localhost for development, e.g., `http://localhost:8000`) +3. Your Azure tenant ID (found in Azure Portal under Microsoft Entra ID) + +### Step 1: Create an Azure App Registration + +Create an App registration in Azure Portal to get the credentials needed for authentication: + + + + Go to the [Azure Portal](https://portal.azure.com) and navigate to **Microsoft Entra ID → App registrations**. + + Click **"New registration"** to create a new application. + + + + Fill in the application details: + + - **Name**: Choose a name users will recognize (e.g., "My FastMCP Server") + - **Supported account types**: Choose based on your needs: + - **Single tenant**: Only users in your organization + - **Multitenant**: Users in any Microsoft Entra directory + - **Multitenant + personal accounts**: Any Microsoft account + - **Redirect URI**: Select "Web" and enter your server URL + `/auth/callback` (e.g., `http://localhost:8000/auth/callback`) + + + The redirect URI must match exactly. The default path is `/auth/callback`, but you can customize it using the `redirect_path` parameter. For local development, Azure allows `http://localhost` URLs. For production, you must use HTTPS. + + + + If you want to use a custom callback path (e.g., `/auth/azure/callback`), make sure to set the same path in both your Azure App registration and the `redirect_path` parameter when configuring the AzureProvider. + + + - **Expose an API**: Configure your Application ID URI and define scopes + - Go to **Expose an API** in the App registration sidebar. + - Click **Set** next to "Application ID URI" and choose one of: + - Keep the default `api://{client_id}` + - Set a custom value, following the supported formats (see [Identifier URI restrictions](https://learn.microsoft.com/en-us/entra/identity-platform/identifier-uri-restrictions)) + - Click **Add a scope** and create a scope your app will require, for example: + - Scope name: `read` (or `write`, etc.) + - Admin consent display name/description: as appropriate for your org + - Who can consent: as needed (Admins only or Admins and users) + + - **Configure Access Token Version**: Ensure your app uses access token v2 + - Go to **Manifest** in the App registration sidebar. + - Find the `requestedAccessTokenVersion` property and set it to `2`: + ```json + "api": { + "requestedAccessTokenVersion": 2 + } + ``` + - Click **Save** at the top of the manifest editor. + + + Access token v2 is required for FastMCP's Azure integration to work correctly. If this is not set, you may encounter authentication errors. + + + + In FastMCP's `AzureProvider`, set `identifier_uri` to your Application ID URI (optional; defaults to `api://{client_id}`) and set `required_scopes` to the unprefixed scope names (e.g., `read`, `write`). During authorization, FastMCP automatically prefixes scopes with your `identifier_uri`. + + + + + + + + After registration, navigate to **Certificates & secrets** in your app's settings. + + - Click **"New client secret"** + - Add a description (e.g., "FastMCP Server") + - Choose an expiration period + - Click **"Add"** + + + Copy the secret value immediately - it won't be shown again! You'll need to create a new secret if you lose it. + + + + + From the **Overview** page of your app registration, note: + + - **Application (client) ID**: A UUID like `835f09b6-0f0f-40cc-85cb-f32c5829a149` + - **Directory (tenant) ID**: A UUID like `08541b6e-646d-43de-a0eb-834e6713d6d5` + - **Client Secret**: The value you copied in the previous step + + + Store these credentials securely. Never commit them to version control. Use environment variables or a secrets manager in production. + + + + +### Step 2: FastMCP Configuration + +Create your FastMCP server using the `AzureProvider`, which handles Azure's OAuth flow automatically: + +```python server.py +from fastmcp import FastMCP +from fastmcp.server.auth.providers.azure import AzureProvider + +# The AzureProvider handles Azure's token format and validation +auth_provider = AzureProvider( + client_id="835f09b6-0f0f-40cc-85cb-f32c5829a149", # Your Azure App Client ID + client_secret="your-client-secret", # Your Azure App Client Secret + tenant_id="08541b6e-646d-43de-a0eb-834e6713d6d5", # Your Azure Tenant ID (REQUIRED) + base_url="http://localhost:8000", # Must match your App registration + required_scopes=["your-scope"], # At least one scope REQUIRED - name of scope from your App + # identifier_uri defaults to api://{client_id} + # identifier_uri="api://your-api-id", + # Optional: request additional upstream scopes in the authorize request + # additional_authorize_scopes=["User.Read", "openid", "email"], + # redirect_path="/auth/callback" # Default value, customize if needed + # base_authority="login.microsoftonline.us" # For Azure Government (default: login.microsoftonline.com) +) + +mcp = FastMCP(name="Azure Secured App", auth=auth_provider) + +# Add a protected tool to test authentication +@mcp.tool +async def get_user_info() -> dict: + """Returns information about the authenticated Azure user.""" + from fastmcp.server.dependencies import get_access_token + + token = get_access_token() + # The AzureProvider stores user data in token claims + return { + "azure_id": token.claims.get("sub"), + "email": token.claims.get("email"), + "name": token.claims.get("name"), + "job_title": token.claims.get("job_title"), + "office_location": token.claims.get("office_location") + } +``` + + +**Important**: The `tenant_id` parameter is **REQUIRED**. Azure no longer supports using "common" for new applications due to security requirements. You must use one of: + +- **Your specific tenant ID**: Found in Azure Portal (e.g., `08541b6e-646d-43de-a0eb-834e6713d6d5`) +- **"organizations"**: For work and school accounts only +- **"consumers"**: For personal Microsoft accounts only + +Using your specific tenant ID is recommended for better security and control. + + + +**Important**: The `required_scopes` parameter is **REQUIRED** and must include at least one scope. Azure's OAuth API requires the `scope` parameter in all authorization requests - you cannot authenticate without specifying at least one scope. Use the unprefixed scope names from your Azure App registration (e.g., `["read", "write"]`). These scopes must be created under **Expose an API** in your App registration. + + +### Scope Handling + +FastMCP automatically prefixes `required_scopes` with your `identifier_uri` (e.g., `api://your-client-id`) since these are your custom API scopes. Scopes in `additional_authorize_scopes` are sent as-is since they target external resources like Microsoft Graph. + +**`required_scopes`** — Your custom API scopes, defined in Azure "Expose an API": + +| You write | Sent to Azure | Validated on tokens | +|-----------|---------------|---------------------| +| `mcp-read` | `api://xxx/mcp-read` | ✓ | +| `my.scope` | `api://xxx/my.scope` | ✓ | +| `openid` | `openid` | ✗ (OIDC scope) | +| `api://xxx/read` | `api://xxx/read` | ✓ | + +**`additional_authorize_scopes`** — External scopes (e.g., Microsoft Graph) for server-side use: + +| You write | Sent to Azure | Validated on tokens | +|-----------|---------------|---------------------| +| `User.Read` | `User.Read` | ✗ | +| `Mail.Send` | `Mail.Send` | ✗ | + + +`offline_access` is automatically included to obtain refresh tokens. FastMCP manages token refreshing automatically. + + + +**Why aren't `additional_authorize_scopes` validated?** Azure issues separate tokens per resource. The access token FastMCP receives is for *your API*—Graph scopes aren't in its `scp` claim. To call Graph APIs, your server uses the upstream Azure token in an on-behalf-of (OBO) flow. + + + +OIDC scopes (`openid`, `profile`, `email`, `offline_access`) are never prefixed and excluded from validation because Azure doesn't include them in access token `scp` claims. + + +## Testing + +### Running the Server + +Start your FastMCP server with HTTP transport to enable OAuth flows: + +```bash +fastmcp run server.py --transport http --port 8000 +``` + +Your server is now running and protected by Azure OAuth authentication. + +### Testing with a Client + +Create a test client that authenticates with your Azure-protected server: + +```python test_client.py +from fastmcp import Client +import asyncio + +async def main(): + # The client will automatically handle Azure OAuth + async with Client("http://localhost:8000/mcp", auth="oauth") as client: + # First-time connection will open Azure login in your browser + print("✓ Authenticated with Azure!") + + # Test the protected tool + result = await client.call_tool("get_user_info") + print(f"Azure user: {result['email']}") + print(f"Name: {result['name']}") + +if __name__ == "__main__": + asyncio.run(main()) +``` + +When you run the client for the first time: +1. Your browser will open to Microsoft's authorization page +2. Sign in with your Microsoft account (work, school, or personal based on your tenant configuration) +3. Grant the requested permissions +4. After authorization, you'll be redirected back +5. The client receives the token and can make authenticated requests + + +The client caches tokens locally, so you won't need to re-authenticate for subsequent runs unless the token expires or you explicitly clear the cache. + + +## Production Configuration + + + +For production deployments with persistent token management across server restarts, configure `jwt_signing_key` and `client_storage`: + +```python server.py +import os +from fastmcp import FastMCP +from fastmcp.server.auth.providers.azure import AzureProvider +from key_value.aio.stores.redis import RedisStore +from key_value.aio.wrappers.encryption import FernetEncryptionWrapper +from cryptography.fernet import Fernet + +# Production setup with encrypted persistent token storage +auth_provider = AzureProvider( + client_id="835f09b6-0f0f-40cc-85cb-f32c5829a149", + client_secret="your-client-secret", + tenant_id="08541b6e-646d-43de-a0eb-834e6713d6d5", + base_url="https://your-production-domain.com", + required_scopes=["your-scope"], + + # Production token management + jwt_signing_key=os.environ["JWT_SIGNING_KEY"], + client_storage=FernetEncryptionWrapper( + key_value=RedisStore( + host=os.environ["REDIS_HOST"], + port=int(os.environ["REDIS_PORT"]) + ), + fernet=Fernet(os.environ["STORAGE_ENCRYPTION_KEY"]) + ) +) + +mcp = FastMCP(name="Production Azure App", auth=auth_provider) +``` + + +Parameters (`jwt_signing_key` and `client_storage`) work together to ensure tokens and client registrations survive server restarts. **Wrap your storage in `FernetEncryptionWrapper` to encrypt sensitive OAuth tokens at rest** - without it, tokens are stored in plaintext. Store secrets in environment variables and use a persistent storage backend like Redis for distributed deployments. + +For complete details on these parameters, see the [OAuth Proxy documentation](/servers/auth/oauth-proxy#configuration-parameters). + + +## Token Verification Only (Managed Identity) + + + +For deployments where your server only needs to **validate incoming tokens** — such as Azure Container Apps with Managed Identity — use `AzureJWTVerifier` with `RemoteAuthProvider` instead of the full `AzureProvider`. + +This pattern is ideal when: +- Your infrastructure handles authentication (e.g., Managed Identity) +- You don't need the OAuth proxy flow (no `client_secret` required) +- You just need to verify that incoming Azure AD tokens are valid + +```python server.py +from fastmcp import FastMCP +from fastmcp.server.auth import RemoteAuthProvider +from fastmcp.server.auth.providers.azure import AzureJWTVerifier +from pydantic import AnyHttpUrl + +tenant_id = "your-tenant-id" +client_id = "your-client-id" + +# AzureJWTVerifier auto-configures JWKS, issuer, and audience +verifier = AzureJWTVerifier( + client_id=client_id, + tenant_id=tenant_id, + required_scopes=["access_as_user"], # Scope names from Azure Portal +) + +auth = RemoteAuthProvider( + token_verifier=verifier, + authorization_servers=[ + AnyHttpUrl(f"https://login.microsoftonline.com/{tenant_id}/v2.0") + ], + base_url="https://your-container-app.azurecontainerapps.io", +) + +mcp = FastMCP(name="Azure MI App", auth=auth) +``` + +`AzureJWTVerifier` handles Azure's scope format automatically. You write scope names exactly as they appear in Azure Portal under **Expose an API** (e.g., `access_as_user`). The verifier validates tokens using the short-form scopes that Azure puts in the `scp` claim, while advertising the full URI scopes (e.g., `api://your-client-id/access_as_user`) in OAuth metadata so MCP clients know what to request. + + +For Azure Government, pass `base_authority="login.microsoftonline.us"` to `AzureJWTVerifier`. + + +## On-Behalf-Of (OBO) + + + +The On-Behalf-Of (OBO) flow allows your FastMCP server to call downstream Microsoft APIs—like Microsoft Graph—using the authenticated user's identity. When a user authenticates to your MCP server, you receive a token for your API. OBO exchanges that token for a new token that can call other services, maintaining the user's identity and permissions throughout the chain. + +This pattern is useful when your tools need to access user-specific data from Microsoft services: reading emails, accessing calendar events, querying SharePoint, or any other Graph API operation that requires user context. + + +OBO features require the `azure` extra: + +```bash +pip install 'fastmcp[azure]' +``` + + +### Azure Portal Setup + +OBO requires additional configuration in your Azure App registration beyond basic authentication. + + + + In your App registration, navigate to **API permissions** and add the Microsoft Graph permissions your tools will need. + + - Click **Add a permission** → **Microsoft Graph** → **Delegated permissions** + - Select the permissions required for your use case (e.g., `Mail.Read`, `Calendars.Read`, `User.Read`) + - Repeat for any other APIs you need to call + + + Only add delegated permissions for OBO. Application permissions bypass user context entirely and are inappropriate for the OBO flow. + + + + + OBO requires admin consent for the permissions you've added. In the **API permissions** page, click **Grant admin consent for [Your Organization]**. + + Without admin consent, OBO token exchanges will fail with an `AADSTS65001` error indicating the user or administrator hasn't consented to use the application. + + + For development, you can grant consent for just your own account. For production, an Azure AD administrator must grant tenant-wide consent. + + + + +### Configure AzureProvider for OBO + +The `additional_authorize_scopes` parameter tells Azure which downstream API permissions to include during the initial authorization. These scopes establish what your server can request through OBO later. + +```python server.py +from fastmcp import FastMCP +from fastmcp.server.auth.providers.azure import AzureProvider + +auth_provider = AzureProvider( + client_id="your-client-id", + client_secret="your-client-secret", + tenant_id="your-tenant-id", + base_url="http://localhost:8000", + required_scopes=["mcp-access"], # Your API scope + # Include Graph scopes for OBO + additional_authorize_scopes=[ + "https://graph.microsoft.com/Mail.Read", + "https://graph.microsoft.com/User.Read", + "offline_access", # Enables refresh tokens + ], +) + +mcp = FastMCP(name="Graph-Enabled Server", auth=auth_provider) +``` + +Scopes listed in `additional_authorize_scopes` are requested during the initial OAuth flow but aren't validated on incoming tokens. They establish permission for your server to later exchange the user's token for downstream API access. + + +Use fully-qualified scope URIs for downstream APIs (e.g., `https://graph.microsoft.com/Mail.Read`). Short forms like `Mail.Read` work for authorization requests, but fully-qualified URIs are clearer and avoid ambiguity. + + +### EntraOBOToken Dependency + +The `EntraOBOToken` dependency handles the complete OBO flow automatically. Declare it as a parameter default with the scopes you need, and FastMCP exchanges the user's token for a downstream API token before your function runs. + +```python +from fastmcp import FastMCP +from fastmcp.server.auth.providers.azure import AzureProvider, EntraOBOToken +import httpx + +auth_provider = AzureProvider( + client_id="your-client-id", + client_secret="your-client-secret", + tenant_id="your-tenant-id", + base_url="http://localhost:8000", + required_scopes=["mcp-access"], + additional_authorize_scopes=[ + "https://graph.microsoft.com/Mail.Read", + "https://graph.microsoft.com/User.Read", + ], +) + +mcp = FastMCP(name="Email Reader", auth=auth_provider) + +@mcp.tool +async def get_recent_emails( + count: int = 10, + graph_token: str = EntraOBOToken(["https://graph.microsoft.com/Mail.Read"]), +) -> list[dict]: + """Get the user's recent emails from Microsoft Graph.""" + async with httpx.AsyncClient() as client: + response = await client.get( + f"https://graph.microsoft.com/v1.0/me/messages?$top={count}", + headers={"Authorization": f"Bearer {graph_token}"}, + ) + response.raise_for_status() + data = response.json() + + return [ + {"subject": msg["subject"], "from": msg["from"]["emailAddress"]["address"]} + for msg in data.get("value", []) + ] +``` + +The `graph_token` parameter receives a ready-to-use access token for Microsoft Graph. FastMCP handles the OBO exchange transparently—your function just uses the token to call the API. + + +**Scope alignment is critical.** The scopes passed to `EntraOBOToken` must be a subset of the scopes in `additional_authorize_scopes`. If you request a scope during OBO that wasn't included in the initial authorization, the exchange will fail. + + + +For advanced OBO scenarios, use `CurrentAccessToken()` to get the user's token, then construct an `azure.identity.aio.OnBehalfOfCredential` directly with your Azure credentials. + + + +For a complete working example of Azure OBO with FastMCP, see [Pamela Fox's blog post on OBO flow for Entra-based MCP servers](https://blog.pamelafox.org/2026/01/using-on-behalf-of-flow-for-entra-based.html). + diff --git a/docs/integrations/chatgpt.mdx b/docs/integrations/chatgpt.mdx new file mode 100644 index 000000000..92ddb7404 --- /dev/null +++ b/docs/integrations/chatgpt.mdx @@ -0,0 +1,156 @@ +--- +title: ChatGPT 🤝 FastMCP +sidebarTitle: ChatGPT +description: Connect FastMCP servers to ChatGPT in Chat and Deep Research modes +icon: message-smile +--- + +[ChatGPT](https://chatgpt.com/) supports MCP servers through remote HTTP connections in two modes: **Chat mode** for interactive conversations and **Deep Research mode** for comprehensive information retrieval. + + +**Developer Mode Required for Chat Mode**: To use MCP servers in regular ChatGPT conversations, you must first enable Developer Mode in your ChatGPT settings. This feature is available for ChatGPT Pro, Team, Enterprise, and Edu users. + + + +OpenAI's official MCP documentation and examples are built with **FastMCP v2**! Learn more from their [MCP documentation](https://platform.openai.com/docs/mcp) and [Developer Mode guide](https://platform.openai.com/docs/guides/developer-mode). + + +## Build a Server + +First, let's create a simple FastMCP server: + +```python server.py +from fastmcp import FastMCP +import random + +mcp = FastMCP("Demo Server") + +@mcp.tool +def roll_dice(sides: int = 6) -> int: + """Roll a dice with the specified number of sides.""" + return random.randint(1, sides) + +if __name__ == "__main__": + mcp.run(transport="http", port=8000) +``` + +### Deploy Your Server + +Your server must be accessible from the internet. For development, use `ngrok`: + + +```bash Terminal 1 +python server.py +``` + +```bash Terminal 2 +ngrok http 8000 +``` + + +Note your public URL (e.g., `https://abc123.ngrok.io`) for the next steps. + +## Chat Mode + +Chat mode lets you use MCP tools directly in ChatGPT conversations. See [OpenAI's Developer Mode guide](https://platform.openai.com/docs/guides/developer-mode) for the latest requirements. + +### Add to ChatGPT + +#### 1. Enable Developer Mode + +1. Open ChatGPT and go to **Settings** → **Connectors** +2. Under **Advanced**, toggle **Developer Mode** to enabled + +#### 2. Create Connector + +1. In **Settings** → **Connectors**, click **Create** +2. Enter: + - **Name**: Your server name + - **Server URL**: `https://your-server.ngrok.io/mcp/` +3. Check **I trust this provider** +4. Add authentication if needed +5. Click **Create** + + +**Without Developer Mode**: If you don't have search/fetch tools, ChatGPT will reject the server. With Developer Mode enabled, you don't need search/fetch tools for Chat mode. + + +#### 3. Use in Chat + +1. Start a new chat +2. Click the **+** button → **More** → **Developer Mode** +3. **Enable your MCP server connector** (required - the connector must be explicitly added to each chat) +4. Now you can use your tools: + +Example usage: +- "Roll a 20-sided dice" +- "Roll dice" (uses default 6 sides) + + +The connector must be explicitly enabled in each chat session through Developer Mode. Once added, it remains active for the entire conversation. + + +### Skip Confirmations + +Use `annotations={"readOnlyHint": True}` to skip confirmation prompts for read-only tools: + +```python +@mcp.tool(annotations={"readOnlyHint": True}) +def get_status() -> str: + """Check system status.""" + return "All systems operational" + +@mcp.tool() # No annotation - ChatGPT may ask for confirmation +def delete_item(id: str) -> str: + """Delete an item.""" + return f"Deleted {id}" +``` + +## Deep Research Mode + +Deep Research mode provides systematic information retrieval with citations. See [OpenAI's MCP documentation](https://platform.openai.com/docs/mcp) for the latest Deep Research specifications. + + +**Search and Fetch Required**: Without Developer Mode, ChatGPT will reject any server that doesn't have both `search` and `fetch` tools. Even in Developer Mode, Deep Research only uses these two tools. + + +### Tool Implementation + +Deep Research tools must follow this pattern: + +```python +@mcp.tool() +def search(query: str) -> dict: + """ + Search for records matching the query. + Must return {"ids": [list of string IDs]} + """ + # Your search logic + matching_ids = ["id1", "id2", "id3"] + return {"ids": matching_ids} + +@mcp.tool() +def fetch(id: str) -> dict: + """ + Fetch a complete record by ID. + Return the full record data for ChatGPT to analyze. + """ + # Your fetch logic + return { + "id": id, + "title": "Record Title", + "content": "Full record content...", + "metadata": {"author": "Jane Doe", "date": "2024"} + } +``` + +### Using Deep Research + +1. Ensure your server is added to ChatGPT's connectors (same as Chat mode) +2. Start a new chat +3. Click **+** → **Deep Research** +4. Select your MCP server as a source +5. Ask research questions + +ChatGPT will use your `search` and `fetch` tools to find and cite relevant information. + diff --git a/docs/integrations/claude-code.mdx b/docs/integrations/claude-code.mdx new file mode 100644 index 000000000..8098ff51e --- /dev/null +++ b/docs/integrations/claude-code.mdx @@ -0,0 +1,177 @@ +--- +title: Claude Code 🤝 FastMCP +sidebarTitle: Claude Code +description: Install and use FastMCP servers in Claude Code +icon: message-smile +--- + +import { VersionBadge } from "/snippets/version-badge.mdx" +import { LocalFocusTip } from "/snippets/local-focus.mdx" + + + +[Claude Code](https://docs.anthropic.com/en/docs/claude-code) supports MCP servers through multiple transport methods including STDIO, SSE, and HTTP, allowing you to extend Claude's capabilities with custom tools, resources, and prompts from your FastMCP servers. + +## Requirements + +This integration uses STDIO transport to run your FastMCP server locally. For remote deployments, you can run your FastMCP server with HTTP or SSE transport and configure it directly using Claude Code's built-in MCP management commands. + +## Create a Server + +The examples in this guide will use the following simple dice-rolling server, saved as `server.py`. + +```python server.py +import random +from fastmcp import FastMCP + +mcp = FastMCP(name="Dice Roller") + +@mcp.tool +def roll_dice(n_dice: int) -> list[int]: + """Roll `n_dice` 6-sided dice and return the results.""" + return [random.randint(1, 6) for _ in range(n_dice)] + +if __name__ == "__main__": + mcp.run() +``` + +## Install the Server + +### FastMCP CLI + + +The easiest way to install a FastMCP server in Claude Code is using the `fastmcp install claude-code` command. This automatically handles the configuration, dependency management, and calls Claude Code's built-in MCP management system. + +```bash +fastmcp install claude-code server.py +``` + +The install command supports the same `file.py:object` notation as the `run` command. If no object is specified, it will automatically look for a FastMCP server object named `mcp`, `server`, or `app` in your file: + +```bash +# These are equivalent if your server object is named 'mcp' +fastmcp install claude-code server.py +fastmcp install claude-code server.py:mcp + +# Use explicit object name if your server has a different name +fastmcp install claude-code server.py:my_custom_server +``` + +The command will automatically configure the server with Claude Code's `claude mcp add` command. + +#### Dependencies + +FastMCP provides flexible dependency management options for your Claude Code servers: + +**Individual packages**: Use the `--with` flag to specify packages your server needs. You can use this flag multiple times: + +```bash +fastmcp install claude-code server.py --with pandas --with requests +``` + +**Requirements file**: If you maintain a `requirements.txt` file with all your dependencies, use `--with-requirements` to install them: + +```bash +fastmcp install claude-code server.py --with-requirements requirements.txt +``` + +**Editable packages**: For local packages under development, use `--with-editable` to install them in editable mode: + +```bash +fastmcp install claude-code server.py --with-editable ./my-local-package +``` + +Alternatively, you can use a `fastmcp.json` configuration file (recommended): + +```json fastmcp.json +{ + "$schema": "https://gofastmcp.com/public/schemas/fastmcp.json/v1.json", + "source": { + "path": "server.py", + "entrypoint": "mcp" + }, + "environment": { + "dependencies": ["pandas", "requests"] + } +} +``` + + +#### Python Version and Project Configuration + +Control the Python environment for your server with these options: + +**Python version**: Use `--python` to specify which Python version your server requires. This ensures compatibility when your server needs specific Python features: + +```bash +fastmcp install claude-code server.py --python 3.11 +``` + +**Project directory**: Use `--project` to run your server within a specific project context. This tells `uv` to use the project's configuration files and virtual environment: + +```bash +fastmcp install claude-code server.py --project /path/to/my-project +``` + +#### Environment Variables + +If your server needs environment variables (like API keys), you must include them: + +```bash +fastmcp install claude-code server.py --server-name "Weather Server" \ + --env API_KEY=your-api-key \ + --env DEBUG=true +``` + +Or load them from a `.env` file: + +```bash +fastmcp install claude-code server.py --server-name "Weather Server" --env-file .env +``` + + +**Claude Code must be installed**. The integration looks for the Claude Code CLI at the default installation location (`~/.claude/local/claude`) and uses the `claude mcp add` command to register servers. + + +### Manual Configuration + +For more control over the configuration, you can manually use Claude Code's built-in MCP management commands. This gives you direct control over how your server is launched: + +```bash +# Add a server with custom configuration +claude mcp add dice-roller -- uv run --with fastmcp fastmcp run server.py + +# Add with environment variables +claude mcp add weather-server -e API_KEY=secret -e DEBUG=true -- uv run --with fastmcp fastmcp run server.py + +# Add with specific scope (local, user, or project) +claude mcp add my-server --scope user -- uv run --with fastmcp fastmcp run server.py +``` + +You can also manually specify Python versions and project directories in your Claude Code commands: + +```bash +# With specific Python version +claude mcp add ml-server -- uv run --python 3.11 --with fastmcp fastmcp run server.py + +# Within a project directory +claude mcp add project-server -- uv run --project /path/to/project --with fastmcp fastmcp run server.py +``` + +## Using the Server + +Once your server is installed, you can start using your FastMCP server with Claude Code. + +Try asking Claude something like: + +> "Roll some dice for me" + +Claude will automatically detect your `roll_dice` tool and use it to fulfill your request, returning something like: + +> I'll roll some dice for you! Here are your results: [4, 2, 6] +> +> You rolled three dice and got a 4, a 2, and a 6! + +Claude Code can now access all the tools, resources, and prompts you've defined in your FastMCP server. + +If your server provides resources, you can reference them with `@` mentions using the format `@server:protocol://resource/path`. If your server provides prompts, you can use them as slash commands with `/mcp__servername__promptname`. \ No newline at end of file diff --git a/docs/integrations/claude-desktop.mdx b/docs/integrations/claude-desktop.mdx new file mode 100644 index 000000000..4478bcc37 --- /dev/null +++ b/docs/integrations/claude-desktop.mdx @@ -0,0 +1,299 @@ +--- +title: Claude Desktop 🤝 FastMCP +sidebarTitle: Claude Desktop +description: Connect FastMCP servers to Claude Desktop +icon: message-smile +--- + +import { VersionBadge } from "/snippets/version-badge.mdx" +import { LocalFocusTip } from "/snippets/local-focus.mdx" + + + +[Claude Desktop](https://www.claude.com/download) supports MCP servers through local STDIO connections and remote servers (beta), allowing you to extend Claude's capabilities with custom tools, resources, and prompts from your FastMCP servers. + + +Remote MCP server support is currently in beta and available for users on Claude Pro, Max, Team, and Enterprise plans (as of June 2025). Most users will still need to use local STDIO connections. + + + +This guide focuses specifically on using FastMCP servers with Claude Desktop. For general Claude Desktop MCP setup and official examples, see the [official Claude Desktop quickstart guide](https://modelcontextprotocol.io/quickstart/user). + + + +## Requirements + +Claude Desktop traditionally requires MCP servers to run locally using STDIO transport, where your server communicates with Claude through standard input/output rather than HTTP. However, users on certain plans now have access to remote server support as well. + + +If you don't have access to remote server support or need to connect to remote servers, you can create a **proxy server** that runs locally via STDIO and forwards requests to remote HTTP servers. See the [Proxy Servers](#proxy-servers) section below. + + +## Create a Server + +The examples in this guide will use the following simple dice-rolling server, saved as `server.py`. + +```python server.py +import random +from fastmcp import FastMCP + +mcp = FastMCP(name="Dice Roller") + +@mcp.tool +def roll_dice(n_dice: int) -> list[int]: + """Roll `n_dice` 6-sided dice and return the results.""" + return [random.randint(1, 6) for _ in range(n_dice)] + +if __name__ == "__main__": + mcp.run() +``` + +## Install the Server + +### FastMCP CLI + + +The easiest way to install a FastMCP server in Claude Desktop is using the `fastmcp install claude-desktop` command. This automatically handles the configuration and dependency management. + + +Prior to version 2.10.3, Claude Desktop could be managed by running `fastmcp install ` without specifying the client. + + +```bash +fastmcp install claude-desktop server.py +``` + +The install command supports the same `file.py:object` notation as the `run` command. If no object is specified, it will automatically look for a FastMCP server object named `mcp`, `server`, or `app` in your file: + +```bash +# These are equivalent if your server object is named 'mcp' +fastmcp install claude-desktop server.py +fastmcp install claude-desktop server.py:mcp + +# Use explicit object name if your server has a different name +fastmcp install claude-desktop server.py:my_custom_server +``` + +After installation, restart Claude Desktop completely. You should see a hammer icon (🔨) in the bottom left of the input box, indicating that MCP tools are available. + +#### Dependencies + +FastMCP provides several ways to manage your server's dependencies when installing in Claude Desktop: + +**Individual packages**: Use the `--with` flag to specify packages your server needs. You can use this flag multiple times: + +```bash +fastmcp install claude-desktop server.py --with pandas --with requests +``` + +**Requirements file**: If you have a `requirements.txt` file listing all your dependencies, use `--with-requirements` to install them all at once: + +```bash +fastmcp install claude-desktop server.py --with-requirements requirements.txt +``` + +**Editable packages**: For local packages in development, use `--with-editable` to install them in editable mode: + +```bash +fastmcp install claude-desktop server.py --with-editable ./my-local-package +``` + +Alternatively, you can use a `fastmcp.json` configuration file (recommended): + +```json fastmcp.json +{ + "$schema": "https://gofastmcp.com/public/schemas/fastmcp.json/v1.json", + "source": { + "path": "server.py", + "entrypoint": "mcp" + }, + "environment": { + "dependencies": ["pandas", "requests"] + } +} +``` + + +#### Python Version and Project Directory + +FastMCP allows you to control the Python environment for your server: + +**Python version**: Use `--python` to specify which Python version your server should run with. This is particularly useful when your server requires a specific Python version: + +```bash +fastmcp install claude-desktop server.py --python 3.11 +``` + +**Project directory**: Use `--project` to run your server within a specific project directory. This ensures that `uv` will discover all `pyproject.toml`, `uv.toml`, and `.python-version` files from that project: + +```bash +fastmcp install claude-desktop server.py --project /path/to/my-project +``` + +When you specify a project directory, all relative paths in your server will be resolved from that directory, and the project's virtual environment will be used. + +#### Environment Variables + + +Claude Desktop runs servers in a completely isolated environment with no access to your shell environment or locally installed applications. You must explicitly pass any environment variables your server needs. + + +If your server needs environment variables (like API keys), you must include them: + +```bash +fastmcp install claude-desktop server.py --server-name "Weather Server" \ + --env API_KEY=your-api-key \ + --env DEBUG=true +``` + +Or load them from a `.env` file: + +```bash +fastmcp install claude-desktop server.py --server-name "Weather Server" --env-file .env +``` + +- **`uv` must be installed and available in your system PATH**. Claude Desktop runs in its own isolated environment and needs `uv` to manage dependencies. +- **On macOS, it is recommended to install `uv` globally with Homebrew** so that Claude Desktop will detect it: `brew install uv`. Installing `uv` with other methods may not make it accessible to Claude Desktop. + + + +### Manual Configuration + +For more control over the configuration, you can manually edit Claude Desktop's configuration file. You can open the configuration file from Claude's developer settings, or find it in the following locations: +- **macOS**: `~/Library/Application Support/Claude/claude_desktop_config.json` +- **Windows**: `%APPDATA%\Claude\claude_desktop_config.json` + +The configuration file is a JSON object with a `mcpServers` key, which contains the configuration for each MCP server. + +```json +{ + "mcpServers": { + "dice-roller": { + "command": "python", + "args": ["path/to/your/server.py"] + } + } +} +``` + +After updating the configuration file, restart Claude Desktop completely. Look for the hammer icon (🔨) to confirm your server is loaded. + +#### Dependencies + +If your server has dependencies, you can use `uv` or another package manager to set up the environment. + + +When manually configuring dependencies, the recommended approach is to use `uv` with FastMCP. The configuration uses `uv run` to create an isolated environment with your specified packages: + +```json +{ + "mcpServers": { + "dice-roller": { + "command": "uv", + "args": [ + "run", + "--with", "fastmcp", + "--with", "pandas", + "--with", "requests", + "fastmcp", + "run", + "path/to/your/server.py" + ] + } + } +} +``` + +You can also manually specify Python versions and project directories in your configuration. Add `--python` to use a specific Python version, or `--project` to run within a project directory: + +```json +{ + "mcpServers": { + "dice-roller": { + "command": "uv", + "args": [ + "run", + "--python", "3.11", + "--project", "/path/to/project", + "--with", "fastmcp", + "fastmcp", + "run", + "path/to/your/server.py" + ] + } + } +} +``` + +The order of arguments matters: Python version and project settings come before package specifications, which come before the actual command to run. + + +- **`uv` must be installed and available in your system PATH**. Claude Desktop runs in its own isolated environment and needs `uv` to manage dependencies. +- **On macOS, it is recommended to install `uv` globally with Homebrew** so that Claude Desktop will detect it: `brew install uv`. Installing `uv` with other methods may not make it accessible to Claude Desktop. + + +#### Environment Variables + +You can also specify environment variables in the configuration: + +```json +{ + "mcpServers": { + "weather-server": { + "command": "python", + "args": ["path/to/weather_server.py"], + "env": { + "API_KEY": "your-api-key", + "DEBUG": "true" + } + } + } +} +``` + +Claude Desktop runs servers in a completely isolated environment with no access to your shell environment or locally installed applications. You must explicitly pass any environment variables your server needs. + + + +## Remote Servers + + +Users on Claude Pro, Max, Team, and Enterprise plans have first-class remote server support via integrations. For other users, or as an alternative approach, FastMCP can create a proxy server that forwards requests to a remote HTTP server. You can install the proxy server in Claude Desktop. + +Create a proxy server that connects to a remote HTTP server: + +```python proxy_server.py +from fastmcp.server import create_proxy + +# Create a proxy to a remote server +proxy = create_proxy( + "https://example.com/mcp/sse", + name="Remote Server Proxy" +) + +if __name__ == "__main__": + proxy.run() # Runs via STDIO for Claude Desktop +``` + +### Authentication + +For authenticated remote servers, create an authenticated client following the guidance in the [client auth documentation](/clients/auth/bearer) and pass it to the proxy: + +```python auth_proxy_server.py {7} +from fastmcp import Client +from fastmcp.client.auth import BearerAuth +from fastmcp.server import create_proxy + +# Create authenticated client +client = Client( + "https://api.example.com/mcp/sse", + auth=BearerAuth(token="your-access-token") +) + +# Create proxy using the authenticated client +proxy = create_proxy(client, name="Authenticated Proxy") + +if __name__ == "__main__": + proxy.run() +``` + diff --git a/docs/integrations/cursor-install-mcp.png b/docs/integrations/cursor-install-mcp.png new file mode 100644 index 000000000..5681d70d7 Binary files /dev/null and b/docs/integrations/cursor-install-mcp.png differ diff --git a/docs/integrations/cursor.mdx b/docs/integrations/cursor.mdx new file mode 100644 index 000000000..da0744ee0 --- /dev/null +++ b/docs/integrations/cursor.mdx @@ -0,0 +1,284 @@ +--- +title: Cursor 🤝 FastMCP +sidebarTitle: Cursor +description: Install and use FastMCP servers in Cursor +icon: message-smile +--- + +import { VersionBadge } from "/snippets/version-badge.mdx" +import { LocalFocusTip } from "/snippets/local-focus.mdx" + + + +[Cursor](https://www.cursor.com/) supports MCP servers through multiple transport methods including STDIO, SSE, and Streamable HTTP, allowing you to extend Cursor's AI assistant with custom tools, resources, and prompts from your FastMCP servers. + +## Requirements + +This integration uses STDIO transport to run your FastMCP server locally. For remote deployments, you can run your FastMCP server with HTTP or SSE transport and configure it directly in Cursor's settings. + +## Create a Server + +The examples in this guide will use the following simple dice-rolling server, saved as `server.py`. + +```python server.py +import random +from fastmcp import FastMCP + +mcp = FastMCP(name="Dice Roller") + +@mcp.tool +def roll_dice(n_dice: int) -> list[int]: + """Roll `n_dice` 6-sided dice and return the results.""" + return [random.randint(1, 6) for _ in range(n_dice)] + +if __name__ == "__main__": + mcp.run() +``` + +## Install the Server + +### FastMCP CLI + + +The easiest way to install a FastMCP server in Cursor is using the `fastmcp install cursor` command. This automatically handles the configuration, dependency management, and opens Cursor with a deeplink to install the server. + +```bash +fastmcp install cursor server.py +``` + +#### Workspace Installation + + +By default, FastMCP installs servers globally for Cursor. You can also install servers to project-specific workspaces using the `--workspace` flag: + +```bash +# Install to current directory's .cursor/ folder +fastmcp install cursor server.py --workspace . + +# Install to specific workspace +fastmcp install cursor server.py --workspace /path/to/project +``` + +This creates a `.cursor/mcp.json` configuration file in the specified workspace directory, allowing different projects to have their own MCP server configurations. + +The install command supports the same `file.py:object` notation as the `run` command. If no object is specified, it will automatically look for a FastMCP server object named `mcp`, `server`, or `app` in your file: + +```bash +# These are equivalent if your server object is named 'mcp' +fastmcp install cursor server.py +fastmcp install cursor server.py:mcp + +# Use explicit object name if your server has a different name +fastmcp install cursor server.py:my_custom_server +``` + +After running the command, Cursor will open automatically and prompt you to install the server. The command will be `uv`, which is expected as this is a Python STDIO server. Click "Install" to confirm: + +![Cursor install prompt](./cursor-install-mcp.png) + +#### Dependencies + +FastMCP offers multiple ways to manage dependencies for your Cursor servers: + +**Individual packages**: Use the `--with` flag to specify packages your server needs. You can use this flag multiple times: + +```bash +fastmcp install cursor server.py --with pandas --with requests +``` + +**Requirements file**: For projects with a `requirements.txt` file, use `--with-requirements` to install all dependencies at once: + +```bash +fastmcp install cursor server.py --with-requirements requirements.txt +``` + +**Editable packages**: When developing local packages, use `--with-editable` to install them in editable mode: + +```bash +fastmcp install cursor server.py --with-editable ./my-local-package +``` + +Alternatively, you can use a `fastmcp.json` configuration file (recommended): + +```json fastmcp.json +{ + "$schema": "https://gofastmcp.com/public/schemas/fastmcp.json/v1.json", + "source": { + "path": "server.py", + "entrypoint": "mcp" + }, + "environment": { + "dependencies": ["pandas", "requests"] + } +} +``` + + +#### Python Version and Project Configuration + +Control your server's Python environment with these options: + +**Python version**: Use `--python` to specify which Python version your server should use. This is essential when your server requires specific Python features: + +```bash +fastmcp install cursor server.py --python 3.11 +``` + +**Project directory**: Use `--project` to run your server within a specific project context. This ensures `uv` discovers all project configuration files and uses the correct virtual environment: + +```bash +fastmcp install cursor server.py --project /path/to/my-project +``` + +#### Environment Variables + + +Cursor runs servers in a completely isolated environment with no access to your shell environment or locally installed applications. You must explicitly pass any environment variables your server needs. + + +If your server needs environment variables (like API keys), you must include them: + +```bash +fastmcp install cursor server.py --server-name "Weather Server" \ + --env API_KEY=your-api-key \ + --env DEBUG=true +``` + +Or load them from a `.env` file: + +```bash +fastmcp install cursor server.py --server-name "Weather Server" --env-file .env +``` + + +**`uv` must be installed and available in your system PATH**. Cursor runs in its own isolated environment and needs `uv` to manage dependencies. + + +### Generate MCP JSON + + +**Use the first-class integration above for the best experience.** The MCP JSON generation is useful for advanced use cases, manual configuration, or integration with other tools. + + +You can generate MCP JSON configuration for manual use: + +```bash +# Generate configuration and output to stdout +fastmcp install mcp-json server.py --server-name "Dice Roller" --with pandas + +# Copy configuration to clipboard for easy pasting +fastmcp install mcp-json server.py --server-name "Dice Roller" --copy +``` + +This generates the standard `mcpServers` configuration format that can be used with any MCP-compatible client. + +### Manual Configuration + +For more control over the configuration, you can manually edit Cursor's configuration file. The configuration file is located at: +- **All platforms**: `~/.cursor/mcp.json` + +The configuration file is a JSON object with a `mcpServers` key, which contains the configuration for each MCP server. + +```json +{ + "mcpServers": { + "dice-roller": { + "command": "python", + "args": ["path/to/your/server.py"] + } + } +} +``` + +After updating the configuration file, your server should be available in Cursor. + +#### Dependencies + +If your server has dependencies, you can use `uv` or another package manager to set up the environment. + +When manually configuring dependencies, the recommended approach is to use `uv` with FastMCP. The configuration should use `uv run` to create an isolated environment with your specified packages: + +```json +{ + "mcpServers": { + "dice-roller": { + "command": "uv", + "args": [ + "run", + "--with", "fastmcp", + "--with", "pandas", + "--with", "requests", + "fastmcp", + "run", + "path/to/your/server.py" + ] + } + } +} +``` + +You can also manually specify Python versions and project directories in your configuration: + +```json +{ + "mcpServers": { + "dice-roller": { + "command": "uv", + "args": [ + "run", + "--python", "3.11", + "--project", "/path/to/project", + "--with", "fastmcp", + "fastmcp", + "run", + "path/to/your/server.py" + ] + } + } +} +``` + +Note that the order of arguments is important: Python version and project settings should come before package specifications. + + +**`uv` must be installed and available in your system PATH**. Cursor runs in its own isolated environment and needs `uv` to manage dependencies. + + +#### Environment Variables + +You can also specify environment variables in the configuration: + +```json +{ + "mcpServers": { + "weather-server": { + "command": "python", + "args": ["path/to/weather_server.py"], + "env": { + "API_KEY": "your-api-key", + "DEBUG": "true" + } + } + } +} +``` + + +Cursor runs servers in a completely isolated environment with no access to your shell environment or locally installed applications. You must explicitly pass any environment variables your server needs. + + +## Using the Server + +Once your server is installed, you can start using your FastMCP server with Cursor's AI assistant. + +Try asking Cursor something like: + +> "Roll some dice for me" + +Cursor will automatically detect your `roll_dice` tool and use it to fulfill your request, returning something like: + +> 🎲 Here are your dice rolls: 4, 6, 4 +> +> You rolled 3 dice with a total of 14! The 6 was a nice high roll there! + +The AI assistant can now access all the tools, resources, and prompts you've defined in your FastMCP server. diff --git a/docs/integrations/descope.mdx b/docs/integrations/descope.mdx new file mode 100644 index 000000000..dba9b3509 --- /dev/null +++ b/docs/integrations/descope.mdx @@ -0,0 +1,113 @@ +--- +title: Descope 🤝 FastMCP +sidebarTitle: Descope +description: Secure your FastMCP server with Descope +icon: shield-check +--- + +import { VersionBadge } from "/snippets/version-badge.mdx"; + + + +This guide shows you how to secure your FastMCP server using [**Descope**](https://www.descope.com), a complete authentication and user management solution. This integration uses the [**Remote OAuth**](/servers/auth/remote-oauth) pattern, where Descope handles user login and your FastMCP server validates the tokens. + +## Configuration + +### Prerequisites + +Before you begin, you will need: + +1. To [sign up](https://www.descope.com/sign-up) for a Free Forever Descope account +2. Your FastMCP server's URL (can be localhost for development, e.g., `http://localhost:3000`) + +### Step 1: Configure Descope + + + + 1. Go to the [MCP Servers page](https://app.descope.com/mcp-servers) of the Descope Console, and create a new MCP Server. + 2. Give the MCP server a name and description. + 3. Ensure that **Dynamic Client Registration (DCR)** is enabled. Then click **Create**. + 4. Once you've created the MCP Server, note your Well-Known URL. + + + + DCR is required for FastMCP clients to automatically register with your authentication server. + + + + + Save your Well-Known URL from [MCP Server Settings](https://app.descope.com/mcp-servers): + ``` + Well-Known URL: https://.../v1/apps/agentic/P.../M.../.well-known/openid-configuration + ``` + + + +### Step 2: Environment Setup + +Create a `.env` file with your Descope configuration: + +```bash +DESCOPE_CONFIG_URL=https://.../v1/apps/agentic/P.../M.../.well-known/openid-configuration # Your Descope Well-Known URL +SERVER_URL=http://localhost:3000 # Your server's base URL +``` + +### Step 3: FastMCP Configuration + +Create your FastMCP server file and use the DescopeProvider to handle all the OAuth integration automatically: + +```python server.py +from fastmcp import FastMCP +from fastmcp.server.auth.providers.descope import DescopeProvider + +# The DescopeProvider automatically discovers Descope endpoints +# and configures JWT token validation +auth_provider = DescopeProvider( + config_url=https://.../.well-known/openid-configuration, # Your MCP Server .well-known URL + base_url=SERVER_URL, # Your server's public URL +) + +# Create FastMCP server with auth +mcp = FastMCP(name="My Descope Protected Server", auth=auth_provider) + +``` + +## Testing + +To test your server, you can use the `fastmcp` CLI to run it locally. Assuming you've saved the above code to `server.py` (after replacing the environment variables with your actual values!), you can run the following command: + +```bash +fastmcp run server.py --transport http --port 8000 +``` + +Now, you can use a FastMCP client to test that you can reach your server after authenticating: + +```python +from fastmcp import Client +import asyncio + +async def main(): + async with Client("http://localhost:8000/mcp", auth="oauth") as client: + assert await client.ping() + +if __name__ == "__main__": + asyncio.run(main()) +``` + +## Production Configuration + +For production deployments, load configuration from environment variables: + +```python server.py +import os +from fastmcp import FastMCP +from fastmcp.server.auth.providers.descope import DescopeProvider + +# Load configuration from environment variables +auth = DescopeProvider( + config_url=os.environ.get("DESCOPE_CONFIG_URL"), + base_url=os.environ.get("BASE_URL", "https://your-server.com") +) + +mcp = FastMCP(name="My Descope Protected Server", auth=auth) +``` diff --git a/docs/integrations/discord.mdx b/docs/integrations/discord.mdx new file mode 100644 index 000000000..5d6c643b7 --- /dev/null +++ b/docs/integrations/discord.mdx @@ -0,0 +1,183 @@ +--- +title: Discord OAuth 🤝 FastMCP +sidebarTitle: Discord +description: Secure your FastMCP server with Discord OAuth +icon: discord +--- + +import { VersionBadge } from "/snippets/version-badge.mdx" + + + +This guide shows you how to secure your FastMCP server using **Discord OAuth**. Since Discord doesn't support Dynamic Client Registration, this integration uses the [**OAuth Proxy**](/servers/auth/oauth-proxy) pattern to bridge Discord's traditional OAuth with MCP's authentication requirements. + +## Configuration + +### Prerequisites + +Before you begin, you will need: +1. A **[Discord Account](https://discord.com/)** with access to create applications +2. Your FastMCP server's URL (can be localhost for development, e.g., `http://localhost:8000`) + +### Step 1: Create a Discord Application + +Create an application in the Discord Developer Portal to get the credentials needed for authentication: + + + + Go to the [Discord Developer Portal](https://discord.com/developers/applications). + + Click **"New Application"** and give it a name users will recognize (e.g., "My FastMCP Server"). + + + + In the left sidebar, click **"OAuth2"**. + + In the **Redirects** section, click **"Add Redirect"** and enter your callback URL: + - For development: `http://localhost:8000/auth/callback` + - For production: `https://your-domain.com/auth/callback` + + + The redirect URL must match exactly. The default path is `/auth/callback`, but you can customize it using the `redirect_path` parameter. Discord allows `http://localhost` URLs for development. For production, use HTTPS. + + + + + On the same OAuth2 page, you'll find: + + - **Client ID**: A numeric string like `12345` + - **Client Secret**: Click "Reset Secret" to generate one + + + Store these credentials securely. Never commit them to version control. Use environment variables or a secrets manager in production. + + + + +### Step 2: FastMCP Configuration + +Create your FastMCP server using the `DiscordProvider`, which handles Discord's OAuth flow automatically: + +```python server.py +from fastmcp import FastMCP +from fastmcp.server.auth.providers.discord import DiscordProvider + +auth_provider = DiscordProvider( + client_id="12345", # Your Discord Application Client ID + client_secret="your-client-secret", # Your Discord OAuth Client Secret + base_url="http://localhost:8000", # Must match your OAuth configuration +) + +mcp = FastMCP(name="Discord Secured App", auth=auth_provider) + +@mcp.tool +async def get_user_info() -> dict: + """Returns information about the authenticated Discord user.""" + from fastmcp.server.dependencies import get_access_token + + token = get_access_token() + return { + "discord_id": token.claims.get("sub"), + "username": token.claims.get("username"), + "avatar": token.claims.get("avatar"), + } +``` + +## Testing + +### Running the Server + +Start your FastMCP server with HTTP transport to enable OAuth flows: + +```bash +fastmcp run server.py --transport http --port 8000 +``` + +Your server is now running and protected by Discord OAuth authentication. + +### Testing with a Client + +Create a test client that authenticates with your Discord-protected server: + +```python test_client.py +from fastmcp import Client +import asyncio + +async def main(): + async with Client("http://localhost:8000/mcp", auth="oauth") as client: + print("✓ Authenticated with Discord!") + + result = await client.call_tool("get_user_info") + print(f"Discord user: {result['username']}") + +if __name__ == "__main__": + asyncio.run(main()) +``` + +When you run the client for the first time: +1. Your browser will open to Discord's authorization page +2. Sign in with your Discord account and authorize the app +3. After authorization, you'll be redirected back +4. The client receives the token and can make authenticated requests + + +The client caches tokens locally, so you won't need to re-authenticate for subsequent runs unless the token expires or you explicitly clear the cache. + + +## Discord Scopes + +Discord OAuth supports several scopes for accessing different types of user data: + +| Scope | Description | +|-------|-------------| +| `identify` | Access username, avatar, and discriminator (default) | +| `email` | Access the user's email address | +| `guilds` | Access the user's list of servers | +| `guilds.join` | Ability to add the user to a server | + +To request additional scopes: + +```python +auth_provider = DiscordProvider( + client_id="...", + client_secret="...", + base_url="http://localhost:8000", + required_scopes=["identify", "email"], +) +``` + +## Production Configuration + +For production deployments with persistent token management across server restarts, configure `jwt_signing_key` and `client_storage`: + +```python server.py +import os +from fastmcp import FastMCP +from fastmcp.server.auth.providers.discord import DiscordProvider +from key_value.aio.stores.redis import RedisStore +from key_value.aio.wrappers.encryption import FernetEncryptionWrapper +from cryptography.fernet import Fernet + +auth_provider = DiscordProvider( + client_id="12345", + client_secret=os.environ["DISCORD_CLIENT_SECRET"], + base_url="https://your-production-domain.com", + + jwt_signing_key=os.environ["JWT_SIGNING_KEY"], + client_storage=FernetEncryptionWrapper( + key_value=RedisStore( + host=os.environ["REDIS_HOST"], + port=int(os.environ["REDIS_PORT"]) + ), + fernet=Fernet(os.environ["STORAGE_ENCRYPTION_KEY"]) + ) +) + +mcp = FastMCP(name="Production Discord App", auth=auth_provider) +``` + + +Parameters (`jwt_signing_key` and `client_storage`) work together to ensure tokens and client registrations survive server restarts. **Wrap your storage in `FernetEncryptionWrapper` to encrypt sensitive OAuth tokens at rest** - without it, tokens are stored in plaintext. Store secrets in environment variables and use a persistent storage backend like Redis for distributed deployments. + +For complete details on these parameters, see the [OAuth Proxy documentation](/servers/auth/oauth-proxy#configuration-parameters). + diff --git a/docs/integrations/eunomia-authorization.mdx b/docs/integrations/eunomia-authorization.mdx new file mode 100644 index 000000000..2fd2ca4a5 --- /dev/null +++ b/docs/integrations/eunomia-authorization.mdx @@ -0,0 +1,129 @@ +--- +title: Eunomia Authorization 🤝 FastMCP +sidebarTitle: Eunomia Auth +description: Add policy-based authorization to your FastMCP servers with Eunomia +icon: shield-check +--- + +Add **policy-based authorization** to your FastMCP servers with one-line code addition with the **[Eunomia][eunomia-github] authorization middleware**. + +Control which tools, resources and prompts MCP clients can view and execute on your server. Define dynamic JSON-based policies and obtain a comprehensive audit log of all access attempts and violations. + +## How it Works + +Exploiting FastMCP's [Middleware][fastmcp-middleware], the Eunomia middleware intercepts all MCP requests to your server and automatically maps MCP methods to authorization checks. + +### Listing Operations + +The middleware behaves as a filter for listing operations (`tools/list`, `resources/list`, `prompts/list`), hiding to the client components that are not authorized by the defined policies. + +```mermaid +sequenceDiagram + participant MCPClient as MCP Client + participant EunomiaMiddleware as Eunomia Middleware + participant MCPServer as FastMCP Server + participant EunomiaServer as Eunomia Server + + MCPClient->>EunomiaMiddleware: MCP Listing Request (e.g., tools/list) + EunomiaMiddleware->>MCPServer: MCP Listing Request + MCPServer-->>EunomiaMiddleware: MCP Listing Response + EunomiaMiddleware->>EunomiaServer: Authorization Checks + EunomiaServer->>EunomiaMiddleware: Authorization Decisions + EunomiaMiddleware-->>MCPClient: Filtered MCP Listing Response +``` + +### Execution Operations + +The middleware behaves as a firewall for execution operations (`tools/call`, `resources/read`, `prompts/get`), blocking operations that are not authorized by the defined policies. + +```mermaid +sequenceDiagram + participant MCPClient as MCP Client + participant EunomiaMiddleware as Eunomia Middleware + participant MCPServer as FastMCP Server + participant EunomiaServer as Eunomia Server + + MCPClient->>EunomiaMiddleware: MCP Execution Request (e.g., tools/call) + EunomiaMiddleware->>EunomiaServer: Authorization Check + EunomiaServer->>EunomiaMiddleware: Authorization Decision + EunomiaMiddleware-->>MCPClient: MCP Unauthorized Error (if denied) + EunomiaMiddleware->>MCPServer: MCP Execution Request (if allowed) + MCPServer-->>EunomiaMiddleware: MCP Execution Response (if allowed) + EunomiaMiddleware-->>MCPClient: MCP Execution Response (if allowed) +``` + +## Add Authorization to Your Server + + +Eunomia is an AI-specific authorization server that handles policy decisions. The server runs embedded within your MCP server by default for a zero-effort configuration, but can alternatively be run remotely for centralized policy decisions. + + + +### Create a Server with Authorization + +First, install the `eunomia-mcp` package: + +```bash +pip install eunomia-mcp +``` + +Then create a FastMCP server and add the Eunomia middleware in one line: + +```python server.py +from fastmcp import FastMCP +from eunomia_mcp import create_eunomia_middleware + +# Create your FastMCP server +mcp = FastMCP("Secure MCP Server 🔒") + +@mcp.tool() +def add(a: int, b: int) -> int: + """Add two numbers""" + return a + b + +# Add middleware to your server +middleware = create_eunomia_middleware(policy_file="mcp_policies.json") +mcp.add_middleware(middleware) + +if __name__ == "__main__": + mcp.run() +``` + +### Configure Access Policies + +Use the `eunomia-mcp` CLI in your terminal to manage your authorization policies: + +```bash +# Create a default policy file +eunomia-mcp init + +# Or create a policy file customized for your FastMCP server +eunomia-mcp init --custom-mcp "app.server:mcp" +``` + +This creates `mcp_policies.json` file that you can further edit to your access control needs. + +```bash +# Once edited, validate your policy file +eunomia-mcp validate mcp_policies.json +``` + +### Run the Server + +Start your FastMCP server normally: + +```bash +python server.py +``` + +The middleware will now intercept all MCP requests and check them against your policies. Requests include agent identification through headers like `X-Agent-ID`, `X-User-ID`, `User-Agent`, or `Authorization` and an automatic mapping of MCP methods to authorization resources and actions. + + + For detailed policy configuration, custom authentication, and remote + deployments, visit the [Eunomia MCP Middleware + repository][eunomia-mcp-github]. + + +[eunomia-github]: https://github.com/whataboutyou-ai/eunomia +[eunomia-mcp-github]: https://github.com/whataboutyou-ai/eunomia/tree/main/pkgs/extensions/mcp +[fastmcp-middleware]: /servers/middleware diff --git a/docs/integrations/fastapi.mdx b/docs/integrations/fastapi.mdx new file mode 100644 index 000000000..abdc1d0e7 --- /dev/null +++ b/docs/integrations/fastapi.mdx @@ -0,0 +1,445 @@ +--- +title: FastAPI 🤝 FastMCP +sidebarTitle: FastAPI +description: Integrate FastMCP with FastAPI applications +icon: bolt +--- + +import { VersionBadge } from '/snippets/version-badge.mdx' + +FastMCP provides two powerful ways to integrate with FastAPI applications: + +1. **[Generate an MCP server FROM your FastAPI app](#generating-an-mcp-server)** - Convert existing API endpoints into MCP tools +2. **[Mount an MCP server INTO your FastAPI app](#mounting-an-mcp-server)** - Add MCP functionality to your web application + + +When generating an MCP server from FastAPI, FastMCP uses OpenAPIProvider (v3.0.0+) under the hood to source tools from your FastAPI app's OpenAPI spec. See [Providers](/servers/providers/overview) to understand how FastMCP sources components. + + + + +Generating MCP servers from OpenAPI is a great way to get started with FastMCP, but in practice LLMs achieve **significantly better performance** with well-designed and curated MCP servers than with auto-converted OpenAPI servers. This is especially true for complex APIs with many endpoints and parameters. + +We recommend using the FastAPI integration for bootstrapping and prototyping, not for mirroring your API to LLM clients. See the post [Stop Converting Your REST APIs to MCP](https://www.jlowin.dev/blog/stop-converting-rest-apis-to-mcp) for more details. + + + + +FastMCP does *not* include FastAPI as a dependency; you must install it separately to use this integration. + + +## Example FastAPI Application + +Throughout this guide, we'll use this e-commerce API as our example (click the `Copy` button to copy it for use with other code blocks): + +```python [expandable] +# Copy this FastAPI server into other code blocks in this guide + +from fastapi import FastAPI, HTTPException +from pydantic import BaseModel + +# Models +class Product(BaseModel): + name: str + price: float + category: str + description: str | None = None + +class ProductResponse(BaseModel): + id: int + name: str + price: float + category: str + description: str | None = None + +# Create FastAPI app +app = FastAPI(title="E-commerce API", version="1.0.0") + +# In-memory database +products_db = { + 1: ProductResponse( + id=1, name="Laptop", price=999.99, category="Electronics" + ), + 2: ProductResponse( + id=2, name="Mouse", price=29.99, category="Electronics" + ), + 3: ProductResponse( + id=3, name="Desk Chair", price=299.99, category="Furniture" + ), +} +next_id = 4 + +@app.get("/products", response_model=list[ProductResponse]) +def list_products( + category: str | None = None, + max_price: float | None = None, +) -> list[ProductResponse]: + """List all products with optional filtering.""" + products = list(products_db.values()) + if category: + products = [p for p in products if p.category == category] + if max_price: + products = [p for p in products if p.price <= max_price] + return products + +@app.get("/products/{product_id}", response_model=ProductResponse) +def get_product(product_id: int): + """Get a specific product by ID.""" + if product_id not in products_db: + raise HTTPException(status_code=404, detail="Product not found") + return products_db[product_id] + +@app.post("/products", response_model=ProductResponse) +def create_product(product: Product): + """Create a new product.""" + global next_id + product_response = ProductResponse(id=next_id, **product.model_dump()) + products_db[next_id] = product_response + next_id += 1 + return product_response + +@app.put("/products/{product_id}", response_model=ProductResponse) +def update_product(product_id: int, product: Product): + """Update an existing product.""" + if product_id not in products_db: + raise HTTPException(status_code=404, detail="Product not found") + products_db[product_id] = ProductResponse( + id=product_id, + **product.model_dump(), + ) + return products_db[product_id] + +@app.delete("/products/{product_id}") +def delete_product(product_id: int): + """Delete a product.""" + if product_id not in products_db: + raise HTTPException(status_code=404, detail="Product not found") + del products_db[product_id] + return {"message": "Product deleted"} +``` + + +All subsequent code examples in this guide assume you have the above FastAPI application code already defined. Each example builds upon this base application, `app`. + + +## Generating an MCP Server + + + +One of the most common ways to bootstrap an MCP server is to generate it from an existing FastAPI application. FastMCP will expose your FastAPI endpoints as MCP components (tools, by default) in order to expose your API to LLM clients. + + + +### Basic Conversion + +Convert the FastAPI app to an MCP server with a single line: + +```python {5} +# Assumes the FastAPI app from above is already defined +from fastmcp import FastMCP + +# Convert to MCP server +mcp = FastMCP.from_fastapi(app=app) + +if __name__ == "__main__": + mcp.run() +``` + +### Adding Components + +Your converted MCP server is a full FastMCP instance, meaning you can add new tools, resources, and other components to it just like you would with any other FastMCP instance. + +```python {8-11} +# Assumes the FastAPI app from above is already defined +from fastmcp import FastMCP + +# Convert to MCP server +mcp = FastMCP.from_fastapi(app=app) + +# Add a new tool +@mcp.tool +def get_product(product_id: int) -> ProductResponse: + """Get a product by ID.""" + return products_db[product_id] + +# Run the MCP server +if __name__ == "__main__": + mcp.run() +``` + + + + + +### Interacting with the MCP Server + +Once you've converted your FastAPI app to an MCP server, you can interact with it using the FastMCP client to test functionality before deploying it to an LLM-based application. + +```python {3, } +# Assumes the FastAPI app from above is already defined +from fastmcp import FastMCP +from fastmcp.client import Client +import asyncio + +# Convert to MCP server +mcp = FastMCP.from_fastapi(app=app) + +async def demo(): + async with Client(mcp) as client: + # List available tools + tools = await client.list_tools() + print(f"Available tools: {[t.name for t in tools]}") + + # Create a product + result = await client.call_tool( + "create_product_products_post", + { + "name": "Wireless Keyboard", + "price": 79.99, + "category": "Electronics", + "description": "Bluetooth mechanical keyboard" + } + ) + print(f"Created product: {result.data}") + + # List electronics under $100 + result = await client.call_tool( + "list_products_products_get", + {"category": "Electronics", "max_price": 100} + ) + print(f"Affordable electronics: {result.data}") + +if __name__ == "__main__": + asyncio.run(demo()) +``` + +### Custom Route Mapping + +Because FastMCP's FastAPI integration is based on its [OpenAPI integration](/integrations/openapi), you can customize how endpoints are converted to MCP components in exactly the same way. For example, here we use a `RouteMap` to map all GET requests to MCP resources, and all POST/PUT/DELETE requests to MCP tools: + +```python +# Assumes the FastAPI app from above is already defined +from fastmcp import FastMCP +from fastmcp.server.openapi import RouteMap, MCPType + +# Custom mapping rules +mcp = FastMCP.from_fastapi( + app=app, + route_maps=[ + # GET with path params → ResourceTemplates + RouteMap( + methods=["GET"], + pattern=r".*\{.*\}.*", + mcp_type=MCPType.RESOURCE_TEMPLATE + ), + # Other GETs → Resources + RouteMap( + methods=["GET"], + pattern=r".*", + mcp_type=MCPType.RESOURCE + ), + # POST/PUT/DELETE → Tools (default) + ], +) + +# Now: +# - GET /products → Resource +# - GET /products/{id} → ResourceTemplate +# - POST/PUT/DELETE → Tools +``` + + +To learn more about customizing the conversion process, see the [OpenAPI Integration guide](/integrations/openapi). + + +### Authentication and Headers + +You can configure headers and other client options via the `httpx_client_kwargs` parameter. For example, to add authentication to your FastAPI app, you can pass a `headers` dictionary to the `httpx_client_kwargs` parameter: + +```python {27-31} +# Assumes the FastAPI app from above is already defined +from fastmcp import FastMCP + +# Add authentication to your FastAPI app +from fastapi import Depends, Header +from fastapi.security import HTTPBearer, HTTPAuthorizationCredentials + +security = HTTPBearer() + +def verify_token(credentials: HTTPAuthorizationCredentials = Depends(security)): + if credentials.credentials != "secret-token": + raise HTTPException(status_code=401, detail="Invalid authentication") + return credentials.credentials + +# Add a protected endpoint +@app.get("/admin/stats", dependencies=[Depends(verify_token)]) +def get_admin_stats(): + return { + "total_products": len(products_db), + "categories": list(set(p.category for p in products_db.values())) + } + +# Create MCP server with authentication headers +mcp = FastMCP.from_fastapi( + app=app, + httpx_client_kwargs={ + "headers": { + "Authorization": "Bearer secret-token", + } + } +) +``` + +## Mounting an MCP Server + + + +In addition to generating servers, FastMCP can facilitate adding MCP servers to your existing FastAPI application. You can do this by mounting the MCP ASGI application. + +### Basic Mounting + +To mount an MCP server, you can use the `http_app` method on your FastMCP instance. This will return an ASGI application that can be mounted to your FastAPI application. + +```python {23-30} +from fastmcp import FastMCP +from fastapi import FastAPI + +# Create MCP server +mcp = FastMCP("Analytics Tools") + +@mcp.tool +def analyze_pricing(category: str) -> dict: + """Analyze pricing for a category.""" + products = [p for p in products_db.values() if p.category == category] + if not products: + return {"error": f"No products in {category}"} + + prices = [p.price for p in products] + return { + "category": category, + "avg_price": round(sum(prices) / len(prices), 2), + "min": min(prices), + "max": max(prices), + } + +# Create ASGI app from MCP server +mcp_app = mcp.http_app(path='/mcp') + +# Key: Pass lifespan to FastAPI +app = FastAPI(title="E-commerce API", lifespan=mcp_app.lifespan) + +# Mount the MCP server +app.mount("/analytics", mcp_app) + +# Now: API at /products/*, MCP at /analytics/mcp/ +``` + +## Offering an LLM-Friendly API + +A common pattern is to generate an MCP server from your FastAPI app and serve both interfaces from the same application. This provides an LLM-optimized interface alongside your regular API: + +```python +# Assumes the FastAPI app from above is already defined +from fastmcp import FastMCP +from fastapi import FastAPI + +# 1. Generate MCP server from your API +mcp = FastMCP.from_fastapi(app=app, name="E-commerce MCP") + +# 2. Create the MCP's ASGI app +mcp_app = mcp.http_app(path='/mcp') + +# 3. Create a new FastAPI app that combines both sets of routes +combined_app = FastAPI( + title="E-commerce API with MCP", + routes=[ + *mcp_app.routes, # MCP routes + *app.routes, # Original API routes + ], + lifespan=mcp_app.lifespan, +) + +# Now you have: +# - Regular API: http://localhost:8000/products +# - LLM-friendly MCP: http://localhost:8000/mcp +# Both served from the same FastAPI application! +``` + +This approach lets you maintain a single codebase while offering both traditional REST endpoints and MCP-compatible endpoints for LLM clients. + +## Key Considerations + +### Operation IDs + +FastAPI operation IDs become MCP component names. Always specify meaningful operation IDs: + +```python +# Good - explicit operation_id +@app.get("/users/{user_id}", operation_id="get_user_by_id") +def get_user(user_id: int): + return {"id": user_id} + +# Less ideal - auto-generated name +@app.get("/users/{user_id}") +def get_user(user_id: int): + return {"id": user_id} +``` + +### Lifespan Management + +When mounting MCP servers, always pass the lifespan context: + +```python +# Correct - lifespan passed, path="/" since we mount at /mcp +mcp_app = mcp.http_app(path="/") +app = FastAPI(lifespan=mcp_app.lifespan) +app.mount("/mcp", mcp_app) # MCP endpoint at /mcp + +# Incorrect - missing lifespan +app = FastAPI() +app.mount("/mcp", mcp.http_app(path="/")) # Session manager won't initialize +``` + +If you're mounting an authenticated MCP server under a path prefix, see [Mounting Authenticated Servers](/deployment/http#mounting-authenticated-servers) for important OAuth routing considerations. + +### CORS Middleware + +If your FastAPI app uses `CORSMiddleware` and you're mounting an OAuth-protected FastMCP server, avoid adding application-wide CORS middleware. FastMCP and the MCP SDK already handle CORS for OAuth routes, and layering CORS middleware can cause conflicts (such as 404 errors on `.well-known` routes or OPTIONS requests). + +If you need CORS on your own FastAPI routes, use the sub-app pattern: mount your API and FastMCP as separate apps, each with their own middleware, rather than adding top-level `CORSMiddleware` to the combined application. + +### Combining Lifespans + +If your FastAPI app already has a lifespan (for database connections, startup tasks, etc.), you can't simply replace it with the MCP lifespan. Use `combine_lifespans` to run both: + +```python +from fastapi import FastAPI +from fastmcp import FastMCP +from fastmcp.utilities.lifespan import combine_lifespans +from contextlib import asynccontextmanager + +# Your existing lifespan +@asynccontextmanager +async def app_lifespan(app: FastAPI): + print("Starting up the app...") + yield + print("Shutting down the app...") + +# Create MCP server +mcp = FastMCP("Tools") +mcp_app = mcp.http_app(path="/") + +# Combine both lifespans +app = FastAPI(lifespan=combine_lifespans(app_lifespan, mcp_app.lifespan)) +app.mount("/mcp", mcp_app) # MCP endpoint at /mcp +``` + +`combine_lifespans` enters lifespans in order and exits in reverse order. + +### Performance Tips + +1. **Use in-memory transport for testing** - Pass MCP servers directly to clients +2. **Design purpose-built MCP tools** - Better than auto-converting complex APIs +3. **Keep tool parameters simple** - LLMs perform better with focused interfaces + +For more details on configuration options, see the [OpenAPI Integration guide](/integrations/openapi). \ No newline at end of file diff --git a/docs/integrations/gemini-cli.mdx b/docs/integrations/gemini-cli.mdx new file mode 100644 index 000000000..10613fb1b --- /dev/null +++ b/docs/integrations/gemini-cli.mdx @@ -0,0 +1,173 @@ +--- +title: Gemini CLI 🤝 FastMCP +sidebarTitle: Gemini CLI +description: Install and use FastMCP servers in Gemini CLI +icon: message-smile +--- + +import { VersionBadge } from "/snippets/version-badge.mdx" +import { LocalFocusTip } from "/snippets/local-focus.mdx" + + + +[Gemini CLI](https://geminicli.com/) supports MCP servers through multiple transport methods including STDIO, SSE, and HTTP, allowing you to extend Gemini's capabilities with custom tools, resources, and prompts from your FastMCP servers. + +## Requirements + +This integration uses STDIO transport to run your FastMCP server locally. For remote deployments, you can run your FastMCP server with HTTP or SSE transport and configure it directly using Gemini CLI's built-in MCP management commands. + +## Create a Server + +The examples in this guide will use the following simple dice-rolling server, saved as `server.py`. + +```python server.py +import random +from fastmcp import FastMCP + +mcp = FastMCP(name="Dice Roller") + +@mcp.tool +def roll_dice(n_dice: int) -> list[int]: + """Roll `n_dice` 6-sided dice and return the results.""" + return [random.randint(1, 6) for _ in range(n_dice)] + +if __name__ == "__main__": + mcp.run() +``` + +## Install the Server + +### FastMCP CLI + + +The easiest way to install a FastMCP server in Gemini CLI is using the `fastmcp install gemini-cli` command. This automatically handles the configuration, dependency management, and calls Gemini CLI's built-in MCP management system. + +```bash +fastmcp install gemini-cli server.py +``` + +The install command supports the same `file.py:object` notation as the `run` command. If no object is specified, it will automatically look for a FastMCP server object named `mcp`, `server`, or `app` in your file: + +```bash +# These are equivalent if your server object is named 'mcp' +fastmcp install gemini-cli server.py +fastmcp install gemini-cli server.py:mcp + +# Use explicit object name if your server has a different name +fastmcp install gemini-cli server.py:my_custom_server +``` + +The command will automatically configure the server with Gemini CLI's `gemini mcp add` command. + +#### Dependencies + +FastMCP provides flexible dependency management options for your Gemini CLI servers: + +**Individual packages**: Use the `--with` flag to specify packages your server needs. You can use this flag multiple times: + +```bash +fastmcp install gemini-cli server.py --with pandas --with requests +``` + +**Requirements file**: If you maintain a `requirements.txt` file with all your dependencies, use `--with-requirements` to install them: + +```bash +fastmcp install gemini-cli server.py --with-requirements requirements.txt +``` + +**Editable packages**: For local packages under development, use `--with-editable` to install them in editable mode: + +```bash +fastmcp install gemini-cli server.py --with-editable ./my-local-package +``` + +Alternatively, you can use a `fastmcp.json` configuration file (recommended): + +```json fastmcp.json +{ + "$schema": "https://gofastmcp.com/public/schemas/fastmcp.json/v1.json", + "source": { + "path": "server.py", + "entrypoint": "mcp" + }, + "environment": { + "dependencies": ["pandas", "requests"] + } +} +``` + + +#### Python Version and Project Configuration + +Control the Python environment for your server with these options: + +**Python version**: Use `--python` to specify which Python version your server requires. This ensures compatibility when your server needs specific Python features: + +```bash +fastmcp install gemini-cli server.py --python 3.11 +``` + +**Project directory**: Use `--project` to run your server within a specific project context. This tells `uv` to use the project's configuration files and virtual environment: + +```bash +fastmcp install gemini-cli server.py --project /path/to/my-project +``` + +#### Environment Variables + +If your server needs environment variables (like API keys), you must include them: + +```bash +fastmcp install gemini-cli server.py --server-name "Weather Server" \ + --env API_KEY=your-api-key \ + --env DEBUG=true +``` + +Or load them from a `.env` file: + +```bash +fastmcp install gemini-cli server.py --server-name "Weather Server" --env-file .env +``` + + +**Gemini CLI must be installed**. The integration looks for the Gemini CLI and uses the `gemini mcp add` command to register servers. + + +### Manual Configuration + +For more control over the configuration, you can manually use Gemini CLI's built-in MCP management commands. This gives you direct control over how your server is launched: + +```bash +# Add a server with custom configuration +gemini mcp add dice-roller uv -- run --with fastmcp fastmcp run server.py + +# Add with environment variables +gemini mcp add weather-server -e API_KEY=secret -e DEBUG=true uv -- run --with fastmcp fastmcp run server.py + +# Add with specific scope (user, or project) +gemini mcp add my-server --scope user uv -- run --with fastmcp fastmcp run server.py +``` + +You can also manually specify Python versions and project directories in your Gemini CLI commands: + +```bash +# With specific Python version +gemini mcp add ml-server uv -- run --python 3.11 --with fastmcp fastmcp run server.py + +# Within a project directory +gemini mcp add project-server uv -- run --project /path/to/project --with fastmcp fastmcp run server.py +``` + +## Using the Server + +Once your server is installed, you can start using your FastMCP server with Gemini CLI. + +Try asking Gemini something like: + +> "Roll some dice for me" + +Gemini will automatically detect your `roll_dice` tool and use it to fulfill your request. + +Gemini CLI can now access all the tools and prompts you've defined in your FastMCP server. + +If your server provides prompts, you can use them as slash commands with `/prompt_name`. diff --git a/docs/integrations/gemini.mdx b/docs/integrations/gemini.mdx new file mode 100644 index 000000000..159e662a5 --- /dev/null +++ b/docs/integrations/gemini.mdx @@ -0,0 +1,108 @@ +--- +title: Gemini SDK 🤝 FastMCP +sidebarTitle: Gemini SDK +description: Connect FastMCP servers to the Google Gemini SDK +icon: message-code +--- + +import { VersionBadge } from "/snippets/version-badge.mdx" + +Google's Gemini API includes built-in support for MCP servers in their Python and JavaScript SDKs, allowing you to connect directly to MCP servers and use their tools seamlessly with Gemini models. + +## Gemini Python SDK + +Google's [Gemini Python SDK](https://ai.google.dev/gemini-api/docs) can use FastMCP clients directly. + + +Google's MCP integration is currently experimental and available in the Python and JavaScript SDKs. The API automatically calls MCP tools when needed and can connect to both local and remote MCP servers. + + + +Currently, Gemini's MCP support only accesses **tools** from MCP servers—it queries the `list_tools` endpoint and exposes those functions to the AI. Other MCP features like resources and prompts are not currently supported. + + +### Create a Server + +First, create a FastMCP server with the tools you want to expose. For this example, we'll create a server with a single tool that rolls dice. + +```python server.py +import random +from fastmcp import FastMCP + +mcp = FastMCP(name="Dice Roller") + +@mcp.tool +def roll_dice(n_dice: int) -> list[int]: + """Roll `n_dice` 6-sided dice and return the results.""" + return [random.randint(1, 6) for _ in range(n_dice)] + +if __name__ == "__main__": + mcp.run() +``` + +### Call the Server + + +To use the Gemini API with MCP, you'll need to install the Google Generative AI SDK: + +```bash +pip install google-genai +``` + +You'll also need to authenticate with Google. You can do this by setting the `GEMINI_API_KEY` environment variable. Consult the Gemini SDK documentation for more information. + +```bash +export GEMINI_API_KEY="your-api-key" +``` + +Gemini's SDK interacts directly with the MCP client session. To call the server, you'll need to instantiate a FastMCP client, enter its connection context, and pass the client session to the Gemini SDK. + +```python {5, 9, 15} +from fastmcp import Client +from google import genai +import asyncio + +mcp_client = Client("server.py") +gemini_client = genai.Client() + +async def main(): + async with mcp_client: + response = await gemini_client.aio.models.generate_content( + model="gemini-2.0-flash", + contents="Roll 3 dice!", + config=genai.types.GenerateContentConfig( + temperature=0, + tools=[mcp_client.session], # Pass the FastMCP client session + ), + ) + print(response.text) + +if __name__ == "__main__": + asyncio.run(main()) +``` + +If you run this code, you'll see output like: + +```text +Okay, I rolled 3 dice and got a 5, 4, and 1. +``` + +### Remote & Authenticated Servers + +In the above example, we connected to our local server using `stdio` transport. Because we're using a FastMCP client, you can also connect to any local or remote MCP server, using any [transport](/clients/transports) or [auth](/clients/auth) method supported by FastMCP, simply by changing the client configuration. + +For example, to connect to a remote, authenticated server, you can use the following client: + +```python +from fastmcp import Client +from fastmcp.client.auth import BearerAuth + +mcp_client = Client( + "https://my-server.com/mcp/", + auth=BearerAuth(""), +) +``` + +The rest of the code remains the same. + + diff --git a/docs/integrations/github.mdx b/docs/integrations/github.mdx new file mode 100644 index 000000000..72e65d3ce --- /dev/null +++ b/docs/integrations/github.mdx @@ -0,0 +1,175 @@ +--- +title: GitHub OAuth 🤝 FastMCP +sidebarTitle: GitHub +description: Secure your FastMCP server with GitHub OAuth +icon: github +--- + +import { VersionBadge } from "/snippets/version-badge.mdx" + + + +This guide shows you how to secure your FastMCP server using **GitHub OAuth**. Since GitHub doesn't support Dynamic Client Registration, this integration uses the [**OAuth Proxy**](/servers/auth/oauth-proxy) pattern to bridge GitHub's traditional OAuth with MCP's authentication requirements. + +## Configuration + +### Prerequisites + +Before you begin, you will need: +1. A **[GitHub Account](https://github.com/)** with access to create OAuth Apps +2. Your FastMCP server's URL (can be localhost for development, e.g., `http://localhost:8000`) + +### Step 1: Create a GitHub OAuth App + +Create an OAuth App in your GitHub settings to get the credentials needed for authentication: + + + + Go to **Settings → Developer settings → OAuth Apps** in your GitHub account, or visit [github.com/settings/developers](https://github.com/settings/developers). + + Click **"New OAuth App"** to create a new application. + + + + Fill in the application details: + + - **Application name**: Choose a name users will recognize (e.g., "My FastMCP Server") + - **Homepage URL**: Your application's homepage or documentation URL + - **Authorization callback URL**: Your server URL + `/auth/callback` (e.g., `http://localhost:8000/auth/callback`) + + + The callback URL must match exactly. The default path is `/auth/callback`, but you can customize it using the `redirect_path` parameter. For local development, GitHub allows `http://localhost` URLs. For production, you must use HTTPS. + + + + If you want to use a custom callback path (e.g., `/auth/github/callback`), make sure to set the same path in both your GitHub OAuth App settings and the `redirect_path` parameter when configuring the GitHubProvider. + + + + + After creating the app, you'll see: + + - **Client ID**: A public identifier like `Ov23liAbcDefGhiJkLmN` + - **Client Secret**: Click "Generate a new client secret" and save the value securely + + + Store these credentials securely. Never commit them to version control. Use environment variables or a secrets manager in production. + + + + +### Step 2: FastMCP Configuration + +Create your FastMCP server using the `GitHubProvider`, which handles GitHub's OAuth quirks automatically: + +```python server.py +from fastmcp import FastMCP +from fastmcp.server.auth.providers.github import GitHubProvider + +# The GitHubProvider handles GitHub's token format and validation +auth_provider = GitHubProvider( + client_id="Ov23liAbcDefGhiJkLmN", # Your GitHub OAuth App Client ID + client_secret="github_pat_...", # Your GitHub OAuth App Client Secret + base_url="http://localhost:8000", # Must match your OAuth App configuration + # redirect_path="/auth/callback" # Default value, customize if needed +) + +mcp = FastMCP(name="GitHub Secured App", auth=auth_provider) + +# Add a protected tool to test authentication +@mcp.tool +async def get_user_info() -> dict: + """Returns information about the authenticated GitHub user.""" + from fastmcp.server.dependencies import get_access_token + + token = get_access_token() + # The GitHubProvider stores user data in token claims + return { + "github_user": token.claims.get("login"), + "name": token.claims.get("name"), + "email": token.claims.get("email") + } +``` + +## Testing + +### Running the Server + +Start your FastMCP server with HTTP transport to enable OAuth flows: + +```bash +fastmcp run server.py --transport http --port 8000 +``` + +Your server is now running and protected by GitHub OAuth authentication. + +### Testing with a Client + +Create a test client that authenticates with your GitHub-protected server: + +```python test_client.py +from fastmcp import Client +import asyncio + +async def main(): + # The client will automatically handle GitHub OAuth + async with Client("http://localhost:8000/mcp", auth="oauth") as client: + # First-time connection will open GitHub login in your browser + print("✓ Authenticated with GitHub!") + + # Test the protected tool + result = await client.call_tool("get_user_info") + print(f"GitHub user: {result['github_user']}") + +if __name__ == "__main__": + asyncio.run(main()) +``` + +When you run the client for the first time: +1. Your browser will open to GitHub's authorization page +2. After you authorize the app, you'll be redirected back +3. The client receives the token and can make authenticated requests + + +The client caches tokens locally, so you won't need to re-authenticate for subsequent runs unless the token expires or you explicitly clear the cache. + + +## Production Configuration + + + +For production deployments with persistent token management across server restarts, configure `jwt_signing_key` and `client_storage`: + +```python server.py +import os +from fastmcp import FastMCP +from fastmcp.server.auth.providers.github import GitHubProvider +from key_value.aio.stores.redis import RedisStore +from key_value.aio.wrappers.encryption import FernetEncryptionWrapper +from cryptography.fernet import Fernet + +# Production setup with encrypted persistent token storage +auth_provider = GitHubProvider( + client_id="Ov23liAbcDefGhiJkLmN", + client_secret="github_pat_...", + base_url="https://your-production-domain.com", + + # Production token management + jwt_signing_key=os.environ["JWT_SIGNING_KEY"], + client_storage=FernetEncryptionWrapper( + key_value=RedisStore( + host=os.environ["REDIS_HOST"], + port=int(os.environ["REDIS_PORT"]) + ), + fernet=Fernet(os.environ["STORAGE_ENCRYPTION_KEY"]) + ) +) + +mcp = FastMCP(name="Production GitHub App", auth=auth_provider) +``` + + +Parameters (`jwt_signing_key` and `client_storage`) work together to ensure tokens and client registrations survive server restarts. **Wrap your storage in `FernetEncryptionWrapper` to encrypt sensitive OAuth tokens at rest** - without it, tokens are stored in plaintext. Store secrets in environment variables and use a persistent storage backend like Redis for distributed deployments. + +For complete details on these parameters, see the [OAuth Proxy documentation](/servers/auth/oauth-proxy#configuration-parameters). + diff --git a/docs/integrations/google.mdx b/docs/integrations/google.mdx new file mode 100644 index 000000000..17d49d12f --- /dev/null +++ b/docs/integrations/google.mdx @@ -0,0 +1,189 @@ +--- +title: Google OAuth 🤝 FastMCP +sidebarTitle: Google +description: Secure your FastMCP server with Google OAuth +icon: google +--- + +import { VersionBadge } from "/snippets/version-badge.mdx" + + + +This guide shows you how to secure your FastMCP server using **Google OAuth**. Since Google doesn't support Dynamic Client Registration, this integration uses the [**OAuth Proxy**](/servers/auth/oauth-proxy) pattern to bridge Google's traditional OAuth with MCP's authentication requirements. + +## Configuration + +### Prerequisites + +Before you begin, you will need: +1. A **[Google Cloud Account](https://console.cloud.google.com/)** with access to create OAuth 2.0 Client IDs +2. Your FastMCP server's URL (can be localhost for development, e.g., `http://localhost:8000`) + +### Step 1: Create a Google OAuth 2.0 Client ID + +Create an OAuth 2.0 Client ID in your Google Cloud Console to get the credentials needed for authentication: + + + + Go to the [Google Cloud Console](https://console.cloud.google.com/apis/credentials) and select your project (or create a new one). + + First, configure the OAuth consent screen by navigating to **APIs & Services → OAuth consent screen**. Choose "External" for testing or "Internal" for G Suite organizations. + + + + Navigate to **APIs & Services → Credentials** and click **"+ CREATE CREDENTIALS"** → **"OAuth client ID"**. + + Configure your OAuth client: + + - **Application type**: Web application + - **Name**: Choose a descriptive name (e.g., "FastMCP Server") + - **Authorized JavaScript origins**: Add your server's base URL (e.g., `http://localhost:8000`) + - **Authorized redirect URIs**: Add your server URL + `/auth/callback` (e.g., `http://localhost:8000/auth/callback`) + + + The redirect URI must match exactly. The default path is `/auth/callback`, but you can customize it using the `redirect_path` parameter. For local development, Google allows `http://localhost` URLs with various ports. For production, you must use HTTPS. + + + + If you want to use a custom callback path (e.g., `/auth/google/callback`), make sure to set the same path in both your Google OAuth Client settings and the `redirect_path` parameter when configuring the GoogleProvider. + + + + + After creating the client, you'll receive: + + - **Client ID**: A string ending in `.apps.googleusercontent.com` + - **Client Secret**: A string starting with `GOCSPX-` + + Download the JSON credentials or copy these values securely. + + + Store these credentials securely. Never commit them to version control. Use environment variables or a secrets manager in production. + + + + +### Step 2: FastMCP Configuration + +Create your FastMCP server using the `GoogleProvider`, which handles Google's OAuth flow automatically: + +```python server.py +from fastmcp import FastMCP +from fastmcp.server.auth.providers.google import GoogleProvider + +# The GoogleProvider handles Google's token format and validation +auth_provider = GoogleProvider( + client_id="123456789.apps.googleusercontent.com", # Your Google OAuth Client ID + client_secret="GOCSPX-abc123...", # Your Google OAuth Client Secret + base_url="http://localhost:8000", # Must match your OAuth configuration + required_scopes=[ # Request user information + "openid", + "https://www.googleapis.com/auth/userinfo.email", + ], + # redirect_path="/auth/callback" # Default value, customize if needed +) + +mcp = FastMCP(name="Google Secured App", auth=auth_provider) + +# Add a protected tool to test authentication +@mcp.tool +async def get_user_info() -> dict: + """Returns information about the authenticated Google user.""" + from fastmcp.server.dependencies import get_access_token + + token = get_access_token() + # The GoogleProvider stores user data in token claims + return { + "google_id": token.claims.get("sub"), + "email": token.claims.get("email"), + "name": token.claims.get("name"), + "picture": token.claims.get("picture"), + "locale": token.claims.get("locale") + } +``` + +## Testing + +### Running the Server + +Start your FastMCP server with HTTP transport to enable OAuth flows: + +```bash +fastmcp run server.py --transport http --port 8000 +``` + +Your server is now running and protected by Google OAuth authentication. + +### Testing with a Client + +Create a test client that authenticates with your Google-protected server: + +```python test_client.py +from fastmcp import Client +import asyncio + +async def main(): + # The client will automatically handle Google OAuth + async with Client("http://localhost:8000/mcp", auth="oauth") as client: + # First-time connection will open Google login in your browser + print("✓ Authenticated with Google!") + + # Test the protected tool + result = await client.call_tool("get_user_info") + print(f"Google user: {result['email']}") + print(f"Name: {result['name']}") + +if __name__ == "__main__": + asyncio.run(main()) +``` + +When you run the client for the first time: +1. Your browser will open to Google's authorization page +2. Sign in with your Google account and grant the requested permissions +3. After authorization, you'll be redirected back +4. The client receives the token and can make authenticated requests + + +The client caches tokens locally, so you won't need to re-authenticate for subsequent runs unless the token expires or you explicitly clear the cache. + + +## Production Configuration + + + +For production deployments with persistent token management across server restarts, configure `jwt_signing_key` and `client_storage`: + +```python server.py +import os +from fastmcp import FastMCP +from fastmcp.server.auth.providers.google import GoogleProvider +from key_value.aio.stores.redis import RedisStore +from key_value.aio.wrappers.encryption import FernetEncryptionWrapper +from cryptography.fernet import Fernet + +# Production setup with encrypted persistent token storage +auth_provider = GoogleProvider( + client_id="123456789.apps.googleusercontent.com", + client_secret="GOCSPX-abc123...", + base_url="https://your-production-domain.com", + required_scopes=["openid", "https://www.googleapis.com/auth/userinfo.email"], + + # Production token management + jwt_signing_key=os.environ["JWT_SIGNING_KEY"], + client_storage=FernetEncryptionWrapper( + key_value=RedisStore( + host=os.environ["REDIS_HOST"], + port=int(os.environ["REDIS_PORT"]) + ), + fernet=Fernet(os.environ["STORAGE_ENCRYPTION_KEY"]) + ) +) + +mcp = FastMCP(name="Production Google App", auth=auth_provider) +``` + + +Parameters (`jwt_signing_key` and `client_storage`) work together to ensure tokens and client registrations survive server restarts. **Wrap your storage in `FernetEncryptionWrapper` to encrypt sensitive OAuth tokens at rest** - without it, tokens are stored in plaintext. Store secrets in environment variables and use a persistent storage backend like Redis for distributed deployments. + +For complete details on these parameters, see the [OAuth Proxy documentation](/servers/auth/oauth-proxy#configuration-parameters). + \ No newline at end of file diff --git a/docs/integrations/goose.mdx b/docs/integrations/goose.mdx new file mode 100644 index 000000000..fc2ff8e39 --- /dev/null +++ b/docs/integrations/goose.mdx @@ -0,0 +1,178 @@ +--- +title: Goose 🤝 FastMCP +sidebarTitle: Goose +description: Install and use FastMCP servers in Goose +icon: message-smile +--- + +import { VersionBadge } from "/snippets/version-badge.mdx" +import { LocalFocusTip } from "/snippets/local-focus.mdx" + + + +[Goose](https://block.github.io/goose/) is an open-source AI agent from Block that supports MCP servers as extensions. FastMCP can install your server directly into Goose using its deeplink protocol — one command opens Goose with an install dialog ready to go. + +## Requirements + +This integration uses Goose's deeplink protocol to register your server as a STDIO extension running via `uvx`. You must have Goose installed on your system for the deeplink to open automatically. + +For remote deployments, configure your FastMCP server with HTTP transport and add it to Goose directly using `goose configure` or the config file. + +## Create a Server + +The examples in this guide will use the following simple dice-rolling server, saved as `server.py`. + +```python server.py +import random +from fastmcp import FastMCP + +mcp = FastMCP(name="Dice Roller") + +@mcp.tool +def roll_dice(n_dice: int) -> list[int]: + """Roll `n_dice` 6-sided dice and return the results.""" + return [random.randint(1, 6) for _ in range(n_dice)] + +if __name__ == "__main__": + mcp.run() +``` + +## Install the Server + +### FastMCP CLI + + +The easiest way to install a FastMCP server in Goose is using the `fastmcp install goose` command. This generates a `goose://` deeplink and opens it, prompting Goose to install the server. + +```bash +fastmcp install goose server.py +``` + +The install command supports the same `file.py:object` notation as the `run` command. If no object is specified, it will automatically look for a FastMCP server object named `mcp`, `server`, or `app` in your file: + +```bash +# These are equivalent if your server object is named 'mcp' +fastmcp install goose server.py +fastmcp install goose server.py:mcp + +# Use explicit object name if your server has a different name +fastmcp install goose server.py:my_custom_server +``` + +Under the hood, the generated command uses `uvx` to run your server in an isolated environment. Goose requires `uvx` rather than `uv run`, so the install produces a command like: + +```bash +uvx --with pandas fastmcp run /path/to/server.py +``` + +#### Dependencies + +Use the `--with` flag to specify additional packages your server needs: + +```bash +fastmcp install goose server.py --with pandas --with requests +``` + +Alternatively, you can use a `fastmcp.json` configuration file (recommended): + +```json fastmcp.json +{ + "$schema": "https://gofastmcp.com/public/schemas/fastmcp.json/v1.json", + "source": { + "path": "server.py", + "entrypoint": "mcp" + }, + "environment": { + "dependencies": ["pandas", "requests"] + } +} +``` + +#### Python Version + +Use `--python` to specify which Python version your server should use: + +```bash +fastmcp install goose server.py --python 3.11 +``` + + +The Goose install uses `uvx`, which does not support `--project`, `--with-requirements`, or `--with-editable`. If you need these options, use `fastmcp install mcp-json` to generate a full configuration and add it to Goose manually. + + +#### Environment Variables + +Goose's deeplink protocol does not support environment variables. If your server needs them (like API keys), you have two options: + +1. **Configure after install**: Run `goose configure` and add environment variables to the extension. +2. **Manual config**: Use `fastmcp install mcp-json` to generate the full configuration, then add it to `~/.config/goose/config.yaml` with the `envs` field. + +### Manual Configuration + +For more control, you can manually edit Goose's configuration file at `~/.config/goose/config.yaml`: + +```yaml +extensions: + dice-roller: + name: Dice Roller + cmd: uvx + args: [fastmcp, run, /path/to/server.py] + enabled: true + type: stdio + timeout: 300 +``` + +#### Dependencies + +When manually configuring, add packages using `--with` flags in the args: + +```yaml +extensions: + dice-roller: + name: Dice Roller + cmd: uvx + args: [--with, pandas, --with, requests, fastmcp, run, /path/to/server.py] + enabled: true + type: stdio + timeout: 300 +``` + +#### Environment Variables + +Environment variables can be specified in the `envs` field: + +```yaml +extensions: + weather-server: + name: Weather Server + cmd: uvx + args: [fastmcp, run, /path/to/weather_server.py] + enabled: true + envs: + API_KEY: your-api-key + DEBUG: "true" + type: stdio + timeout: 300 +``` + +You can also use `goose configure` to add extensions interactively, which prompts for environment variables. + + +**`uvx` (from `uv`) must be installed and available in your system PATH**. Goose uses `uvx` to run Python-based extensions in isolated environments. + + +## Using the Server + +Once your server is installed, you can start using your FastMCP server with Goose. + +Try asking Goose something like: + +> "Roll some dice for me" + +Goose will automatically detect your `roll_dice` tool and use it to fulfill your request, returning something like: + +> 🎲 Here are your dice rolls: 4, 6, 4 +> +> You rolled 3 dice with a total of 14! + +Goose can now access all the tools, resources, and prompts you've defined in your FastMCP server. diff --git a/docs/integrations/images/authkit/enable_dcr.png b/docs/integrations/images/authkit/enable_dcr.png new file mode 100644 index 000000000..e5942f60e Binary files /dev/null and b/docs/integrations/images/authkit/enable_dcr.png differ diff --git a/docs/integrations/images/oci/ociaddapplication.png b/docs/integrations/images/oci/ociaddapplication.png new file mode 100644 index 000000000..690f8d391 Binary files /dev/null and b/docs/integrations/images/oci/ociaddapplication.png differ diff --git a/docs/integrations/images/oci/ocieditdomainsettings.png b/docs/integrations/images/oci/ocieditdomainsettings.png new file mode 100644 index 000000000..08812ba9b Binary files /dev/null and b/docs/integrations/images/oci/ocieditdomainsettings.png differ diff --git a/docs/integrations/images/oci/ocieditdomainsettingsbutton.png b/docs/integrations/images/oci/ocieditdomainsettingsbutton.png new file mode 100644 index 000000000..3954dab07 Binary files /dev/null and b/docs/integrations/images/oci/ocieditdomainsettingsbutton.png differ diff --git a/docs/integrations/images/oci/ocioauthconfiguration.png b/docs/integrations/images/oci/ocioauthconfiguration.png new file mode 100644 index 000000000..f00782154 Binary files /dev/null and b/docs/integrations/images/oci/ocioauthconfiguration.png differ diff --git a/docs/integrations/images/permit/abac_condition_example.png b/docs/integrations/images/permit/abac_condition_example.png new file mode 100644 index 000000000..a5592abca Binary files /dev/null and b/docs/integrations/images/permit/abac_condition_example.png differ diff --git a/docs/integrations/images/permit/abac_policy_example.png b/docs/integrations/images/permit/abac_policy_example.png new file mode 100644 index 000000000..bd4b5cf33 Binary files /dev/null and b/docs/integrations/images/permit/abac_policy_example.png differ diff --git a/docs/integrations/images/permit/policy_mapping.png b/docs/integrations/images/permit/policy_mapping.png new file mode 100644 index 000000000..d100b1eab Binary files /dev/null and b/docs/integrations/images/permit/policy_mapping.png differ diff --git a/docs/integrations/images/permit/role_assignement.png b/docs/integrations/images/permit/role_assignement.png new file mode 100644 index 000000000..c65e34181 Binary files /dev/null and b/docs/integrations/images/permit/role_assignement.png differ diff --git a/docs/integrations/mcp-json-configuration.mdx b/docs/integrations/mcp-json-configuration.mdx new file mode 100644 index 000000000..b44b15e76 --- /dev/null +++ b/docs/integrations/mcp-json-configuration.mdx @@ -0,0 +1,422 @@ +--- +title: MCP JSON Configuration 🤝 FastMCP +sidebarTitle: MCP.json +description: Generate standard MCP configuration files for any compatible client +icon: brackets-curly +--- + +import { VersionBadge } from "/snippets/version-badge.mdx" + + + +FastMCP can generate standard MCP JSON configuration files that work with any MCP-compatible client including Claude Desktop, VS Code, Cursor, and other applications that support the Model Context Protocol. + +## MCP JSON Configuration Standard + +The MCP JSON configuration format is an **emergent standard** that has developed across the MCP ecosystem. This format defines how MCP clients should configure and launch MCP servers, providing a consistent way to specify server commands, arguments, and environment variables. + +### Configuration Structure + +The standard uses a `mcpServers` object where each key represents a server name and the value contains the server's configuration: + +```json +{ + "mcpServers": { + "server-name": { + "command": "executable", + "args": ["arg1", "arg2"], + "env": { + "VAR": "value" + } + } + } +} +``` + +### Server Configuration Fields + +#### `command` (required) +The executable command to run the MCP server. This should be an absolute path or a command available in the system PATH. + +```json +{ + "command": "python" +} +``` + +#### `args` (optional) +An array of command-line arguments passed to the server executable. Arguments are passed in order. + +```json +{ + "args": ["server.py", "--verbose", "--port", "8080"] +} +``` + +#### `env` (optional) +An object containing environment variables to set when launching the server. All values must be strings. + +```json +{ + "env": { + "API_KEY": "secret-key", + "DEBUG": "true", + "PORT": "8080" + } +} +``` + +### Client Adoption + +This format is widely adopted across the MCP ecosystem: + +- **Claude Desktop**: Uses `~/.claude/claude_desktop_config.json` +- **Cursor**: Uses `~/.cursor/mcp.json` +- **VS Code**: Uses workspace `.vscode/mcp.json` +- **Other clients**: Many MCP-compatible applications follow this standard + +## Overview + + +**For the best experience, use FastMCP's first-class integrations:** [`fastmcp install claude-code`](/integrations/claude-code), [`fastmcp install claude-desktop`](/integrations/claude-desktop), or [`fastmcp install cursor`](/integrations/cursor). Use MCP JSON generation for advanced use cases and unsupported clients. + + +The `fastmcp install mcp-json` command generates configuration in the standard `mcpServers` format used across the MCP ecosystem. This is useful when: + +- **Working with unsupported clients** - Any MCP client not directly integrated with FastMCP +- **CI/CD environments** - Automated configuration generation for deployments +- **Configuration sharing** - Easy distribution of server setups to team members +- **Custom tooling** - Integration with your own MCP management tools +- **Manual setup** - When you prefer to manually configure your MCP client + +## Basic Usage + +Generate configuration and output to stdout (useful for piping): + +```bash +fastmcp install mcp-json server.py +``` + +This outputs the server configuration JSON with the server name as the root key: + +```json +{ + "My Server": { + "command": "uv", + "args": [ + "run", + "--with", + "fastmcp", + "fastmcp", + "run", + "/absolute/path/to/server.py" + ] + } +} +``` + +To use this in a client configuration file, add it to the `mcpServers` object in your client's configuration: + +```json +{ + "mcpServers": { + "My Server": { + "command": "uv", + "args": [ + "run", + "--with", + "fastmcp", + "fastmcp", + "run", + "/absolute/path/to/server.py" + ] + } + } +} +``` + + +When using `--python`, `--project`, or `--with-requirements`, the generated configuration will include these options in the `uv run` command, ensuring your server runs with the correct Python version and dependencies. + + + +Different MCP clients may have specific configuration requirements or formatting needs. Always consult your client's documentation to ensure proper integration. + + +## Configuration Options + +### Server Naming + +```bash +# Use server's built-in name (from FastMCP constructor) +fastmcp install mcp-json server.py + +# Override with custom name +fastmcp install mcp-json server.py --name "Custom Server Name" +``` + +### Dependencies + +Add Python packages your server needs: + +```bash +# Single package +fastmcp install mcp-json server.py --with pandas + +# Multiple packages +fastmcp install mcp-json server.py --with pandas --with requests --with httpx + +# Editable local package +fastmcp install mcp-json server.py --with-editable ./my-package + +# From requirements file +fastmcp install mcp-json server.py --with-requirements requirements.txt +``` + +You can also use a `fastmcp.json` configuration file (recommended): + +```json fastmcp.json +{ + "$schema": "https://gofastmcp.com/public/schemas/fastmcp.json/v1.json", + "source": { + "path": "server.py", + "entrypoint": "mcp" + }, + "environment": { + "dependencies": ["pandas", "matplotlib", "seaborn"] + } +} +``` + +Then simply install with: +```bash +fastmcp install mcp-json fastmcp.json +``` + + +### Environment Variables + +```bash +# Individual environment variables +fastmcp install mcp-json server.py \ + --env API_KEY=your-secret-key \ + --env DEBUG=true + +# Load from .env file +fastmcp install mcp-json server.py --env-file .env +``` + +### Python Version and Project Directory + +Specify Python version or run within a specific project: + +```bash +# Use specific Python version +fastmcp install mcp-json server.py --python 3.11 + +# Run within a project directory +fastmcp install mcp-json server.py --project /path/to/project +``` + +### Server Object Selection + +Use the same `file.py:object` notation as other FastMCP commands: + +```bash +# Auto-detects server object (looks for 'mcp', 'server', or 'app') +fastmcp install mcp-json server.py + +# Explicit server object +fastmcp install mcp-json server.py:my_custom_server +``` + +## Clipboard Integration + +Copy configuration directly to your clipboard for easy pasting: + +```bash +fastmcp install mcp-json server.py --copy +``` + + +The `--copy` flag requires the `pyperclip` Python package. If not installed, you'll see an error message with installation instructions. + + +## Usage Examples + +### Basic Server + +```bash +fastmcp install mcp-json dice_server.py +``` + +Output: +```json +{ + "Dice Server": { + "command": "uv", + "args": [ + "run", + "--with", + "fastmcp", + "fastmcp", + "run", + "/home/user/dice_server.py" + ] + } +} +``` + +### Production Server with Dependencies + +```bash +fastmcp install mcp-json api_server.py \ + --name "Production API Server" \ + --with requests \ + --with python-dotenv \ + --env API_BASE_URL=https://api.example.com \ + --env TIMEOUT=30 +``` + +### Advanced Configuration + +```bash +fastmcp install mcp-json ml_server.py \ + --name "ML Analysis Server" \ + --python 3.11 \ + --with-requirements requirements.txt \ + --project /home/user/ml-project \ + --env GPU_DEVICE=0 +``` + +Output: +```json +{ + "Production API Server": { + "command": "uv", + "args": [ + "run", + "--with", + "fastmcp", + "--with", + "python-dotenv", + "--with", + "requests", + "fastmcp", + "run", + "/home/user/api_server.py" + ], + "env": { + "API_BASE_URL": "https://api.example.com", + "TIMEOUT": "30" + } + } +} +``` + +The advanced configuration example generates: +```json +{ + "ML Analysis Server": { + "command": "uv", + "args": [ + "run", + "--python", + "3.11", + "--project", + "/home/user/ml-project", + "--with", + "fastmcp", + "--with-requirements", + "requirements.txt", + "fastmcp", + "run", + "/home/user/ml_server.py" + ], + "env": { + "GPU_DEVICE": "0" + } + } +} +``` + +### Pipeline Usage + +Save configuration to file: + +```bash +fastmcp install mcp-json server.py > mcp-config.json +``` + +Use in shell scripts: + +```bash +#!/bin/bash +CONFIG=$(fastmcp install mcp-json server.py --name "CI Server") +echo "$CONFIG" | jq '."CI Server".command' +# Output: "uv" +``` + +## Integration with MCP Clients + +The generated configuration works with any MCP-compatible application: + +### Claude Desktop + +**Prefer [`fastmcp install claude-desktop`](/integrations/claude-desktop)** for automatic installation. Use MCP JSON for advanced configuration needs. + +Copy the `mcpServers` object into `~/.claude/claude_desktop_config.json` + +### Cursor + +**Prefer [`fastmcp install cursor`](/integrations/cursor)** for automatic installation. Use MCP JSON for advanced configuration needs. + +Add to `~/.cursor/mcp.json` + +### VS Code +Add to your workspace's `.vscode/mcp.json` file + +### Custom Applications +Use the JSON configuration with any application that supports the MCP protocol + +## Configuration Format + +The generated configuration outputs a server object with the server name as the root key: + +```json +{ + "": { + "command": "", + "args": ["", "", "..."], + "env": { + "": "" + } + } +} +``` + +To use this in an MCP client, add it to the client's `mcpServers` configuration object. + +**Fields:** +- `command`: The executable to run (always `uv` for FastMCP servers) +- `args`: Command-line arguments including dependencies and server path +- `env`: Environment variables (only included if specified) + + +**All file paths in the generated configuration are absolute paths**. This ensures the configuration works regardless of the working directory when the MCP client starts the server. + + +## Requirements + +- **uv**: Must be installed and available in your system PATH +- **pyperclip** (optional): Required only for `--copy` functionality + +Install uv if not already available: + +```bash +# macOS +brew install uv + +# Linux/Windows +curl -LsSf https://astral.sh/uv/install.sh | sh +``` diff --git a/docs/integrations/oci.mdx b/docs/integrations/oci.mdx new file mode 100644 index 000000000..02fa36dae --- /dev/null +++ b/docs/integrations/oci.mdx @@ -0,0 +1,248 @@ +--- +title: OCI IAM OAuth 🤝 FastMCP +sidebarTitle: Oracle +description: Secure your FastMCP server with OCI IAM OAuth +icon: shield-check +--- + +import { VersionBadge } from "/snippets/version-badge.mdx" + + + +This guide shows you how to secure your FastMCP server using **OCI IAM OAuth**. Since OCI IAM doesn't support Dynamic Client Registration, this integration uses the [**OIDC Proxy**](/servers/auth/oidc-proxy) pattern to bridge OCI's traditional OAuth with MCP's authentication requirements. + +## Configuration + +### Prerequisites + +1. An OCI cloud Account with access to create an Integrated Application in an Identity Domain. +2. Your FastMCP server's URL (For dev environments, it is http://localhost:8000. For PROD environments, it could be https://mcp.yourdomain.com) + +### Step 1: Make sure client access is enabled for JWK's URL + + + + + Login to OCI console (https://cloud.oracle.com for OCI commercial cloud). + From "Identity & Security" menu, open Domains page. + On the Domains list page, select the domain that you are using for MCP Authentication. + Open Settings tab. + Click on "Edit Domain Settings" button. + + + OCI console showing the Edit Domain Settings button in the IAM Domain settings page + + + + + + Enable "Configure client access" checkbox as shown in the screenshot. + + + OCI IAM Domain Settings + + + + +### Step 2: Create OAuth client for MCP server authentication + +Follow the Steps as mentioned below to create an OAuth client. + + + + + Login to OCI console (https://cloud.oracle.com for OCI commercial cloud). + From "Identity & Security" menu, open Domains page. + On the Domains list page, select the domain in which you want to create MCP server OAuth client. If you need help finding the list page for the domain, see [Listing Identity Domains.](https://docs.oracle.com/en-us/iaas/Content/Identity/domains/to-view-identity-domains.htm#view-identity-domains). + On the details page, select Integrated applications. A list of applications in the domain is displayed. + + + + + Select Add application. + In the Add application window, select Confidential Application. + Select Launch workflow. + In the Add application details page, Enter name and description as shown below. + + + Adding a Confidential Integrated Application in OCI IAM Domain + + + + + + Once the Integrated Application is created, Click on "OAuth configuration" tab. + Click on "Edit OAuth configuration" button. + Configure the application as OAuth client by selecting "Configure this application as a client now" radio button. + Select "Authorization code" grant type. If you are planning to use the same OAuth client application for token exchange, select "Client credentials" grant type as well. In the sample, we will use the same client. + For Authorization grant type, select redirect URL. In most cases, this will be the MCP server URL followed by "/oauth/callback". + + + OAuth Configuration for an Integrated Application in OCI IAM Domain + + + + + + Click on "Submit" button to update OAuth configuration for the client application. + **Note: You don't need to do any special configuration to support PKCE for the OAuth client.** + Make sure to Activate the client application. + Note down client ID and client secret for the application. You'll use these values when configuring the OCIProvider in your code. + + + +This is all you need to implement MCP server authentication against OCI IAM. However, you may want to use an authenticated user token to invoke OCI control plane APIs and propagate identity to the OCI control plane instead of using a service user account. In that case, you need to implement token exchange. + +### Step 3: Token Exchange Setup (Only if MCP server needs to talk to OCI Control Plane) + +Token exchange helps you exchange a logged-in user's OCI IAM token for an OCI control plane session token, also known as UPST (User Principal Session Token). To learn more about token exchange, refer to my [Workload Identity Federation Blog](https://www.ateam-oracle.com/post/workload-identity-federation) + +For token exchange, we need to configure Identity propagation trust. The blog above discusses setting up the trust using REST APIs. However, you can also use OCI CLI. Before using the CLI command below, ensure that you have created a token exchange OAuth client. In most cases, you can use the same OAuth client that you created above. Replace `` and `` in the CLI command below with your actual values. + +```bash +oci identity-domains identity-propagation-trust create \ +--schemas '["urn:ietf:params:scim:schemas:oracle:idcs:IdentityPropagationTrust"]' \ +--public-key-endpoint "https://.identity.oraclecloud.com/admin/v1/SigningCert/jwk" \ +--name "For Token Exchange" --type "JWT" \ +--issuer "https://identity.oraclecloud.com/" --active true \ +--endpoint "https://.identity.oraclecloud.com" \ +--subject-claim-name "sub" --allow-impersonation false \ +--subject-mapping-attribute "username" \ +--subject-type "User" --client-claim-name "iss" \ +--client-claim-values '["https://identity.oraclecloud.com/"]' \ +--oauth-clients '[""]' +``` + +To exchange access token for OCI token and create a signer object, you need to add below code in MCP server. You can then use the signer object to create any OCI control plane client. + +```python + +from fastmcp.server.dependencies import get_access_token +from fastmcp.utilities.logging import get_logger +from oci.auth.signers import TokenExchangeSigner +import os + +logger = get_logger(__name__) + +# Load configuration from environment +OCI_IAM_GUID = os.environ.get("OCI_IAM_GUID") +OCI_CLIENT_ID = os.environ.get("OCI_CLIENT_ID") +OCI_CLIENT_SECRET = os.environ.get("OCI_CLIENT_SECRET") + +_global_token_cache = {} #In memory cache for OCI session token signer + +def get_oci_signer() -> TokenExchangeSigner: + + authntoken = get_access_token() + tokenID = authntoken.claims.get("jti") + token = authntoken.token + + #Check if the signer exists for the token ID in memory cache + cached_signer = _global_token_cache.get(tokenID) + logger.debug(f"Global cached signer: {cached_signer}") + if cached_signer: + logger.debug(f"Using globally cached signer for token ID: {tokenID}") + return cached_signer + + #If the signer is not yet created for the token then create new OCI signer object + logger.debug(f"Creating new signer for token ID: {tokenID}") + signer = TokenExchangeSigner( + jwt_or_func=token, + oci_domain_id=OCI_IAM_GUID.split(".")[0] if OCI_IAM_GUID else "", + client_id=OCI_CLIENT_ID, + client_secret=OCI_CLIENT_SECRET, + ) + logger.debug(f"Signer {signer} created for token ID: {tokenID}") + + #Cache the signer object in memory cache + _global_token_cache[tokenID] = signer + logger.debug(f"Signer cached for token ID: {tokenID}") + + return signer +``` + +## Running MCP server + +Once the setup is complete, to run the MCP server, run the below command. +```bash +fastmcp run server.py:mcp --transport http --port 8000 +``` + +To run MCP client, run the below command. +```bash +python3 client.py +``` + +MCP Client sample is as below. +```python client.py +from fastmcp import Client +import asyncio + +async def main(): + # The client will automatically handle OCI OAuth flows + async with Client("http://localhost:8000/mcp/", auth="oauth") as client: + # First-time connection will open OCI login in your browser + print("✓ Authenticated with OCI IAM") + + tools = await client.list_tools() + print(f"🔧 Available tools ({len(tools)}):") + for tool in tools: + print(f" - {tool.name}: {tool.description}") + +if __name__ == "__main__": + asyncio.run(main()) +``` + +When you run the client for the first time: +1. Your browser will open to OCI IAM's login page +2. Sign in with your OCI account and grant the requested consent +3. After authorization, you'll be redirected back to the redirect path +4. The client receives the token and can make authenticated requests + +## Production Configuration + + + +For production deployments with persistent token management across server restarts, configure `jwt_signing_key`, and `client_storage`: + +```python server.py + +import os +from fastmcp import FastMCP +from fastmcp.server.auth.providers.oci import OCIProvider + +from key_value.aio.stores.redis import RedisStore +from key_value.aio.wrappers.encryption import FernetEncryptionWrapper +from cryptography.fernet import Fernet + +# Load configuration from environment +# Production setup with encrypted persistent token storage +auth_provider = OCIProvider( + config_url=os.environ.get("OCI_CONFIG_URL"), + client_id=os.environ.get("OCI_CLIENT_ID"), + client_secret=os.environ.get("OCI_CLIENT_SECRET"), + base_url=os.environ.get("BASE_URL", "https://your-production-domain.com"), + + # Production token management + jwt_signing_key=os.environ["JWT_SIGNING_KEY"], + client_storage=FernetEncryptionWrapper( + key_value=RedisStore( + host=os.environ["REDIS_HOST"], + port=int(os.environ["REDIS_PORT"]) + ), + fernet=Fernet(os.environ["STORAGE_ENCRYPTION_KEY"]) + ) +) + +mcp = FastMCP(name="Production OCI App", auth=auth_provider) +``` + + +Parameters (`jwt_signing_key` and `client_storage`) work together to ensure tokens and client registrations survive server restarts. **Wrap your storage in `FernetEncryptionWrapper` to encrypt sensitive OAuth tokens at Rest** - without it, tokens are stored in plaintext. Store secrets in environment variables and use a persistent storage backend like Redis for distributed deployments. + +For complete details on these parameters, see the [OAuth Proxy documentation](/servers/auth/oauth-proxy#configuration-parameters). + + + +The client caches tokens locally, so you won't need to re-authenticate for subsequent runs unless the token expires or you explicitly clear the cache. + \ No newline at end of file diff --git a/docs/integrations/openai.mdx b/docs/integrations/openai.mdx new file mode 100644 index 000000000..6f88193f5 --- /dev/null +++ b/docs/integrations/openai.mdx @@ -0,0 +1,227 @@ +--- +title: OpenAI API 🤝 FastMCP +sidebarTitle: OpenAI API +description: Connect FastMCP servers to the OpenAI API +icon: message-code +--- + +import { VersionBadge } from "/snippets/version-badge.mdx" + + +## Responses API + +OpenAI's [Responses API](https://platform.openai.com/docs/api-reference/responses) supports [MCP servers](https://platform.openai.com/docs/guides/tools-remote-mcp) as remote tool sources, allowing you to extend AI capabilities with custom functions. + + +The Responses API is a distinct API from OpenAI's Completions API or Assistants API. At this time, only the Responses API supports MCP. + + + +Currently, the Responses API only accesses **tools** from MCP servers—it queries the `list_tools` endpoint and exposes those functions to the AI agent. Other MCP features like resources and prompts are not currently supported. + + + +### Create a Server + +First, create a FastMCP server with the tools you want to expose. For this example, we'll create a server with a single tool that rolls dice. + +```python server.py +import random +from fastmcp import FastMCP + +mcp = FastMCP(name="Dice Roller") + +@mcp.tool +def roll_dice(n_dice: int) -> list[int]: + """Roll `n_dice` 6-sided dice and return the results.""" + return [random.randint(1, 6) for _ in range(n_dice)] + +if __name__ == "__main__": + mcp.run(transport="http", port=8000) +``` + +### Deploy the Server + +Your server must be deployed to a public URL in order for OpenAI to access it. + +For development, you can use tools like `ngrok` to temporarily expose a locally-running server to the internet. We'll do that for this example (you may need to install `ngrok` and create a free account), but you can use any other method to deploy your server. + +Assuming you saved the above code as `server.py`, you can run the following two commands in two separate terminals to deploy your server and expose it to the internet: + + +```bash FastMCP server +python server.py +``` + +```bash ngrok +ngrok http 8000 +``` + + + +This exposes your unauthenticated server to the internet. Only run this command in a safe environment if you understand the risks. + + +### Call the Server + +To use the Responses API, you'll need to install the OpenAI Python SDK (not included with FastMCP): + +```bash +pip install openai +``` + +You'll also need to authenticate with OpenAI. You can do this by setting the `OPENAI_API_KEY` environment variable. Consult the OpenAI SDK documentation for more information. + +```bash +export OPENAI_API_KEY="your-api-key" +``` + +Here is an example of how to call your server from Python. Note that you'll need to replace `https://your-server-url.com` with the actual URL of your server. In addition, we use `/mcp/` as the endpoint because we deployed a streamable-HTTP server with the default path; you may need to use a different endpoint if you customized your server's deployment. + +```python {4, 11-16} +from openai import OpenAI + +# Your server URL (replace with your actual URL) +url = 'https://your-server-url.com' + +client = OpenAI() + +resp = client.responses.create( + model="gpt-4.1", + tools=[ + { + "type": "mcp", + "server_label": "dice_server", + "server_url": f"{url}/mcp/", + "require_approval": "never", + }, + ], + input="Roll a few dice!", +) + +print(resp.output_text) +``` +If you run this code, you'll see something like the following output: + +```text +You rolled 3 dice and got the following results: 6, 4, and 2! +``` + +### Authentication + + + +The Responses API can include headers to authenticate the request, which means you don't have to worry about your server being publicly accessible. + +#### Server Authentication + +The simplest way to add authentication to the server is to use a bearer token scheme. + +For this example, we'll quickly generate our own tokens with FastMCP's `RSAKeyPair` utility, but this may not be appropriate for production use. For more details, see the complete server-side [Token Verification](/servers/auth/token-verification) documentation. + +We'll start by creating an RSA key pair to sign and verify tokens. + +```python +from fastmcp.server.auth.providers.jwt import RSAKeyPair + +key_pair = RSAKeyPair.generate() +access_token = key_pair.create_token(audience="dice-server") +``` + + +FastMCP's `RSAKeyPair` utility is for development and testing only. + + +Next, we'll create a `JWTVerifier` to authenticate the server. + +```python +from fastmcp import FastMCP +from fastmcp.server.auth import JWTVerifier + +auth = JWTVerifier( + public_key=key_pair.public_key, + audience="dice-server", +) + +mcp = FastMCP(name="Dice Roller", auth=auth) +``` + +Here is a complete example that you can copy/paste. For simplicity and the purposes of this example only, it will print the token to the console. **Do NOT do this in production!** + +```python server.py [expandable] +from fastmcp import FastMCP +from fastmcp.server.auth import JWTVerifier +from fastmcp.server.auth.providers.jwt import RSAKeyPair +import random + +key_pair = RSAKeyPair.generate() +access_token = key_pair.create_token(audience="dice-server") + +auth = JWTVerifier( + public_key=key_pair.public_key, + audience="dice-server", +) + +mcp = FastMCP(name="Dice Roller", auth=auth) + +@mcp.tool +def roll_dice(n_dice: int) -> list[int]: + """Roll `n_dice` 6-sided dice and return the results.""" + return [random.randint(1, 6) for _ in range(n_dice)] + +if __name__ == "__main__": + print(f"\n---\n\n🔑 Dice Roller access token:\n\n{access_token}\n\n---\n") + mcp.run(transport="http", port=8000) +``` + +#### Client Authentication + +If you try to call the authenticated server with the same OpenAI code we wrote earlier, you'll get an error like this: + +```python +pythonAPIStatusError: Error code: 424 - { + "error": { + "message": "Error retrieving tool list from MCP server: 'dice_server'. Http status code: 401 (Unauthorized)", + "type": "external_connector_error", + "param": "tools", + "code": "http_error" + } +} +``` + +As expected, the server is rejecting the request because it's not authenticated. + +To authenticate the client, you can pass the token in the `Authorization` header with the `Bearer` scheme: + + +```python {4, 7, 19-21} [expandable] +from openai import OpenAI + +# Your server URL (replace with your actual URL) +url = 'https://your-server-url.com' + +# Your access token (replace with your actual token) +access_token = 'your-access-token' + +client = OpenAI() + +resp = client.responses.create( + model="gpt-4.1", + tools=[ + { + "type": "mcp", + "server_label": "dice_server", + "server_url": f"{url}/mcp/", + "require_approval": "never", + "headers": { + "Authorization": f"Bearer {access_token}" + } + }, + ], + input="Roll a few dice!", +) + +print(resp.output_text) +``` + +You should now see the dice roll results in the output. \ No newline at end of file diff --git a/docs/integrations/openapi.mdx b/docs/integrations/openapi.mdx new file mode 100644 index 000000000..88dc19b14 --- /dev/null +++ b/docs/integrations/openapi.mdx @@ -0,0 +1,455 @@ +--- +title: OpenAPI 🤝 FastMCP +sidebarTitle: OpenAPI +description: Generate MCP servers from any OpenAPI specification +icon: list-tree +--- + +import { VersionBadge } from '/snippets/version-badge.mdx' + + + +FastMCP can automatically generate an MCP server from any OpenAPI specification, allowing AI models to interact with existing APIs through the MCP protocol. Instead of manually creating tools and resources, you provide an OpenAPI spec and FastMCP intelligently converts API endpoints into the appropriate MCP components. + + +Under the hood, OpenAPI integration uses OpenAPIProvider (v3.0.0+) to source tools from the specification. See [Providers](/servers/providers/overview) to understand how FastMCP sources components. + + + +Generating MCP servers from OpenAPI is a great way to get started with FastMCP, but in practice LLMs achieve **significantly better performance** with well-designed and curated MCP servers than with auto-converted OpenAPI servers. This is especially true for complex APIs with many endpoints and parameters. + +We recommend using the FastAPI integration for bootstrapping and prototyping, not for mirroring your API to LLM clients. See the post [Stop Converting Your REST APIs to MCP](https://www.jlowin.dev/blog/stop-converting-rest-apis-to-mcp) for more details. + + +## Create a Server + +To convert an OpenAPI specification to an MCP server, use the `FastMCP.from_openapi()` class method: + +```python server.py +import httpx +from fastmcp import FastMCP + +# Create an HTTP client for your API +client = httpx.AsyncClient(base_url="https://api.example.com") + +# Load your OpenAPI spec +openapi_spec = httpx.get("https://api.example.com/openapi.json").json() + +# Create the MCP server +mcp = FastMCP.from_openapi( + openapi_spec=openapi_spec, + client=client, + name="My API Server" +) + +if __name__ == "__main__": + mcp.run() +``` + +### Authentication + +If your API requires authentication, configure it on the HTTP client: + +```python +import httpx +from fastmcp import FastMCP + +# Bearer token authentication +api_client = httpx.AsyncClient( + base_url="https://api.example.com", + headers={"Authorization": "Bearer YOUR_TOKEN"} +) + +# Create MCP server with authenticated client +mcp = FastMCP.from_openapi( + openapi_spec=spec, + client=api_client, + timeout=30.0 # 30 second timeout for all requests +) +``` + +## Route Mapping + +By default, FastMCP converts **every endpoint** in your OpenAPI specification into an MCP **Tool**. This provides a simple, predictable starting point that ensures all your API's functionality is immediately available to the vast majority of LLM clients which only support MCP tools. + +While this is a pragmatic default for maximum compatibility, you can easily customize this behavior. Internally, FastMCP uses an ordered list of `RouteMap` objects to determine how to map OpenAPI routes to various MCP component types. + +Each `RouteMap` specifies a combination of methods, patterns, and tags, as well as a corresponding MCP component type. Each OpenAPI route is checked against each `RouteMap` in order, and the first one that matches every criteria is used to determine its converted MCP type. A special type, `EXCLUDE`, can be used to exclude routes from the MCP server entirely. + +- **Methods**: HTTP methods to match (e.g. `["GET", "POST"]` or `"*"` for all) +- **Pattern**: Regex pattern to match the route path (e.g. `r"^/users/.*"` or `r".*"` for all) +- **Tags**: A set of OpenAPI tags that must all be present. An empty set (`{}`) means no tag filtering, so the route matches regardless of its tags. +- **MCP type**: What MCP component type to create (`TOOL`, `RESOURCE`, `RESOURCE_TEMPLATE`, or `EXCLUDE`) +- **MCP tags**: A set of custom tags to add to components created from matching routes + +Here is FastMCP's default rule: + +```python +from fastmcp.server.openapi import RouteMap, MCPType + +DEFAULT_ROUTE_MAPPINGS = [ + # All routes become tools + RouteMap(mcp_type=MCPType.TOOL), +] +``` + +### Custom Route Maps + +When creating your FastMCP server, you can customize routing behavior by providing your own list of `RouteMap` objects. Your custom maps are processed before the default route maps, and routes will be assigned to the first matching custom map. + +For example, prior to FastMCP 2.8.0, GET requests were automatically mapped to `Resource` and `ResourceTemplate` components based on whether they had path parameters. (This was changed solely for client compatibility reasons.) You can restore this behavior by providing custom route maps: + +```python +from fastmcp import FastMCP +from fastmcp.server.openapi import RouteMap, MCPType + +# Restore pre-2.8.0 semantic mapping +semantic_maps = [ + # GET requests with path parameters become ResourceTemplates + RouteMap(methods=["GET"], pattern=r".*\{.*\}.*", mcp_type=MCPType.RESOURCE_TEMPLATE), + # All other GET requests become Resources + RouteMap(methods=["GET"], pattern=r".*", mcp_type=MCPType.RESOURCE), +] + +mcp = FastMCP.from_openapi( + openapi_spec=spec, + client=client, + route_maps=semantic_maps, +) +``` + +With these maps, `GET` requests are handled semantically, and all other methods (`POST`, `PUT`, etc.) will fall through to the default rule and become `Tool`s. + +Here is a more complete example that uses custom route maps to convert all `GET` endpoints under `/analytics/` to tools while excluding all admin endpoints and all routes tagged "internal". All other routes will be handled by the default rules: + +```python +from fastmcp import FastMCP +from fastmcp.server.openapi import RouteMap, MCPType + +mcp = FastMCP.from_openapi( + openapi_spec=spec, + client=client, + route_maps=[ + # Analytics `GET` endpoints are tools + RouteMap( + methods=["GET"], + pattern=r"^/analytics/.*", + mcp_type=MCPType.TOOL, + ), + + # Exclude all admin endpoints + RouteMap( + pattern=r"^/admin/.*", + mcp_type=MCPType.EXCLUDE, + ), + + # Exclude all routes tagged "internal" + RouteMap( + tags={"internal"}, + mcp_type=MCPType.EXCLUDE, + ), + ], +) +``` + + +The default route maps are always applied after your custom maps, so you do not have to create route maps for every possible route. + + +### Excluding Routes + +To exclude routes from the MCP server, use a route map to assign them to `MCPType.EXCLUDE`. + +You can use this to remove sensitive or internal routes by targeting them specifically: + +```python +from fastmcp import FastMCP +from fastmcp.server.openapi import RouteMap, MCPType + +mcp = FastMCP.from_openapi( + openapi_spec=spec, + client=client, + route_maps=[ + RouteMap(pattern=r"^/admin/.*", mcp_type=MCPType.EXCLUDE), + RouteMap(tags={"internal"}, mcp_type=MCPType.EXCLUDE), + ], +) +``` + +Or you can use a catch-all rule to exclude everything that your maps don't handle explicitly: + +```python +from fastmcp import FastMCP +from fastmcp.server.openapi import RouteMap, MCPType + +mcp = FastMCP.from_openapi( + openapi_spec=spec, + client=client, + route_maps=[ + # custom mapping logic goes here + # ... your specific route maps ... + # exclude all remaining routes + RouteMap(mcp_type=MCPType.EXCLUDE), + ], +) +``` + + +Using a catch-all exclusion rule will prevent the default route mappings from being applied, since it will match every remaining route. This is useful if you want to explicitly allow-list certain routes. + + +### Advanced Route Mapping + + + +For advanced use cases that require more complex logic, you can provide a `route_map_fn` callable. After the route map logic is applied, this function is called on each matched route and its assigned MCP component type. It can optionally return a different component type to override the mapped assignment. If it returns `None`, the assigned type is used. + +In addition to more precise targeting of methods, patterns, and tags, this function can access any additional OpenAPI metadata about the route. + + +The `route_map_fn` is called on all routes, even those that matched `MCPType.EXCLUDE` in your custom maps. This gives you an opportunity to customize the mapping or even override an exclusion. + + +```python +from fastmcp import FastMCP +from fastmcp.server.openapi import RouteMap, MCPType, HTTPRoute + +def custom_route_mapper(route: HTTPRoute, mcp_type: MCPType) -> MCPType | None: + """Advanced route type mapping.""" + # Convert all admin routes to tools regardless of HTTP method + if "/admin/" in route.path: + return MCPType.TOOL + + elif "internal" in route.tags: + return MCPType.EXCLUDE + + # Convert user detail routes to templates even if they're POST + elif route.path.startswith("/users/") and route.method == "POST": + return MCPType.RESOURCE_TEMPLATE + + # Use defaults for all other routes + return None + +mcp = FastMCP.from_openapi( + openapi_spec=spec, + client=client, + route_map_fn=custom_route_mapper, +) +``` + +## Customization + +### Component Names + + + +FastMCP automatically generates names for MCP components based on the OpenAPI specification. By default, it uses the `operationId` from your OpenAPI spec, up to the first double underscore (`__`). + +All component names are automatically: +- **Slugified**: Spaces and special characters are converted to underscores or removed +- **Truncated**: Limited to 56 characters maximum to ensure compatibility +- **Unique**: If multiple components have the same name, a number is automatically appended to make them unique + +For more control over component names, you can provide an `mcp_names` dictionary that maps `operationId` values to your desired names. The `operationId` must be exactly as it appears in the OpenAPI spec. The provided name will always be slugified and truncated. + +```python +mcp = FastMCP.from_openapi( + openapi_spec=spec, + client=client, + mcp_names={ + "list_users__with_pagination": "user_list", + "create_user__admin_required": "create_user", + "get_user_details__admin_required": "user_detail", + } +) +``` + +Any `operationId` not found in `mcp_names` will use the default strategy (operationId up to the first `__`). + +### Tags + + + +FastMCP provides several ways to add tags to your MCP components, allowing you to categorize and organize them for better discoverability and filtering. Tags are combined from multiple sources to create the final set of tags on each component. + +#### RouteMap Tags + +You can add custom tags to components created from specific routes using the `mcp_tags` parameter in `RouteMap`. These tags will be applied to all components created from routes that match that particular route map. + +```python +from fastmcp.server.openapi import RouteMap, MCPType + +mcp = FastMCP.from_openapi( + openapi_spec=spec, + client=client, + route_maps=[ + # Add custom tags to all POST endpoints + RouteMap( + methods=["POST"], + pattern=r".*", + mcp_type=MCPType.TOOL, + mcp_tags={"write-operation", "api-mutation"} + ), + + # Add different tags to detail view endpoints + RouteMap( + methods=["GET"], + pattern=r".*\{.*\}.*", + mcp_type=MCPType.RESOURCE_TEMPLATE, + mcp_tags={"detail-view", "parameterized"} + ), + + # Add tags to list endpoints + RouteMap( + methods=["GET"], + pattern=r".*", + mcp_type=MCPType.RESOURCE, + mcp_tags={"list-data", "collection"} + ), + ], +) +``` + +#### Global Tags + +You can add tags to **all** components by providing a `tags` parameter when creating your MCP server. These global tags will be applied to every component created from your OpenAPI specification. + +```python +mcp = FastMCP.from_openapi( + openapi_spec=spec, + client=client, + tags={"api-v2", "production", "external"} +) +``` + +#### OpenAPI Tags in Client Meta + +FastMCP automatically includes OpenAPI tags from your specification in the component's metadata. These tags are available to MCP clients through the `meta.fastmcp.tags` field, allowing clients to filter and organize components based on the original OpenAPI tagging: + + +```json {5} OpenAPI spec with tags +{ + "paths": { + "/users": { + "get": { + "tags": ["users", "public"], + "operationId": "list_users", + "summary": "List all users" + } + } + } +} +``` +```python {6-9} Access OpenAPI tags in MCP client +async with client: + tools = await client.list_tools() + for tool in tools: + if tool.meta: + # OpenAPI tags are now available in fastmcp namespace! + fastmcp_meta = tool.meta.get('fastmcp', {}) + openapi_tags = fastmcp_meta.get('tags', []) + if 'users' in openapi_tags: + print(f"Found user-related tool: {tool.name}") +``` + + +This makes it easy for clients to understand and organize API endpoints based on their original OpenAPI categorization. + +### Advanced Customization + + + +By default, FastMCP creates MCP components using a variety of metadata from the OpenAPI spec, such as incorporating the OpenAPI description into the MCP component description. + +At times you may want to modify those MCP components in a variety of ways, such as adding LLM-specific instructions or tags. For fine-grained customization, you can provide a `mcp_component_fn` when creating the MCP server. After each MCP component has been created, this function is called on it and has the opportunity to modify it in-place. + + +Your `mcp_component_fn` is expected to modify the component in-place, not to return a new component. The result of the function is ignored. + + +```python +from fastmcp.server.openapi import ( + HTTPRoute, + OpenAPITool, + OpenAPIResource, + OpenAPIResourceTemplate, +) + +def customize_components( + route: HTTPRoute, + component: OpenAPITool | OpenAPIResource | OpenAPIResourceTemplate, +) -> None: + # Add custom tags to all components + component.tags.add("openapi") + + # Customize based on component type + if isinstance(component, OpenAPITool): + component.description = f"🔧 {component.description} (via API)" + + if isinstance(component, OpenAPIResource): + component.description = f"📊 {component.description}" + component.tags.add("data") + +mcp = FastMCP.from_openapi( + openapi_spec=spec, + client=client, + mcp_component_fn=customize_components, +) +``` + +## Request Parameter Handling + +FastMCP intelligently handles different types of parameters in OpenAPI requests: + +### Query Parameters + +By default, FastMCP only includes query parameters that have non-empty values. Parameters with `None` values or empty strings are automatically filtered out. + +```python +# When calling this tool... +await client.call_tool("search_products", { + "category": "electronics", # ✅ Included + "min_price": 100, # ✅ Included + "max_price": None, # ❌ Excluded + "brand": "", # ❌ Excluded +}) + +# The HTTP request will be: GET /products?category=electronics&min_price=100 +``` + +### Path Parameters + +Path parameters are typically required by REST APIs. FastMCP: +- Filters out `None` values +- Validates that all required path parameters are provided +- Raises clear errors for missing required parameters + +```python +# ✅ This works +await client.call_tool("get_user", {"user_id": 123}) + +# ❌ This raises: "Missing required path parameters: {'user_id'}" +await client.call_tool("get_user", {"user_id": None}) +``` + +### Array Parameters + +FastMCP handles array parameters according to OpenAPI specifications: + +- **Query arrays**: Serialized based on the `explode` parameter (default: `True`) +- **Path arrays**: Serialized as comma-separated values (OpenAPI 'simple' style) + +```python +# Query array with explode=true (default) +# ?tags=red&tags=blue&tags=green + +# Query array with explode=false +# ?tags=red,blue,green + +# Path array (always comma-separated) +# /items/red,blue,green +``` + +### Headers + +Header parameters are automatically converted to strings and included in the HTTP request. \ No newline at end of file diff --git a/docs/integrations/permit.mdx b/docs/integrations/permit.mdx new file mode 100644 index 000000000..066f5b1ea --- /dev/null +++ b/docs/integrations/permit.mdx @@ -0,0 +1,352 @@ +--- +title: Permit.io Authorization 🤝 FastMCP +sidebarTitle: Permit.io +description: Add fine-grained authorization to your FastMCP servers with Permit.io +icon: shield-check +--- + +Add **policy-based authorization** to your FastMCP servers with one-line code addition with the **[Permit.io][permit-github] authorization middleware**. + +Control which tools, resources and prompts MCP clients can view and execute on your server. Define dynamic policies using Permit.io's powerful RBAC, ABAC, and REBAC capabilities, and obtain comprehensive audit logs of all access attempts and violations. + +## How it Works + +Leveraging FastMCP's [Middleware][fastmcp-middleware], the Permit.io middleware intercepts all MCP requests to your server and automatically maps MCP methods to authorization checks against your Permit.io policies; covering both server methods and tool execution. + +### Policy Mapping + +The middleware automatically maps MCP methods to Permit.io resources and actions: + +- **MCP server methods** (e.g., `tools/list`, `resources/read`): + - **Resource**: `{server_name}_{component}` (e.g., `myserver_tools`) + - **Action**: The method verb (e.g., `list`, `read`) +- **Tool execution** (method `tools/call`): + - **Resource**: `{server_name}` (e.g., `myserver`) + - **Action**: The tool name (e.g., `greet`) + +![Permit.io Policy Mapping Example](./images/permit/policy_mapping.png) + +*Example: In Permit.io, the 'Admin' role is granted permissions on resources and actions as mapped by the middleware. For example, 'greet', 'greet-jwt', and 'login' are actions on the 'mcp_server' resource, and 'list' is an action on the 'mcp_server_tools' resource.* + +> **Note:** +> Don't forget to assign the relevant role (e.g., Admin, User) to the user authenticating to your MCP server (such as the user in the JWT) in the Permit.io Directory. Without the correct role assignment, users will not have access to the resources and actions you've configured in your policies. +> +> ![Permit.io Directory Role Assignment Example](./images/permit/role_assignement.png) +> +> *Example: In Permit.io Directory, both 'client' and 'admin' users are assigned the 'Admin' role, granting them the permissions defined in your policy mapping.* + +For detailed policy mapping examples and configuration, see [Detailed Policy Mapping](https://github.com/permitio/permit-fastmcp/blob/main/docs/policy-mapping.md). + +### Listing Operations + +The middleware behaves as a filter for listing operations (`tools/list`, `resources/list`, `prompts/list`), hiding to the client components that are not authorized by the defined policies. + +```mermaid +sequenceDiagram + participant MCPClient as MCP Client + participant PermitMiddleware as Permit.io Middleware + participant MCPServer as FastMCP Server + participant PermitPDP as Permit.io PDP + + MCPClient->>PermitMiddleware: MCP Listing Request (e.g., tools/list) + PermitMiddleware->>MCPServer: MCP Listing Request + MCPServer-->>PermitMiddleware: MCP Listing Response + PermitMiddleware->>PermitPDP: Authorization Checks + PermitPDP->>PermitMiddleware: Authorization Decisions + PermitMiddleware-->>MCPClient: Filtered MCP Listing Response +``` + +### Execution Operations + +The middleware behaves as an enforcement point for execution operations (`tools/call`, `resources/read`, `prompts/get`), blocking operations that are not authorized by the defined policies. + +```mermaid +sequenceDiagram + participant MCPClient as MCP Client + participant PermitMiddleware as Permit.io Middleware + participant MCPServer as FastMCP Server + participant PermitPDP as Permit.io PDP + + MCPClient->>PermitMiddleware: MCP Execution Request (e.g., tools/call) + PermitMiddleware->>PermitPDP: Authorization Check + PermitPDP->>PermitMiddleware: Authorization Decision + PermitMiddleware-->>MCPClient: MCP Unauthorized Error (if denied) + PermitMiddleware->>MCPServer: MCP Execution Request (if allowed) + MCPServer-->>PermitMiddleware: MCP Execution Response (if allowed) + PermitMiddleware-->>MCPClient: MCP Execution Response (if allowed) +``` + +## Add Authorization to Your Server + + +Permit.io is a cloud-native authorization service. You need a Permit.io account and a running Policy Decision Point (PDP) for the middleware to function. You can run the PDP locally with Docker or use Permit.io's cloud PDP. + + +### Prerequisites + +1. **Permit.io Account**: Sign up at [permit.io](https://permit.io) +2. **PDP Setup**: Run the Permit.io PDP locally or use the cloud PDP (RBAC only) +3. **API Key**: Get your Permit.io API key from the dashboard + +### Run the Permit.io PDP + +Run the PDP locally with Docker: + +```bash +docker run -p 7766:7766 permitio/pdp:latest +``` + +Or use the cloud PDP URL: `https://cloudpdp.api.permit.io` + +### Create a Server with Authorization + +First, install the `permit-fastmcp` package: + +```bash +# Using UV (recommended) +uv add permit-fastmcp + +# Using pip +pip install permit-fastmcp +``` + +Then create a FastMCP server and add the Permit.io middleware: + +```python server.py +from fastmcp import FastMCP +from permit_fastmcp.middleware.middleware import PermitMcpMiddleware + +mcp = FastMCP("Secure FastMCP Server 🔒") + +@mcp.tool +def greet(name: str) -> str: + """Greet a user by name""" + return f"Hello, {name}!" + +@mcp.tool +def add(a: int, b: int) -> int: + """Add two numbers""" + return a + b + +# Add Permit.io authorization middleware +mcp.add_middleware(PermitMcpMiddleware( + permit_pdp_url="http://localhost:7766", + permit_api_key="your-permit-api-key" +)) + +if __name__ == "__main__": + mcp.run(transport="http") +``` + +### Configure Access Policies + +Create your authorization policies in the Permit.io dashboard: + +1. **Create Resources**: Define resources like `mcp_server` and `mcp_server_tools` +2. **Define Actions**: Add actions like `greet`, `add`, `list`, `read` +3. **Create Roles**: Define roles like `Admin`, `User`, `Guest` +4. **Assign Permissions**: Grant roles access to specific resources and actions +5. **Assign Users**: Assign roles to users in the Permit.io Directory + +For step-by-step setup instructions and troubleshooting, see [Getting Started & FAQ](https://github.com/permitio/permit-fastmcp/blob/main/docs/getting-started.md). + +#### Example Policy Configuration + +Policies are defined in the Permit.io dashboard, but you can also use the [Permit.io Terraform provider](https://github.com/permitio/terraform-provider-permitio) to define policies in code. + + +```terraform +# Resources +resource "permitio_resource" "mcp_server" { + name = "mcp_server" + key = "mcp_server" + + actions = { + "greet" = { name = "greet" } + "add" = { name = "add" } + } +} + +resource "permitio_resource" "mcp_server_tools" { + name = "mcp_server_tools" + key = "mcp_server_tools" + + actions = { + "list" = { name = "list" } + } +} + +# Roles +resource "permitio_role" "Admin" { + key = "Admin" + name = "Admin" + permissions = [ + "mcp_server:greet", + "mcp_server:add", + "mcp_server_tools:list" + ] +} +``` + +You can also use the [Permit.io CLI](https://github.com/permitio/permit-cli), [API](https://api.permit.io/scalar) or [SDKs](https://github.com/permitio/permit-python) to manage policies, as well as writing policies directly in REGO (Open Policy Agent's policy language). + +For complete policy examples including ABAC and RBAC configurations, see [Example Policies](https://github.com/permitio/permit-fastmcp/tree/main/docs/example_policies). + +### Identity Management + +The middleware supports multiple identity extraction modes: + +- **Fixed Identity**: Use a fixed identity for all requests +- **Header-based**: Extract identity from HTTP headers +- **JWT-based**: Extract and verify JWT tokens +- **Source-based**: Use the MCP context source field + +For detailed identity mode configuration and environment variables, see [Identity Modes & Environment Variables](https://github.com/permitio/permit-fastmcp/blob/main/docs/identity-modes.md). + +#### JWT Authentication Example + +```python +import os + +# Configure JWT identity extraction +os.environ["PERMIT_MCP_IDENTITY_MODE"] = "jwt" +os.environ["PERMIT_MCP_IDENTITY_JWT_SECRET"] = "your-jwt-secret" + +mcp.add_middleware(PermitMcpMiddleware( + permit_pdp_url="http://localhost:7766", + permit_api_key="your-permit-api-key" +)) +``` + +### ABAC Policies with Tool Arguments + +The middleware supports Attribute-Based Access Control (ABAC) policies that can evaluate tool arguments as attributes. Tool arguments are automatically flattened as individual attributes (e.g., `arg_name`, `arg_number`) for granular policy conditions. + +![ABAC Condition Example](./images/permit/abac_condition_example.png) + +*Example: Create dynamic resources with conditions like `resource.arg_number greater-than 10` to allow the `conditional-greet` tool only when the number argument exceeds 10.* + +#### Example: Conditional Access + +Create a dynamic resource with conditions like `resource.arg_number greater-than 10` to allow the `conditional-greet` tool only when the number argument exceeds 10. + +```python +@mcp.tool +def conditional_greet(name: str, number: int) -> str: + """Greet a user only if number > 10""" + return f"Hello, {name}! Your number is {number}" +``` + +![ABAC Policy Example](./images/permit/abac_policy_example.png) + +*Example: The Admin role is granted access to the "conditional-greet" action on the "Big-greets" dynamic resource, while other tools like "greet", "greet-jwt", and "login" are granted on the base "mcp_server" resource.* + +For comprehensive ABAC configuration and advanced policy examples, see [ABAC Policies with Tool Arguments](https://github.com/permitio/permit-fastmcp/blob/main/docs/policy-mapping.md#abac-policies-with-tool-arguments). + +### Run the Server + +Start your FastMCP server normally: + +```bash +python server.py +``` + +The middleware will now intercept all MCP requests and check them against your Permit.io policies. Requests include user identification through the configured identity mode and automatic mapping of MCP methods to authorization resources and actions. + +## Advanced Configuration + +### Environment Variables + +Configure the middleware using environment variables: + +```bash +# Permit.io configuration +export PERMIT_MCP_PERMIT_PDP_URL="http://localhost:7766" +export PERMIT_MCP_PERMIT_API_KEY="your-api-key" + +# Identity configuration +export PERMIT_MCP_IDENTITY_MODE="jwt" +export PERMIT_MCP_IDENTITY_JWT_SECRET="your-jwt-secret" + +# Method configuration +export PERMIT_MCP_KNOWN_METHODS='["tools/list","tools/call"]' +export PERMIT_MCP_BYPASSED_METHODS='["initialize","ping"]' + +# Logging configuration +export PERMIT_MCP_ENABLE_AUDIT_LOGGING="true" +``` + +For a complete list of all configuration options and environment variables, see [Configuration Reference](https://github.com/permitio/permit-fastmcp/blob/main/docs/configuration-reference.md). + +### Custom Middleware Configuration + +```python +from permit_fastmcp.middleware.middleware import PermitMcpMiddleware + +middleware = PermitMcpMiddleware( + permit_pdp_url="http://localhost:7766", + permit_api_key="your-api-key", + enable_audit_logging=True, + bypass_methods=["initialize", "ping", "health/*"] +) + +mcp.add_middleware(middleware) +``` + +For advanced configuration options and custom middleware extensions, see [Advanced Configuration](https://github.com/permitio/permit-fastmcp/blob/main/docs/advanced-configuration.md). + +## Example: Complete JWT Authentication Server + +See the [example server](https://github.com/permitio/permit-fastmcp/blob/main/permit_fastmcp/example_server/example.py) for a full implementation with JWT-based authentication. For additional examples and usage patterns, see [Example Server](https://github.com/permitio/permit-fastmcp/blob/main/permit_fastmcp/example_server/): + +```python +from fastmcp import FastMCP, Context +from permit_fastmcp.middleware.middleware import PermitMcpMiddleware +import jwt +import datetime + +# Configure JWT identity extraction +os.environ["PERMIT_MCP_IDENTITY_MODE"] = "jwt" +os.environ["PERMIT_MCP_IDENTITY_JWT_SECRET"] = "mysecretkey" + +mcp = FastMCP("My MCP Server") + +@mcp.tool +def login(username: str, password: str) -> str: + """Login to get a JWT token""" + if username == "admin" and password == "password": + token = jwt.encode( + {"sub": username, "exp": datetime.datetime.utcnow() + datetime.timedelta(hours=1)}, + "mysecretkey", + algorithm="HS256" + ) + return f"Bearer {token}" + raise Exception("Invalid credentials") + +@mcp.tool +def greet_jwt(ctx: Context) -> str: + """Greet a user by extracting their name from JWT""" + # JWT extraction handled by middleware + return "Hello, authenticated user!" + +mcp.add_middleware(PermitMcpMiddleware( + permit_pdp_url="http://localhost:7766", + permit_api_key="your-permit-api-key" +)) + +if __name__ == "__main__": + mcp.run(transport="http") +``` + + + For detailed policy configuration, custom authentication, and advanced + deployment patterns, visit the [Permit.io FastMCP Middleware + repository][permit-fastmcp-github]. For troubleshooting common issues, see [Troubleshooting](https://github.com/permitio/permit-fastmcp/blob/main/docs/troubleshooting.md). + + + +[permit.io]: https://www.permit.io +[permit-github]: https://github.com/permitio +[permit-fastmcp-github]: https://github.com/permitio/permit-fastmcp +[Agent.Security]: https://agent.security +[fastmcp-middleware]: /servers/middleware diff --git a/docs/integrations/propelauth.mdx b/docs/integrations/propelauth.mdx new file mode 100644 index 000000000..7f21d2010 --- /dev/null +++ b/docs/integrations/propelauth.mdx @@ -0,0 +1,164 @@ +--- +title: PropelAuth 🤝 FastMCP +sidebarTitle: PropelAuth +description: Secure your FastMCP server with PropelAuth +icon: shield-check +--- + +import { VersionBadge } from "/snippets/version-badge.mdx"; + + + +This guide shows you how to secure your FastMCP server using [**PropelAuth**](https://www.propelauth.com), a complete authentication and user management solution. This integration uses the [**Remote OAuth**](/servers/auth/remote-oauth) pattern, where PropelAuth handles user login, consent management, and your FastMCP server validates the tokens. + +## Configuration + +### Prerequisites + +Before you begin, you will need: + +1. A [PropelAuth](https://www.propelauth.com) account +2. Your FastMCP server's base URL (can be localhost for development, e.g., `http://localhost:8000`) + +### Step 1: Configure PropelAuth + + + + Navigate to the **MCP** section in your PropelAuth dashboard, click **Enable MCP**, and choose which environments to enable it for (Test, Staging, Prod). + + + + Under **MCP > Allowed MCP Clients**, add redirect URIs for each MCP client you want to allow. PropelAuth provides templates for popular clients like Claude, Cursor, and ChatGPT. + + + + Under **MCP > Scopes**, define the permissions available to MCP clients (e.g., `read:user_data`). + + + + Under **MCP > Settings > How Do Users Create OAuth Clients?**, you can optionally enable: + - **Dynamic Client Registration** — clients self-register automatically via the DCR protocol + - **Manually via Hosted Pages** — PropelAuth creates a UI for your users to register OAuth clients + + You can enable neither, one, or both. If you enable neither, you'll manage OAuth client creation yourself. + + + + Go to **MCP > Request Validation** and click **Create Credentials**. Note the **Client ID** and **Client Secret** - you'll need these to validate tokens. + + + + Find your Auth URL in the **Backend Integration** section of the dashboard (e.g., `https://auth.yourdomain.com`). + + + +For more details, see the [PropelAuth MCP documentation](https://docs.propelauth.com/mcp-authentication/overview). + +### Step 2: Environment Setup + +Create a `.env` file with your PropelAuth configuration: + +```bash +PROPELAUTH_AUTH_URL=https://auth.yourdomain.com # From Backend Integration page +PROPELAUTH_INTROSPECTION_CLIENT_ID=your-client-id # From MCP > Request Validation +PROPELAUTH_INTROSPECTION_CLIENT_SECRET=your-client-secret # From MCP > Request Validation +SERVER_URL=http://localhost:8000 # Your server's base URL +``` + +### Step 3: FastMCP Configuration + +Create your FastMCP server file and use the PropelAuthProvider to handle all the OAuth integration automatically: + +```python server.py +import os +from fastmcp import FastMCP +from fastmcp.server.auth.providers.propelauth import PropelAuthProvider + +auth_provider = PropelAuthProvider( + auth_url=os.environ["PROPELAUTH_AUTH_URL"], + introspection_client_id=os.environ["PROPELAUTH_INTROSPECTION_CLIENT_ID"], + introspection_client_secret=os.environ["PROPELAUTH_INTROSPECTION_CLIENT_SECRET"], + base_url=os.environ["SERVER_URL"], + required_scopes=["read:user_data"], # Optional scope enforcement +) + +mcp = FastMCP(name="My PropelAuth Protected Server", auth=auth_provider) +``` + +## Testing + +With your `.env` loaded, start the server: + +```bash +fastmcp run server.py --transport http --port 8000 +``` + +Then use a FastMCP client to verify authentication works: + +```python +from fastmcp import Client +import asyncio + +async def main(): + async with Client("http://localhost:8000/mcp", auth="oauth") as client: + assert await client.ping() + +if __name__ == "__main__": + asyncio.run(main()) +``` + +## Accessing User Information + +You can use `get_access_token()` inside your tools to identify the authenticated user: + +```python server.py +import os +from fastmcp import FastMCP +from fastmcp.server.auth.providers.propelauth import PropelAuthProvider +from fastmcp.server.dependencies import get_access_token + +auth = PropelAuthProvider( + auth_url=os.environ["PROPELAUTH_AUTH_URL"], + introspection_client_id=os.environ["PROPELAUTH_INTROSPECTION_CLIENT_ID"], + introspection_client_secret=os.environ["PROPELAUTH_INTROSPECTION_CLIENT_SECRET"], + base_url=os.environ["SERVER_URL"], + required_scopes=["read:user_data"], +) + +mcp = FastMCP(name="My PropelAuth Protected Server", auth=auth) + +@mcp.tool +def whoami() -> dict: + """Return the authenticated user's ID.""" + token = get_access_token() + if token is None: + return {"error": "Not authenticated"} + user_id = token.claims.get("sub") + return {"user_id": user_id} +``` + +## Advanced Configuration + +The `PropelAuthProvider` supports optional overrides for token introspection behavior, including caching and request timeouts: + +```python server.py +import os +from fastmcp import FastMCP +from fastmcp.server.auth.providers.propelauth import PropelAuthProvider + +auth = PropelAuthProvider( + auth_url=os.environ["PROPELAUTH_AUTH_URL"], + introspection_client_id=os.environ["PROPELAUTH_INTROSPECTION_CLIENT_ID"], + introspection_client_secret=os.environ["PROPELAUTH_INTROSPECTION_CLIENT_SECRET"], + base_url=os.environ.get("BASE_URL", "https://your-server.com"), + required_scopes=["read:user_data"], + resource="https://your-server.com/mcp", # Restrict to tokens intended for this server (RFC 8707) + token_introspection_overrides={ + "cache_ttl_seconds": 300, # Cache introspection results for 5 minutes + "max_cache_size": 1000, # Maximum cached tokens + "timeout_seconds": 15, # HTTP request timeout + }, +) + +mcp = FastMCP(name="My PropelAuth Protected Server", auth=auth) +``` diff --git a/docs/integrations/scalekit.mdx b/docs/integrations/scalekit.mdx new file mode 100644 index 000000000..191b81ca2 --- /dev/null +++ b/docs/integrations/scalekit.mdx @@ -0,0 +1,155 @@ +--- +title: Scalekit 🤝 FastMCP +sidebarTitle: Scalekit +description: Secure your FastMCP server with Scalekit +icon: shield-check +--- + +import { VersionBadge } from "/snippets/version-badge.mdx" + + + +Install auth stack to your FastMCP server with [Scalekit](https://scalekit.com) using the [Remote OAuth](/servers/auth/remote-oauth) pattern: Scalekit handles user authentication, and the MCP server validates issued tokens. + +### Prerequisites + +Before you begin + +1. Get a [Scalekit account](https://app.scalekit.com/) and grab your **Environment URL** from _Dashboard > Settings_ . +2. Have your FastMCP server's base URL ready (can be localhost for development, e.g., `http://localhost:8000/`) + +### Step 1: Configure MCP server in Scalekit environment + + + + +In your Scalekit dashboard: + 1. Open the **MCP Servers** section, then select **Create new server** + 2. Enter server details: a name, a resource identifier, and the desired MCP client authentication settings + 3. Save, then copy the **Resource ID** (for example, res_92015146095) + +In your FastMCP project's `.env`: + +```sh +SCALEKIT_ENVIRONMENT_URL= +SCALEKIT_RESOURCE_ID= # res_926EXAMPLE5878 +BASE_URL=http://localhost:8000/ +# Optional: additional scopes tokens must have +# SCALEKIT_REQUIRED_SCOPES=read,write +``` + + + + +### Step 2: Add auth to FastMCP server + +Create your FastMCP server file and use the ScalekitProvider to handle all the OAuth integration automatically: + +> **Warning:** The legacy `mcp_url` and `client_id` parameters are deprecated and will be removed in a future release. Use `base_url` instead of `mcp_url` and remove `client_id` from your configuration. + +```python server.py +from fastmcp import FastMCP +from fastmcp.server.auth.providers.scalekit import ScalekitProvider + +# Discovers Scalekit endpoints and set up JWT token validation +auth_provider = ScalekitProvider( + environment_url=SCALEKIT_ENVIRONMENT_URL, # Scalekit environment URL + resource_id=SCALEKIT_RESOURCE_ID, # Resource server ID + base_url=SERVER_URL, # Public MCP endpoint + required_scopes=["read"], # Optional scope enforcement +) + +# Create FastMCP server with auth +mcp = FastMCP(name="My Scalekit Protected Server", auth=auth_provider) + +@mcp.tool +def auth_status() -> dict: + """Show Scalekit authentication status.""" + # Extract user claims from the JWT + return { + "message": "This tool requires authentication via Scalekit", + "authenticated": True, + "provider": "Scalekit" + } + +``` + + +Set `required_scopes` when you need tokens to carry specific permissions. Leave it unset to allow any token issued for the resource. + + +## Testing + +### Start the MCP server + +```sh +uv run python server.py +``` + +Use any MCP client (for example, mcp-inspector, Claude, VS Code, or Windsurf) to connect to the running serve. Verify that authentication succeeds and requests are authorized as expected. + +## Production Configuration + +For production deployments, load configuration from environment variables: + +```python server.py +import os +from fastmcp import FastMCP +from fastmcp.server.auth.providers.scalekit import ScalekitProvider + +# Load configuration from environment variables +auth = ScalekitProvider( + environment_url=os.environ.get("SCALEKIT_ENVIRONMENT_URL"), + resource_id=os.environ.get("SCALEKIT_RESOURCE_ID"), + base_url=os.environ.get("BASE_URL", "https://your-server.com") +) + +mcp = FastMCP(name="My Scalekit Protected Server", auth=auth) + +@mcp.tool +def protected_action() -> str: + """A tool that requires authentication.""" + return "Access granted via Scalekit!" +``` + +## Capabilities + +Scalekit supports OAuth 2.1 with Dynamic Client Registration for MCP clients and enterprise SSO, and provides built‑in JWT validation and security controls. + +**OAuth 2.1/DCR**: clients self‑register, use PKCE, and work with the Remote OAuth pattern without pre‑provisioned credentials. + +**Validation and SSO**: tokens are verified (keys, RS256, issuer, audience, expiry), and SAML, OIDC, OAuth 2.0, ADFS, Azure AD, and Google Workspace are supported; use HTTPS in production and review auth logs as needed. + +## Debugging + +Enable detailed logging to troubleshoot authentication issues: + +```python +import logging +logging.basicConfig(level=logging.DEBUG) +``` + +### Token inspection + +You can inspect JWT tokens in your tools to understand the user context: + +```python +from fastmcp.server.context import request_ctx +import jwt + +@mcp.tool +def inspect_token() -> dict: + """Inspect the current JWT token claims.""" + context = request_ctx.get() + + # Extract token from Authorization header + if hasattr(context, 'request') and hasattr(context.request, 'headers'): + auth_header = context.request.headers.get('authorization', '') + if auth_header.startswith('Bearer '): + token = auth_header[7:] + # Decode without verification (already verified by provider) + claims = jwt.decode(token, options={"verify_signature": False}) + return claims + + return {"error": "No token found"} +``` diff --git a/docs/integrations/supabase.mdx b/docs/integrations/supabase.mdx new file mode 100644 index 000000000..9ffda444d --- /dev/null +++ b/docs/integrations/supabase.mdx @@ -0,0 +1,123 @@ +--- +title: Supabase 🤝 FastMCP +sidebarTitle: Supabase +description: Secure your FastMCP server with Supabase Auth +icon: shield-check +--- + +import { VersionBadge } from "/snippets/version-badge.mdx" + + + +This guide shows you how to secure your FastMCP server using **Supabase Auth**. This integration uses the [**Remote OAuth**](/servers/auth/remote-oauth) pattern, where Supabase handles user authentication and your FastMCP server validates the tokens. + + +Supabase Auth does not currently support [RFC 8707](https://www.rfc-editor.org/rfc/rfc8707.html) resource indicators, so FastMCP cannot validate that tokens were issued for the specific resource server. + + +## Consent UI Requirement + +Supabase's OAuth Server delegates the user consent screen to your application. When an MCP client initiates authorization, Supabase authenticates the user and then redirects to your application at a configured callback URL (e.g., `https://your-app.com/oauth/callback?authorization_id=...`). Your application must host a page that calls Supabase's `approveAuthorization()` or `denyAuthorization()` APIs to complete the flow. + +`SupabaseProvider` handles the resource server side (token verification and metadata), but you are responsible for building and hosting the consent UI separately. See [Supabase's OAuth Server documentation](https://supabase.com/docs/guides/auth/oauth-server/getting-started) for details on implementing the authorization page. + +## Configuration + +### Prerequisites + +Before you begin, you will need: +1. A **[Supabase Account](https://supabase.com/)** with a project or a self-hosted **Supabase Auth** instance +2. **OAuth Server enabled** in your Supabase Dashboard (Authentication → OAuth Server) +3. **Dynamic Client Registration enabled** in the same settings +4. A **consent UI** hosted at your configured authorization path (see above) +5. Your FastMCP server's URL (can be localhost for development, e.g., `http://localhost:8000`) + +### Step 1: Enable Supabase OAuth Server + +In your Supabase Dashboard: +1. Go to **Authentication → OAuth Server** +2. Enable the **OAuth Server** +3. Set your **Site URL** to where your consent UI is hosted +4. Set the **Authorization Path** (e.g., `/oauth/callback`) +5. Enable **Allow Dynamic OAuth Apps** for MCP client registration + +### Step 2: Get Supabase Project URL + +In your Supabase Dashboard: +1. Go to **Project Settings** +2. Copy your **Project URL** (e.g., `https://abc123.supabase.co`) + +### Step 3: FastMCP Configuration + +Create your FastMCP server using the `SupabaseProvider`: + +```python server.py +from fastmcp import FastMCP +from fastmcp.server.auth.providers.supabase import SupabaseProvider + +auth = SupabaseProvider( + project_url="https://abc123.supabase.co", + base_url="http://localhost:8000", +) + +mcp = FastMCP("Supabase Protected Server", auth=auth) + +@mcp.tool +def protected_tool(message: str) -> str: + """This tool requires authentication.""" + return f"Authenticated user says: {message}" + +if __name__ == "__main__": + mcp.run(transport="http", port=8000) +``` + +## Testing + +### Running the Server + +Start your FastMCP server with HTTP transport to enable OAuth flows: + +```bash +fastmcp run server.py --transport http --port 8000 +``` + +### Testing with a Client + +Create a test client that authenticates with your Supabase-protected server: + +```python client.py +from fastmcp import Client +import asyncio + +async def main(): + async with Client("http://localhost:8000/mcp", auth="oauth") as client: + print("Authenticated with Supabase!") + + result = await client.call_tool("protected_tool", {"message": "Hello!"}) + print(result) + +if __name__ == "__main__": + asyncio.run(main()) +``` + +When you run the client for the first time: +1. Your browser will open to Supabase's authorization endpoint +2. After authenticating, Supabase redirects to your consent UI +3. After you approve, the client receives the token and can make authenticated requests + +## Production Configuration + +For production deployments, load configuration from environment variables: + +```python server.py +import os +from fastmcp import FastMCP +from fastmcp.server.auth.providers.supabase import SupabaseProvider + +auth = SupabaseProvider( + project_url=os.environ["SUPABASE_PROJECT_URL"], + base_url=os.environ.get("BASE_URL", "https://your-server.com"), +) + +mcp = FastMCP(name="Supabase Secured App", auth=auth) +``` diff --git a/docs/integrations/workos.mdx b/docs/integrations/workos.mdx new file mode 100644 index 000000000..4f13a5512 --- /dev/null +++ b/docs/integrations/workos.mdx @@ -0,0 +1,200 @@ +--- +title: WorkOS 🤝 FastMCP +sidebarTitle: WorkOS +description: Authenticate FastMCP servers with WorkOS Connect +icon: shield-check +--- + +import { VersionBadge } from "/snippets/version-badge.mdx" + + + +Secure your FastMCP server with WorkOS Connect authentication. This integration uses the OAuth Proxy pattern to handle authentication through WorkOS Connect while maintaining compatibility with MCP clients. + + +This guide covers WorkOS Connect applications. For Dynamic Client Registration (DCR) with AuthKit, see the [AuthKit integration](/integrations/authkit) instead. + + +## Configuration + +### Prerequisites + +Before you begin, you will need: +1. A **[WorkOS Account](https://workos.com/)** with access to create OAuth Apps +2. Your FastMCP server's URL (can be localhost for development, e.g., `http://localhost:8000`) + +### Step 1: Create a WorkOS OAuth App + +Create an OAuth App in your WorkOS dashboard to get the credentials needed for authentication: + + + +In your WorkOS dashboard: +1. Navigate to **Applications** +2. Click **Create Application** +3. Select **OAuth Application** +4. Name your application + + + +In your OAuth application settings: +1. Copy your **Client ID** (starts with `client_`) +2. Click **Generate Client Secret** and save it securely +3. Copy your **AuthKit Domain** (e.g., `https://your-app.authkit.app`) + + + +In the **Redirect URIs** section: +- Add: `http://localhost:8000/auth/callback` (for development) +- For production, add your server's public URL + `/auth/callback` + + +The callback URL must match exactly. The default path is `/auth/callback`, but you can customize it using the `redirect_path` parameter. + + + + +### Step 2: FastMCP Configuration + +Create your FastMCP server using the `WorkOSProvider`: + +```python server.py +from fastmcp import FastMCP +from fastmcp.server.auth.providers.workos import WorkOSProvider + +# Configure WorkOS OAuth +auth = WorkOSProvider( + client_id="client_YOUR_CLIENT_ID", + client_secret="YOUR_CLIENT_SECRET", + authkit_domain="https://your-app.authkit.app", + base_url="http://localhost:8000", + required_scopes=["openid", "profile", "email"] +) + +mcp = FastMCP("WorkOS Protected Server", auth=auth) + +@mcp.tool +def protected_tool(message: str) -> str: + """This tool requires authentication.""" + return f"Authenticated user says: {message}" + +if __name__ == "__main__": + mcp.run(transport="http", port=8000) +``` + +## Testing + +### Running the Server + +Start your FastMCP server with HTTP transport to enable OAuth flows: + +```bash +fastmcp run server.py --transport http --port 8000 +``` + +Your server is now running and protected by WorkOS OAuth authentication. + +### Testing with a Client + +Create a test client that authenticates with your WorkOS-protected server: + +```python client.py +from fastmcp import Client +import asyncio + +async def main(): + # The client will automatically handle WorkOS OAuth + async with Client("http://localhost:8000/mcp", auth="oauth") as client: + # First-time connection will open WorkOS login in your browser + print("✓ Authenticated with WorkOS!") + + # Test the protected tool + result = await client.call_tool("protected_tool", {"message": "Hello!"}) + print(result) + +if __name__ == "__main__": + asyncio.run(main()) +``` + +When you run the client for the first time: +1. Your browser will open to WorkOS's authorization page +2. After you authorize the app, you'll be redirected back +3. The client receives the token and can make authenticated requests + + +The client caches tokens locally, so you won't need to re-authenticate for subsequent runs unless the token expires or you explicitly clear the cache. + + +## Production Configuration + + + +For production deployments with persistent token management across server restarts, configure `jwt_signing_key`, and `client_storage`: + +```python server.py +import os +from fastmcp import FastMCP +from fastmcp.server.auth.providers.workos import WorkOSProvider +from key_value.aio.stores.redis import RedisStore +from key_value.aio.wrappers.encryption import FernetEncryptionWrapper +from cryptography.fernet import Fernet + +# Production setup with encrypted persistent token storage +auth = WorkOSProvider( + client_id="client_YOUR_CLIENT_ID", + client_secret="YOUR_CLIENT_SECRET", + authkit_domain="https://your-app.authkit.app", + base_url="https://your-production-domain.com", + required_scopes=["openid", "profile", "email"], + + # Production token management + jwt_signing_key=os.environ["JWT_SIGNING_KEY"], + client_storage=FernetEncryptionWrapper( + key_value=RedisStore( + host=os.environ["REDIS_HOST"], + port=int(os.environ["REDIS_PORT"]) + ), + fernet=Fernet(os.environ["STORAGE_ENCRYPTION_KEY"]) + ) +) + +mcp = FastMCP(name="Production WorkOS App", auth=auth) +``` + + +Parameters (`jwt_signing_key` and `client_storage`) work together to ensure tokens and client registrations survive server restarts. **Wrap your storage in `FernetEncryptionWrapper` to encrypt sensitive OAuth tokens at rest** - without it, tokens are stored in plaintext. Store secrets in environment variables and use a persistent storage backend like Redis for distributed deployments. + +For complete details on these parameters, see the [OAuth Proxy documentation](/servers/auth/oauth-proxy#configuration-parameters). + + +## Configuration Options + + + +WorkOS OAuth application client ID + + + +WorkOS OAuth application client secret + + + +Your WorkOS AuthKit domain URL (e.g., `https://your-app.authkit.app`) + + + +Your FastMCP server's public URL + + + +OAuth scopes to request + + + +OAuth callback path + + + +API request timeout + + \ No newline at end of file diff --git a/docs/more/settings.mdx b/docs/more/settings.mdx new file mode 100644 index 000000000..d2b4d0443 --- /dev/null +++ b/docs/more/settings.mdx @@ -0,0 +1,93 @@ +--- +title: Settings +description: Configure FastMCP behavior through environment variables or a .env file. +icon: gear +--- + +FastMCP uses [pydantic-settings](https://docs.pydantic.dev/latest/concepts/pydantic_settings/) for configuration. Every setting is available as an environment variable with a `FASTMCP_` prefix. Settings are loaded from environment variables and from a `.env` file (see the [Tasks (Docket)](#tasks-docket) section for a caveat about nested settings in `.env` files). + +```bash +# Set via environment +export FASTMCP_LOG_LEVEL=DEBUG +export FASTMCP_PORT=3000 + +# Or use a .env file (loaded automatically) +echo "FASTMCP_LOG_LEVEL=DEBUG" >> .env +``` + +You can change which `.env` file is loaded by setting the `FASTMCP_ENV_FILE` environment variable (defaults to `.env`). Because this controls which file is loaded, it must be set as an environment variable — it cannot be set inside a `.env` file itself. + +## Logging + +| Environment Variable | Type | Default | Description | +|---|---|---|---| +| `FASTMCP_LOG_LEVEL` | `Literal["DEBUG", "INFO", "WARNING", "ERROR", "CRITICAL"]` | `INFO` | Log level. Case-insensitive. | +| `FASTMCP_LOG_ENABLED` | `bool` | `true` | Enable or disable FastMCP logging entirely. | +| `FASTMCP_ENABLE_RICH_LOGGING` | `bool` | `true` | Use rich formatting for log output. Set to `false` for plain Python logging. | +| `FASTMCP_ENABLE_RICH_TRACEBACKS` | `bool` | `true` | Use rich tracebacks for errors. | +| `FASTMCP_DEPRECATION_WARNINGS` | `bool` | `true` | Show deprecation warnings. | + +## Transport & HTTP + +These control how the server listens when running with an HTTP transport. + +| Environment Variable | Type | Default | Description | +|---|---|---|---| +| `FASTMCP_TRANSPORT` | `Literal["stdio", "http", "sse", "streamable-http"]` | `stdio` | Default transport. | +| `FASTMCP_HOST` | `str` | `127.0.0.1` | Host to bind to. | +| `FASTMCP_PORT` | `int` | `8000` | Port to bind to. | +| `FASTMCP_SSE_PATH` | `str` | `/sse` | Path for SSE endpoint. | +| `FASTMCP_MESSAGE_PATH` | `str` | `/messages/` | Path for SSE message endpoint. | +| `FASTMCP_STREAMABLE_HTTP_PATH` | `str` | `/mcp` | Path for Streamable HTTP endpoint. | +| `FASTMCP_STATELESS_HTTP` | `bool` | `false` | Enable stateless HTTP mode (new transport per request). Useful for multi-worker deployments. | +| `FASTMCP_JSON_RESPONSE` | `bool` | `false` | Use JSON responses instead of SSE for Streamable HTTP. | +| `FASTMCP_DEBUG` | `bool` | `false` | Enable debug mode. | + +## Error Handling + +| Environment Variable | Type | Default | Description | +|---|---|---|---| +| `FASTMCP_MASK_ERROR_DETAILS` | `bool` | `false` | Mask error details before sending to clients. When enabled, only messages from explicitly raised `ToolError`, `ResourceError`, or `PromptError` are included in responses. | +| `FASTMCP_STRICT_INPUT_VALIDATION` | `bool` | `false` | Strictly validate tool inputs against the JSON schema. When disabled, compatible inputs are coerced (e.g., the string `"10"` becomes the integer `10`). | +| `FASTMCP_MOUNTED_COMPONENTS_RAISE_ON_LOAD_ERROR` | `bool` | `false` | Raise errors when loading mounted components instead of logging warnings. | + +## Client + +| Environment Variable | Type | Default | Description | +|---|---|---|---| +| `FASTMCP_CLIENT_INIT_TIMEOUT` | `float \| None` | None | Timeout in seconds for the client initialization handshake. Set to `0` or leave unset to disable. | +| `FASTMCP_CLIENT_RAISE_FIRST_EXCEPTIONGROUP_ERROR` | `bool` | `true` | When an `ExceptionGroup` is raised, re-raise the first error directly instead of the group. Simplifies debugging but may mask secondary errors. | + +## CLI & Display + +| Environment Variable | Type | Default | Description | +|---|---|---|---| +| `FASTMCP_SHOW_SERVER_BANNER` | `bool` | `true` | Show the server banner on startup. Also controllable via `--no-banner` or `server.run(show_banner=False)`. | +| `FASTMCP_CHECK_FOR_UPDATES` | `Literal["stable", "prerelease", "off"]` | `stable` | Update checking on CLI startup. `stable` checks stable releases only, `prerelease` includes pre-releases, `off` disables checking. | + +## Tasks (Docket) + +These configure the [Docket](https://github.com/prefecthq/docket) task queue used by [server tasks](/servers/tasks). All use the `FASTMCP_DOCKET_` prefix. + + +When setting Docket values in a `.env` file, use a **double** underscore: `FASTMCP_DOCKET__URL` (not `FASTMCP_DOCKET_URL`). This is because `.env` values are resolved through the parent `Settings` class, which uses `__` as its nested delimiter. As regular environment variables (e.g., `export`), the single-underscore form `FASTMCP_DOCKET_URL` works fine. + + +| Environment Variable | Type | Default | Description | +|---|---|---|---| +| `FASTMCP_DOCKET_NAME` | `str` | `fastmcp` | Queue name. Servers and workers sharing the same name and backend URL share a task queue. | +| `FASTMCP_DOCKET_URL` | `str` | `memory://` | Backend URL. Use `memory://` for single-process or `redis://host:port/db` for distributed workers. | +| `FASTMCP_DOCKET_WORKER_NAME` | `str \| None` | None | Worker name. Auto-generated if unset. | +| `FASTMCP_DOCKET_CONCURRENCY` | `int` | `10` | Maximum concurrent tasks per worker. | +| `FASTMCP_DOCKET_REDELIVERY_TIMEOUT` | `timedelta` | `300s` | If a worker doesn't complete a task within this time, it's redelivered to another worker. | +| `FASTMCP_DOCKET_RECONNECTION_DELAY` | `timedelta` | `5s` | Delay between reconnection attempts when the worker loses its backend connection. | + +## Advanced + +| Environment Variable | Type | Default | Description | +|---|---|---|---| +| `FASTMCP_HOME` | `Path` | Platform default | Data directory for FastMCP. Defaults to the platform-specific user data directory. | +| `FASTMCP_ENV_FILE` | `str` | `.env` | Path to the `.env` file to load settings from. Must be set as an environment variable (see above). | +| `FASTMCP_SERVER_DEPENDENCIES` | `list[str]` | `[]` | Additional dependencies to install in the server environment. | +| `FASTMCP_DECORATOR_MODE` | `Literal["function", "object"]` | `function` | Controls what `@tool`, `@resource`, and `@prompt` decorators return. `function` returns the original function (default); `object` returns component objects (deprecated, will be removed). | +| `FASTMCP_TEST_MODE` | `bool` | `false` | Enable test mode. | diff --git a/docs/patterns/cli.mdx b/docs/patterns/cli.mdx new file mode 100644 index 000000000..fe32bdd75 --- /dev/null +++ b/docs/patterns/cli.mdx @@ -0,0 +1,851 @@ +--- +title: FastMCP CLI +sidebarTitle: CLI +description: Learn how to use the FastMCP command-line interface +icon: terminal +--- + +import { VersionBadge } from "/snippets/version-badge.mdx" + + +FastMCP provides a command-line interface (CLI) that makes it easy to run, develop, and install your MCP servers. The CLI is automatically installed when you install FastMCP. + +```bash +fastmcp --help +``` + +## Commands Overview + +| Command | Purpose | Dependency Management | +| ------- | ------- | --------------------- | +| `list` | List tools on any MCP server | **Supports:** URLs, local files, MCPConfig JSON, stdio commands. **Deps:** N/A (connects to existing servers) | +| `call` | Call a tool on any MCP server | **Supports:** URLs, local files, MCPConfig JSON, stdio commands. **Deps:** N/A (connects to existing servers) | +| `run` | Run a FastMCP server directly | **Supports:** Local files, factory functions, URLs, fastmcp.json configs, MCP configs. **Deps:** Uses your local environment directly. With `--python`, `--with`, `--project`, or `--with-requirements`: Runs via `uv run` subprocess. With fastmcp.json: Automatically manages dependencies based on configuration | +| `dev` | Run a server with the MCP Inspector for testing | **Supports:** Local files and fastmcp.json configs. **Deps:** Always runs via `uv run` subprocess (never uses your local environment); dependencies must be specified or available in a uv-managed project. With fastmcp.json: Uses configured dependencies | +| `install` | Install a server in MCP client applications | **Supports:** Local files and fastmcp.json configs. **Deps:** Creates an isolated environment; dependencies must be explicitly specified with `--with` and/or `--with-editable`. With fastmcp.json: Uses configured dependencies | +| `inspect` | Generate a JSON report about a FastMCP server | **Supports:** Local files and fastmcp.json configs. **Deps:** Uses your current environment; you are responsible for ensuring all dependencies are available | +| `project prepare` | Create a persistent uv project from fastmcp.json environment config | **Supports:** fastmcp.json configs only. **Deps:** Creates a uv project directory with all dependencies pre-installed for reuse with `--project` flag | +| `auth cimd` | Create and validate CIMD documents for OAuth authentication | N/A | +| `version` | Display version information | N/A | + +## `fastmcp list` + +List tools available on any MCP server. This works with remote URLs, local Python files, MCPConfig JSON files, and arbitrary stdio commands. Together with `fastmcp call`, these commands are especially useful for giving LLMs that don't have built-in MCP support access to MCP tools via shell commands. + +```bash +fastmcp list http://localhost:8000/mcp +fastmcp list server.py +fastmcp list mcp.json +fastmcp list --command 'npx -y @modelcontextprotocol/server-github' +``` + +By default, the output shows each tool's signature and description. Use `--input-schema` or `--output-schema` to include full JSON schemas, or `--json` for machine-readable output. + +### Options + +| Option | Flag | Description | +| ------ | ---- | ----------- | +| Command | `--command` | Connect to a stdio server command (e.g. `'npx -y @mcp/server'`) | +| Transport | `--transport`, `-t` | Force transport type for URL targets (`http` or `sse`) | +| Resources | `--resources` | Also list resources | +| Prompts | `--prompts` | Also list prompts | +| Input Schema | `--input-schema` | Show full input schemas | +| Output Schema | `--output-schema` | Show full output schemas | +| JSON | `--json` | Output as JSON | +| Timeout | `--timeout` | Connection timeout in seconds | +| Auth | `--auth` | Auth method: `oauth` (default for HTTP), a bearer token, or `none` to disable | + +### Server Targets + +The `` argument accepts: + +1. **URLs** — `http://` or `https://` endpoints. Uses Streamable HTTP by default; pass `--transport sse` for SSE servers. +2. **Python files** — `.py` files are run via `fastmcp run` automatically. +3. **MCPConfig JSON** — `.json` files with an `mcpServers` key are treated as multi-server configs. +4. **Stdio commands** — Use `--command` to connect to any MCP server via stdio (e.g. `npx`, `uvx`). + +### Examples + +```bash +# List tools on a remote server +fastmcp list http://localhost:8000/mcp + +# List tools from a local Python file +fastmcp list server.py + +# Include full input schemas +fastmcp list server.py --input-schema + +# Machine-readable JSON +fastmcp list server.py --json + +# SSE server +fastmcp list http://localhost:8000/mcp --transport sse + +# Stdio command +fastmcp list --command 'npx -y @modelcontextprotocol/server-github' + +# Include resources and prompts +fastmcp list server.py --resources --prompts +``` + +## `fastmcp call` + +Call a tool on any MCP server. Arguments can be passed as `key=value` pairs, a single JSON object, or via `--input-json`. + +```bash +fastmcp call server.py greet name=World +fastmcp call http://localhost:8000/mcp search query=hello limit=5 +fastmcp call server.py create_item '{"name": "x", "tags": ["a", "b"]}' +``` + +Tool arguments are automatically coerced to the correct type based on the tool's input schema — string values like `limit=5` become integers when the schema expects one. + +### Options + +| Option | Flag | Description | +| ------ | ---- | ----------- | +| Command | `--command` | Connect to a stdio server command (e.g. `'npx -y @mcp/server'`) | +| Transport | `--transport`, `-t` | Force transport type for URL targets (`http` or `sse`) | +| Input JSON | `--input-json` | JSON string of tool arguments (merged with key=value args) | +| JSON | `--json` | Output raw JSON result | +| Timeout | `--timeout` | Connection timeout in seconds | +| Auth | `--auth` | Auth method: `oauth` (default for HTTP), a bearer token, or `none` to disable | + +### Argument Passing + +There are three ways to pass arguments: + +**Key=value pairs** are the simplest for flat arguments. Values are coerced using the tool's JSON schema (strings become ints, bools, etc.): + +```bash +fastmcp call server.py search query=hello limit=5 verbose=true +``` + +**A single JSON object** works when you have structured or nested arguments: + +```bash +fastmcp call server.py create_item '{"name": "Widget", "tags": ["new", "sale"]}' +``` + +**`--input-json`** provides a base dict that key=value pairs can override: + +```bash +fastmcp call server.py search --input-json '{"query": "hello", "limit": 5}' limit=10 +``` + +### Examples + +```bash +# Call a tool with simple args +fastmcp call server.py greet name=World + +# Call with JSON object +fastmcp call server.py create '{"name": "x", "tags": ["a"]}' + +# Get JSON output for scripting +fastmcp call server.py add a=3 b=4 --json + +# Call a tool on a remote server +fastmcp call http://localhost:8000/mcp search query=hello + +# Call via stdio command +fastmcp call --command 'npx -y @mcp/server' tool_name arg=value + +# Disable OAuth for HTTP targets +fastmcp call http://localhost:8000/mcp search query=hello --auth none +``` + + +If you call a tool that doesn't exist, FastMCP will suggest similar tool names. Use `fastmcp list` to see all available tools on a server. + + +## `fastmcp run` + +Run a FastMCP server directly or proxy a remote server. + +```bash +fastmcp run server.py +``` + + +By default, this command runs the server directly in your current Python environment. You are responsible for ensuring all dependencies are available. When using `--python`, `--with`, `--project`, or `--with-requirements` options, it runs the server via `uv run` subprocess instead. + + +### Options + +| Option | Flag | Description | +| ------ | ---- | ----------- | +| Transport | `--transport`, `-t` | Transport protocol to use (`stdio`, `http`, or `sse`) | +| Host | `--host` | Host to bind to when using http transport (default: 127.0.0.1) | +| Port | `--port`, `-p` | Port to bind to when using http transport (default: 8000) | +| Path | `--path` | Path to bind to when using http transport (default: `/mcp/` or `/sse/` for SSE) | +| Log Level | `--log-level`, `-l` | Log level (DEBUG, INFO, WARNING, ERROR, CRITICAL) | +| No Banner | `--no-banner` | Disable the startup banner display | +| Auto-Reload | `--reload` / `--no-reload` | Enable auto-reload on file changes (development mode) | +| Reload Directories | `--reload-dir` | Directories to watch for changes (can be used multiple times) | +| No Environment | `--skip-env` | Skip environment setup with uv (use when already in a uv environment) | +| Python Version | `--python` | Python version to use (e.g., 3.10, 3.11) | +| Additional Packages | `--with` | Additional packages to install (can be used multiple times) | +| Project Directory | `--project` | Run the command within the given project directory | +| Requirements File | `--with-requirements` | Requirements file to install dependencies from | + + +### Entrypoints + + +The `fastmcp run` command supports the following entrypoints: + +1. **[Inferred server instance](#inferred-server-instance)**: `server.py` - imports the module and looks for a FastMCP server instance named `mcp`, `server`, or `app`. Errors if no such object is found. +2. **[Explicit server entrypoint](#explicit-server-entrypoint)**: `server.py:custom_name` - imports and uses the specified server entrypoint +3. **[Factory function](#factory-function)**: `server.py:create_server` - calls the specified function (sync or async) to create a server instance +4. **[Remote server proxy](#remote-server-proxy)**: `https://example.com/mcp-server` - connects to a remote server and creates a **local proxy server** +5. **[FastMCP configuration file](#fastmcp-configuration)**: `fastmcp.json` - runs servers using FastMCP's declarative configuration format (auto-detects files in current directory) +6. **MCP configuration file**: `mcp.json` - runs servers defined in a standard MCP configuration file + + +Note: When using `fastmcp run` with a local file, it **completely ignores** the `if __name__ == "__main__"` block. This means: +- Any setup code in `__main__` will NOT run +- Server configuration in `__main__` is bypassed +- `fastmcp run` finds your server entrypoint/factory and runs it with its own transport settings + +If you need setup code to run, use the **factory pattern** instead. + + +#### Inferred Server Instance + +If you provide a path to a file, `fastmcp run` will load the file and look for a FastMCP server instance stored as a variable named `mcp`, `server`, or `app`. If no such object is found, it will raise an error. + +For example, if you have a file called `server.py` with the following content: + +```python server.py +from fastmcp import FastMCP + +mcp = FastMCP("MyServer") +``` + +You can run it with: + +```bash +fastmcp run server.py +``` + +#### Explicit Server Entrypoint + +If your server is stored as a variable with a custom name, or you want to be explicit about which server to run, you can use the following syntax to load a specific server entrypoint: + +```bash +fastmcp run server.py:custom_name +``` + +For example, if you have a file called `server.py` with the following content: + +```python +from fastmcp import FastMCP + +my_server = FastMCP("CustomServer") + +@my_server.tool +def hello() -> str: + return "Hello from custom server!" +``` + +You can run it with: + +```bash +fastmcp run server.py:my_server +``` + +#### Factory Function + + +Since `fastmcp run` ignores the `if __name__ == "__main__"` block, you can use a factory function to run setup code before your server starts. Factory functions are called without any arguments and must return a FastMCP server instance. Both sync and async factory functions are supported. + +The syntax for using a factory function is the same as for an explicit server entrypoint: `fastmcp run server.py:factory_fn`. FastMCP will automatically detect that you have identified a function rather than a server Instance + +For example, if you have a file called `server.py` with the following content: + +```python +from fastmcp import FastMCP + +async def create_server() -> FastMCP: + mcp = FastMCP("MyServer") + + @mcp.tool + def add(x: int, y: int) -> int: + return x + y + + # Setup that runs with fastmcp run + tool = await mcp.get_tool("add") + tool.disable() + + return mcp +``` + +You can run it with: + +```bash +fastmcp run server.py:create_server +``` + +#### Remote Server Proxy + +FastMCP run can also start a local proxy server that connects to a remote server. This is useful when you want to run a remote server locally for testing or development purposes, or to use with a client that doesn't support direct connections to remote servers. + +To start a local proxy, you can use the following syntax: + +```bash +fastmcp run https://example.com/mcp +``` + +#### FastMCP Configuration + + +FastMCP supports declarative configuration through `fastmcp.json` files. When you run `fastmcp run` without arguments, it automatically looks for a `fastmcp.json` file in the current directory: + +```bash +# Auto-detect fastmcp.json in current directory +fastmcp run + +# Or explicitly specify a configuration file +fastmcp run my-config.fastmcp.json +``` + +The configuration file handles dependencies, environment variables, and transport settings. Command-line arguments override configuration file values: + +```bash +# Override port from config file +fastmcp run fastmcp.json --port 8080 + +# Skip environment setup when already in a uv environment +fastmcp run fastmcp.json --skip-env +``` + + +The `--skip-env` flag is useful when: +- You're already in an activated virtual environment +- You're inside a Docker container with pre-installed dependencies +- You're in a uv-managed environment (prevents infinite recursion) +- You want to test the server without environment setup + + +See [Server Configuration](/deployment/server-configuration) for detailed documentation on fastmcp.json. + +#### MCP Configuration + +FastMCP can also run servers defined in a standard MCP configuration file. This is useful when you want to run multiple servers from a single file, or when you want to use a client that doesn't support direct connections to remote servers. + +To run a MCP configuration file, you can use the following syntax: + +```bash +fastmcp run mcp.json +``` + +This will run all the servers defined in the file. + +## `fastmcp dev` + +The `dev` command group contains development tools for MCP servers. + +### `fastmcp dev inspector` + +Run a MCP server with the [MCP Inspector](https://github.com/modelcontextprotocol/inspector) for testing. Auto-reload is enabled by default, so your server automatically restarts when you save changes to source files. + +```bash +fastmcp dev inspector server.py +``` + + +This command always runs your server via `uv run` subprocess (never your local environment) to work with the MCP Inspector. Dependencies can be: +- Specified using `--with` and/or `--with-editable` options +- Defined in a `fastmcp.json` configuration file +- Available in a uv-managed project + +When using `fastmcp.json`, the dev command automatically uses the configured dependencies. + + + +The `dev inspector` command is a shortcut for testing a server over STDIO only. When the Inspector launches, you may need to: +1. Select "STDIO" from the transport dropdown +2. Connect manually + +This command does not support HTTP testing. To test a server over Streamable HTTP or SSE: +1. Start your server manually with the appropriate transport using either the command line: + ```bash + fastmcp run server.py --transport http + ``` + or by setting the transport in your code: + ```bash + python server.py # Assuming your __main__ block sets Streamable HTTP transport + ``` +2. Open the MCP Inspector separately and connect to your running server + + +#### Options + +| Option | Flag | Description | +| ------ | ---- | ----------- | +| Editable Package | `--with-editable`, `-e` | Directory containing pyproject.toml to install in editable mode | +| Additional Packages | `--with` | Additional packages to install (can be used multiple times) | +| Inspector Version | `--inspector-version` | Version of the MCP Inspector to use | +| UI Port | `--ui-port` | Port for the MCP Inspector UI | +| Server Port | `--server-port` | Port for the MCP Inspector Proxy server | +| Auto-Reload | `--reload` / `--no-reload` | Enable/disable auto-reload on file changes (enabled by default) | +| Reload Directories | `--reload-dir` | Directories to watch for changes (can be used multiple times) | +| Python Version | `--python` | Python version to use (e.g., 3.10, 3.11) | +| Project Directory | `--project` | Run the command within the given project directory | +| Requirements File | `--with-requirements` | Requirements file to install dependencies from | + +#### Entrypoints + +The `dev inspector` command supports local FastMCP server files and configuration: + +1. **Inferred server instance**: `server.py` - imports the module and looks for a FastMCP server instance named `mcp`, `server`, or `app`. Errors if no such object is found. +2. **Explicit server entrypoint**: `server.py:custom_name` - imports and uses the specified server entrypoint +3. **Factory function**: `server.py:create_server` - calls the specified function (sync or async) to create a server instance +4. **FastMCP configuration**: `fastmcp.json` - uses FastMCP's declarative configuration (auto-detects in current directory) + + +The `dev inspector` command **only supports local files and fastmcp.json** - no URLs, remote servers, or standard MCP configuration files. + + +**Examples** + +```bash +# Run dev server with editable mode and additional packages +fastmcp dev inspector server.py -e . --with pandas --with matplotlib + +# Run dev server with fastmcp.json configuration (auto-detects) +fastmcp dev inspector + +# Run dev server with explicit fastmcp.json file +fastmcp dev inspector dev.fastmcp.json + +# Run dev server with specific Python version +fastmcp dev inspector server.py --python 3.11 + +# Run dev server with requirements file +fastmcp dev inspector server.py --with-requirements requirements.txt + +# Run dev server within a specific project directory +fastmcp dev inspector server.py --project /path/to/project +``` + +## `fastmcp install` + + +Install a MCP server in MCP client applications. FastMCP currently supports the following clients: + +- **Claude Code** - Installs via Claude Code's built-in MCP management system +- **Claude Desktop** - Installs via direct configuration file modification +- **Cursor** - Installs via deeplink that opens Cursor for user confirmation +- **Gemini CLI** - Installs via Gemini CLI's built-in MCP management system +- **Goose** - Installs via deeplink that opens Goose for user confirmation (uses `uvx`) +- **MCP JSON** - Generates standard MCP JSON configuration for manual use +- **Stdio** - Outputs the shell command to run a server over stdio transport + +```bash +fastmcp install claude-code server.py +fastmcp install claude-desktop server.py +fastmcp install cursor server.py +fastmcp install gemini-cli server.py +fastmcp install goose server.py +fastmcp install mcp-json server.py +fastmcp install stdio server.py +``` + +Note that for security reasons, MCP clients usually run every server in a completely isolated environment. Therefore, all dependencies must be explicitly specified using the `--with` and/or `--with-editable` options (following `uv` conventions) or by attaching them to your server in code via the `dependencies` parameter. You should not assume that the MCP server will have access to your local environment. + + +**`uv` must be installed and available in your system PATH**. Both Claude Desktop and Cursor run in isolated environments and need `uv` to manage dependencies. On macOS, install `uv` globally with Homebrew for Claude Desktop compatibility: `brew install uv`. + + + +**Python Version Considerations**: The install commands now support the `--python` option to specify a Python version directly. You can also use `--project` to run within a specific project directory or `--with-requirements` to install dependencies from a requirements file. + + + +**FastMCP `install` commands focus on local server files with STDIO transport.** For remote servers running with HTTP or SSE transport, use your client's native configuration - FastMCP's value is simplifying the complex local setup with dependencies and `uv` commands. + + +### Options + +| Option | Flag | Description | +| ------ | ---- | ----------- | +| Server Name | `--server-name`, `-n` | Custom name for the server (defaults to server's name attribute or file name) | +| Editable Package | `--with-editable`, `-e` | Directory containing pyproject.toml to install in editable mode | +| Additional Packages | `--with` | Additional packages to install (can be used multiple times) | +| Environment Variables | `--env` | Environment variables in KEY=VALUE format (can be used multiple times) | +| Environment File | `--env-file`, `-f` | Load environment variables from a .env file | +| Python Version | `--python` | Python version to use (e.g., 3.10, 3.11) | +| Project Directory | `--project` | Run the command within the given project directory | +| Requirements File | `--with-requirements` | Requirements file to install dependencies from | + +### Entrypoints + +The `install` command supports local FastMCP server files and configuration: + +1. **Inferred server instance**: `server.py` - imports the module and looks for a FastMCP server instance named `mcp`, `server`, or `app`. Errors if no such object is found. +2. **Explicit server entrypoint**: `server.py:custom_name` - imports and uses the specified server entrypoint +3. **Factory function**: `server.py:create_server` - calls the specified function (sync or async) to create a server instance +4. **FastMCP configuration**: `fastmcp.json` - uses FastMCP's declarative configuration with dependencies and settings + + +Factory functions are particularly useful for install commands since they allow setup code to run that would otherwise be ignored when the MCP client runs your server. When using fastmcp.json, dependencies are automatically handled. + + + +The `install` command **only supports local files and fastmcp.json** - no URLs, remote servers, or standard MCP configuration files. For remote servers, use your MCP client's native configuration. + + +**Examples** + +```bash +# Auto-detects server entrypoint (looks for 'mcp', 'server', or 'app') +fastmcp install claude-desktop server.py + +# Install with fastmcp.json configuration (auto-detects) +fastmcp install claude-desktop + +# Install with explicit fastmcp.json file +fastmcp install claude-desktop my-config.fastmcp.json + +# Uses specific server entrypoint +fastmcp install claude-desktop server.py:my_server + +# With custom name and dependencies +fastmcp install claude-desktop server.py:my_server --server-name "My Analysis Server" --with pandas + +# Install in Claude Code with environment variables +fastmcp install claude-code server.py --env API_KEY=secret --env DEBUG=true + +# Install in Cursor with environment variables +fastmcp install cursor server.py --env API_KEY=secret --env DEBUG=true + +# Install with environment file +fastmcp install cursor server.py --env-file .env + +# Install in Goose (uses uvx deeplink) +fastmcp install goose server.py --with pandas + +# Install with specific Python version +fastmcp install claude-desktop server.py --python 3.11 + +# Install with requirements file +fastmcp install claude-code server.py --with-requirements requirements.txt + +# Install within a project directory +fastmcp install cursor server.py --project /path/to/project + +# Generate MCP JSON configuration +fastmcp install mcp-json server.py --name "My Server" --with pandas + +# Copy JSON configuration to clipboard +fastmcp install mcp-json server.py --copy + +# Output the stdio command for running a server +fastmcp install stdio server.py + +# Output the stdio command from a fastmcp.json (includes configured dependencies) +fastmcp install stdio fastmcp.json + +# Copy the stdio command to clipboard +fastmcp install stdio server.py --copy +``` + +### MCP JSON Generation + +The `mcp-json` subcommand generates standard MCP JSON configuration that can be used with any MCP-compatible client. This is useful when: + +- Working with MCP clients not directly supported by FastMCP +- Creating configuration for CI/CD environments +- Sharing server configurations with others +- Integration with custom tooling + +The generated JSON follows the standard MCP server configuration format used by Claude Desktop, VS Code, Cursor, and other MCP clients, with the server name as the root key: + +```json +{ + "server-name": { + "command": "uv", + "args": [ + "run", + "--with", + "fastmcp", + "fastmcp", + "run", + "/path/to/server.py" + ], + "env": { + "API_KEY": "value" + } + } +} +``` + + +To use this configuration with your MCP client, you'll typically need to add it to the client's `mcpServers` object. Consult your client's documentation for any specific configuration requirements or formatting needs. + + +**Options specific to mcp-json:** + +| Option | Flag | Description | +| ------ | ---- | ----------- | +| Copy to Clipboard | `--copy` | Copy configuration to clipboard instead of printing to stdout | + +### Stdio Command + +The `stdio` subcommand outputs the shell command an MCP host uses to start your server over stdio transport. Use it when you need a ready-to-paste `uv run --with fastmcp fastmcp run ...` command for a tool or script without a dedicated install target. + +```bash +# Print the command to stdout +fastmcp install stdio server.py + +# Output: uv run --with fastmcp fastmcp run /absolute/path/to/server.py +``` + +When you pass a `fastmcp.json`, FastMCP automatically includes dependencies from the configuration: + +```bash +fastmcp install stdio fastmcp.json + +# Output: uv run --with fastmcp --with pillow --with 'qrcode[pil]>=8.0' fastmcp run /absolute/path/to/qr_server.py +``` + +Use `--copy` to send the command directly to your clipboard: + +```bash +fastmcp install stdio server.py --copy +# ✓ Command copied to clipboard +``` + +**Options specific to stdio:** + +| Option | Flag | Description | +| ------ | ---- | ----------- | +| Copy to Clipboard | `--copy` | Copy command to clipboard instead of printing to stdout | + +## `fastmcp inspect` + + + +Inspect a FastMCP server to view summary information or generate a detailed JSON report. + +```bash +# Show text summary +fastmcp inspect server.py + +# Output FastMCP JSON to stdout +fastmcp inspect server.py --format fastmcp + +# Save MCP JSON to file (format required with -o) +fastmcp inspect server.py --format mcp -o manifest.json +``` + +### Options + +| Option | Flag | Description | +| ------ | ---- | ----------- | +| Format | `--format`, `-f` | Output format: `fastmcp` (FastMCP-specific) or `mcp` (MCP protocol). Required when using `-o` | +| Output File | `--output`, `-o` | Save JSON report to file instead of stdout. Requires `--format` | + +### Output Formats + +#### FastMCP Format (`--format fastmcp`) +The default and most comprehensive format, includes all FastMCP-specific metadata: +- Server name, instructions, and version +- FastMCP version and MCP version +- Tool tags and enabled status +- Output schemas for tools +- Annotations and custom metadata +- Uses snake_case field names +- **Use this for**: Complete server introspection and debugging FastMCP servers + +#### MCP Protocol Format (`--format mcp`) +Shows exactly what MCP clients will see via the protocol: +- Only includes standard MCP protocol fields +- Matches output from `client.list_tools()`, `client.list_prompts()`, etc. +- Uses camelCase field names (e.g., `inputSchema`) +- Excludes FastMCP-specific fields like tags and enabled status +- **Use this for**: Debugging client visibility and ensuring MCP compatibility + +### Entrypoints + +The `inspect` command supports local FastMCP server files and configuration: + +1. **Inferred server instance**: `server.py` - imports the module and looks for a FastMCP server instance named `mcp`, `server`, or `app`. Errors if no such object is found. +2. **Explicit server entrypoint**: `server.py:custom_name` - imports and uses the specified server entrypoint +3. **Factory function**: `server.py:create_server` - calls the specified function (sync or async) to create a server instance +4. **FastMCP configuration**: `fastmcp.json` - inspects servers defined with FastMCP's declarative configuration + + +The `inspect` command **only supports local files and fastmcp.json** - no URLs, remote servers, or standard MCP configuration files. + + +### Examples + +```bash +# Show text summary (no JSON output) +fastmcp inspect server.py +# Output: +# Server: MyServer +# Instructions: A helpful MCP server +# Version: 1.0.0 +# +# Components: +# Tools: 5 +# Prompts: 2 +# Resources: 3 +# Templates: 1 +# +# Environment: +# FastMCP: 2.0.0 +# MCP: 1.0.0 +# +# Use --format [fastmcp|mcp] for complete JSON output + +# Output FastMCP format to stdout +fastmcp inspect server.py --format fastmcp + +# Specify server entrypoint +fastmcp inspect server.py:my_server + +# Output MCP protocol format to stdout +fastmcp inspect server.py --format mcp + +# Save to file (format required) +fastmcp inspect server.py --format fastmcp -o server-manifest.json + +# Save MCP format with custom server object +fastmcp inspect server.py:my_server --format mcp -o mcp-manifest.json + +# Error: format required with output file +fastmcp inspect server.py -o output.json +# Error: --format is required when using -o/--output +``` + +## `fastmcp project prepare` + +Create a persistent uv project directory from a fastmcp.json file's environment configuration. This allows you to pre-install all dependencies once and reuse them with the `--project` flag. + +```bash +fastmcp project prepare fastmcp.json --output-dir ./env +``` + +### Options + +| Option | Flag | Description | +| ------ | ---- | ----------- | +| Output Directory | `--output-dir` | **Required.** Directory where the persistent uv project will be created | + +### Usage Pattern + +```bash +# Step 1: Prepare the environment (installs dependencies) +fastmcp project prepare fastmcp.json --output-dir ./my-env + +# Step 2: Run using the prepared environment (fast, no dependency installation) +fastmcp run fastmcp.json --project ./my-env +``` + +The prepare command creates a uv project with: +- A `pyproject.toml` containing all dependencies from the fastmcp.json +- A `.venv` with all packages pre-installed +- A `uv.lock` file for reproducible environments + +This is useful when you want to separate environment setup from server execution, such as in deployment scenarios where dependencies are installed once and the server is run multiple times. + +## `fastmcp auth` + + + +Authentication-related utilities and configuration commands. + +### `fastmcp auth cimd create` + +Generate a CIMD (Client ID Metadata Document) for hosting. This creates a JSON document that you can host at an HTTPS URL to use as your OAuth client identity. + +```bash +fastmcp auth cimd create --name "My App" --redirect-uri "http://localhost:*/callback" +``` + +#### Options + +| Option | Flag | Description | +| ------ | ---- | ----------- | +| Name | `--name` | **Required.** Human-readable name of the client application | +| Redirect URI | `--redirect-uri` | **Required.** Allowed redirect URIs (can specify multiple) | +| Client URI | `--client-uri` | URL of the client's home page | +| Logo URI | `--logo-uri` | URL of the client's logo image | +| Scope | `--scope` | Space-separated list of scopes the client may request | +| Output | `--output`, `-o` | Output file path (default: stdout) | +| Pretty | `--pretty` | Pretty-print JSON output (default: true) | + +#### Example + +```bash +# Generate document to stdout +fastmcp auth cimd create \ + --name "My Production App" \ + --redirect-uri "http://localhost:*/callback" \ + --redirect-uri "https://myapp.example.com/callback" \ + --client-uri "https://myapp.example.com" \ + --scope "read write" + +# Save to file +fastmcp auth cimd create \ + --name "My App" \ + --redirect-uri "http://localhost:*/callback" \ + --output client.json +``` + +The generated document includes a placeholder `client_id` that you must update to match the URL where you'll host the document before deploying. + +### `fastmcp auth cimd validate` + +Validate a hosted CIMD document by fetching it from its URL and checking that it conforms to the CIMD specification. + +```bash +fastmcp auth cimd validate https://myapp.example.com/oauth/client.json +``` + +#### Options + +| Option | Flag | Description | +| ------ | ---- | ----------- | +| Timeout | `--timeout`, `-t` | HTTP request timeout in seconds (default: 10) | + +The validator checks: + +- The URL is a valid CIMD URL (HTTPS with non-root path) +- The document is valid JSON and conforms to the CIMD schema +- The `client_id` field in the document matches the URL +- No shared-secret authentication methods are used + +On success, it displays the document details: + +``` +→ Fetching https://myapp.example.com/oauth/client.json... +✓ Valid CIMD document + +Document details: + client_id: https://myapp.example.com/oauth/client.json + client_name: My App + token_endpoint_auth_method: none + redirect_uris: + • http://localhost:*/callback +``` + +## `fastmcp version` + +Display version information about FastMCP and related components. + +```bash +fastmcp version +``` + +### Options + +| Option | Flag | Description | +| ------ | ---- | ----------- | +| Copy to Clipboard | `--copy` | Copy version information to clipboard | diff --git a/docs/patterns/contrib.mdx b/docs/patterns/contrib.mdx new file mode 100644 index 000000000..d2f812f52 --- /dev/null +++ b/docs/patterns/contrib.mdx @@ -0,0 +1,45 @@ +--- +title: "Contrib Modules" +description: "Community-contributed modules extending FastMCP" +icon: "cubes" +--- + +import { VersionBadge } from "/snippets/version-badge.mdx" + + + +FastMCP includes a `contrib` package that holds community-contributed modules. These modules extend FastMCP's functionality but aren't officially maintained by the core team. + +Contrib modules provide additional features, integrations, or patterns that complement the core FastMCP library. They offer a way for the community to share useful extensions while keeping the core library focused and maintainable. + +The available modules can be viewed in the [contrib directory](https://github.com/PrefectHQ/fastmcp/tree/main/src/fastmcp/contrib). + +## Usage + +To use a contrib module, import it from the `fastmcp.contrib` package: + +```python +from fastmcp.contrib import my_module +``` + +## Important Considerations + +- **Stability**: Modules in `contrib` may have different testing requirements or stability guarantees compared to the core library. +- **Compatibility**: Changes to core FastMCP might break modules in `contrib` without explicit warnings in the main changelog. +- **Dependencies**: Contrib modules may have additional dependencies not required by the core library. These dependencies are typically documented in the module's README or separate requirements files. + +## Contributing + +We welcome contributions to the `contrib` package! If you have a module that extends FastMCP in a useful way, consider contributing it: + +1. Create a new directory in `src/fastmcp/contrib/` for your module +3. Add proper tests for your module in `tests/contrib/` +2. Include comprehensive documentation in a README.md file, including usage and examples, as well as any additional dependencies or installation instructions +5. Submit a pull request + +The ideal contrib module: +- Solves a specific use case or integration need +- Follows FastMCP coding standards +- Includes thorough documentation and examples +- Has comprehensive tests +- Specifies any additional dependencies diff --git a/docs/patterns/testing.mdx b/docs/patterns/testing.mdx new file mode 100644 index 000000000..7bd8600c5 --- /dev/null +++ b/docs/patterns/testing.mdx @@ -0,0 +1,104 @@ +--- +title: Testing your FastMCP Server +sidebarTitle: Testing +description: How to test your FastMCP server. +icon: vial +--- + +The best way to ensure a reliable and maintainable FastMCP Server is to test it! The FastMCP Client combined with Pytest provides a simple and powerful way to test your FastMCP servers. + +## Prerequisites + +Testing FastMCP servers requires `pytest-asyncio` to handle async test functions and fixtures. Install it as a development dependency: + +```bash +pip install pytest-asyncio +``` + +We recommend configuring pytest to automatically handle async tests by setting the asyncio mode to `auto` in your `pyproject.toml`: + +```toml +[tool.pytest.ini_options] +asyncio_mode = "auto" +``` + +This eliminates the need to decorate every async test with `@pytest.mark.asyncio`. + +## Testing with Pytest Fixtures + +Using Pytest Fixtures, you can wrap your FastMCP Server in a Client instance that makes interacting with your server fast and easy. This is especially useful when building your own MCP Servers and enables a tight development loop by allowing you to avoid using a separate tool like MCP Inspector during development: + +```python +import pytest +from fastmcp.client import Client +from fastmcp.client.transports import FastMCPTransport + +from my_project.main import mcp + +@pytest.fixture +async def main_mcp_client(): + async with Client(transport=mcp) as mcp_client: + yield mcp_client + +async def test_list_tools(main_mcp_client: Client[FastMCPTransport]): + list_tools = await main_mcp_client.list_tools() + + assert len(list_tools) == 5 +``` + +We recommend the [inline-snapshot library](https://github.com/15r10nk/inline-snapshot) for asserting complex data structures coming from your MCP Server. This library allows you to write tests that are easy to read and understand, and are also easy to update when the data structure changes. + +```python +from inline_snapshot import snapshot + +async def test_list_tools(main_mcp_client: Client[FastMCPTransport]): + list_tools = await main_mcp_client.list_tools() + + assert list_tools == snapshot() +``` + +Simply run `pytest --inline-snapshot=fix,create` to fill in the `snapshot()` with actual data. + + +For values that change you can leverage the [dirty-equals](https://github.com/samuelcolvin/dirty-equals) library to perform flexible equality assertions on dynamic or non-deterministic values. + + +Using the pytest `parametrize` decorator, you can easily test your tools with a wide variety of inputs. + +```python +import pytest +from my_project.main import mcp + +from fastmcp.client import Client +from fastmcp.client.transports import FastMCPTransport +@pytest.fixture +async def main_mcp_client(): + async with Client(mcp) as client: + yield client + + +@pytest.mark.parametrize( + "first_number, second_number, expected", + [ + (1, 2, 3), + (2, 3, 5), + (3, 4, 7), + ], +) +async def test_add( + first_number: int, + second_number: int, + expected: int, + main_mcp_client: Client[FastMCPTransport], +): + result = await main_mcp_client.call_tool( + name="add", arguments={"x": first_number, "y": second_number} + ) + assert result.data is not None + assert isinstance(result.data, int) + assert result.data == expected +``` + + +The [FastMCP Repository contains thousands of tests](https://github.com/PrefectHQ/fastmcp/tree/main/tests) for the FastMCP Client and Server. Everything from connecting to remote MCP servers, to testing tools, resources, and prompts is covered, take a look for inspiration! + \ No newline at end of file diff --git a/docs/public/schemas/fastmcp.json/latest.json b/docs/public/schemas/fastmcp.json/latest.json new file mode 100644 index 000000000..aa1f59ce4 --- /dev/null +++ b/docs/public/schemas/fastmcp.json/latest.json @@ -0,0 +1,365 @@ +{ + "$defs": { + "Deployment": { + "description": "Configuration for server deployment and runtime settings.", + "properties": { + "transport": { + "anyOf": [ + { + "enum": [ + "stdio", + "http", + "sse", + "streamable-http" + ], + "type": "string" + }, + { + "type": "null" + } + ], + "default": null, + "description": "Transport protocol to use", + "title": "Transport" + }, + "host": { + "anyOf": [ + { + "type": "string" + }, + { + "type": "null" + } + ], + "default": null, + "description": "Host to bind to when using HTTP transport", + "examples": [ + "127.0.0.1", + "0.0.0.0", + "localhost" + ], + "title": "Host" + }, + "port": { + "anyOf": [ + { + "type": "integer" + }, + { + "type": "null" + } + ], + "default": null, + "description": "Port to bind to when using HTTP transport", + "examples": [ + 8000, + 3000, + 5000 + ], + "title": "Port" + }, + "path": { + "anyOf": [ + { + "type": "string" + }, + { + "type": "null" + } + ], + "default": null, + "description": "URL path for the server endpoint", + "examples": [ + "/mcp/", + "/api/mcp/", + "/sse/" + ], + "title": "Path" + }, + "log_level": { + "anyOf": [ + { + "enum": [ + "DEBUG", + "INFO", + "WARNING", + "ERROR", + "CRITICAL" + ], + "type": "string" + }, + { + "type": "null" + } + ], + "default": null, + "description": "Log level for the server", + "title": "Log Level" + }, + "cwd": { + "anyOf": [ + { + "type": "string" + }, + { + "type": "null" + } + ], + "default": null, + "description": "Working directory for the server process", + "examples": [ + ".", + "./src", + "/app" + ], + "title": "Cwd" + }, + "env": { + "anyOf": [ + { + "additionalProperties": { + "type": "string" + }, + "type": "object" + }, + { + "type": "null" + } + ], + "default": null, + "description": "Environment variables to set when running the server", + "examples": [ + { + "API_KEY": "secret", + "DEBUG": "true" + } + ], + "title": "Env" + }, + "args": { + "anyOf": [ + { + "items": { + "type": "string" + }, + "type": "array" + }, + { + "type": "null" + } + ], + "default": null, + "description": "Arguments to pass to the server (after --)", + "examples": [ + [ + "--config", + "config.json", + "--debug" + ] + ], + "title": "Args" + } + }, + "title": "Deployment", + "type": "object" + }, + "FileSystemSource": { + "description": "Source for local Python files.", + "properties": { + "type": { + "const": "filesystem", + "default": "filesystem", + "title": "Type", + "type": "string" + }, + "path": { + "description": "Path to Python file containing the server", + "title": "Path", + "type": "string" + }, + "entrypoint": { + "anyOf": [ + { + "type": "string" + }, + { + "type": "null" + } + ], + "default": null, + "description": "Name of server instance or factory function (a no-arg function that returns a FastMCP server)", + "title": "Entrypoint" + } + }, + "required": [ + "path" + ], + "title": "FileSystemSource", + "type": "object" + }, + "UVEnvironment": { + "description": "Configuration for Python environment setup.", + "properties": { + "type": { + "const": "uv", + "default": "uv", + "title": "Type", + "type": "string" + }, + "python": { + "anyOf": [ + { + "type": "string" + }, + { + "type": "null" + } + ], + "default": null, + "description": "Python version constraint", + "examples": [ + "3.10", + "3.11", + "3.12" + ], + "title": "Python" + }, + "dependencies": { + "anyOf": [ + { + "items": { + "type": "string" + }, + "type": "array" + }, + { + "type": "null" + } + ], + "default": null, + "description": "Python packages to install with PEP 508 specifiers", + "examples": [ + [ + "fastmcp>=2.0,<3", + "httpx", + "pandas>=2.0" + ] + ], + "title": "Dependencies" + }, + "requirements": { + "anyOf": [ + { + "format": "path", + "type": "string" + }, + { + "type": "null" + } + ], + "default": null, + "description": "Path to requirements.txt file", + "examples": [ + "requirements.txt", + "../requirements/prod.txt" + ], + "title": "Requirements" + }, + "project": { + "anyOf": [ + { + "format": "path", + "type": "string" + }, + { + "type": "null" + } + ], + "default": null, + "description": "Path to project directory containing pyproject.toml", + "examples": [ + ".", + "../my-project" + ], + "title": "Project" + }, + "editable": { + "anyOf": [ + { + "items": { + "format": "path", + "type": "string" + }, + "type": "array" + }, + { + "type": "null" + } + ], + "default": null, + "description": "Directories to install in editable mode", + "examples": [ + [ + ".", + "../my-package" + ], + [ + "/path/to/package" + ] + ], + "title": "Editable" + } + }, + "title": "UVEnvironment", + "type": "object" + } + }, + "description": "Configuration file for FastMCP servers", + "properties": { + "$schema": { + "anyOf": [ + { + "type": "string" + }, + { + "type": "null" + } + ], + "default": "https://gofastmcp.com/public/schemas/fastmcp.json/v1.json", + "description": "JSON schema for IDE support and validation", + "title": "$Schema" + }, + "source": { + "$ref": "#/$defs/FileSystemSource", + "description": "Source configuration for the server", + "examples": [ + { + "path": "server.py" + }, + { + "entrypoint": "app", + "path": "server.py" + }, + { + "entrypoint": "mcp", + "path": "src/server.py", + "type": "filesystem" + } + ] + }, + "environment": { + "$ref": "#/$defs/UVEnvironment", + "description": "Python environment setup configuration" + }, + "deployment": { + "$ref": "#/$defs/Deployment", + "description": "Server deployment and runtime settings" + } + }, + "required": [ + "source" + ], + "title": "FastMCP Configuration", + "type": "object", + "$id": "https://gofastmcp.com/public/schemas/fastmcp.json/v1.json" +} diff --git a/docs/public/schemas/fastmcp.json/v1.json b/docs/public/schemas/fastmcp.json/v1.json new file mode 100644 index 000000000..aa1f59ce4 --- /dev/null +++ b/docs/public/schemas/fastmcp.json/v1.json @@ -0,0 +1,365 @@ +{ + "$defs": { + "Deployment": { + "description": "Configuration for server deployment and runtime settings.", + "properties": { + "transport": { + "anyOf": [ + { + "enum": [ + "stdio", + "http", + "sse", + "streamable-http" + ], + "type": "string" + }, + { + "type": "null" + } + ], + "default": null, + "description": "Transport protocol to use", + "title": "Transport" + }, + "host": { + "anyOf": [ + { + "type": "string" + }, + { + "type": "null" + } + ], + "default": null, + "description": "Host to bind to when using HTTP transport", + "examples": [ + "127.0.0.1", + "0.0.0.0", + "localhost" + ], + "title": "Host" + }, + "port": { + "anyOf": [ + { + "type": "integer" + }, + { + "type": "null" + } + ], + "default": null, + "description": "Port to bind to when using HTTP transport", + "examples": [ + 8000, + 3000, + 5000 + ], + "title": "Port" + }, + "path": { + "anyOf": [ + { + "type": "string" + }, + { + "type": "null" + } + ], + "default": null, + "description": "URL path for the server endpoint", + "examples": [ + "/mcp/", + "/api/mcp/", + "/sse/" + ], + "title": "Path" + }, + "log_level": { + "anyOf": [ + { + "enum": [ + "DEBUG", + "INFO", + "WARNING", + "ERROR", + "CRITICAL" + ], + "type": "string" + }, + { + "type": "null" + } + ], + "default": null, + "description": "Log level for the server", + "title": "Log Level" + }, + "cwd": { + "anyOf": [ + { + "type": "string" + }, + { + "type": "null" + } + ], + "default": null, + "description": "Working directory for the server process", + "examples": [ + ".", + "./src", + "/app" + ], + "title": "Cwd" + }, + "env": { + "anyOf": [ + { + "additionalProperties": { + "type": "string" + }, + "type": "object" + }, + { + "type": "null" + } + ], + "default": null, + "description": "Environment variables to set when running the server", + "examples": [ + { + "API_KEY": "secret", + "DEBUG": "true" + } + ], + "title": "Env" + }, + "args": { + "anyOf": [ + { + "items": { + "type": "string" + }, + "type": "array" + }, + { + "type": "null" + } + ], + "default": null, + "description": "Arguments to pass to the server (after --)", + "examples": [ + [ + "--config", + "config.json", + "--debug" + ] + ], + "title": "Args" + } + }, + "title": "Deployment", + "type": "object" + }, + "FileSystemSource": { + "description": "Source for local Python files.", + "properties": { + "type": { + "const": "filesystem", + "default": "filesystem", + "title": "Type", + "type": "string" + }, + "path": { + "description": "Path to Python file containing the server", + "title": "Path", + "type": "string" + }, + "entrypoint": { + "anyOf": [ + { + "type": "string" + }, + { + "type": "null" + } + ], + "default": null, + "description": "Name of server instance or factory function (a no-arg function that returns a FastMCP server)", + "title": "Entrypoint" + } + }, + "required": [ + "path" + ], + "title": "FileSystemSource", + "type": "object" + }, + "UVEnvironment": { + "description": "Configuration for Python environment setup.", + "properties": { + "type": { + "const": "uv", + "default": "uv", + "title": "Type", + "type": "string" + }, + "python": { + "anyOf": [ + { + "type": "string" + }, + { + "type": "null" + } + ], + "default": null, + "description": "Python version constraint", + "examples": [ + "3.10", + "3.11", + "3.12" + ], + "title": "Python" + }, + "dependencies": { + "anyOf": [ + { + "items": { + "type": "string" + }, + "type": "array" + }, + { + "type": "null" + } + ], + "default": null, + "description": "Python packages to install with PEP 508 specifiers", + "examples": [ + [ + "fastmcp>=2.0,<3", + "httpx", + "pandas>=2.0" + ] + ], + "title": "Dependencies" + }, + "requirements": { + "anyOf": [ + { + "format": "path", + "type": "string" + }, + { + "type": "null" + } + ], + "default": null, + "description": "Path to requirements.txt file", + "examples": [ + "requirements.txt", + "../requirements/prod.txt" + ], + "title": "Requirements" + }, + "project": { + "anyOf": [ + { + "format": "path", + "type": "string" + }, + { + "type": "null" + } + ], + "default": null, + "description": "Path to project directory containing pyproject.toml", + "examples": [ + ".", + "../my-project" + ], + "title": "Project" + }, + "editable": { + "anyOf": [ + { + "items": { + "format": "path", + "type": "string" + }, + "type": "array" + }, + { + "type": "null" + } + ], + "default": null, + "description": "Directories to install in editable mode", + "examples": [ + [ + ".", + "../my-package" + ], + [ + "/path/to/package" + ] + ], + "title": "Editable" + } + }, + "title": "UVEnvironment", + "type": "object" + } + }, + "description": "Configuration file for FastMCP servers", + "properties": { + "$schema": { + "anyOf": [ + { + "type": "string" + }, + { + "type": "null" + } + ], + "default": "https://gofastmcp.com/public/schemas/fastmcp.json/v1.json", + "description": "JSON schema for IDE support and validation", + "title": "$Schema" + }, + "source": { + "$ref": "#/$defs/FileSystemSource", + "description": "Source configuration for the server", + "examples": [ + { + "path": "server.py" + }, + { + "entrypoint": "app", + "path": "server.py" + }, + { + "entrypoint": "mcp", + "path": "src/server.py", + "type": "filesystem" + } + ] + }, + "environment": { + "$ref": "#/$defs/UVEnvironment", + "description": "Python environment setup configuration" + }, + "deployment": { + "$ref": "#/$defs/Deployment", + "description": "Server deployment and runtime settings" + } + }, + "required": [ + "source" + ], + "title": "FastMCP Configuration", + "type": "object", + "$id": "https://gofastmcp.com/public/schemas/fastmcp.json/v1.json" +} diff --git a/docs/python-sdk/fastmcp-cli-__init__.mdx b/docs/python-sdk/fastmcp-cli-__init__.mdx new file mode 100644 index 000000000..d2873740a --- /dev/null +++ b/docs/python-sdk/fastmcp-cli-__init__.mdx @@ -0,0 +1,9 @@ +--- +title: __init__ +sidebarTitle: __init__ +--- + +# `fastmcp.cli` + + +FastMCP CLI package. diff --git a/docs/python-sdk/fastmcp-cli-auth.mdx b/docs/python-sdk/fastmcp-cli-auth.mdx new file mode 100644 index 000000000..586a53505 --- /dev/null +++ b/docs/python-sdk/fastmcp-cli-auth.mdx @@ -0,0 +1,9 @@ +--- +title: auth +sidebarTitle: auth +--- + +# `fastmcp.cli.auth` + + +Authentication-related CLI commands. diff --git a/docs/python-sdk/fastmcp-cli-cimd.mdx b/docs/python-sdk/fastmcp-cli-cimd.mdx new file mode 100644 index 000000000..2b4b73457 --- /dev/null +++ b/docs/python-sdk/fastmcp-cli-cimd.mdx @@ -0,0 +1,43 @@ +--- +title: cimd +sidebarTitle: cimd +--- + +# `fastmcp.cli.cimd` + + +CIMD (Client ID Metadata Document) CLI commands. + +## Functions + +### `create_command` + +```python +create_command() -> None +``` + + +Generate a CIMD document for hosting. + +Create a Client ID Metadata Document that you can host at an HTTPS URL. +The URL where you host this document becomes your client_id. + +After creating the document, host it at an HTTPS URL with a non-root path, +for example: https://myapp.example.com/oauth/client.json + + +### `validate_command` + +```python +validate_command(url: Annotated[str, cyclopts.Parameter(help='URL of the CIMD document to validate')]) -> None +``` + + +Validate a hosted CIMD document. + +Fetches the document from the given URL and validates: +- URL is valid CIMD URL (HTTPS, non-root path) +- Document is valid JSON +- Document conforms to CIMD schema +- client_id in document matches the URL + diff --git a/docs/python-sdk/fastmcp-cli-cli.mdx b/docs/python-sdk/fastmcp-cli-cli.mdx new file mode 100644 index 000000000..60804a298 --- /dev/null +++ b/docs/python-sdk/fastmcp-cli-cli.mdx @@ -0,0 +1,130 @@ +--- +title: cli +sidebarTitle: cli +--- + +# `fastmcp.cli.cli` + + +FastMCP CLI tools using Cyclopts. + +## Functions + +### `with_argv` + +```python +with_argv(args: list[str] | None) +``` + + +Temporarily replace sys.argv if args provided. + +This context manager is used at the CLI boundary to inject +server arguments when needed, without mutating sys.argv deep +in the source loading logic. + +Args are provided without the script name, so we preserve sys.argv[0] +and replace the rest. + + +### `version` + +```python +version() +``` + + +Display version information and platform details. + + +### `inspector` + +```python +inspector(server_spec: str | None = None) -> None +``` + + +Run an MCP server with the MCP Inspector for development. + +**Args:** +- `server_spec`: Python file to run, optionally with \:object suffix, or None to auto-detect fastmcp.json + + +### `run` + +```python +run(server_spec: str | None = None, *server_args: str) -> None +``` + + +Run an MCP server or connect to a remote one. + +The server can be specified in several ways: +1. Module approach: "server.py" - runs the module directly, looking for an object named 'mcp', 'server', or 'app' +2. Import approach: "server.py:app" - imports and runs the specified server object +3. URL approach: "http://server-url" - connects to a remote server and creates a proxy +4. MCPConfig file: "mcp.json" - runs as a proxy server for the MCP Servers in the MCPConfig file +5. FastMCP config: "fastmcp.json" - runs server using FastMCP configuration +6. No argument: looks for fastmcp.json in current directory +7. Module mode: "-m my_module" - runs the module directly via python -m + +Server arguments can be passed after -- : +fastmcp run server.py -- --config config.json --debug + +**Args:** +- `server_spec`: Python file, object specification (file\:obj), config file, URL, or None to auto-detect + + +### `inspect` + +```python +inspect(server_spec: str | None = None) -> None +``` + + +Inspect an MCP server and display information or generate a JSON report. + +This command analyzes an MCP server. Without flags, it displays a text summary. +Use --format to output complete JSON data. + +**Examples:** + +# Show text summary +fastmcp inspect server.py + +# Output FastMCP format JSON to stdout +fastmcp inspect server.py --format fastmcp + +# Save MCP protocol format to file (format required with -o) +fastmcp inspect server.py --format mcp -o manifest.json + +# Inspect from fastmcp.json configuration +fastmcp inspect fastmcp.json +fastmcp inspect # auto-detect fastmcp.json + +**Args:** +- `server_spec`: Python file to inspect, optionally with \:object suffix, or fastmcp.json + + +### `prepare` + +```python +prepare(config_path: Annotated[str | None, cyclopts.Parameter(help='Path to fastmcp.json configuration file')] = None, output_dir: Annotated[str | None, cyclopts.Parameter(help='Directory to create the persistent environment in')] = None, skip_source: Annotated[bool, cyclopts.Parameter(help='Skip source preparation (e.g., git clone)')] = False) -> None +``` + + +Prepare a FastMCP project by creating a persistent uv environment. + +This command creates a persistent uv project with all dependencies installed: +- Creates a pyproject.toml with dependencies from the config +- Installs all Python packages into a .venv +- Prepares the source (git clone, download, etc.) unless --skip-source + +After running this command, you can use: +fastmcp run <config> --project <output-dir> + +This is useful for: +- CI/CD pipelines with separate build and run stages +- Docker images where you prepare during build +- Production deployments where you want fast startup times + diff --git a/docs/python-sdk/fastmcp-cli-client.mdx b/docs/python-sdk/fastmcp-cli-client.mdx new file mode 100644 index 000000000..726663bfb --- /dev/null +++ b/docs/python-sdk/fastmcp-cli-client.mdx @@ -0,0 +1,135 @@ +--- +title: client +sidebarTitle: client +--- + +# `fastmcp.cli.client` + + +Client-side CLI commands for querying and invoking MCP servers. + +## Functions + +### `resolve_server_spec` + +```python +resolve_server_spec(server_spec: str | None) -> str | dict[str, Any] | ClientTransport +``` + + +Turn CLI inputs into something ``Client()`` accepts. + +Exactly one of ``server_spec`` or ``command`` should be provided. + +Resolution order for ``server_spec``: +1. URLs (``http://``, ``https://``) — passed through as-is. + If ``--transport`` is ``sse``, the URL is rewritten to end with ``/sse`` + so ``infer_transport`` picks the right transport. +2. Existing file paths, or strings ending in ``.py``/``.js``/``.json``. +3. Anything else — name-based resolution via ``resolve_name``. + +When ``command`` is provided, the string is shell-split into a +``StdioTransport(command, args)``. + + +### `coerce_value` + +```python +coerce_value(raw: str, schema: dict[str, Any]) -> Any +``` + + +Coerce a string CLI value according to a JSON-Schema type hint. + + +### `parse_tool_arguments` + +```python +parse_tool_arguments(raw_args: tuple[str, ...], input_json: str | None, input_schema: dict[str, Any]) -> dict[str, Any] +``` + + +Build a tool-call argument dict from CLI inputs. + +A single JSON object argument is treated as the full argument dict. +``--input-json`` provides the base dict; ``key=value`` pairs override. +Values are coerced using the tool's ``inputSchema``. + + +### `format_tool_signature` + +```python +format_tool_signature(tool: mcp.types.Tool) -> str +``` + + +Build ``name(param: type, ...) -> return_type`` from a tool's JSON schemas. + + +### `list_command` + +```python +list_command(server_spec: Annotated[str | None, cyclopts.Parameter(help='Server URL, Python file, MCPConfig JSON, or .js file')] = None) -> None +``` + + +List tools available on an MCP server. + +**Examples:** + +fastmcp list http://localhost:8000/mcp +fastmcp list server.py +fastmcp list mcp.json --json +fastmcp list --command 'npx -y @mcp/server' --resources +fastmcp list http://server/mcp --transport sse + + +### `call_command` + +```python +call_command(server_spec: Annotated[str | None, cyclopts.Parameter(help='Server URL, Python file, MCPConfig JSON, or .js file')] = None, target: Annotated[str, cyclopts.Parameter(help='Tool name, resource URI, or prompt name (with --prompt)')] = '', *arguments: str) -> None +``` + + +Call a tool, read a resource, or get a prompt on an MCP server. + +By default the target is treated as a tool name. If the target +contains ``://`` it is treated as a resource URI. Pass ``--prompt`` +to treat it as a prompt name. + +Arguments are passed as key=value pairs. Use --input-json for complex +or nested arguments. + +**Examples:** + +``` +fastmcp call server.py greet name=World +fastmcp call server.py resource://docs/readme +fastmcp call server.py analyze --prompt data='[1,2,3]' +fastmcp call http://server/mcp create --input-json '{"tags": ["a","b"]}' +``` + + +### `discover_command` + +```python +discover_command() -> None +``` + + +Discover MCP servers configured in editor and project configs. + +Scans Claude Desktop, Claude Code, Cursor, Gemini CLI, Goose, and +project-level mcp.json files for MCP server definitions. + +Discovered server names can be used directly with ``fastmcp list`` +and ``fastmcp call`` instead of specifying a URL or file path. + +**Examples:** + +fastmcp discover +fastmcp discover --source claude-code +fastmcp discover --source cursor --source gemini --json +fastmcp list weather +fastmcp call cursor:weather get_forecast city=London + diff --git a/docs/python-sdk/fastmcp-cli-discovery.mdx b/docs/python-sdk/fastmcp-cli-discovery.mdx new file mode 100644 index 000000000..5892df9af --- /dev/null +++ b/docs/python-sdk/fastmcp-cli-discovery.mdx @@ -0,0 +1,71 @@ +--- +title: discovery +sidebarTitle: discovery +--- + +# `fastmcp.cli.discovery` + + +Discover MCP servers configured in editor config files. + +Scans filesystem-readable config files from editors like Claude Desktop, +Claude Code, Cursor, Gemini CLI, and Goose, as well as project-level +``mcp.json`` files. Each discovered server can be resolved by name +(or ``source:name``) so the CLI can connect without requiring a URL +or file path. + + +## Functions + +### `discover_servers` + +```python +discover_servers(start_dir: Path | None = None) -> list[DiscoveredServer] +``` + + +Run all scanners and return the combined results. + +Duplicate names across sources are preserved — callers can +use :pyattr:`DiscoveredServer.qualified_name` to disambiguate. + + +### `resolve_name` + +```python +resolve_name(name: str, start_dir: Path | None = None) -> ClientTransport +``` + + +Resolve a server name (or ``source:name``) to a transport. + +Raises :class:`ValueError` when the name is not found or is ambiguous. + + +## Classes + +### `DiscoveredServer` + + +A single MCP server found in an editor or project config. + + +**Methods:** + +#### `qualified_name` + +```python +qualified_name(self) -> str +``` + +Fully qualified ``source:name`` identifier. + + +#### `transport_summary` + +```python +transport_summary(self) -> str +``` + +Human-readable one-liner describing the transport. + diff --git a/docs/python-sdk/fastmcp-cli-generate.mdx b/docs/python-sdk/fastmcp-cli-generate.mdx new file mode 100644 index 000000000..ebedaa186 --- /dev/null +++ b/docs/python-sdk/fastmcp-cli-generate.mdx @@ -0,0 +1,66 @@ +--- +title: generate +sidebarTitle: generate +--- + +# `fastmcp.cli.generate` + + +Generate a standalone CLI script and agent skill from an MCP server. + +## Functions + +### `serialize_transport` + +```python +serialize_transport(resolved: str | dict[str, Any] | ClientTransport) -> tuple[str, set[str]] +``` + + +Serialize a resolved transport to a Python expression string. + +Returns ``(expression, extra_imports)`` where *extra_imports* is a set of +import lines needed by the expression. + + +### `generate_cli_script` + +```python +generate_cli_script(server_name: str, server_spec: str, transport_code: str, extra_imports: set[str], tools: list[mcp.types.Tool]) -> str +``` + + +Generate the full CLI script source code. + + +### `generate_skill_content` + +```python +generate_skill_content(server_name: str, cli_filename: str, tools: list[mcp.types.Tool]) -> str +``` + + +Generate a SKILL.md file for a generated CLI script. + + +### `generate_cli_command` + +```python +generate_cli_command(server_spec: Annotated[str, cyclopts.Parameter(help='Server URL, Python file, MCPConfig JSON, discovered name, or .js file')], output: Annotated[str, cyclopts.Parameter(help='Output file path (default: cli.py)')] = 'cli.py') -> None +``` + + +Generate a standalone CLI script from an MCP server. + +Connects to the server, reads its tools/resources/prompts, and writes +a Python script that can invoke them directly. Also generates a SKILL.md +agent skill file unless --no-skill is passed. + +**Examples:** + +fastmcp generate-cli weather +fastmcp generate-cli weather my_cli.py +fastmcp generate-cli http://localhost:8000/mcp +fastmcp generate-cli server.py output.py -f +fastmcp generate-cli weather --no-skill + diff --git a/docs/python-sdk/fastmcp-cli-install-__init__.mdx b/docs/python-sdk/fastmcp-cli-install-__init__.mdx new file mode 100644 index 000000000..3909565f2 --- /dev/null +++ b/docs/python-sdk/fastmcp-cli-install-__init__.mdx @@ -0,0 +1,9 @@ +--- +title: __init__ +sidebarTitle: __init__ +--- + +# `fastmcp.cli.install` + + +Install subcommands for FastMCP CLI using Cyclopts. diff --git a/docs/python-sdk/fastmcp-cli-install-claude_code.mdx b/docs/python-sdk/fastmcp-cli-install-claude_code.mdx new file mode 100644 index 000000000..0a3393077 --- /dev/null +++ b/docs/python-sdk/fastmcp-cli-install-claude_code.mdx @@ -0,0 +1,71 @@ +--- +title: claude_code +sidebarTitle: claude_code +--- + +# `fastmcp.cli.install.claude_code` + + +Claude Code integration for FastMCP install using Cyclopts. + +## Functions + +### `find_claude_command` + +```python +find_claude_command() -> str | None +``` + + +Find the Claude Code CLI command. + +Checks common installation locations since 'claude' is often a shell alias +that doesn't work with subprocess calls. + + +### `check_claude_code_available` + +```python +check_claude_code_available() -> bool +``` + + +Check if Claude Code CLI is available. + + +### `install_claude_code` + +```python +install_claude_code(file: Path, server_object: str | None, name: str) -> bool +``` + + +Install FastMCP server in Claude Code. + +**Args:** +- `file`: Path to the server file +- `server_object`: Optional server object name (for \:object suffix) +- `name`: Name for the server in Claude Code +- `with_editable`: Optional list of directories to install in editable mode +- `with_packages`: Optional list of additional packages to install +- `env_vars`: Optional dictionary of environment variables +- `python_version`: Optional Python version to use +- `with_requirements`: Optional requirements file to install from +- `project`: Optional project directory to run within + +**Returns:** +- True if installation was successful, False otherwise + + +### `claude_code_command` + +```python +claude_code_command(server_spec: str) -> None +``` + + +Install an MCP server in Claude Code. + +**Args:** +- `server_spec`: Python file to install, optionally with \:object suffix + diff --git a/docs/python-sdk/fastmcp-cli-install-claude_desktop.mdx b/docs/python-sdk/fastmcp-cli-install-claude_desktop.mdx new file mode 100644 index 000000000..23f7a1b27 --- /dev/null +++ b/docs/python-sdk/fastmcp-cli-install-claude_desktop.mdx @@ -0,0 +1,58 @@ +--- +title: claude_desktop +sidebarTitle: claude_desktop +--- + +# `fastmcp.cli.install.claude_desktop` + + +Claude Desktop integration for FastMCP install using Cyclopts. + +## Functions + +### `get_claude_config_path` + +```python +get_claude_config_path() -> Path | None +``` + + +Get the Claude config directory based on platform. + + +### `install_claude_desktop` + +```python +install_claude_desktop(file: Path, server_object: str | None, name: str) -> bool +``` + + +Install FastMCP server in Claude Desktop. + +**Args:** +- `file`: Path to the server file +- `server_object`: Optional server object name (for \:object suffix) +- `name`: Name for the server in Claude's config +- `with_editable`: Optional list of directories to install in editable mode +- `with_packages`: Optional list of additional packages to install +- `env_vars`: Optional dictionary of environment variables +- `python_version`: Optional Python version to use +- `with_requirements`: Optional requirements file to install from +- `project`: Optional project directory to run within + +**Returns:** +- True if installation was successful, False otherwise + + +### `claude_desktop_command` + +```python +claude_desktop_command(server_spec: str) -> None +``` + + +Install an MCP server in Claude Desktop. + +**Args:** +- `server_spec`: Python file to install, optionally with \:object suffix + diff --git a/docs/python-sdk/fastmcp-cli-install-cursor.mdx b/docs/python-sdk/fastmcp-cli-install-cursor.mdx new file mode 100644 index 000000000..a61bca0ff --- /dev/null +++ b/docs/python-sdk/fastmcp-cli-install-cursor.mdx @@ -0,0 +1,107 @@ +--- +title: cursor +sidebarTitle: cursor +--- + +# `fastmcp.cli.install.cursor` + + +Cursor integration for FastMCP install using Cyclopts. + +## Functions + +### `generate_cursor_deeplink` + +```python +generate_cursor_deeplink(server_name: str, server_config: StdioMCPServer) -> str +``` + + +Generate a Cursor deeplink for installing the MCP server. + +**Args:** +- `server_name`: Name of the server +- `server_config`: Server configuration + +**Returns:** +- Deeplink URL that can be clicked to install the server + + +### `open_deeplink` + +```python +open_deeplink(deeplink: str) -> bool +``` + + +Attempt to open a Cursor deeplink URL using the system's default handler. + +**Args:** +- `deeplink`: The deeplink URL to open + +**Returns:** +- True if the command succeeded, False otherwise + + +### `install_cursor_workspace` + +```python +install_cursor_workspace(file: Path, server_object: str | None, name: str, workspace_path: Path) -> bool +``` + + +Install FastMCP server to workspace-specific Cursor configuration. + +**Args:** +- `file`: Path to the server file +- `server_object`: Optional server object name (for \:object suffix) +- `name`: Name for the server in Cursor +- `workspace_path`: Path to the workspace directory +- `with_editable`: Optional list of directories to install in editable mode +- `with_packages`: Optional list of additional packages to install +- `env_vars`: Optional dictionary of environment variables +- `python_version`: Optional Python version to use +- `with_requirements`: Optional requirements file to install from +- `project`: Optional project directory to run within + +**Returns:** +- True if installation was successful, False otherwise + + +### `install_cursor` + +```python +install_cursor(file: Path, server_object: str | None, name: str) -> bool +``` + + +Install FastMCP server in Cursor. + +**Args:** +- `file`: Path to the server file +- `server_object`: Optional server object name (for \:object suffix) +- `name`: Name for the server in Cursor +- `with_editable`: Optional list of directories to install in editable mode +- `with_packages`: Optional list of additional packages to install +- `env_vars`: Optional dictionary of environment variables +- `python_version`: Optional Python version to use +- `with_requirements`: Optional requirements file to install from +- `project`: Optional project directory to run within +- `workspace`: Optional workspace directory for project-specific installation + +**Returns:** +- True if installation was successful, False otherwise + + +### `cursor_command` + +```python +cursor_command(server_spec: str) -> None +``` + + +Install an MCP server in Cursor. + +**Args:** +- `server_spec`: Python file to install, optionally with \:object suffix + diff --git a/docs/python-sdk/fastmcp-cli-install-gemini_cli.mdx b/docs/python-sdk/fastmcp-cli-install-gemini_cli.mdx new file mode 100644 index 000000000..9cb51f0f4 --- /dev/null +++ b/docs/python-sdk/fastmcp-cli-install-gemini_cli.mdx @@ -0,0 +1,68 @@ +--- +title: gemini_cli +sidebarTitle: gemini_cli +--- + +# `fastmcp.cli.install.gemini_cli` + + +Gemini CLI integration for FastMCP install using Cyclopts. + +## Functions + +### `find_gemini_command` + +```python +find_gemini_command() -> str | None +``` + + +Find the Gemini CLI command. + + +### `check_gemini_cli_available` + +```python +check_gemini_cli_available() -> bool +``` + + +Check if Gemini CLI is available. + + +### `install_gemini_cli` + +```python +install_gemini_cli(file: Path, server_object: str | None, name: str) -> bool +``` + + +Install FastMCP server in Gemini CLI. + +**Args:** +- `file`: Path to the server file +- `server_object`: Optional server object name (for \:object suffix) +- `name`: Name for the server in Gemini CLI +- `with_editable`: Optional list of directories to install in editable mode +- `with_packages`: Optional list of additional packages to install +- `env_vars`: Optional dictionary of environment variables +- `python_version`: Optional Python version to use +- `with_requirements`: Optional requirements file to install from +- `project`: Optional project directory to run within + +**Returns:** +- True if installation was successful, False otherwise + + +### `gemini_cli_command` + +```python +gemini_cli_command(server_spec: str) -> None +``` + + +Install an MCP server in Gemini CLI. + +**Args:** +- `server_spec`: Python file to install, optionally with \:object suffix + diff --git a/docs/python-sdk/fastmcp-cli-install-goose.mdx b/docs/python-sdk/fastmcp-cli-install-goose.mdx new file mode 100644 index 000000000..cd2a8cc9a --- /dev/null +++ b/docs/python-sdk/fastmcp-cli-install-goose.mdx @@ -0,0 +1,67 @@ +--- +title: goose +sidebarTitle: goose +--- + +# `fastmcp.cli.install.goose` + + +Goose integration for FastMCP install using Cyclopts. + +## Functions + +### `generate_goose_deeplink` + +```python +generate_goose_deeplink(name: str, command: str, args: list[str]) -> str +``` + + +Generate a Goose deeplink for installing an MCP extension. + +**Args:** +- `name`: Human-readable display name for the extension. +- `command`: The executable command (e.g. "uv"). +- `args`: Arguments to the command. +- `description`: Short description shown in Goose. + +**Returns:** +- A goose://extension?... deeplink URL. + + +### `install_goose` + +```python +install_goose(file: Path, server_object: str | None, name: str) -> bool +``` + + +Install FastMCP server in Goose via deeplink. + +**Args:** +- `file`: Path to the server file. +- `server_object`: Optional server object name (for \:object suffix). +- `name`: Name for the extension in Goose. +- `with_packages`: Optional list of additional packages to install. +- `python_version`: Optional Python version to use. + +**Returns:** +- True if installation was successful, False otherwise. + + +### `goose_command` + +```python +goose_command(server_spec: str) -> None +``` + + +Install an MCP server in Goose. + +Uses uvx to run the server. Environment variables are not included +in the deeplink; use `fastmcp install mcp-json` to generate a full +config for manual installation. + +**Args:** +- `server_spec`: Python file to install, optionally with \:object suffix + diff --git a/docs/python-sdk/fastmcp-cli-install-mcp_json.mdx b/docs/python-sdk/fastmcp-cli-install-mcp_json.mdx new file mode 100644 index 000000000..a9eca1e51 --- /dev/null +++ b/docs/python-sdk/fastmcp-cli-install-mcp_json.mdx @@ -0,0 +1,49 @@ +--- +title: mcp_json +sidebarTitle: mcp_json +--- + +# `fastmcp.cli.install.mcp_json` + + +MCP configuration JSON generation for FastMCP install using Cyclopts. + +## Functions + +### `install_mcp_json` + +```python +install_mcp_json(file: Path, server_object: str | None, name: str) -> bool +``` + + +Generate MCP configuration JSON for manual installation. + +**Args:** +- `file`: Path to the server file +- `server_object`: Optional server object name (for \:object suffix) +- `name`: Name for the server in MCP config +- `with_editable`: Optional list of directories to install in editable mode +- `with_packages`: Optional list of additional packages to install +- `env_vars`: Optional dictionary of environment variables +- `copy`: If True, copy to clipboard instead of printing to stdout +- `python_version`: Optional Python version to use +- `with_requirements`: Optional requirements file to install from +- `project`: Optional project directory to run within + +**Returns:** +- True if generation was successful, False otherwise + + +### `mcp_json_command` + +```python +mcp_json_command(server_spec: str) -> None +``` + + +Generate MCP configuration JSON for manual installation. + +**Args:** +- `server_spec`: Python file to install, optionally with \:object suffix + diff --git a/docs/python-sdk/fastmcp-cli-install-shared.mdx b/docs/python-sdk/fastmcp-cli-install-shared.mdx new file mode 100644 index 000000000..a1fe2119c --- /dev/null +++ b/docs/python-sdk/fastmcp-cli-install-shared.mdx @@ -0,0 +1,50 @@ +--- +title: shared +sidebarTitle: shared +--- + +# `fastmcp.cli.install.shared` + + +Shared utilities for install commands. + +## Functions + +### `parse_env_var` + +```python +parse_env_var(env_var: str) -> tuple[str, str] +``` + + +Parse environment variable string in format KEY=VALUE. + + +### `process_common_args` + +```python +process_common_args(server_spec: str, server_name: str | None, with_packages: list[str] | None, env_vars: list[str] | None, env_file: Path | None) -> tuple[Path, str | None, str, list[str], dict[str, str] | None] +``` + + +Process common arguments shared by all install commands. + +Handles both fastmcp.json config files and traditional file.py:object syntax. + + +### `open_deeplink` + +```python +open_deeplink(url: str) -> bool +``` + + +Attempt to open a deeplink URL using the system's default handler. + +**Args:** +- `url`: The deeplink URL to open. +- `expected_scheme`: The URL scheme to validate (e.g. "cursor", "goose"). + +**Returns:** +- True if the command succeeded, False otherwise. + diff --git a/docs/python-sdk/fastmcp-cli-install-stdio.mdx b/docs/python-sdk/fastmcp-cli-install-stdio.mdx new file mode 100644 index 000000000..62bdc8fde --- /dev/null +++ b/docs/python-sdk/fastmcp-cli-install-stdio.mdx @@ -0,0 +1,50 @@ +--- +title: stdio +sidebarTitle: stdio +--- + +# `fastmcp.cli.install.stdio` + + +Stdio command generation for FastMCP install using Cyclopts. + +## Functions + +### `install_stdio` + +```python +install_stdio(file: Path, server_object: str | None) -> bool +``` + + +Generate the stdio command for running a FastMCP server. + +**Args:** +- `file`: Path to the server file +- `server_object`: Optional server object name (for \:object suffix) +- `with_editable`: Optional list of directories to install in editable mode +- `with_packages`: Optional list of additional packages to install +- `copy`: If True, copy to clipboard instead of printing to stdout +- `python_version`: Optional Python version to use +- `with_requirements`: Optional requirements file to install from +- `project`: Optional project directory to run within + +**Returns:** +- True if generation was successful, False otherwise + + +### `stdio_command` + +```python +stdio_command(server_spec: str) -> None +``` + + +Generate the stdio command for running a FastMCP server. + +Outputs the shell command that an MCP host would use to start this server +over stdio transport. Useful for manual configuration or debugging. + +**Args:** +- `server_spec`: Python file to run, optionally with \:object suffix + diff --git a/docs/python-sdk/fastmcp-cli-run.mdx b/docs/python-sdk/fastmcp-cli-run.mdx new file mode 100644 index 000000000..0b341c459 --- /dev/null +++ b/docs/python-sdk/fastmcp-cli-run.mdx @@ -0,0 +1,136 @@ +--- +title: run +sidebarTitle: run +--- + +# `fastmcp.cli.run` + + +FastMCP run command implementation with enhanced type hints. + +## Functions + +### `is_url` + +```python +is_url(path: str) -> bool +``` + + +Check if a string is a URL. + + +### `create_client_server` + +```python +create_client_server(url: str) -> Any +``` + + +Create a FastMCP server from a client URL. + +**Args:** +- `url`: The URL to connect to + +**Returns:** +- A FastMCP server instance + + +### `create_mcp_config_server` + +```python +create_mcp_config_server(mcp_config_path: Path) -> FastMCP[None] +``` + + +Create a FastMCP server from a MCPConfig. + + +### `load_mcp_server_config` + +```python +load_mcp_server_config(config_path: Path) -> MCPServerConfig +``` + + +Load a FastMCP configuration from a fastmcp.json file. + +**Args:** +- `config_path`: Path to fastmcp.json file + +**Returns:** +- MCPServerConfig object + + +### `run_command` + +```python +run_command(server_spec: str, transport: TransportType | None = None, host: str | None = None, port: int | None = None, path: str | None = None, log_level: LogLevelType | None = None, server_args: list[str] | None = None, show_banner: bool = True, use_direct_import: bool = False, skip_source: bool = False, stateless: bool = False) -> None +``` + + +Run a MCP server or connect to a remote one. + +**Args:** +- `server_spec`: Python file, object specification (file\:obj), config file, or URL +- `transport`: Transport protocol to use +- `host`: Host to bind to when using http transport +- `port`: Port to bind to when using http transport +- `path`: Path to bind to when using http transport +- `log_level`: Log level +- `server_args`: Additional arguments to pass to the server +- `show_banner`: Whether to show the server banner +- `use_direct_import`: Whether to use direct import instead of subprocess +- `skip_source`: Whether to skip source preparation step +- `stateless`: Whether to run in stateless mode (no session) + + +### `run_module_command` + +```python +run_module_command(module_name: str) -> None +``` + + +Run a Python module directly using ``python -m ``. + +When ``-m`` is used, the module manages its own server startup. +No server-object discovery or transport overrides are applied. + +**Args:** +- `module_name`: Dotted module name (e.g. ``my_package``). +- `env_command_builder`: An optional callable that wraps a command list +with environment setup (e.g. ``UVEnvironment.build_command``). +- `extra_args`: Extra arguments forwarded after the module name. + + +### `run_v1_server_async` + +```python +run_v1_server_async(server: FastMCP1x, host: str | None = None, port: int | None = None, transport: TransportType | None = None) -> None +``` + + +Run a FastMCP 1.x server using async methods. + +**Args:** +- `server`: FastMCP 1.x server instance +- `host`: Host to bind to +- `port`: Port to bind to +- `transport`: Transport protocol to use + + +### `run_with_reload` + +```python +run_with_reload(cmd: list[str], reload_dirs: list[Path] | None = None, is_stdio: bool = False) -> None +``` + + +Run a command with file watching and auto-reload. + +**Args:** +- `cmd`: Command to run as subprocess (should include --no-reload) +- `reload_dirs`: Directories to watch for changes (default\: cwd) +- `is_stdio`: Whether this is stdio transport + diff --git a/docs/python-sdk/fastmcp-cli-tasks.mdx b/docs/python-sdk/fastmcp-cli-tasks.mdx new file mode 100644 index 000000000..99f5dac1f --- /dev/null +++ b/docs/python-sdk/fastmcp-cli-tasks.mdx @@ -0,0 +1,41 @@ +--- +title: tasks +sidebarTitle: tasks +--- + +# `fastmcp.cli.tasks` + + +FastMCP tasks CLI for Docket task management. + +## Functions + +### `check_distributed_backend` + +```python +check_distributed_backend() -> None +``` + + +Check if Docket is configured with a distributed backend. + +The CLI worker runs as a separate process, so it needs Redis/Valkey +to coordinate with the main server process. + +**Raises:** +- `SystemExit`: If using memory\:// URL + + +### `worker` + +```python +worker(server_spec: Annotated[str | None, cyclopts.Parameter(help='Python file to run, optionally with :object suffix, or None to auto-detect fastmcp.json')] = None) -> None +``` + + +Start an additional worker to process background tasks. + +Connects to your Docket backend and processes tasks in parallel with +any other running workers. Configure via environment variables +(FASTMCP_DOCKET_*). + diff --git a/docs/python-sdk/fastmcp-client-__init__.mdx b/docs/python-sdk/fastmcp-client-__init__.mdx new file mode 100644 index 000000000..bc145d4b7 --- /dev/null +++ b/docs/python-sdk/fastmcp-client-__init__.mdx @@ -0,0 +1,8 @@ +--- +title: __init__ +sidebarTitle: __init__ +--- + +# `fastmcp.client` + +*This module is empty or contains only private/internal implementations.* diff --git a/docs/python-sdk/fastmcp-client-auth-__init__.mdx b/docs/python-sdk/fastmcp-client-auth-__init__.mdx new file mode 100644 index 000000000..28242780d --- /dev/null +++ b/docs/python-sdk/fastmcp-client-auth-__init__.mdx @@ -0,0 +1,8 @@ +--- +title: __init__ +sidebarTitle: __init__ +--- + +# `fastmcp.client.auth` + +*This module is empty or contains only private/internal implementations.* diff --git a/docs/python-sdk/fastmcp-client-auth-bearer.mdx b/docs/python-sdk/fastmcp-client-auth-bearer.mdx new file mode 100644 index 000000000..a6a53a3a6 --- /dev/null +++ b/docs/python-sdk/fastmcp-client-auth-bearer.mdx @@ -0,0 +1,18 @@ +--- +title: bearer +sidebarTitle: bearer +--- + +# `fastmcp.client.auth.bearer` + +## Classes + +### `BearerAuth` + +**Methods:** + +#### `auth_flow` + +```python +auth_flow(self, request) +``` diff --git a/docs/python-sdk/fastmcp-client-auth-oauth.mdx b/docs/python-sdk/fastmcp-client-auth-oauth.mdx new file mode 100644 index 000000000..455ea1337 --- /dev/null +++ b/docs/python-sdk/fastmcp-client-auth-oauth.mdx @@ -0,0 +1,104 @@ +--- +title: oauth +sidebarTitle: oauth +--- + +# `fastmcp.client.auth.oauth` + +## Functions + +### `check_if_auth_required` + +```python +check_if_auth_required(mcp_url: str, httpx_kwargs: dict[str, Any] | None = None) -> bool +``` + + +Check if the MCP endpoint requires authentication by making a test request. + +**Returns:** +- True if auth appears to be required, False otherwise + + +## Classes + +### `ClientNotFoundError` + + +Raised when OAuth client credentials are not found on the server. + + +### `TokenStorageAdapter` + +**Methods:** + +#### `clear` + +```python +clear(self) -> None +``` + +#### `get_tokens` + +```python +get_tokens(self) -> OAuthToken | None +``` + +#### `set_tokens` + +```python +set_tokens(self, tokens: OAuthToken) -> None +``` + +#### `get_client_info` + +```python +get_client_info(self) -> OAuthClientInformationFull | None +``` + +#### `set_client_info` + +```python +set_client_info(self, client_info: OAuthClientInformationFull) -> None +``` + +### `OAuth` + + +OAuth client provider for MCP servers with browser-based authentication. + +This class provides OAuth authentication for FastMCP clients by opening +a browser for user authorization and running a local callback server. + + +**Methods:** + +#### `redirect_handler` + +```python +redirect_handler(self, authorization_url: str) -> None +``` + +Open browser for authorization, with pre-flight check for invalid client. + + +#### `callback_handler` + +```python +callback_handler(self) -> tuple[str, str | None] +``` + +Handle OAuth callback and return (auth_code, state). + + +#### `async_auth_flow` + +```python +async_auth_flow(self, request: httpx.Request) -> AsyncGenerator[httpx.Request, httpx.Response] +``` + +HTTPX auth flow with automatic retry on stale cached credentials. + +If the OAuth flow fails due to invalid/stale client credentials, +clears the cache and retries once with fresh registration. + diff --git a/docs/python-sdk/fastmcp-client-client.mdx b/docs/python-sdk/fastmcp-client-client.mdx new file mode 100644 index 000000000..6c3ac689a --- /dev/null +++ b/docs/python-sdk/fastmcp-client-client.mdx @@ -0,0 +1,286 @@ +--- +title: client +sidebarTitle: client +--- + +# `fastmcp.client.client` + +## Classes + +### `ClientSessionState` + + +Holds all session-related state for a Client instance. + +This allows clean separation of configuration (which is copied) from +session state (which should be fresh for each new client instance). + + +### `CallToolResult` + + +Parsed result from a tool call. + + +### `Client` + + +MCP client that delegates connection management to a Transport instance. + +The Client class is responsible for MCP protocol logic, while the Transport +handles connection establishment and management. Client provides methods for +working with resources, prompts, tools and other MCP capabilities. + +This client supports reentrant context managers (multiple concurrent +`async with client:` blocks) using reference counting and background session +management. This allows efficient session reuse in any scenario with +nested or concurrent client usage. + +MCP SDK 1.10 introduced automatic list_tools() calls during call_tool() +execution. This created a race condition where events could be reset while +other tasks were waiting on them, causing deadlocks. The issue was exposed +in proxy scenarios but affects any reentrant usage. + +The solution uses reference counting to track active context managers, +a background task to manage the session lifecycle, events to coordinate +between tasks, and ensures all session state changes happen within a lock. +Events are only created when needed, never reset outside locks. + +This design prevents race conditions where tasks wait on events that get +replaced by other tasks, ensuring reliable coordination in concurrent scenarios. + +**Args:** +- `transport`: +Connection source specification, which can be\: + + - ClientTransport\: Direct transport instance + - FastMCP\: In-process FastMCP server + - AnyUrl or str\: URL to connect to + - Path\: File path for local socket + - MCPConfig\: MCP server configuration + - dict\: Transport configuration +- `roots`: Optional RootsList or RootsHandler for filesystem access +- `sampling_handler`: Optional handler for sampling requests +- `log_handler`: Optional handler for log messages +- `message_handler`: Optional handler for protocol messages +- `progress_handler`: Optional handler for progress notifications +- `timeout`: Optional timeout for requests (seconds or timedelta) +- `init_timeout`: Optional timeout for initial connection (seconds or timedelta). +Set to 0 to disable. If None, uses the value in the FastMCP global settings. + +**Examples:** + +```python +# Connect to FastMCP server +client = Client("http://localhost:8080") + +async with client: + # List available resources + resources = await client.list_resources() + + # Call a tool + result = await client.call_tool("my_tool", {"param": "value"}) +``` + + +**Methods:** + +#### `session` + +```python +session(self) -> ClientSession +``` + +Get the current active session. Raises RuntimeError if not connected. + + +#### `initialize_result` + +```python +initialize_result(self) -> mcp.types.InitializeResult | None +``` + +Get the result of the initialization request. + + +#### `set_roots` + +```python +set_roots(self, roots: RootsList | RootsHandler) -> None +``` + +Set the roots for the client. This does not automatically call `send_roots_list_changed`. + + +#### `set_sampling_callback` + +```python +set_sampling_callback(self, sampling_callback: SamplingHandler, sampling_capabilities: mcp.types.SamplingCapability | None = None) -> None +``` + +Set the sampling callback for the client. + + +#### `set_elicitation_callback` + +```python +set_elicitation_callback(self, elicitation_callback: ElicitationHandler) -> None +``` + +Set the elicitation callback for the client. + + +#### `is_connected` + +```python +is_connected(self) -> bool +``` + +Check if the client is currently connected. + + +#### `new` + +```python +new(self) -> Client[ClientTransportT] +``` + +Create a new client instance with the same configuration but fresh session state. + +This creates a new client with the same transport, handlers, and configuration, +but with no active session. Useful for creating independent sessions that don't +share state with the original client. + +**Returns:** +- A new Client instance with the same configuration but disconnected state. + + +#### `initialize` + +```python +initialize(self, timeout: datetime.timedelta | float | int | None = None) -> mcp.types.InitializeResult +``` + +Send an initialize request to the server. + +This method performs the MCP initialization handshake with the server, +exchanging capabilities and server information. It is idempotent - calling +it multiple times returns the cached result from the first call. + +The initialization happens automatically when entering the client context +manager unless `auto_initialize=False` was set during client construction. +Manual calls to this method are only needed when auto-initialization is disabled. + +**Args:** +- `timeout`: Optional timeout for the initialization request (seconds or timedelta). +If None, uses the client's init_timeout setting. + +**Returns:** +- The server's initialization response containing server info, +capabilities, protocol version, and optional instructions. + +**Raises:** +- `RuntimeError`: If the client is not connected or initialization times out. + + +#### `close` + +```python +close(self) +``` + +#### `ping` + +```python +ping(self) -> bool +``` + +Send a ping request. + + +#### `cancel` + +```python +cancel(self, request_id: str | int, reason: str | None = None) -> None +``` + +Send a cancellation notification for an in-progress request. + + +#### `progress` + +```python +progress(self, progress_token: str | int, progress: float, total: float | None = None, message: str | None = None) -> None +``` + +Send a progress notification. + + +#### `set_logging_level` + +```python +set_logging_level(self, level: mcp.types.LoggingLevel) -> None +``` + +Send a logging/setLevel request. + + +#### `send_roots_list_changed` + +```python +send_roots_list_changed(self) -> None +``` + +Send a roots/list_changed notification. + + +#### `complete_mcp` + +```python +complete_mcp(self, ref: mcp.types.ResourceTemplateReference | mcp.types.PromptReference, argument: dict[str, str], context_arguments: dict[str, Any] | None = None) -> mcp.types.CompleteResult +``` + +Send a completion request and return the complete MCP protocol result. + +**Args:** +- `ref`: The reference to complete. +- `argument`: Arguments to pass to the completion request. +- `context_arguments`: Optional context arguments to +include with the completion request. Defaults to None. + +**Returns:** +- mcp.types.CompleteResult: The complete response object from the protocol, +containing the completion and any additional metadata. + +**Raises:** +- `RuntimeError`: If called while the client is not connected. +- `McpError`: If the request results in a TimeoutError | JSONRPCError + + +#### `complete` + +```python +complete(self, ref: mcp.types.ResourceTemplateReference | mcp.types.PromptReference, argument: dict[str, str], context_arguments: dict[str, Any] | None = None) -> mcp.types.Completion +``` + +Send a completion request to the server. + +**Args:** +- `ref`: The reference to complete. +- `argument`: Arguments to pass to the completion request. +- `context_arguments`: Optional context arguments to +include with the completion request. Defaults to None. + +**Returns:** +- mcp.types.Completion: The completion object. + +**Raises:** +- `RuntimeError`: If called while the client is not connected. +- `McpError`: If the request results in a TimeoutError | JSONRPCError + + +#### `generate_name` + +```python +generate_name(cls, name: str | None = None) -> str +``` diff --git a/docs/python-sdk/fastmcp-client-elicitation.mdx b/docs/python-sdk/fastmcp-client-elicitation.mdx new file mode 100644 index 000000000..c9db14702 --- /dev/null +++ b/docs/python-sdk/fastmcp-client-elicitation.mdx @@ -0,0 +1,18 @@ +--- +title: elicitation +sidebarTitle: elicitation +--- + +# `fastmcp.client.elicitation` + +## Functions + +### `create_elicitation_callback` + +```python +create_elicitation_callback(elicitation_handler: ElicitationHandler) -> ElicitationFnT +``` + +## Classes + +### `ElicitResult` diff --git a/docs/python-sdk/fastmcp-client-logging.mdx b/docs/python-sdk/fastmcp-client-logging.mdx new file mode 100644 index 000000000..b9453a0be --- /dev/null +++ b/docs/python-sdk/fastmcp-client-logging.mdx @@ -0,0 +1,24 @@ +--- +title: logging +sidebarTitle: logging +--- + +# `fastmcp.client.logging` + +## Functions + +### `default_log_handler` + +```python +default_log_handler(message: LogMessage) -> None +``` + + +Default handler that properly routes server log messages to appropriate log levels. + + +### `create_log_callback` + +```python +create_log_callback(handler: LogHandler | None = None) -> LoggingFnT +``` diff --git a/docs/python-sdk/fastmcp-client-messages.mdx b/docs/python-sdk/fastmcp-client-messages.mdx new file mode 100644 index 000000000..fde8f0cde --- /dev/null +++ b/docs/python-sdk/fastmcp-client-messages.mdx @@ -0,0 +1,107 @@ +--- +title: messages +sidebarTitle: messages +--- + +# `fastmcp.client.messages` + +## Classes + +### `MessageHandler` + + +This class is used to handle MCP messages sent to the client. It is used to handle all messages, +requests, notifications, and exceptions. Users can override any of the hooks + + +**Methods:** + +#### `dispatch` + +```python +dispatch(self, message: Message) -> None +``` + +#### `on_message` + +```python +on_message(self, message: Message) -> None +``` + +#### `on_request` + +```python +on_request(self, message: RequestResponder[mcp.types.ServerRequest, mcp.types.ClientResult]) -> None +``` + +#### `on_ping` + +```python +on_ping(self, message: mcp.types.PingRequest) -> None +``` + +#### `on_list_roots` + +```python +on_list_roots(self, message: mcp.types.ListRootsRequest) -> None +``` + +#### `on_create_message` + +```python +on_create_message(self, message: mcp.types.CreateMessageRequest) -> None +``` + +#### `on_notification` + +```python +on_notification(self, message: mcp.types.ServerNotification) -> None +``` + +#### `on_exception` + +```python +on_exception(self, message: Exception) -> None +``` + +#### `on_progress` + +```python +on_progress(self, message: mcp.types.ProgressNotification) -> None +``` + +#### `on_logging_message` + +```python +on_logging_message(self, message: mcp.types.LoggingMessageNotification) -> None +``` + +#### `on_tool_list_changed` + +```python +on_tool_list_changed(self, message: mcp.types.ToolListChangedNotification) -> None +``` + +#### `on_resource_list_changed` + +```python +on_resource_list_changed(self, message: mcp.types.ResourceListChangedNotification) -> None +``` + +#### `on_prompt_list_changed` + +```python +on_prompt_list_changed(self, message: mcp.types.PromptListChangedNotification) -> None +``` + +#### `on_resource_updated` + +```python +on_resource_updated(self, message: mcp.types.ResourceUpdatedNotification) -> None +``` + +#### `on_cancelled` + +```python +on_cancelled(self, message: mcp.types.CancelledNotification) -> None +``` diff --git a/docs/python-sdk/fastmcp-client-mixins-__init__.mdx b/docs/python-sdk/fastmcp-client-mixins-__init__.mdx new file mode 100644 index 000000000..bc0e32a4c --- /dev/null +++ b/docs/python-sdk/fastmcp-client-mixins-__init__.mdx @@ -0,0 +1,9 @@ +--- +title: __init__ +sidebarTitle: __init__ +--- + +# `fastmcp.client.mixins` + + +Client mixins for FastMCP. diff --git a/docs/python-sdk/fastmcp-client-mixins-prompts.mdx b/docs/python-sdk/fastmcp-client-mixins-prompts.mdx new file mode 100644 index 000000000..3931c03db --- /dev/null +++ b/docs/python-sdk/fastmcp-client-mixins-prompts.mdx @@ -0,0 +1,119 @@ +--- +title: prompts +sidebarTitle: prompts +--- + +# `fastmcp.client.mixins.prompts` + + +Prompt-related methods for FastMCP Client. + +## Classes + +### `ClientPromptsMixin` + + +Mixin providing prompt-related methods for Client. + + +**Methods:** + +#### `list_prompts_mcp` + +```python +list_prompts_mcp(self: Client) -> mcp.types.ListPromptsResult +``` + +Send a prompts/list request and return the complete MCP protocol result. + +**Args:** +- `cursor`: Optional pagination cursor from a previous request's nextCursor. + +**Returns:** +- mcp.types.ListPromptsResult: The complete response object from the protocol, +containing the list of prompts and any additional metadata. + +**Raises:** +- `RuntimeError`: If called while the client is not connected. +- `McpError`: If the request results in a TimeoutError | JSONRPCError + + +#### `list_prompts` + +```python +list_prompts(self: Client) -> list[mcp.types.Prompt] +``` + +Retrieve all prompts available on the server. + +This method automatically fetches all pages if the server paginates results, +returning the complete list. For manual pagination control (e.g., to handle +large result sets incrementally), use list_prompts_mcp() with the cursor parameter. + +**Returns:** +- list\[mcp.types.Prompt]: A list of all Prompt objects. + +**Raises:** +- `RuntimeError`: If called while the client is not connected. +- `McpError`: If the request results in a TimeoutError | JSONRPCError + + +#### `get_prompt_mcp` + +```python +get_prompt_mcp(self: Client, name: str, arguments: dict[str, Any] | None = None, meta: dict[str, Any] | None = None) -> mcp.types.GetPromptResult +``` + +Send a prompts/get request and return the complete MCP protocol result. + +**Args:** +- `name`: The name of the prompt to retrieve. +- `arguments`: Arguments to pass to the prompt. Defaults to None. +- `meta`: Request metadata (e.g., for SEP-1686 tasks). Defaults to None. + +**Returns:** +- mcp.types.GetPromptResult: The complete response object from the protocol, +containing the prompt messages and any additional metadata. + +**Raises:** +- `RuntimeError`: If called while the client is not connected. +- `McpError`: If the request results in a TimeoutError | JSONRPCError + + +#### `get_prompt` + +```python +get_prompt(self: Client, name: str, arguments: dict[str, Any] | None = None) -> mcp.types.GetPromptResult +``` + +#### `get_prompt` + +```python +get_prompt(self: Client, name: str, arguments: dict[str, Any] | None = None) -> PromptTask +``` + +#### `get_prompt` + +```python +get_prompt(self: Client, name: str, arguments: dict[str, Any] | None = None) -> mcp.types.GetPromptResult | PromptTask +``` + +Retrieve a rendered prompt message list from the server. + +**Args:** +- `name`: The name of the prompt to retrieve. +- `arguments`: Arguments to pass to the prompt. Defaults to None. +- `version`: Specific prompt version to get. If None, gets highest version. +- `meta`: Optional request-level metadata. +- `task`: If True, execute as background task (SEP-1686). Defaults to False. +- `task_id`: Optional client-provided task ID (auto-generated if not provided). +- `ttl`: Time to keep results available in milliseconds (default 60s). + +**Returns:** +- mcp.types.GetPromptResult | PromptTask: The complete response object if task=False, +or a PromptTask object if task=True. + +**Raises:** +- `RuntimeError`: If called while the client is not connected. +- `McpError`: If the request results in a TimeoutError | JSONRPCError + diff --git a/docs/python-sdk/fastmcp-client-mixins-resources.mdx b/docs/python-sdk/fastmcp-client-mixins-resources.mdx new file mode 100644 index 000000000..655101ac3 --- /dev/null +++ b/docs/python-sdk/fastmcp-client-mixins-resources.mdx @@ -0,0 +1,158 @@ +--- +title: resources +sidebarTitle: resources +--- + +# `fastmcp.client.mixins.resources` + + +Resource-related methods for FastMCP Client. + +## Classes + +### `ClientResourcesMixin` + + +Mixin providing resource-related methods for Client. + + +**Methods:** + +#### `list_resources_mcp` + +```python +list_resources_mcp(self: Client) -> mcp.types.ListResourcesResult +``` + +Send a resources/list request and return the complete MCP protocol result. + +**Args:** +- `cursor`: Optional pagination cursor from a previous request's nextCursor. + +**Returns:** +- mcp.types.ListResourcesResult: The complete response object from the protocol, +containing the list of resources and any additional metadata. + +**Raises:** +- `RuntimeError`: If called while the client is not connected. +- `McpError`: If the request results in a TimeoutError | JSONRPCError + + +#### `list_resources` + +```python +list_resources(self: Client) -> list[mcp.types.Resource] +``` + +Retrieve all resources available on the server. + +This method automatically fetches all pages if the server paginates results, +returning the complete list. For manual pagination control (e.g., to handle +large result sets incrementally), use list_resources_mcp() with the cursor parameter. + +**Returns:** +- list\[mcp.types.Resource]: A list of all Resource objects. + +**Raises:** +- `RuntimeError`: If called while the client is not connected. +- `McpError`: If the request results in a TimeoutError | JSONRPCError + + +#### `list_resource_templates_mcp` + +```python +list_resource_templates_mcp(self: Client) -> mcp.types.ListResourceTemplatesResult +``` + +Send a resources/listResourceTemplates request and return the complete MCP protocol result. + +**Args:** +- `cursor`: Optional pagination cursor from a previous request's nextCursor. + +**Returns:** +- mcp.types.ListResourceTemplatesResult: The complete response object from the protocol, +containing the list of resource templates and any additional metadata. + +**Raises:** +- `RuntimeError`: If called while the client is not connected. +- `McpError`: If the request results in a TimeoutError | JSONRPCError + + +#### `list_resource_templates` + +```python +list_resource_templates(self: Client) -> list[mcp.types.ResourceTemplate] +``` + +Retrieve all resource templates available on the server. + +This method automatically fetches all pages if the server paginates results, +returning the complete list. For manual pagination control (e.g., to handle +large result sets incrementally), use list_resource_templates_mcp() with the +cursor parameter. + +**Returns:** +- list\[mcp.types.ResourceTemplate]: A list of all ResourceTemplate objects. + +**Raises:** +- `RuntimeError`: If called while the client is not connected. +- `McpError`: If the request results in a TimeoutError | JSONRPCError + + +#### `read_resource_mcp` + +```python +read_resource_mcp(self: Client, uri: AnyUrl | str, meta: dict[str, Any] | None = None) -> mcp.types.ReadResourceResult +``` + +Send a resources/read request and return the complete MCP protocol result. + +**Args:** +- `uri`: The URI of the resource to read. Can be a string or an AnyUrl object. +- `meta`: Request metadata (e.g., for SEP-1686 tasks). Defaults to None. + +**Returns:** +- mcp.types.ReadResourceResult: The complete response object from the protocol, +containing the resource contents and any additional metadata. + +**Raises:** +- `RuntimeError`: If called while the client is not connected. +- `McpError`: If the request results in a TimeoutError | JSONRPCError + + +#### `read_resource` + +```python +read_resource(self: Client, uri: AnyUrl | str) -> list[mcp.types.TextResourceContents | mcp.types.BlobResourceContents] +``` + +#### `read_resource` + +```python +read_resource(self: Client, uri: AnyUrl | str) -> ResourceTask +``` + +#### `read_resource` + +```python +read_resource(self: Client, uri: AnyUrl | str) -> list[mcp.types.TextResourceContents | mcp.types.BlobResourceContents] | ResourceTask +``` + +Read the contents of a resource or resolved template. + +**Args:** +- `uri`: The URI of the resource to read. Can be a string or an AnyUrl object. +- `version`: Specific version to read. If None, reads highest version. +- `meta`: Optional request-level metadata. +- `task`: If True, execute as background task (SEP-1686). Defaults to False. +- `task_id`: Optional client-provided task ID (auto-generated if not provided). +- `ttl`: Time to keep results available in milliseconds (default 60s). + +**Returns:** +- list\[mcp.types.TextResourceContents | mcp.types.BlobResourceContents] | ResourceTask: +A list of content objects if task=False, or a ResourceTask object if task=True. + +**Raises:** +- `RuntimeError`: If called while the client is not connected. +- `McpError`: If the request results in a TimeoutError | JSONRPCError + diff --git a/docs/python-sdk/fastmcp-client-mixins-task_management.mdx b/docs/python-sdk/fastmcp-client-mixins-task_management.mdx new file mode 100644 index 000000000..90d6d18b8 --- /dev/null +++ b/docs/python-sdk/fastmcp-client-mixins-task_management.mdx @@ -0,0 +1,110 @@ +--- +title: task_management +sidebarTitle: task_management +--- + +# `fastmcp.client.mixins.task_management` + + +Task management methods for FastMCP Client. + +## Classes + +### `ClientTaskManagementMixin` + + +Mixin providing task management methods for Client. + + +**Methods:** + +#### `get_task_status` + +```python +get_task_status(self: Client, task_id: str) -> GetTaskResult +``` + +Query the status of a background task. + +Sends a 'tasks/get' MCP protocol request over the existing transport. + +**Args:** +- `task_id`: The task ID returned from call_tool_as_task + +**Returns:** +- Status information including taskId, status, pollInterval, etc. + +**Raises:** +- `RuntimeError`: If client not connected +- `McpError`: If the request results in a TimeoutError | JSONRPCError + + +#### `get_task_result` + +```python +get_task_result(self: Client, task_id: str) -> Any +``` + +Retrieve the raw result of a completed background task. + +Sends a 'tasks/result' MCP protocol request over the existing transport. +Returns the raw result - callers should parse it appropriately. + +**Args:** +- `task_id`: The task ID returned from call_tool_as_task + +**Returns:** +- The raw result (could be tool, prompt, or resource result) + +**Raises:** +- `RuntimeError`: If client not connected, task not found, or task failed +- `McpError`: If the request results in a TimeoutError | JSONRPCError + + +#### `list_tasks` + +```python +list_tasks(self: Client, cursor: str | None = None, limit: int = 50) -> dict[str, Any] +``` + +List background tasks. + +Sends a 'tasks/list' MCP protocol request to the server. If the server +returns an empty list (indicating client-side tracking), falls back to +querying status for locally tracked task IDs. + +**Args:** +- `cursor`: Optional pagination cursor +- `limit`: Maximum number of tasks to return (default 50) + +**Returns:** +- Response with structure: +- tasks: List of task status dicts with taskId, status, etc. +- nextCursor: Optional cursor for next page + +**Raises:** +- `RuntimeError`: If client not connected +- `McpError`: If the request results in a TimeoutError | JSONRPCError + + +#### `cancel_task` + +```python +cancel_task(self: Client, task_id: str) -> mcp.types.CancelTaskResult +``` + +Cancel a task, transitioning it to cancelled state. + +Sends a 'tasks/cancel' MCP protocol request. Task will halt execution +and transition to cancelled state. + +**Args:** +- `task_id`: The task ID to cancel + +**Returns:** +- The task status showing cancelled state + +**Raises:** +- `RuntimeError`: If task doesn't exist +- `McpError`: If the request results in a TimeoutError | JSONRPCError + diff --git a/docs/python-sdk/fastmcp-client-mixins-tools.mdx b/docs/python-sdk/fastmcp-client-mixins-tools.mdx new file mode 100644 index 000000000..f048ed070 --- /dev/null +++ b/docs/python-sdk/fastmcp-client-mixins-tools.mdx @@ -0,0 +1,141 @@ +--- +title: tools +sidebarTitle: tools +--- + +# `fastmcp.client.mixins.tools` + + +Tool-related methods for FastMCP Client. + +## Classes + +### `ClientToolsMixin` + + +Mixin providing tool-related methods for Client. + + +**Methods:** + +#### `list_tools_mcp` + +```python +list_tools_mcp(self: Client) -> mcp.types.ListToolsResult +``` + +Send a tools/list request and return the complete MCP protocol result. + +**Args:** +- `cursor`: Optional pagination cursor from a previous request's nextCursor. + +**Returns:** +- mcp.types.ListToolsResult: The complete response object from the protocol, +containing the list of tools and any additional metadata. + +**Raises:** +- `RuntimeError`: If called while the client is not connected. +- `McpError`: If the request results in a TimeoutError | JSONRPCError + + +#### `list_tools` + +```python +list_tools(self: Client) -> list[mcp.types.Tool] +``` + +Retrieve all tools available on the server. + +This method automatically fetches all pages if the server paginates results, +returning the complete list. For manual pagination control (e.g., to handle +large result sets incrementally), use list_tools_mcp() with the cursor parameter. + +**Returns:** +- list\[mcp.types.Tool]: A list of all Tool objects. + +**Raises:** +- `RuntimeError`: If called while the client is not connected. +- `McpError`: If the request results in a TimeoutError | JSONRPCError + + +#### `call_tool_mcp` + +```python +call_tool_mcp(self: Client, name: str, arguments: dict[str, Any], progress_handler: ProgressHandler | None = None, timeout: datetime.timedelta | float | int | None = None, meta: dict[str, Any] | None = None) -> mcp.types.CallToolResult +``` + +Send a tools/call request and return the complete MCP protocol result. + +This method returns the raw CallToolResult object, which includes an isError flag +and other metadata. It does not raise an exception if the tool call results in an error. + +**Args:** +- `name`: The name of the tool to call. +- `arguments`: Arguments to pass to the tool. +- `timeout`: The timeout for the tool call. Defaults to None. +- `progress_handler`: The progress handler to use for the tool call. Defaults to None. +- `meta`: Additional metadata to include with the request. +This is useful for passing contextual information (like user IDs, trace IDs, or preferences) +that shouldn't be tool arguments but may influence server-side processing. The server +can access this via `context.request_context.meta`. Defaults to None. + +**Returns:** +- mcp.types.CallToolResult: The complete response object from the protocol, +containing the tool result and any additional metadata. + +**Raises:** +- `RuntimeError`: If called while the client is not connected. +- `McpError`: If the tool call requests results in a TimeoutError | JSONRPCError + + +#### `call_tool` + +```python +call_tool(self: Client, name: str, arguments: dict[str, Any] | None = None) -> CallToolResult +``` + +#### `call_tool` + +```python +call_tool(self: Client, name: str, arguments: dict[str, Any] | None = None) -> ToolTask +``` + +#### `call_tool` + +```python +call_tool(self: Client, name: str, arguments: dict[str, Any] | None = None) -> CallToolResult | ToolTask +``` + +Call a tool on the server. + +Unlike call_tool_mcp, this method raises a ToolError if the tool call results in an error. + +**Args:** +- `name`: The name of the tool to call. +- `arguments`: Arguments to pass to the tool. Defaults to None. +- `version`: Specific tool version to call. If None, calls highest version. +- `timeout`: The timeout for the tool call. Defaults to None. +- `progress_handler`: The progress handler to use for the tool call. Defaults to None. +- `raise_on_error`: Whether to raise an exception if the tool call results in an error. Defaults to True. +- `meta`: Additional metadata to include with the request. +This is useful for passing contextual information (like user IDs, trace IDs, or preferences) +that shouldn't be tool arguments but may influence server-side processing. The server +can access this via `context.request_context.meta`. Defaults to None. +- `task`: If True, execute as background task (SEP-1686). Defaults to False. +- `task_id`: Optional client-provided task ID (auto-generated if not provided). +- `ttl`: Time to keep results available in milliseconds (default 60s). + +**Returns:** +- CallToolResult | ToolTask: The content returned by the tool if task=False, +or a ToolTask object if task=True. If the tool returns structured +outputs, they are returned as a dataclass (if an output schema +is available) or a dictionary; otherwise, a list of content +blocks is returned. Note: to receive both structured and +unstructured outputs, use call_tool_mcp instead and access the +raw result object. + +**Raises:** +- `ToolError`: If the tool call results in an error. +- `McpError`: If the tool call request results in a TimeoutError | JSONRPCError +- `RuntimeError`: If called while the client is not connected. + diff --git a/docs/python-sdk/fastmcp-client-oauth_callback.mdx b/docs/python-sdk/fastmcp-client-oauth_callback.mdx new file mode 100644 index 000000000..c3e3e84fb --- /dev/null +++ b/docs/python-sdk/fastmcp-client-oauth_callback.mdx @@ -0,0 +1,70 @@ +--- +title: oauth_callback +sidebarTitle: oauth_callback +--- + +# `fastmcp.client.oauth_callback` + + + +OAuth callback server for handling authorization code flows. + +This module provides a reusable callback server that can handle OAuth redirects +and display styled responses to users. + + +## Functions + +### `create_callback_html` + +```python +create_callback_html(message: str, is_success: bool = True, title: str = 'FastMCP OAuth', server_url: str | None = None) -> str +``` + + +Create a styled HTML response for OAuth callbacks. + + +### `create_oauth_callback_server` + +```python +create_oauth_callback_server(port: int, callback_path: str = '/callback', server_url: str | None = None, result_container: OAuthCallbackResult | None = None, result_ready: anyio.Event | None = None) -> Server +``` + + +Create an OAuth callback server. + +**Args:** +- `port`: The port to run the server on +- `callback_path`: The path to listen for OAuth redirects on +- `server_url`: Optional server URL to display in success messages +- `result_container`: Optional container to store callback results +- `result_ready`: Optional event to signal when callback is received + +**Returns:** +- Configured uvicorn Server instance (not yet running) + + +## Classes + +### `CallbackResponse` + +**Methods:** + +#### `from_dict` + +```python +from_dict(cls, data: dict[str, str]) -> CallbackResponse +``` + +#### `to_dict` + +```python +to_dict(self) -> dict[str, str] +``` + +### `OAuthCallbackResult` + + +Container for OAuth callback results, used with anyio.Event for async coordination. + diff --git a/docs/python-sdk/fastmcp-client-progress.mdx b/docs/python-sdk/fastmcp-client-progress.mdx new file mode 100644 index 000000000..884dab165 --- /dev/null +++ b/docs/python-sdk/fastmcp-client-progress.mdx @@ -0,0 +1,25 @@ +--- +title: progress +sidebarTitle: progress +--- + +# `fastmcp.client.progress` + +## Functions + +### `default_progress_handler` + +```python +default_progress_handler(progress: float, total: float | None, message: str | None) -> None +``` + + +Default handler for progress notifications. + +Logs progress updates at debug level, properly handling missing total or message values. + +**Args:** +- `progress`: Current progress value +- `total`: Optional total expected value +- `message`: Optional status message + diff --git a/docs/python-sdk/fastmcp-client-roots.mdx b/docs/python-sdk/fastmcp-client-roots.mdx new file mode 100644 index 000000000..8b429856a --- /dev/null +++ b/docs/python-sdk/fastmcp-client-roots.mdx @@ -0,0 +1,20 @@ +--- +title: roots +sidebarTitle: roots +--- + +# `fastmcp.client.roots` + +## Functions + +### `convert_roots_list` + +```python +convert_roots_list(roots: RootsList) -> list[mcp.types.Root] +``` + +### `create_roots_callback` + +```python +create_roots_callback(handler: RootsList | RootsHandler) -> ListRootsFnT +``` diff --git a/docs/python-sdk/fastmcp-client-sampling-__init__.mdx b/docs/python-sdk/fastmcp-client-sampling-__init__.mdx new file mode 100644 index 000000000..609853b1f --- /dev/null +++ b/docs/python-sdk/fastmcp-client-sampling-__init__.mdx @@ -0,0 +1,14 @@ +--- +title: __init__ +sidebarTitle: __init__ +--- + +# `fastmcp.client.sampling` + +## Functions + +### `create_sampling_callback` + +```python +create_sampling_callback(sampling_handler: SamplingHandler) -> SamplingFnT +``` diff --git a/docs/python-sdk/fastmcp-client-sampling-handlers-__init__.mdx b/docs/python-sdk/fastmcp-client-sampling-handlers-__init__.mdx new file mode 100644 index 000000000..43329b5e6 --- /dev/null +++ b/docs/python-sdk/fastmcp-client-sampling-handlers-__init__.mdx @@ -0,0 +1,8 @@ +--- +title: __init__ +sidebarTitle: __init__ +--- + +# `fastmcp.client.sampling.handlers` + +*This module is empty or contains only private/internal implementations.* diff --git a/docs/python-sdk/fastmcp-client-sampling-handlers-anthropic.mdx b/docs/python-sdk/fastmcp-client-sampling-handlers-anthropic.mdx new file mode 100644 index 000000000..976367c28 --- /dev/null +++ b/docs/python-sdk/fastmcp-client-sampling-handlers-anthropic.mdx @@ -0,0 +1,17 @@ +--- +title: anthropic +sidebarTitle: anthropic +--- + +# `fastmcp.client.sampling.handlers.anthropic` + + +Anthropic sampling handler for FastMCP. + +## Classes + +### `AnthropicSamplingHandler` + + +Sampling handler that uses the Anthropic API. + diff --git a/docs/python-sdk/fastmcp-client-sampling-handlers-google_genai.mdx b/docs/python-sdk/fastmcp-client-sampling-handlers-google_genai.mdx new file mode 100644 index 000000000..9681c3a4a --- /dev/null +++ b/docs/python-sdk/fastmcp-client-sampling-handlers-google_genai.mdx @@ -0,0 +1,17 @@ +--- +title: google_genai +sidebarTitle: google_genai +--- + +# `fastmcp.client.sampling.handlers.google_genai` + + +Google GenAI sampling handler with tool support for FastMCP 3.0. + +## Classes + +### `GoogleGenaiSamplingHandler` + + +Sampling handler that uses the Google GenAI API with tool support. + diff --git a/docs/python-sdk/fastmcp-client-sampling-handlers-openai.mdx b/docs/python-sdk/fastmcp-client-sampling-handlers-openai.mdx new file mode 100644 index 000000000..b291bbaa5 --- /dev/null +++ b/docs/python-sdk/fastmcp-client-sampling-handlers-openai.mdx @@ -0,0 +1,17 @@ +--- +title: openai +sidebarTitle: openai +--- + +# `fastmcp.client.sampling.handlers.openai` + + +OpenAI sampling handler for FastMCP. + +## Classes + +### `OpenAISamplingHandler` + + +Sampling handler that uses the OpenAI API. + diff --git a/docs/python-sdk/fastmcp-client-tasks.mdx b/docs/python-sdk/fastmcp-client-tasks.mdx new file mode 100644 index 000000000..547d9bc92 --- /dev/null +++ b/docs/python-sdk/fastmcp-client-tasks.mdx @@ -0,0 +1,219 @@ +--- +title: tasks +sidebarTitle: tasks +--- + +# `fastmcp.client.tasks` + + +SEP-1686 client Task classes. + +## Classes + +### `TaskNotificationHandler` + + +MessageHandler that routes task status notifications to Task objects. + + +**Methods:** + +#### `dispatch` + +```python +dispatch(self, message: Message) -> None +``` + +Dispatch messages, including task status notifications. + + +### `Task` + + +Abstract base class for MCP background tasks (SEP-1686). + +Provides a uniform API whether the server accepts background execution +or executes synchronously (graceful degradation per SEP-1686). + + +**Methods:** + +#### `task_id` + +```python +task_id(self) -> str +``` + +Get the task ID. + + +#### `returned_immediately` + +```python +returned_immediately(self) -> bool +``` + +Check if server executed the task immediately. + +**Returns:** +- True if server executed synchronously (graceful degradation or no task support) +- False if server accepted background execution + + +#### `on_status_change` + +```python +on_status_change(self, callback: Callable[[GetTaskResult], None | Awaitable[None]]) -> None +``` + +Register callback for status change notifications. + +The callback will be invoked when a notifications/tasks/status is received +for this task (optional server feature per SEP-1686 lines 436-444). + +Supports both sync and async callbacks (auto-detected). + +**Args:** +- `callback`: Function to call with GetTaskResult when status changes. + Can return None (sync) or Awaitable[None] (async). + + +#### `status` + +```python +status(self) -> GetTaskResult +``` + +Get current task status. + +If server executed immediately, returns synthetic completed status. +Otherwise queries the server for current status. + + +#### `result` + +```python +result(self) -> TaskResultT +``` + +Wait for and return the task result. + +Must be implemented by subclasses to return the appropriate result type. + + +#### `wait` + +```python +wait(self) -> GetTaskResult +``` + +Wait for task to reach a specific state or complete. + +Uses event-based waiting when notifications are available (fast), +with fallback to polling (reliable). Optimally wakes up immediately +on status changes when server sends notifications/tasks/status. + +**Args:** +- `state`: Desired state ('submitted', 'working', 'completed', 'failed'). + If None, waits for any terminal state (completed/failed) +- `timeout`: Maximum time to wait in seconds + +**Returns:** +- Final task status + +**Raises:** +- `TimeoutError`: If desired state not reached within timeout + + +#### `cancel` + +```python +cancel(self) -> None +``` + +Cancel this task, transitioning it to cancelled state. + +Sends a tasks/cancel protocol request. The server will attempt to halt +execution and move the task to cancelled state. + +Note: If server executed immediately (graceful degradation), this is a no-op +as there's no server-side task to cancel. + + +### `ToolTask` + + +Represents a tool call that may execute in background or immediately. + +Provides a uniform API whether the server accepts background execution +or executes synchronously (graceful degradation per SEP-1686). + + +**Methods:** + +#### `result` + +```python +result(self) -> CallToolResult +``` + +Wait for and return the tool result. + +If server executed immediately, returns the immediate result. +Otherwise waits for background task to complete and retrieves result. + +**Returns:** +- The parsed tool result (same as call_tool returns) + + +### `PromptTask` + + +Represents a prompt call that may execute in background or immediately. + +Provides a uniform API whether the server accepts background execution +or executes synchronously (graceful degradation per SEP-1686). + + +**Methods:** + +#### `result` + +```python +result(self) -> mcp.types.GetPromptResult +``` + +Wait for and return the prompt result. + +If server executed immediately, returns the immediate result. +Otherwise waits for background task to complete and retrieves result. + +**Returns:** +- The prompt result with messages and description + + +### `ResourceTask` + + +Represents a resource read that may execute in background or immediately. + +Provides a uniform API whether the server accepts background execution +or executes synchronously (graceful degradation per SEP-1686). + + +**Methods:** + +#### `result` + +```python +result(self) -> list[mcp.types.TextResourceContents | mcp.types.BlobResourceContents] +``` + +Wait for and return the resource contents. + +If server executed immediately, returns the immediate result. +Otherwise waits for background task to complete and retrieves result. + +**Returns:** +- list\[ReadResourceContents]: The resource contents + diff --git a/docs/python-sdk/fastmcp-client-telemetry.mdx b/docs/python-sdk/fastmcp-client-telemetry.mdx new file mode 100644 index 000000000..9a1f8d260 --- /dev/null +++ b/docs/python-sdk/fastmcp-client-telemetry.mdx @@ -0,0 +1,23 @@ +--- +title: telemetry +sidebarTitle: telemetry +--- + +# `fastmcp.client.telemetry` + + +Client-side telemetry helpers. + +## Functions + +### `client_span` + +```python +client_span(name: str, method: str, component_key: str, session_id: str | None = None, resource_uri: str | None = None) -> Generator[Span, None, None] +``` + + +Create a CLIENT span with standard MCP attributes. + +Automatically records any exception on the span and sets error status. + diff --git a/docs/python-sdk/fastmcp-client-transports-__init__.mdx b/docs/python-sdk/fastmcp-client-transports-__init__.mdx new file mode 100644 index 000000000..1f9b02d38 --- /dev/null +++ b/docs/python-sdk/fastmcp-client-transports-__init__.mdx @@ -0,0 +1,8 @@ +--- +title: __init__ +sidebarTitle: __init__ +--- + +# `fastmcp.client.transports` + +*This module is empty or contains only private/internal implementations.* diff --git a/docs/python-sdk/fastmcp-client-transports-base.mdx b/docs/python-sdk/fastmcp-client-transports-base.mdx new file mode 100644 index 000000000..12c1848d2 --- /dev/null +++ b/docs/python-sdk/fastmcp-client-transports-base.mdx @@ -0,0 +1,62 @@ +--- +title: base +sidebarTitle: base +--- + +# `fastmcp.client.transports.base` + +## Classes + +### `SessionKwargs` + + +Keyword arguments for the MCP ClientSession constructor. + + +### `ClientTransport` + + +Abstract base class for different MCP client transport mechanisms. + +A Transport is responsible for establishing and managing connections +to an MCP server, and providing a ClientSession within an async context. + + +**Methods:** + +#### `connect_session` + +```python +connect_session(self, **session_kwargs: Unpack[SessionKwargs]) -> AsyncIterator[ClientSession] +``` + +Establishes a connection and yields an active ClientSession. + +The ClientSession is *not* expected to be initialized in this context manager. + +The session is guaranteed to be valid only within the scope of the +async context manager. Connection setup and teardown are handled +within this context. + +**Args:** +- `**session_kwargs`: Keyword arguments to pass to the ClientSession + constructor (e.g., callbacks, timeouts). + + +#### `close` + +```python +close(self) +``` + +Close the transport. + + +#### `get_session_id` + +```python +get_session_id(self) -> str | None +``` + +Get the session ID for this transport, if available. + diff --git a/docs/python-sdk/fastmcp-client-transports-config.mdx b/docs/python-sdk/fastmcp-client-transports-config.mdx new file mode 100644 index 000000000..7ad10e0df --- /dev/null +++ b/docs/python-sdk/fastmcp-client-transports-config.mdx @@ -0,0 +1,72 @@ +--- +title: config +sidebarTitle: config +--- + +# `fastmcp.client.transports.config` + +## Classes + +### `MCPConfigTransport` + + +Transport for connecting to one or more MCP servers defined in an MCPConfig. + +This transport provides a unified interface to multiple MCP servers defined in an MCPConfig +object or dictionary matching the MCPConfig schema. It supports two key scenarios: + +1. If the MCPConfig contains exactly one server, it creates a direct transport to that server. +2. If the MCPConfig contains multiple servers, it creates a composite client by mounting + all servers on a single FastMCP instance, with each server's name, by default, used as its mounting prefix. + +In the multiserver case, tools are accessible with the prefix pattern `{server_name}_{tool_name}` +and resources with the pattern `protocol://{server_name}/path/to/resource`. + +This is particularly useful for creating clients that need to interact with multiple specialized +MCP servers through a single interface, simplifying client code. + +**Examples:** + +```python +from fastmcp import Client + +# Create a config with multiple servers +config = { + "mcpServers": { + "weather": { + "url": "https://weather-api.example.com/mcp", + "transport": "http" + }, + "calendar": { + "url": "https://calendar-api.example.com/mcp", + "transport": "http" + } + } +} + +# Create a client with the config +client = Client(config) + +async with client: + # Access tools with prefixes + weather = await client.call_tool("weather_get_forecast", {"city": "London"}) + events = await client.call_tool("calendar_list_events", {"date": "2023-06-01"}) + + # Access resources with prefixed URIs + icons = await client.read_resource("weather://weather/icons/sunny") +``` + + +**Methods:** + +#### `connect_session` + +```python +connect_session(self, **session_kwargs: Unpack[SessionKwargs]) -> AsyncIterator[ClientSession] +``` + +#### `close` + +```python +close(self) +``` diff --git a/docs/python-sdk/fastmcp-client-transports-http.mdx b/docs/python-sdk/fastmcp-client-transports-http.mdx new file mode 100644 index 000000000..a3375240e --- /dev/null +++ b/docs/python-sdk/fastmcp-client-transports-http.mdx @@ -0,0 +1,37 @@ +--- +title: http +sidebarTitle: http +--- + +# `fastmcp.client.transports.http` + + +Streamable HTTP transport for FastMCP Client. + +## Classes + +### `StreamableHttpTransport` + + +Transport implementation that connects to an MCP server via Streamable HTTP Requests. + + +**Methods:** + +#### `connect_session` + +```python +connect_session(self, **session_kwargs: Unpack[SessionKwargs]) -> AsyncIterator[ClientSession] +``` + +#### `get_session_id` + +```python +get_session_id(self) -> str | None +``` + +#### `close` + +```python +close(self) +``` diff --git a/docs/python-sdk/fastmcp-client-transports-inference.mdx b/docs/python-sdk/fastmcp-client-transports-inference.mdx new file mode 100644 index 000000000..730f56845 --- /dev/null +++ b/docs/python-sdk/fastmcp-client-transports-inference.mdx @@ -0,0 +1,56 @@ +--- +title: inference +sidebarTitle: inference +--- + +# `fastmcp.client.transports.inference` + +## Functions + +### `infer_transport` + +```python +infer_transport(transport: ClientTransport | FastMCP | FastMCP1Server | AnyUrl | Path | MCPConfig | dict[str, Any] | str) -> ClientTransport +``` + + +Infer the appropriate transport type from the given transport argument. + +This function attempts to infer the correct transport type from the provided +argument, handling various input types and converting them to the appropriate +ClientTransport subclass. + +The function supports these input types: +- ClientTransport: Used directly without modification +- FastMCP or FastMCP1Server: Creates an in-memory FastMCPTransport +- Path or str (file path): Creates PythonStdioTransport (.py) or NodeStdioTransport (.js) +- AnyUrl or str (URL): Creates StreamableHttpTransport (default) or SSETransport (for /sse endpoints) +- MCPConfig or dict: Creates MCPConfigTransport, potentially connecting to multiple servers + +For HTTP URLs, they are assumed to be Streamable HTTP URLs unless they end in `/sse`. + +For MCPConfig with multiple servers, a composite client is created where each server +is mounted with its name as prefix. This allows accessing tools and resources from multiple +servers through a single unified client interface, using naming patterns like +`servername_toolname` for tools and `protocol://servername/path` for resources. +If the MCPConfig contains only one server, a direct connection is established without prefixing. + +**Examples:** + +```python +# Connect to a local Python script +transport = infer_transport("my_script.py") + +# Connect to a remote server via HTTP +transport = infer_transport("http://example.com/mcp") + +# Connect to multiple servers using MCPConfig +config = { + "mcpServers": { + "weather": {"url": "http://weather.example.com/mcp"}, + "calendar": {"url": "http://calendar.example.com/mcp"} + } +} +transport = infer_transport(config) +``` + diff --git a/docs/python-sdk/fastmcp-client-transports-memory.mdx b/docs/python-sdk/fastmcp-client-transports-memory.mdx new file mode 100644 index 000000000..b5887b8ca --- /dev/null +++ b/docs/python-sdk/fastmcp-client-transports-memory.mdx @@ -0,0 +1,27 @@ +--- +title: memory +sidebarTitle: memory +--- + +# `fastmcp.client.transports.memory` + +## Classes + +### `FastMCPTransport` + + +In-memory transport for FastMCP servers. + +This transport connects directly to a FastMCP server instance in the same +Python process. It works with both FastMCP 2.x servers and FastMCP 1.0 +servers from the low-level MCP SDK. This is particularly useful for unit +tests or scenarios where client and server run in the same runtime. + + +**Methods:** + +#### `connect_session` + +```python +connect_session(self, **session_kwargs: Unpack[SessionKwargs]) -> AsyncIterator[ClientSession] +``` diff --git a/docs/python-sdk/fastmcp-client-transports-sse.mdx b/docs/python-sdk/fastmcp-client-transports-sse.mdx new file mode 100644 index 000000000..59c145401 --- /dev/null +++ b/docs/python-sdk/fastmcp-client-transports-sse.mdx @@ -0,0 +1,25 @@ +--- +title: sse +sidebarTitle: sse +--- + +# `fastmcp.client.transports.sse` + + +Server-Sent Events (SSE) transport for FastMCP Client. + +## Classes + +### `SSETransport` + + +Transport implementation that connects to an MCP server via Server-Sent Events. + + +**Methods:** + +#### `connect_session` + +```python +connect_session(self, **session_kwargs: Unpack[SessionKwargs]) -> AsyncIterator[ClientSession] +``` diff --git a/docs/python-sdk/fastmcp-client-transports-stdio.mdx b/docs/python-sdk/fastmcp-client-transports-stdio.mdx new file mode 100644 index 000000000..eb7d98eb2 --- /dev/null +++ b/docs/python-sdk/fastmcp-client-transports-stdio.mdx @@ -0,0 +1,79 @@ +--- +title: stdio +sidebarTitle: stdio +--- + +# `fastmcp.client.transports.stdio` + +## Classes + +### `StdioTransport` + + +Base transport for connecting to an MCP server via subprocess with stdio. + +This is a base class that can be subclassed for specific command-based +transports like Python, Node, Uvx, etc. + + +**Methods:** + +#### `connect_session` + +```python +connect_session(self, **session_kwargs: Unpack[SessionKwargs]) -> AsyncIterator[ClientSession] +``` + +#### `connect` + +```python +connect(self, **session_kwargs: Unpack[SessionKwargs]) -> ClientSession | None +``` + +#### `disconnect` + +```python +disconnect(self) +``` + +#### `close` + +```python +close(self) +``` + +### `PythonStdioTransport` + + +Transport for running Python scripts. + + +### `FastMCPStdioTransport` + + +Transport for running FastMCP servers using the FastMCP CLI. + + +### `NodeStdioTransport` + + +Transport for running Node.js scripts. + + +### `UvStdioTransport` + + +Transport for running commands via the uv tool. + + +### `UvxStdioTransport` + + +Transport for running commands via the uvx tool. + + +### `NpxStdioTransport` + + +Transport for running commands via the npx tool. + diff --git a/docs/python-sdk/fastmcp-decorators.mdx b/docs/python-sdk/fastmcp-decorators.mdx new file mode 100644 index 000000000..c2cc11dbb --- /dev/null +++ b/docs/python-sdk/fastmcp-decorators.mdx @@ -0,0 +1,39 @@ +--- +title: decorators +sidebarTitle: decorators +--- + +# `fastmcp.decorators` + + +Shared decorator utilities for FastMCP. + +## Functions + +### `resolve_task_config` + +```python +resolve_task_config(task: bool | TaskConfig | None) -> bool | TaskConfig +``` + + +Resolve task config, defaulting None to False. + + +### `get_fastmcp_meta` + +```python +get_fastmcp_meta(fn: Any) -> Any | None +``` + + +Extract FastMCP metadata from a function, handling bound methods and wrappers. + + +## Classes + +### `HasFastMCPMeta` + + +Protocol for callables decorated with FastMCP metadata. + diff --git a/docs/python-sdk/fastmcp-dependencies.mdx b/docs/python-sdk/fastmcp-dependencies.mdx new file mode 100644 index 000000000..f27566ef3 --- /dev/null +++ b/docs/python-sdk/fastmcp-dependencies.mdx @@ -0,0 +1,17 @@ +--- +title: dependencies +sidebarTitle: dependencies +--- + +# `fastmcp.dependencies` + + +Dependency injection exports for FastMCP. + +This module re-exports dependency injection symbols to provide a clean, +centralized import location for all dependency-related functionality. + +DI features (Depends, CurrentContext, CurrentFastMCP) work without pydocket +using the uncalled-for DI engine. Only task-related dependencies (CurrentDocket, +CurrentWorker) and background task execution require fastmcp[tasks]. + diff --git a/docs/python-sdk/fastmcp-exceptions.mdx b/docs/python-sdk/fastmcp-exceptions.mdx new file mode 100644 index 000000000..d8f5a6871 --- /dev/null +++ b/docs/python-sdk/fastmcp-exceptions.mdx @@ -0,0 +1,71 @@ +--- +title: exceptions +sidebarTitle: exceptions +--- + +# `fastmcp.exceptions` + + +Custom exceptions for FastMCP. + +## Classes + +### `FastMCPError` + + +Base error for FastMCP. + + +### `ValidationError` + + +Error in validating parameters or return values. + + +### `ResourceError` + + +Error in resource operations. + + +### `ToolError` + + +Error in tool operations. + + +### `PromptError` + + +Error in prompt operations. + + +### `InvalidSignature` + + +Invalid signature for use with FastMCP. + + +### `ClientError` + + +Error in client operations. + + +### `NotFoundError` + + +Object not found. + + +### `DisabledError` + + +Object is disabled. + + +### `AuthorizationError` + + +Error when authorization check fails. + diff --git a/docs/python-sdk/fastmcp-experimental-__init__.mdx b/docs/python-sdk/fastmcp-experimental-__init__.mdx new file mode 100644 index 000000000..04ef31f33 --- /dev/null +++ b/docs/python-sdk/fastmcp-experimental-__init__.mdx @@ -0,0 +1,8 @@ +--- +title: __init__ +sidebarTitle: __init__ +--- + +# `fastmcp.experimental` + +*This module is empty or contains only private/internal implementations.* diff --git a/docs/python-sdk/fastmcp-experimental-sampling-__init__.mdx b/docs/python-sdk/fastmcp-experimental-sampling-__init__.mdx new file mode 100644 index 000000000..f37691267 --- /dev/null +++ b/docs/python-sdk/fastmcp-experimental-sampling-__init__.mdx @@ -0,0 +1,8 @@ +--- +title: __init__ +sidebarTitle: __init__ +--- + +# `fastmcp.experimental.sampling` + +*This module is empty or contains only private/internal implementations.* diff --git a/docs/python-sdk/fastmcp-experimental-sampling-handlers.mdx b/docs/python-sdk/fastmcp-experimental-sampling-handlers.mdx new file mode 100644 index 000000000..9220684bb --- /dev/null +++ b/docs/python-sdk/fastmcp-experimental-sampling-handlers.mdx @@ -0,0 +1,8 @@ +--- +title: handlers +sidebarTitle: handlers +--- + +# `fastmcp.experimental.sampling.handlers` + +*This module is empty or contains only private/internal implementations.* diff --git a/docs/python-sdk/fastmcp-experimental-transforms-__init__.mdx b/docs/python-sdk/fastmcp-experimental-transforms-__init__.mdx new file mode 100644 index 000000000..a33a00679 --- /dev/null +++ b/docs/python-sdk/fastmcp-experimental-transforms-__init__.mdx @@ -0,0 +1,8 @@ +--- +title: __init__ +sidebarTitle: __init__ +--- + +# `fastmcp.experimental.transforms` + +*This module is empty or contains only private/internal implementations.* diff --git a/docs/python-sdk/fastmcp-experimental-transforms-code_mode.mdx b/docs/python-sdk/fastmcp-experimental-transforms-code_mode.mdx new file mode 100644 index 000000000..0553029eb --- /dev/null +++ b/docs/python-sdk/fastmcp-experimental-transforms-code_mode.mdx @@ -0,0 +1,136 @@ +--- +title: code_mode +sidebarTitle: code_mode +--- + +# `fastmcp.experimental.transforms.code_mode` + +## Classes + +### `SandboxProvider` + + +Interface for executing LLM-generated Python code in a sandbox. + +WARNING: The ``code`` parameter passed to ``run`` contains untrusted, +LLM-generated Python. Implementations MUST execute it in an isolated +sandbox — never with plain ``exec()``. Use ``MontySandboxProvider`` +(backed by ``pydantic-monty``) for production workloads. + + +**Methods:** + +#### `run` + +```python +run(self, code: str) -> Any +``` + +### `MontySandboxProvider` + + +Sandbox provider backed by `pydantic-monty`. + +**Args:** +- `limits`: Resource limits for sandbox execution. Supported keys\: +``max_duration_secs`` (float), ``max_allocations`` (int), +``max_memory`` (int), ``max_recursion_depth`` (int), +``gc_interval`` (int). All are optional; omit a key to +leave that limit uncapped. + + +**Methods:** + +#### `run` + +```python +run(self, code: str) -> Any +``` + +### `Search` + + +Discovery tool factory that searches the catalog by query. + +**Args:** +- `search_fn`: Async callable ``(tools, query) -> matching_tools``. +Defaults to BM25 ranking. +- `name`: Name of the synthetic tool exposed to the LLM. +- `default_detail`: Default detail level for search results. +``"brief"`` returns tool names and descriptions only. +``"detailed"`` returns compact markdown with parameter schemas. +``"full"`` returns complete JSON tool definitions. +- `default_limit`: Maximum number of results to return. +The LLM can override this per call. ``None`` means no limit. + + +### `GetSchemas` + + +Discovery tool factory that returns schemas for tools by name. + +**Args:** +- `name`: Name of the synthetic tool exposed to the LLM. +- `default_detail`: Default detail level for schema results. +``"brief"`` returns tool names and descriptions only. +``"detailed"`` renders compact markdown with parameter names, +types, and required markers. +``"full"`` returns the complete JSON schema. + + +### `GetTags` + + +Discovery tool factory that lists tool tags from the catalog. + +Reads ``tool.tags`` from the catalog and groups tools by tag. Tools +without tags appear under ``"untagged"``. + +**Args:** +- `name`: Name of the synthetic tool exposed to the LLM. +- `default_detail`: Default detail level. +``"brief"`` returns tag names with tool counts. +``"full"`` lists all tools under each tag. + + +### `ListTools` + + +Discovery tool factory that lists all tools in the catalog. + +**Args:** +- `name`: Name of the synthetic tool exposed to the LLM. +- `default_detail`: Default detail level. +``"brief"`` returns tool names and one-line descriptions. +``"detailed"`` returns compact markdown with parameter schemas. +``"full"`` returns the complete JSON schema. + + +### `CodeMode` + + +Transform that collapses all tools into discovery + execute meta-tools. + +Discovery tools are composable via the ``discovery_tools`` parameter. +Each is a callable that receives catalog access and returns a ``Tool``. +By default, ``Search`` and ``GetSchemas`` are included for +progressive disclosure: search finds candidates, get_schema retrieves +parameter details, and execute runs code. + +The ``execute`` tool is always present and provides a sandboxed Python +environment with ``call_tool(name, params)`` in scope. + + +**Methods:** + +#### `transform_tools` + +```python +transform_tools(self, tools: Sequence[Tool]) -> Sequence[Tool] +``` + +#### `get_tool` + +```python +get_tool(self, name: str, call_next: GetToolNext) -> Tool | None +``` diff --git a/docs/python-sdk/fastmcp-mcp_config.mdx b/docs/python-sdk/fastmcp-mcp_config.mdx new file mode 100644 index 000000000..f7d8f6e26 --- /dev/null +++ b/docs/python-sdk/fastmcp-mcp_config.mdx @@ -0,0 +1,188 @@ +--- +title: mcp_config +sidebarTitle: mcp_config +--- + +# `fastmcp.mcp_config` + + +Canonical MCP Configuration Format. + +This module defines the standard configuration format for Model Context Protocol (MCP) servers. +It provides a client-agnostic, extensible format that can be used across all MCP implementations. + +The configuration format supports both stdio and remote (HTTP/SSE) transports, with comprehensive +field definitions for server metadata, authentication, and execution parameters. + +Example configuration: +```json +{ + "mcpServers": { + "my-server": { + "command": "npx", + "args": ["-y", "@my/mcp-server"], + "env": {"API_KEY": "secret"}, + "timeout": 30000, + "description": "My MCP server" + } + } +} +``` + + +## Functions + +### `infer_transport_type_from_url` + +```python +infer_transport_type_from_url(url: str | AnyUrl) -> Literal['http', 'sse'] +``` + + +Infer the appropriate transport type from the given URL. + + +### `update_config_file` + +```python +update_config_file(file_path: Path, server_name: str, server_config: CanonicalMCPServerTypes) -> None +``` + + +Update an MCP configuration file from a server object, preserving existing fields. + +This is used for updating the mcpServer configurations of third-party tools so we do not +worry about transforming server objects here. + + +## Classes + +### `StdioMCPServer` + + +MCP server configuration for stdio transport. + +This is the canonical configuration format for MCP servers using stdio transport. + + +**Methods:** + +#### `to_transport` + +```python +to_transport(self) -> StdioTransport +``` + +### `TransformingStdioMCPServer` + + +A Stdio server with tool transforms. + + +### `RemoteMCPServer` + + +MCP server configuration for HTTP/SSE transport. + +This is the canonical configuration format for MCP servers using remote transports. + + +**Methods:** + +#### `to_transport` + +```python +to_transport(self) -> StreamableHttpTransport | SSETransport +``` + +### `TransformingRemoteMCPServer` + + +A Remote server with tool transforms. + + +### `MCPConfig` + + +A configuration object for MCP Servers that conforms to the canonical MCP configuration format +while adding additional fields for enabling FastMCP-specific features like tool transformations +and filtering by tags. + +For an MCPConfig that is strictly canonical, see the `CanonicalMCPConfig` class. + + +**Methods:** + +#### `wrap_servers_at_root` + +```python +wrap_servers_at_root(cls, values: dict[str, Any]) -> dict[str, Any] +``` + +If there's no mcpServers key but there are server configs at root, wrap them. + + +#### `add_server` + +```python +add_server(self, name: str, server: MCPServerTypes) -> None +``` + +Add or update a server in the configuration. + + +#### `from_dict` + +```python +from_dict(cls, config: dict[str, Any]) -> Self +``` + +Parse MCP configuration from dictionary format. + + +#### `to_dict` + +```python +to_dict(self) -> dict[str, Any] +``` + +Convert MCPConfig to dictionary format, preserving all fields. + + +#### `write_to_file` + +```python +write_to_file(self, file_path: Path) -> None +``` + +Write configuration to JSON file. + + +#### `from_file` + +```python +from_file(cls, file_path: Path) -> Self +``` + +Load configuration from JSON file. + + +### `CanonicalMCPConfig` + + +Canonical MCP configuration format. + +This defines the standard configuration format for Model Context Protocol servers. +The format is designed to be client-agnostic and extensible for future use cases. + + +**Methods:** + +#### `add_server` + +```python +add_server(self, name: str, server: CanonicalMCPServerTypes) -> None +``` + +Add or update a server in the configuration. + diff --git a/docs/python-sdk/fastmcp-prompts-__init__.mdx b/docs/python-sdk/fastmcp-prompts-__init__.mdx new file mode 100644 index 000000000..8ef80b59e --- /dev/null +++ b/docs/python-sdk/fastmcp-prompts-__init__.mdx @@ -0,0 +1,8 @@ +--- +title: __init__ +sidebarTitle: __init__ +--- + +# `fastmcp.prompts` + +*This module is empty or contains only private/internal implementations.* diff --git a/docs/python-sdk/fastmcp-prompts-function_prompt.mdx b/docs/python-sdk/fastmcp-prompts-function_prompt.mdx new file mode 100644 index 000000000..a3222afc0 --- /dev/null +++ b/docs/python-sdk/fastmcp-prompts-function_prompt.mdx @@ -0,0 +1,106 @@ +--- +title: function_prompt +sidebarTitle: function_prompt +--- + +# `fastmcp.prompts.function_prompt` + + +Standalone @prompt decorator for FastMCP. + +## Functions + +### `prompt` + +```python +prompt(name_or_fn: str | Callable[..., Any] | None = None) -> Any +``` + + +Standalone decorator to mark a function as an MCP prompt. + +Returns the original function with metadata attached. Register with a server +using mcp.add_prompt(). + + +## Classes + +### `DecoratedPrompt` + + +Protocol for functions decorated with @prompt. + + +### `PromptMeta` + + +Metadata attached to functions by the @prompt decorator. + + +### `FunctionPrompt` + + +A prompt that is a function. + + +**Methods:** + +#### `from_function` + +```python +from_function(cls, fn: Callable[..., Any]) -> FunctionPrompt +``` + +Create a Prompt from a function. + +**Args:** +- `fn`: The function to wrap +- `metadata`: PromptMeta object with all configuration. If provided, +individual parameters must not be passed. +- `name, title, etc.`: Individual parameters for backwards compatibility. +Cannot be used together with metadata parameter. + +The function can return: +- str: wrapped as single user Message +- list\[Message | str]: converted to list\[Message] +- PromptResult: used directly + + +#### `render` + +```python +render(self, arguments: dict[str, Any] | None = None) -> PromptResult +``` + +Render the prompt with arguments. + + +#### `register_with_docket` + +```python +register_with_docket(self, docket: Docket) -> None +``` + +Register this prompt with docket for background execution. + +FunctionPrompt registers the underlying function, which has the user's +Depends parameters for docket to resolve. + + +#### `add_to_docket` + +```python +add_to_docket(self, docket: Docket, arguments: dict[str, Any] | None, **kwargs: Any) -> Execution +``` + +Schedule this prompt for background execution via docket. + +FunctionPrompt splats the arguments dict since .fn expects **kwargs. + +**Args:** +- `docket`: The Docket instance +- `arguments`: Prompt arguments +- `fn_key`: Function lookup key in Docket registry (defaults to self.key) +- `task_key`: Redis storage key for the result +- `**kwargs`: Additional kwargs passed to docket.add() + diff --git a/docs/python-sdk/fastmcp-prompts-prompt.mdx b/docs/python-sdk/fastmcp-prompts-prompt.mdx new file mode 100644 index 000000000..2fe759342 --- /dev/null +++ b/docs/python-sdk/fastmcp-prompts-prompt.mdx @@ -0,0 +1,145 @@ +--- +title: prompt +sidebarTitle: prompt +--- + +# `fastmcp.prompts.prompt` + + +Base classes for FastMCP prompts. + +## Classes + +### `Message` + + +Wrapper for prompt message with auto-serialization. + +Accepts any content - strings pass through, other types +(dict, list, BaseModel) are JSON-serialized to text. + + +**Methods:** + +#### `to_mcp_prompt_message` + +```python +to_mcp_prompt_message(self) -> PromptMessage +``` + +Convert to MCP PromptMessage. + + +### `PromptArgument` + + +An argument that can be passed to a prompt. + + +### `PromptResult` + + +Canonical result type for prompt rendering. + +Provides explicit control over prompt responses: multiple messages, +roles, and metadata at both the message and result level. + + +**Methods:** + +#### `to_mcp_prompt_result` + +```python +to_mcp_prompt_result(self) -> GetPromptResult +``` + +Convert to MCP GetPromptResult. + + +### `Prompt` + + +A prompt template that can be rendered with parameters. + + +**Methods:** + +#### `to_mcp_prompt` + +```python +to_mcp_prompt(self, **overrides: Any) -> SDKPrompt +``` + +Convert the prompt to an MCP prompt. + + +#### `from_function` + +```python +from_function(cls, fn: Callable[..., Any]) -> FunctionPrompt +``` + +Create a Prompt from a function. + +The function can return: +- str: wrapped as single user Message +- list\[Message | str]: converted to list\[Message] +- PromptResult: used directly + + +#### `render` + +```python +render(self, arguments: dict[str, Any] | None = None) -> str | list[Message | str] | PromptResult +``` + +Render the prompt with arguments. + +Subclasses must implement this method. Return one of: +- str: Wrapped as single user Message +- list\[Message | str]: Converted to list\[Message] +- PromptResult: Used directly + + +#### `convert_result` + +```python +convert_result(self, raw_value: Any) -> PromptResult +``` + +Convert a raw return value to PromptResult. + +**Raises:** +- `TypeError`: for unsupported types + + +#### `register_with_docket` + +```python +register_with_docket(self, docket: Docket) -> None +``` + +Register this prompt with docket for background execution. + + +#### `add_to_docket` + +```python +add_to_docket(self, docket: Docket, arguments: dict[str, Any] | None, **kwargs: Any) -> Execution +``` + +Schedule this prompt for background execution via docket. + +**Args:** +- `docket`: The Docket instance +- `arguments`: Prompt arguments +- `fn_key`: Function lookup key in Docket registry (defaults to self.key) +- `task_key`: Redis storage key for the result +- `**kwargs`: Additional kwargs passed to docket.add() + + +#### `get_span_attributes` + +```python +get_span_attributes(self) -> dict[str, Any] +``` diff --git a/docs/python-sdk/fastmcp-resources-__init__.mdx b/docs/python-sdk/fastmcp-resources-__init__.mdx new file mode 100644 index 000000000..cc5fd2786 --- /dev/null +++ b/docs/python-sdk/fastmcp-resources-__init__.mdx @@ -0,0 +1,8 @@ +--- +title: __init__ +sidebarTitle: __init__ +--- + +# `fastmcp.resources` + +*This module is empty or contains only private/internal implementations.* diff --git a/docs/python-sdk/fastmcp-resources-function_resource.mdx b/docs/python-sdk/fastmcp-resources-function_resource.mdx new file mode 100644 index 000000000..3a7d346e1 --- /dev/null +++ b/docs/python-sdk/fastmcp-resources-function_resource.mdx @@ -0,0 +1,93 @@ +--- +title: function_resource +sidebarTitle: function_resource +--- + +# `fastmcp.resources.function_resource` + + +Standalone @resource decorator for FastMCP. + +## Functions + +### `resource` + +```python +resource(uri: str) -> Callable[[F], F] +``` + + +Standalone decorator to mark a function as an MCP resource. + +Returns the original function with metadata attached. Register with a server +using mcp.add_resource(). + + +## Classes + +### `DecoratedResource` + + +Protocol for functions decorated with @resource. + + +### `ResourceMeta` + + +Metadata attached to functions by the @resource decorator. + + +### `FunctionResource` + + +A resource that defers data loading by wrapping a function. + +The function is only called when the resource is read, allowing for lazy loading +of potentially expensive data. This is particularly useful when listing resources, +as the function won't be called until the resource is actually accessed. + +The function can return: +- str for text content (default) +- bytes for binary content +- other types will be converted to JSON + + +**Methods:** + +#### `from_function` + +```python +from_function(cls, fn: Callable[..., Any], uri: str | AnyUrl | None = None) -> FunctionResource +``` + +Create a FunctionResource from a function. + +**Args:** +- `fn`: The function to wrap +- `uri`: The URI for the resource (required if metadata not provided) +- `metadata`: ResourceMeta object with all configuration. If provided, +individual parameters must not be passed. +- `name, title, etc.`: Individual parameters for backwards compatibility. +Cannot be used together with metadata parameter. + + +#### `read` + +```python +read(self) -> str | bytes | ResourceResult +``` + +Read the resource by calling the wrapped function. + + +#### `register_with_docket` + +```python +register_with_docket(self, docket: Docket) -> None +``` + +Register this resource with docket for background execution. + +FunctionResource registers the underlying function, which has the user's +Depends parameters for docket to resolve. + diff --git a/docs/python-sdk/fastmcp-resources-resource.mdx b/docs/python-sdk/fastmcp-resources-resource.mdx new file mode 100644 index 000000000..029b48700 --- /dev/null +++ b/docs/python-sdk/fastmcp-resources-resource.mdx @@ -0,0 +1,180 @@ +--- +title: resource +sidebarTitle: resource +--- + +# `fastmcp.resources.resource` + + +Base classes and interfaces for FastMCP resources. + +## Classes + +### `ResourceContent` + + +Wrapper for resource content with optional MIME type and metadata. + +Accepts any value for content - strings and bytes pass through directly, +other types (dict, list, BaseModel, etc.) are automatically JSON-serialized. + + +**Methods:** + +#### `to_mcp_resource_contents` + +```python +to_mcp_resource_contents(self, uri: AnyUrl | str) -> mcp.types.TextResourceContents | mcp.types.BlobResourceContents +``` + +Convert to MCP resource contents type. + +**Args:** +- `uri`: The URI of the resource (required by MCP types) + +**Returns:** +- TextResourceContents for str content, BlobResourceContents for bytes + + +### `ResourceResult` + + +Canonical result type for resource reads. + +Provides explicit control over resource responses: multiple content items, +per-item MIME types, and metadata at both the item and result level. + + +**Methods:** + +#### `to_mcp_result` + +```python +to_mcp_result(self, uri: AnyUrl | str) -> mcp.types.ReadResourceResult +``` + +Convert to MCP ReadResourceResult. + +**Args:** +- `uri`: The URI of the resource (required by MCP types) + +**Returns:** +- MCP ReadResourceResult with converted contents + + +### `Resource` + + +Base class for all resources. + + +**Methods:** + +#### `from_function` + +```python +from_function(cls, fn: Callable[..., Any], uri: str | AnyUrl) -> FunctionResource +``` + +#### `set_default_mime_type` + +```python +set_default_mime_type(cls, mime_type: str | None) -> str +``` + +Set default MIME type if not provided. + + +#### `set_default_name` + +```python +set_default_name(self) -> Self +``` + +Set default name from URI if not provided. + + +#### `read` + +```python +read(self) -> str | bytes | ResourceResult +``` + +Read the resource content. + +Subclasses implement this to return resource data. Supported return types: + - str: Text content + - bytes: Binary content + - ResourceResult: Full control over contents and result-level meta + + +#### `convert_result` + +```python +convert_result(self, raw_value: Any) -> ResourceResult +``` + +Convert a raw result to ResourceResult. + +This is used in two contexts: +1. In _read() to convert user function return values to ResourceResult +2. In tasks_result_handler() to convert Docket task results to ResourceResult + +Handles ResourceResult passthrough and converts raw values using +ResourceResult's normalization. When the raw value is a plain +string or bytes, the resource's own ``mime_type`` is forwarded so +that ``ui://`` resources (and others with non-default MIME types) +don't fall back to ``text/plain``. + +The resource's component-level ``meta`` (e.g. ``ui`` metadata for +MCP Apps CSP/permissions) is propagated to each content item so +that hosts can read it from the ``resources/read`` response. + + +#### `to_mcp_resource` + +```python +to_mcp_resource(self, **overrides: Any) -> SDKResource +``` + +Convert the resource to an SDKResource. + + +#### `key` + +```python +key(self) -> str +``` + +The globally unique lookup key for this resource. + + +#### `register_with_docket` + +```python +register_with_docket(self, docket: Docket) -> None +``` + +Register this resource with docket for background execution. + + +#### `add_to_docket` + +```python +add_to_docket(self, docket: Docket, **kwargs: Any) -> Execution +``` + +Schedule this resource for background execution via docket. + +**Args:** +- `docket`: The Docket instance +- `fn_key`: Function lookup key in Docket registry (defaults to self.key) +- `task_key`: Redis storage key for the result +- `**kwargs`: Additional kwargs passed to docket.add() + + +#### `get_span_attributes` + +```python +get_span_attributes(self) -> dict[str, Any] +``` diff --git a/docs/python-sdk/fastmcp-resources-template.mdx b/docs/python-sdk/fastmcp-resources-template.mdx new file mode 100644 index 000000000..89e51c22f --- /dev/null +++ b/docs/python-sdk/fastmcp-resources-template.mdx @@ -0,0 +1,244 @@ +--- +title: template +sidebarTitle: template +--- + +# `fastmcp.resources.template` + + +Resource template functionality. + +## Functions + +### `extract_query_params` + +```python +extract_query_params(uri_template: str) -> set[str] +``` + + +Extract query parameter names from RFC 6570 `{?param1,param2}` syntax. + + +### `build_regex` + +```python +build_regex(template: str) -> re.Pattern +``` + + +Build regex pattern for URI template, handling RFC 6570 syntax. + +Supports: +- `{var}` - simple path parameter +- `{var*}` - wildcard path parameter (captures multiple segments) +- `{?var1,var2}` - query parameters (ignored in path matching) + + +### `match_uri_template` + +```python +match_uri_template(uri: str, uri_template: str) -> dict[str, str] | None +``` + + +Match URI against template and extract both path and query parameters. + +Supports RFC 6570 URI templates: +- Path params: `{var}`, `{var*}` +- Query params: `{?var1,var2}` + + +## Classes + +### `ResourceTemplate` + + +A template for dynamically creating resources. + + +**Methods:** + +#### `from_function` + +```python +from_function(fn: Callable[..., Any], uri_template: str, name: str | None = None, version: str | int | None = None, title: str | None = None, description: str | None = None, icons: list[Icon] | None = None, mime_type: str | None = None, tags: set[str] | None = None, annotations: Annotations | None = None, meta: dict[str, Any] | None = None, task: bool | TaskConfig | None = None, auth: AuthCheck | list[AuthCheck] | None = None) -> FunctionResourceTemplate +``` + +#### `set_default_mime_type` + +```python +set_default_mime_type(cls, mime_type: str | None) -> str +``` + +Set default MIME type if not provided. + + +#### `matches` + +```python +matches(self, uri: str) -> dict[str, Any] | None +``` + +Check if URI matches template and extract parameters. + + +#### `read` + +```python +read(self, arguments: dict[str, Any]) -> str | bytes | ResourceResult +``` + +Read the resource content. + + +#### `convert_result` + +```python +convert_result(self, raw_value: Any) -> ResourceResult +``` + +Convert a raw result to ResourceResult. + +This is used in two contexts: +1. In _read() to convert user function return values to ResourceResult +2. In tasks_result_handler() to convert Docket task results to ResourceResult + +Handles ResourceResult passthrough and converts raw values using +ResourceResult's normalization. + + +#### `create_resource` + +```python +create_resource(self, uri: str, params: dict[str, Any]) -> Resource +``` + +Create a resource from the template with the given parameters. + +The base implementation does not support background tasks. +Use FunctionResourceTemplate for task support. + + +#### `to_mcp_template` + +```python +to_mcp_template(self, **overrides: Any) -> SDKResourceTemplate +``` + +Convert the resource template to an SDKResourceTemplate. + + +#### `from_mcp_template` + +```python +from_mcp_template(cls, mcp_template: SDKResourceTemplate) -> ResourceTemplate +``` + +Creates a FastMCP ResourceTemplate from a raw MCP ResourceTemplate object. + + +#### `key` + +```python +key(self) -> str +``` + +The globally unique lookup key for this template. + + +#### `register_with_docket` + +```python +register_with_docket(self, docket: Docket) -> None +``` + +Register this template with docket for background execution. + + +#### `add_to_docket` + +```python +add_to_docket(self, docket: Docket, params: dict[str, Any], **kwargs: Any) -> Execution +``` + +Schedule this template for background execution via docket. + +**Args:** +- `docket`: The Docket instance +- `params`: Template parameters +- `fn_key`: Function lookup key in Docket registry (defaults to self.key) +- `task_key`: Redis storage key for the result +- `**kwargs`: Additional kwargs passed to docket.add() + + +#### `get_span_attributes` + +```python +get_span_attributes(self) -> dict[str, Any] +``` + +### `FunctionResourceTemplate` + + +A template for dynamically creating resources. + + +**Methods:** + +#### `create_resource` + +```python +create_resource(self, uri: str, params: dict[str, Any]) -> Resource +``` + +Create a resource from the template with the given parameters. + + +#### `read` + +```python +read(self, arguments: dict[str, Any]) -> str | bytes | ResourceResult +``` + +Read the resource content. + + +#### `register_with_docket` + +```python +register_with_docket(self, docket: Docket) -> None +``` + +Register this template with docket for background execution. + +FunctionResourceTemplate registers the underlying function, which has the +user's Depends parameters for docket to resolve. + + +#### `add_to_docket` + +```python +add_to_docket(self, docket: Docket, params: dict[str, Any], **kwargs: Any) -> Execution +``` + +Schedule this template for background execution via docket. + +FunctionResourceTemplate splats the params dict since .fn expects **kwargs. + +**Args:** +- `docket`: The Docket instance +- `params`: Template parameters +- `fn_key`: Function lookup key in Docket registry (defaults to self.key) +- `task_key`: Redis storage key for the result +- `**kwargs`: Additional kwargs passed to docket.add() + + +#### `from_function` + +```python +from_function(cls, fn: Callable[..., Any], uri_template: str, name: str | None = None, version: str | int | None = None, title: str | None = None, description: str | None = None, icons: list[Icon] | None = None, mime_type: str | None = None, tags: set[str] | None = None, annotations: Annotations | None = None, meta: dict[str, Any] | None = None, task: bool | TaskConfig | None = None, auth: AuthCheck | list[AuthCheck] | None = None) -> FunctionResourceTemplate +``` + +Create a template from a function. + diff --git a/docs/python-sdk/fastmcp-resources-types.mdx b/docs/python-sdk/fastmcp-resources-types.mdx new file mode 100644 index 000000000..d19b24eb2 --- /dev/null +++ b/docs/python-sdk/fastmcp-resources-types.mdx @@ -0,0 +1,134 @@ +--- +title: types +sidebarTitle: types +--- + +# `fastmcp.resources.types` + + +Concrete resource implementations. + +## Classes + +### `TextResource` + + +A resource that reads from a string. + + +**Methods:** + +#### `read` + +```python +read(self) -> ResourceResult +``` + +Read the text content. + + +### `BinaryResource` + + +A resource that reads from bytes. + + +**Methods:** + +#### `read` + +```python +read(self) -> ResourceResult +``` + +Read the binary content. + + +### `FileResource` + + +A resource that reads from a file. + +Set is_binary=True to read file as binary data instead of text. + + +**Methods:** + +#### `validate_absolute_path` + +```python +validate_absolute_path(cls, path: Path) -> Path +``` + +Ensure path is absolute. + + +#### `set_binary_from_mime_type` + +```python +set_binary_from_mime_type(cls, is_binary: bool, info: ValidationInfo) -> bool +``` + +Set is_binary based on mime_type if not explicitly set. + + +#### `read` + +```python +read(self) -> ResourceResult +``` + +Read the file content. + + +### `HttpResource` + + +A resource that reads from an HTTP endpoint. + + +**Methods:** + +#### `read` + +```python +read(self) -> ResourceResult +``` + +Read the HTTP content. + + +### `DirectoryResource` + + +A resource that lists files in a directory. + + +**Methods:** + +#### `validate_absolute_path` + +```python +validate_absolute_path(cls, path: Path) -> Path +``` + +Ensure path is absolute. + + +#### `list_files` + +```python +list_files(self) -> list[Path] +``` + +List files in the directory. + + +#### `read` + +```python +read(self) -> ResourceResult +``` + +Read the directory listing. + diff --git a/docs/python-sdk/fastmcp-server-__init__.mdx b/docs/python-sdk/fastmcp-server-__init__.mdx new file mode 100644 index 000000000..157a018ce --- /dev/null +++ b/docs/python-sdk/fastmcp-server-__init__.mdx @@ -0,0 +1,8 @@ +--- +title: __init__ +sidebarTitle: __init__ +--- + +# `fastmcp.server` + +*This module is empty or contains only private/internal implementations.* diff --git a/docs/python-sdk/fastmcp-server-apps.mdx b/docs/python-sdk/fastmcp-server-apps.mdx new file mode 100644 index 000000000..00e53eafe --- /dev/null +++ b/docs/python-sdk/fastmcp-server-apps.mdx @@ -0,0 +1,86 @@ +--- +title: apps +sidebarTitle: apps +--- + +# `fastmcp.server.apps` + + +MCP Apps support — extension negotiation and typed UI metadata models. + +Provides constants and Pydantic models for the MCP Apps extension +(io.modelcontextprotocol/ui), enabling tools and resources to carry +UI metadata for clients that support interactive app rendering. + + +## Functions + +### `app_config_to_meta_dict` + +```python +app_config_to_meta_dict(app: AppConfig | dict[str, Any]) -> dict[str, Any] +``` + + +Convert an AppConfig or dict to the wire-format dict for ``meta["ui"]``. + + +### `resolve_ui_mime_type` + +```python +resolve_ui_mime_type(uri: str, explicit_mime_type: str | None) -> str | None +``` + + +Return the appropriate MIME type for a resource URI. + +For ``ui://`` scheme resources, defaults to ``UI_MIME_TYPE`` when no +explicit MIME type is provided. This ensures UI resources are correctly +identified regardless of how they're registered (via FastMCP.resource, +the standalone @resource decorator, or resource templates). + +**Args:** +- `uri`: The resource URI string +- `explicit_mime_type`: The MIME type explicitly provided by the user + +**Returns:** +- The resolved MIME type (explicit value, UI default, or None) + + +## Classes + +### `ResourceCSP` + + +Content Security Policy for MCP App resources. + +Declares which external origins the app is allowed to connect to or +load resources from. Hosts use these declarations to build the +``Content-Security-Policy`` header for the sandboxed iframe. + + +### `ResourcePermissions` + + +Iframe sandbox permissions for MCP App resources. + +Each field, when set (typically to ``{}``), requests that the host +grant the corresponding Permission Policy feature to the sandboxed +iframe. Hosts MAY honour these; apps should use JS feature detection +as a fallback. + + +### `AppConfig` + + +Configuration for MCP App tools and resources. + +Controls how a tool or resource participates in the MCP Apps extension. +On tools, ``resource_uri`` and ``visibility`` specify which UI resource +to render and where the tool appears. On resources, those fields must +be left unset (the resource itself is the UI). + +All fields use ``exclude_none`` serialization so only explicitly-set +values appear on the wire. Aliases match the MCP Apps wire format +(camelCase). + diff --git a/docs/python-sdk/fastmcp-server-auth-__init__.mdx b/docs/python-sdk/fastmcp-server-auth-__init__.mdx new file mode 100644 index 000000000..c86f07005 --- /dev/null +++ b/docs/python-sdk/fastmcp-server-auth-__init__.mdx @@ -0,0 +1,8 @@ +--- +title: __init__ +sidebarTitle: __init__ +--- + +# `fastmcp.server.auth` + +*This module is empty or contains only private/internal implementations.* diff --git a/docs/python-sdk/fastmcp-server-auth-auth.mdx b/docs/python-sdk/fastmcp-server-auth-auth.mdx new file mode 100644 index 000000000..2186df875 --- /dev/null +++ b/docs/python-sdk/fastmcp-server-auth-auth.mdx @@ -0,0 +1,382 @@ +--- +title: auth +sidebarTitle: auth +--- + +# `fastmcp.server.auth.auth` + +## Classes + +### `AccessToken` + + +AccessToken that includes all JWT claims. + + +### `TokenHandler` + + +TokenHandler that returns MCP-compliant error responses. + +This handler addresses two SDK issues: + +1. Error code: The SDK returns `unauthorized_client` for client authentication + failures, but RFC 6749 Section 5.2 requires `invalid_client` with HTTP 401. + This distinction matters for client re-registration behavior. + +2. Status code: The SDK returns HTTP 400 for all token errors including + `invalid_grant` (expired/invalid tokens). However, the MCP spec requires: + "Invalid or expired tokens MUST receive a HTTP 401 response." + +This handler transforms responses to be compliant with both OAuth 2.1 and MCP specs. + + +**Methods:** + +#### `handle` + +```python +handle(self, request: Any) +``` + +Wrap SDK handle() and transform auth error responses. + + +### `PrivateKeyJWTClientAuthenticator` + + +Client authenticator with private_key_jwt support for CIMD clients. + +Extends the SDK's ClientAuthenticator to add support for the `private_key_jwt` +authentication method per RFC 7523. This is required for CIMD (Client ID Metadata +Document) clients that use asymmetric keys for authentication. + +The authenticator: +1. Delegates to SDK for standard methods (client_secret_basic, client_secret_post, none) +2. Adds private_key_jwt handling for CIMD clients +3. Validates JWT assertions against client's JWKS + + +**Methods:** + +#### `authenticate_request` + +```python +authenticate_request(self, request: Request) -> OAuthClientInformationFull +``` + +Authenticate a client from an HTTP request. + +Extends SDK authentication to support private_key_jwt for CIMD clients. +Delegates to SDK for client_secret_basic (Authorization header) and +client_secret_post (form body) authentication. + + +### `AuthProvider` + + +Base class for all FastMCP authentication providers. + +This class provides a unified interface for all authentication providers, +whether they are simple token verifiers or full OAuth authorization servers. +All providers must be able to verify tokens and can optionally provide +custom authentication routes. + + +**Methods:** + +#### `verify_token` + +```python +verify_token(self, token: str) -> AccessToken | None +``` + +Verify a bearer token and return access info if valid. + +All auth providers must implement token verification. + +**Args:** +- `token`: The token string to validate + +**Returns:** +- AccessToken object if valid, None if invalid or expired + + +#### `set_mcp_path` + +```python +set_mcp_path(self, mcp_path: str | None) -> None +``` + +Set the MCP endpoint path and compute resource URL. + +This method is called by get_routes() to configure the expected +resource URL before route creation. Subclasses can override to +perform additional initialization that depends on knowing the +MCP endpoint path. + +**Args:** +- `mcp_path`: The path where the MCP endpoint is mounted (e.g., "/mcp") + + +#### `get_routes` + +```python +get_routes(self, mcp_path: str | None = None) -> list[Route] +``` + +Get all routes for this authentication provider. + +This includes both well-known discovery routes and operational routes. +Each provider is responsible for creating whatever routes it needs: +- TokenVerifier: typically no routes (default implementation) +- RemoteAuthProvider: protected resource metadata routes +- OAuthProvider: full OAuth authorization server routes +- Custom providers: whatever routes they need + +**Args:** +- `mcp_path`: The path where the MCP endpoint is mounted (e.g., "/mcp") +This is used to advertise the resource URL in metadata, but the +provider does not create the actual MCP endpoint route. + +**Returns:** +- List of all routes for this provider (excluding the MCP endpoint itself) + + +#### `get_well_known_routes` + +```python +get_well_known_routes(self, mcp_path: str | None = None) -> list[Route] +``` + +Get well-known discovery routes for this authentication provider. + +This is a utility method that filters get_routes() to return only +well-known discovery routes (those starting with /.well-known/). + +Well-known routes provide OAuth metadata and discovery endpoints that +clients use to discover authentication capabilities. These routes should +be mounted at the root level of the application to comply with RFC 8414 +and RFC 9728. + +Common well-known routes: +- /.well-known/oauth-authorization-server (authorization server metadata) +- /.well-known/oauth-protected-resource/* (protected resource metadata) + +**Args:** +- `mcp_path`: The path where the MCP endpoint is mounted (e.g., "/mcp") +This is used to construct path-scoped well-known URLs. + +**Returns:** +- List of well-known discovery routes (typically mounted at root level) + + +#### `get_middleware` + +```python +get_middleware(self) -> list +``` + +Get HTTP application-level middleware for this auth provider. + +**Returns:** +- List of Starlette Middleware instances to apply to the HTTP app + + +### `TokenVerifier` + + +Base class for token verifiers (Resource Servers). + +This class provides token verification capability without OAuth server functionality. +Token verifiers typically don't provide authentication routes by default. + + +**Methods:** + +#### `scopes_supported` + +```python +scopes_supported(self) -> list[str] +``` + +Scopes to advertise in OAuth metadata. + +Defaults to required_scopes. Override in subclasses when the +advertised scopes differ from the validation scopes (e.g., Azure AD +where tokens contain short-form scopes but clients request full URI +scopes). + + +#### `verify_token` + +```python +verify_token(self, token: str) -> AccessToken | None +``` + +Verify a bearer token and return access info if valid. + + +### `RemoteAuthProvider` + + +Authentication provider for resource servers that verify tokens from known authorization servers. + +This provider composes a TokenVerifier with authorization server metadata to create +standardized OAuth 2.0 Protected Resource endpoints (RFC 9728). Perfect for: +- JWT verification with known issuers +- Remote token introspection services +- Any resource server that knows where its tokens come from + +Use this when you have token verification logic and want to advertise +the authorization servers that issue valid tokens. + + +**Methods:** + +#### `verify_token` + +```python +verify_token(self, token: str) -> AccessToken | None +``` + +Verify token using the configured token verifier. + + +#### `get_routes` + +```python +get_routes(self, mcp_path: str | None = None) -> list[Route] +``` + +Get routes for this provider. + +Creates protected resource metadata routes (RFC 9728). + + +### `MultiAuth` + + +Composes an optional auth server with additional token verifiers. + +Use this when a single server needs to accept tokens from multiple sources. +For example, an OAuth proxy for interactive clients combined with a JWT +verifier for machine-to-machine tokens. + +Token verification tries the server first (if present), then each verifier +in order, returning the first successful result. Routes and OAuth metadata +come from the server; verifiers contribute only token verification. + + +**Methods:** + +#### `verify_token` + +```python +verify_token(self, token: str) -> AccessToken | None +``` + +Verify a token by trying the server, then each verifier in order. + +Each source is tried independently. If a source raises an exception, +it is logged and treated as a non-match so that remaining sources +still get a chance to verify the token. + + +#### `set_mcp_path` + +```python +set_mcp_path(self, mcp_path: str | None) -> None +``` + +Propagate MCP path to the server and all verifiers. + + +#### `get_routes` + +```python +get_routes(self, mcp_path: str | None = None) -> list[Route] +``` + +Delegate route creation to the server. + + +#### `get_well_known_routes` + +```python +get_well_known_routes(self, mcp_path: str | None = None) -> list[Route] +``` + +Delegate well-known route creation to the server. + +This ensures that server-specific well-known route logic (e.g., +OAuthProvider's RFC 8414 path-aware discovery) is preserved. + + +### `OAuthProvider` + + +OAuth Authorization Server provider. + +This class provides full OAuth server functionality including client registration, +authorization flows, token issuance, and token verification. + + +**Methods:** + +#### `verify_token` + +```python +verify_token(self, token: str) -> AccessToken | None +``` + +Verify a bearer token and return access info if valid. + +This method implements the TokenVerifier protocol by delegating +to our existing load_access_token method. + +**Args:** +- `token`: The token string to validate + +**Returns:** +- AccessToken object if valid, None if invalid or expired + + +#### `get_routes` + +```python +get_routes(self, mcp_path: str | None = None) -> list[Route] +``` + +Get OAuth authorization server routes and optional protected resource routes. + +This method creates the full set of OAuth routes including: +- Standard OAuth authorization server routes (/.well-known/oauth-authorization-server, /authorize, /token, etc.) +- Optional protected resource routes + +**Returns:** +- List of OAuth routes + + +#### `get_well_known_routes` + +```python +get_well_known_routes(self, mcp_path: str | None = None) -> list[Route] +``` + +Get well-known discovery routes with RFC 8414 path-aware support. + +Overrides the base implementation to support path-aware authorization +server metadata discovery per RFC 8414. If issuer_url has a path component, +the authorization server metadata route is adjusted to include that path. + +For example, if issuer_url is "http://example.com/api", the discovery +endpoint will be at "/.well-known/oauth-authorization-server/api" instead +of just "/.well-known/oauth-authorization-server". + +**Args:** +- `mcp_path`: The path where the MCP endpoint is mounted (e.g., "/mcp") + +**Returns:** +- List of well-known discovery routes + diff --git a/docs/python-sdk/fastmcp-server-auth-authorization.mdx b/docs/python-sdk/fastmcp-server-auth-authorization.mdx new file mode 100644 index 000000000..7465c43dc --- /dev/null +++ b/docs/python-sdk/fastmcp-server-auth-authorization.mdx @@ -0,0 +1,129 @@ +--- +title: authorization +sidebarTitle: authorization +--- + +# `fastmcp.server.auth.authorization` + + +Authorization checks for FastMCP components. + +This module provides callable-based authorization for tools, resources, and prompts. +Auth checks are functions that receive an AuthContext and return True to allow access +or False to deny. + +Auth checks can also raise exceptions: +- AuthorizationError: Propagates with the custom message for explicit denial +- Other exceptions: Masked for security (logged, treated as auth failure) + +Example: + ```python + from fastmcp import FastMCP + from fastmcp.server.auth import require_scopes + + mcp = FastMCP() + + @mcp.tool(auth=require_scopes("write")) + def protected_tool(): ... + + @mcp.resource("data://secret", auth=require_scopes("read")) + def secret_data(): ... + + @mcp.prompt(auth=require_scopes("admin")) + def admin_prompt(): ... + ``` + + +## Functions + +### `require_scopes` + +```python +require_scopes(*scopes: str) -> AuthCheck +``` + + +Require specific OAuth scopes. + +Returns an auth check that requires ALL specified scopes to be present +in the token (AND logic). + +**Args:** +- `*scopes`: One or more scope strings that must all be present. + + +### `restrict_tag` + +```python +restrict_tag(tag: str) -> AuthCheck +``` + + +Restrict components with a specific tag to require certain scopes. + +If the component has the specified tag, the token must have ALL the +required scopes. If the component doesn't have the tag, access is allowed. + +**Args:** +- `tag`: The tag that triggers the scope requirement. +- `scopes`: List of scopes required when the tag is present. + + +### `run_auth_checks` + +```python +run_auth_checks(checks: AuthCheck | list[AuthCheck], ctx: AuthContext) -> bool +``` + + +Run auth checks with AND logic. + +All checks must pass for authorization to succeed. Checks can be +synchronous or asynchronous functions. + +Auth checks can: +- Return True to allow access +- Return False to deny access +- Raise AuthorizationError to deny with a custom message (propagates) +- Raise other exceptions (masked for security, treated as denial) + +**Args:** +- `checks`: A single check function or list of check functions. +Each check can be sync (returns bool) or async (returns Awaitable[bool]). +- `ctx`: The auth context to pass to each check. + +**Returns:** +- True if all checks pass, False if any check fails. + +**Raises:** +- `AuthorizationError`: If an auth check explicitly raises it. + + +## Classes + +### `AuthContext` + + +Context passed to auth check callables. + +This object is passed to each auth check function and provides +access to the current authentication token and the component being accessed. + +**Attributes:** +- `token`: The current access token, or None if unauthenticated. +- `component`: The component (tool, resource, or prompt) being accessed. +- `tool`: Backwards-compatible alias for component when it's a Tool. + + +**Methods:** + +#### `tool` + +```python +tool(self) -> Tool | None +``` + +Backwards-compatible access to the component as a Tool. + +Returns the component if it's a Tool, None otherwise. + diff --git a/docs/python-sdk/fastmcp-server-auth-cimd.mdx b/docs/python-sdk/fastmcp-server-auth-cimd.mdx new file mode 100644 index 000000000..dda5d28c6 --- /dev/null +++ b/docs/python-sdk/fastmcp-server-auth-cimd.mdx @@ -0,0 +1,242 @@ +--- +title: cimd +sidebarTitle: cimd +--- + +# `fastmcp.server.auth.cimd` + + +CIMD (Client ID Metadata Document) support for FastMCP. + +.. warning:: + **Beta Feature**: CIMD support is currently in beta. The API may change + in future releases. Please report any issues you encounter. + +CIMD is a simpler alternative to Dynamic Client Registration where clients +host a static JSON document at an HTTPS URL, and that URL becomes their +client_id. See the IETF draft: draft-parecki-oauth-client-id-metadata-document + +This module provides: +- CIMDDocument: Pydantic model for CIMD document validation +- CIMDFetcher: Fetch and validate CIMD documents with SSRF protection +- CIMDClientManager: Manages CIMD client operations + + +## Classes + +### `CIMDDocument` + + +CIMD document per draft-parecki-oauth-client-id-metadata-document. + +The client metadata document is a JSON document containing OAuth client +metadata. The client_id property MUST match the URL where this document +is hosted. + +Key constraint: token_endpoint_auth_method MUST NOT use shared secrets +(client_secret_post, client_secret_basic, client_secret_jwt). + +redirect_uris is required and must contain at least one entry. + + +**Methods:** + +#### `validate_auth_method` + +```python +validate_auth_method(cls, v: str) -> str +``` + +Ensure no shared-secret auth methods are used. + + +#### `validate_redirect_uris` + +```python +validate_redirect_uris(cls, v: list[str]) -> list[str] +``` + +Ensure redirect_uris is non-empty and each entry is a valid URI. + + +### `CIMDValidationError` + + +Raised when CIMD document validation fails. + + +### `CIMDFetchError` + + +Raised when CIMD document fetching fails. + + +### `CIMDFetcher` + + +Fetch and validate CIMD documents with SSRF protection. + +Delegates HTTP fetching to ssrf_safe_fetch_response, which provides DNS +pinning, IP validation, size limits, and timeout enforcement. Documents are +cached using HTTP caching semantics (Cache-Control/ETag/Last-Modified), with +a TTL fallback when response headers do not define caching behavior. + + +**Methods:** + +#### `is_cimd_client_id` + +```python +is_cimd_client_id(self, client_id: str) -> bool +``` + +Check if a client_id looks like a CIMD URL. + +CIMD URLs must be HTTPS with a host and non-root path. + + +#### `fetch` + +```python +fetch(self, client_id_url: str) -> CIMDDocument +``` + +Fetch and validate a CIMD document with SSRF protection. + +Uses ssrf_safe_fetch_response for the HTTP layer, which provides: +- HTTPS only, DNS resolution with IP validation +- DNS pinning (connects to validated IP directly) +- Blocks private/loopback/link-local/multicast IPs +- Response size limit and timeout enforcement +- Redirects disabled + +**Args:** +- `client_id_url`: The URL to fetch (also the expected client_id) + +**Returns:** +- Validated CIMDDocument + +**Raises:** +- `CIMDValidationError`: If document is invalid or URL blocked +- `CIMDFetchError`: If document cannot be fetched + + +#### `validate_redirect_uri` + +```python +validate_redirect_uri(self, doc: CIMDDocument, redirect_uri: str) -> bool +``` + +Validate that a redirect_uri is allowed by the CIMD document. + +**Args:** +- `doc`: The CIMD document +- `redirect_uri`: The redirect URI to validate + +**Returns:** +- True if valid, False otherwise + + +### `CIMDAssertionValidator` + + +Validates JWT assertions for private_key_jwt CIMD clients. + +Implements RFC 7523 (JSON Web Token (JWT) Profile for OAuth 2.0 Client +Authentication and Authorization Grants) for CIMD client authentication. + +JTI replay protection uses TTL-based caching to ensure proper security: +- JTIs are cached with expiration matching the JWT's exp claim +- Expired JTIs are automatically cleaned up +- Maximum assertion lifetime is enforced (5 minutes) + + +**Methods:** + +#### `validate_assertion` + +```python +validate_assertion(self, assertion: str, client_id: str, token_endpoint: str, cimd_doc: CIMDDocument) -> bool +``` + +Validate JWT assertion from client. + +**Args:** +- `assertion`: The JWT assertion string +- `client_id`: Expected client_id (must match iss and sub claims) +- `token_endpoint`: Token endpoint URL (must match aud claim) +- `cimd_doc`: CIMD document containing JWKS for key verification + +**Returns:** +- True if valid + +**Raises:** +- `ValueError`: If validation fails + + +### `CIMDClientManager` + + +Manages all CIMD client operations for OAuth proxy. + +This class encapsulates: +- CIMD client detection +- Document fetching and validation +- Synthetic OAuth client creation +- Private key JWT assertion validation + +This allows the OAuth proxy to delegate all CIMD-specific logic to a +single, focused manager class. + + +**Methods:** + +#### `is_cimd_client_id` + +```python +is_cimd_client_id(self, client_id: str) -> bool +``` + +Check if client_id is a CIMD URL. + +**Args:** +- `client_id`: Client ID to check + +**Returns:** +- True if client_id is an HTTPS URL (CIMD format) + + +#### `get_client` + +```python +get_client(self, client_id_url: str) +``` + +Fetch CIMD document and create synthetic OAuth client. + +**Args:** +- `client_id_url`: HTTPS URL pointing to CIMD document + +**Returns:** +- OAuthProxyClient with CIMD document attached, or None if fetch fails + + +#### `validate_private_key_jwt` + +```python +validate_private_key_jwt(self, assertion: str, client, token_endpoint: str) -> bool +``` + +Validate JWT assertion for private_key_jwt auth. + +**Args:** +- `assertion`: JWT assertion string from client +- `client`: OAuth proxy client (must have cimd_document) +- `token_endpoint`: Token endpoint URL for aud validation + +**Returns:** +- True if assertion is valid + +**Raises:** +- `ValueError`: If client doesn't have CIMD document or validation fails + diff --git a/docs/python-sdk/fastmcp-server-auth-jwt_issuer.mdx b/docs/python-sdk/fastmcp-server-auth-jwt_issuer.mdx new file mode 100644 index 000000000..b30f3090b --- /dev/null +++ b/docs/python-sdk/fastmcp-server-auth-jwt_issuer.mdx @@ -0,0 +1,106 @@ +--- +title: jwt_issuer +sidebarTitle: jwt_issuer +--- + +# `fastmcp.server.auth.jwt_issuer` + + +JWT token issuance and verification for FastMCP OAuth Proxy. + +This module implements the token factory pattern for OAuth proxies, where the proxy +issues its own JWT tokens to clients instead of forwarding upstream provider tokens. +This maintains proper OAuth 2.0 token audience boundaries. + + +## Functions + +### `derive_jwt_key` + +```python +derive_jwt_key() -> bytes +``` + + +Derive JWT signing key from a high-entropy or low-entropy key material and server salt. + + +## Classes + +### `JWTIssuer` + + +Issues and validates FastMCP-signed JWT tokens using HS256. + +This issuer creates JWT tokens for MCP clients with proper audience claims, +maintaining OAuth 2.0 token boundaries. Tokens are signed with HS256 using +a key derived from the upstream client secret. + + +**Methods:** + +#### `issue_access_token` + +```python +issue_access_token(self, client_id: str, scopes: list[str], jti: str, expires_in: int = 3600, upstream_claims: dict[str, Any] | None = None) -> str +``` + +Issue a minimal FastMCP access token. + +FastMCP tokens are reference tokens containing only the minimal claims +needed for validation and lookup. The JTI maps to the upstream token +which contains actual user identity and authorization data. + +**Args:** +- `client_id`: MCP client ID +- `scopes`: Token scopes +- `jti`: Unique token identifier (maps to upstream token) +- `expires_in`: Token lifetime in seconds +- `upstream_claims`: Optional claims from upstream IdP token to include + +**Returns:** +- Signed JWT token + + +#### `issue_refresh_token` + +```python +issue_refresh_token(self, client_id: str, scopes: list[str], jti: str, expires_in: int, upstream_claims: dict[str, Any] | None = None) -> str +``` + +Issue a minimal FastMCP refresh token. + +FastMCP refresh tokens are reference tokens containing only the minimal +claims needed for validation and lookup. The JTI maps to the upstream +token which contains actual user identity and authorization data. + +**Args:** +- `client_id`: MCP client ID +- `scopes`: Token scopes +- `jti`: Unique token identifier (maps to upstream token) +- `expires_in`: Token lifetime in seconds (should match upstream refresh expiry) +- `upstream_claims`: Optional claims from upstream IdP token to include + +**Returns:** +- Signed JWT token + + +#### `verify_token` + +```python +verify_token(self, token: str) -> dict[str, Any] +``` + +Verify and decode a FastMCP token. + +Validates JWT signature, expiration, issuer, and audience. + +**Args:** +- `token`: JWT token to verify + +**Returns:** +- Decoded token payload + +**Raises:** +- `JoseError`: If token is invalid, expired, or has wrong claims + diff --git a/docs/python-sdk/fastmcp-server-auth-middleware.mdx b/docs/python-sdk/fastmcp-server-auth-middleware.mdx new file mode 100644 index 000000000..29217a9fe --- /dev/null +++ b/docs/python-sdk/fastmcp-server-auth-middleware.mdx @@ -0,0 +1,26 @@ +--- +title: middleware +sidebarTitle: middleware +--- + +# `fastmcp.server.auth.middleware` + + +Enhanced authentication middleware with better error messages. + +This module provides enhanced versions of MCP SDK authentication middleware +that return more helpful error messages for developers troubleshooting +authentication issues. + + +## Classes + +### `RequireAuthMiddleware` + + +Enhanced authentication middleware with detailed error messages. + +Extends the SDK's RequireAuthMiddleware to provide more actionable +error messages when authentication fails. This helps developers +understand what went wrong and how to fix it. + diff --git a/docs/python-sdk/fastmcp-server-auth-oauth_proxy-__init__.mdx b/docs/python-sdk/fastmcp-server-auth-oauth_proxy-__init__.mdx new file mode 100644 index 000000000..7c4665aa8 --- /dev/null +++ b/docs/python-sdk/fastmcp-server-auth-oauth_proxy-__init__.mdx @@ -0,0 +1,16 @@ +--- +title: __init__ +sidebarTitle: __init__ +--- + +# `fastmcp.server.auth.oauth_proxy` + + +OAuth Proxy Provider for FastMCP. + +This package provides OAuth proxy functionality split across multiple modules: +- models: Pydantic models and constants +- ui: HTML generation functions +- consent: Consent management mixin +- proxy: Main OAuthProxy class + diff --git a/docs/python-sdk/fastmcp-server-auth-oauth_proxy-consent.mdx b/docs/python-sdk/fastmcp-server-auth-oauth_proxy-consent.mdx new file mode 100644 index 000000000..67c514ee7 --- /dev/null +++ b/docs/python-sdk/fastmcp-server-auth-oauth_proxy-consent.mdx @@ -0,0 +1,28 @@ +--- +title: consent +sidebarTitle: consent +--- + +# `fastmcp.server.auth.oauth_proxy.consent` + + +OAuth Proxy Consent Management. + +This module contains consent management functionality for the OAuth proxy. +The ConsentMixin class provides methods for handling user consent flows, +cookie management, and consent page rendering. + + +## Classes + +### `ConsentMixin` + + +Mixin class providing consent management functionality for OAuthProxy. + +This mixin contains all methods related to: +- Cookie signing and verification +- Consent page rendering +- Consent approval/denial handling +- URI normalization for consent tracking + diff --git a/docs/python-sdk/fastmcp-server-auth-oauth_proxy-models.mdx b/docs/python-sdk/fastmcp-server-auth-oauth_proxy-models.mdx new file mode 100644 index 000000000..a096e9e45 --- /dev/null +++ b/docs/python-sdk/fastmcp-server-auth-oauth_proxy-models.mdx @@ -0,0 +1,105 @@ +--- +title: models +sidebarTitle: models +--- + +# `fastmcp.server.auth.oauth_proxy.models` + + +OAuth Proxy Models and Constants. + +This module contains all Pydantic models and constants used by the OAuth proxy. + + +## Classes + +### `OAuthTransaction` + + +OAuth transaction state for consent flow. + +Stored server-side to track active authorization flows with client context. +Includes CSRF tokens for consent protection per MCP security best practices. + + +### `ClientCode` + + +Client authorization code with PKCE and upstream tokens. + +Stored server-side after upstream IdP callback. Contains the upstream +tokens bound to the client's PKCE challenge for secure token exchange. + + +### `UpstreamTokenSet` + + +Stored upstream OAuth tokens from identity provider. + +These tokens are obtained from the upstream provider (Google, GitHub, etc.) +and stored in plaintext within this model. Encryption is handled transparently +at the storage layer via FernetEncryptionWrapper. Tokens are never exposed to MCP clients. + + +### `JTIMapping` + + +Maps FastMCP token JTI to upstream token ID. + +This allows stateless JWT validation while still being able to look up +the corresponding upstream token when tools need to access upstream APIs. + + +### `RefreshTokenMetadata` + + +Metadata for a refresh token, stored keyed by token hash. + +We store only metadata (not the token itself) for security - if storage +is compromised, attackers get hashes they can't reverse into usable tokens. + + +### `ProxyDCRClient` + + +Client for DCR proxy with configurable redirect URI validation. + +This special client class is critical for the OAuth proxy to work correctly +with Dynamic Client Registration (DCR). Here's why it exists: + +Problem: +-------- +When MCP clients use OAuth, they dynamically register with random localhost +ports (e.g., http://localhost:55454/callback). The OAuth proxy needs to: +1. Accept these dynamic redirect URIs from clients based on configured patterns +2. Use its own fixed redirect URI with the upstream provider (Google, GitHub, etc.) +3. Forward the authorization code back to the client's dynamic URI + +Solution: +--------- +This class validates redirect URIs against configurable patterns, +while the proxy internally uses its own fixed redirect URI with the upstream +provider. This allows the flow to work even when clients reconnect with +different ports or when tokens are cached. + +Without proper validation, clients could get "Redirect URI not registered" errors +when trying to authenticate with cached tokens, or security vulnerabilities could +arise from accepting arbitrary redirect URIs. + + +**Methods:** + +#### `validate_redirect_uri` + +```python +validate_redirect_uri(self, redirect_uri: AnyUrl | None) -> AnyUrl +``` + +Validate redirect URI against proxy patterns and optionally CIMD redirect_uris. + +For CIMD clients: validates against BOTH the CIMD document's redirect_uris +AND the proxy's allowed patterns (if configured). Both must pass. + +For DCR clients: validates against proxy patterns first, falling back to +base validation (registered redirect_uris) if patterns don't match. + diff --git a/docs/python-sdk/fastmcp-server-auth-oauth_proxy-proxy.mdx b/docs/python-sdk/fastmcp-server-auth-oauth_proxy-proxy.mdx new file mode 100644 index 000000000..dd1400086 --- /dev/null +++ b/docs/python-sdk/fastmcp-server-auth-oauth_proxy-proxy.mdx @@ -0,0 +1,323 @@ +--- +title: proxy +sidebarTitle: proxy +--- + +# `fastmcp.server.auth.oauth_proxy.proxy` + + +OAuth Proxy Provider for FastMCP. + +This provider acts as a transparent proxy to an upstream OAuth Authorization Server, +handling Dynamic Client Registration locally while forwarding all other OAuth flows. +This enables authentication with upstream providers that don't support DCR or have +restricted client registration policies. + +Key features: +- Proxies authorization and token endpoints to upstream server +- Implements local Dynamic Client Registration with fixed upstream credentials +- Validates tokens using upstream JWKS +- Maintains minimal local state for bookkeeping +- Enhanced logging with request correlation + +This implementation is based on the OAuth 2.1 specification and is designed for +production use with enterprise identity providers. + + +## Classes + +### `OAuthProxy` + + +OAuth provider that presents a DCR-compliant interface while proxying to non-DCR IDPs. + +Purpose +------- +MCP clients expect OAuth providers to support Dynamic Client Registration (DCR), +where clients can register themselves dynamically and receive unique credentials. +Most enterprise IDPs (Google, GitHub, Azure AD, etc.) don't support DCR and require +pre-registered OAuth applications with fixed credentials. + +This proxy bridges that gap by: +- Presenting a full DCR-compliant OAuth interface to MCP clients +- Translating DCR registration requests to use pre-configured upstream credentials +- Proxying all OAuth flows to the upstream IDP with appropriate translations +- Managing the state and security requirements of both protocols + +Architecture Overview +-------------------- +The proxy maintains a single OAuth app registration with the upstream provider +while allowing unlimited MCP clients to register and authenticate dynamically. +It implements the complete OAuth 2.1 + DCR specification for clients while +translating to whatever OAuth variant the upstream provider requires. + +Key Translation Challenges Solved +--------------------------------- +1. Dynamic Client Registration: + - MCP clients expect to register dynamically and get unique credentials + - Upstream IDPs require pre-registered apps with fixed credentials + - Solution: Accept DCR requests, return shared upstream credentials + +2. Dynamic Redirect URIs: + - MCP clients use random localhost ports that change between sessions + - Upstream IDPs require fixed, pre-registered redirect URIs + - Solution: Use proxy's fixed callback URL with upstream, forward to client's dynamic URI + +3. Authorization Code Mapping: + - Upstream returns codes for the proxy's redirect URI + - Clients expect codes for their own redirect URIs + - Solution: Exchange upstream code server-side, issue new code to client + +4. State Parameter Collision: + - Both client and proxy need to maintain state through the flow + - Only one state parameter available in OAuth + - Solution: Use transaction ID as state with upstream, preserve client's state + +5. Token Management: + - Clients may expect different token formats/claims than upstream provides + - Need to track tokens for revocation and refresh + - Solution: Store token relationships, forward upstream tokens transparently + +OAuth Flow Implementation +------------------------ +1. Client Registration (DCR): + - Accept any client registration request + - Store ProxyDCRClient that accepts dynamic redirect URIs + +2. Authorization: + - Store transaction mapping client details to proxy flow + - Redirect to upstream with proxy's fixed redirect URI + - Use transaction ID as state parameter with upstream + +3. Upstream Callback: + - Exchange upstream authorization code for tokens (server-side) + - Generate new authorization code bound to client's PKCE challenge + - Redirect to client's original dynamic redirect URI + +4. Token Exchange: + - Validate client's code and PKCE verifier + - Return previously obtained upstream tokens + - Clean up one-time use authorization code + +5. Token Refresh: + - Forward refresh requests to upstream using authlib + - Handle token rotation if upstream issues new refresh token + - Update local token mappings + +State Management +--------------- +The proxy maintains minimal but crucial state via pluggable storage (client_storage): +- _oauth_transactions: Active authorization flows with client context +- _client_codes: Authorization codes with PKCE challenges and upstream tokens +- _jti_mapping_store: Maps FastMCP token JTIs to upstream token IDs +- _refresh_token_store: Refresh token metadata (keyed by token hash) + +All state is stored in the configured client_storage backend (Redis, disk, etc.) +enabling horizontal scaling across multiple instances. + +Security Considerations +---------------------- +- Refresh tokens stored by hash only (defense in depth if storage compromised) +- PKCE enforced end-to-end (client to proxy, proxy to upstream) +- Authorization codes are single-use with short expiry +- Transaction IDs are cryptographically random +- All state is cleaned up after use to prevent replay +- Token validation delegates to upstream provider + +Provider Compatibility +--------------------- +Works with any OAuth 2.0 provider that supports: +- Authorization code flow +- Fixed redirect URI (configured in provider's app settings) +- Standard token endpoint + +Handles provider-specific requirements: +- Google: Ensures minimum scope requirements +- GitHub: Compatible with OAuth Apps and GitHub Apps +- Azure AD: Handles tenant-specific endpoints +- Generic: Works with any spec-compliant provider + + +**Methods:** + +#### `set_mcp_path` + +```python +set_mcp_path(self, mcp_path: str | None) -> None +``` + +Set the MCP endpoint path and create JWTIssuer with correct audience. + +This method is called by get_routes() to configure the resource URL +and create the JWTIssuer. The JWT audience is set to the full resource +URL (e.g., http://localhost:8000/mcp) to ensure tokens are bound to +this specific MCP endpoint. + +**Args:** +- `mcp_path`: The path where the MCP endpoint is mounted (e.g., "/mcp") + + +#### `jwt_issuer` + +```python +jwt_issuer(self) -> JWTIssuer +``` + +Get the JWT issuer, ensuring it has been initialized. + +The JWT issuer is created when set_mcp_path() is called (via get_routes()). +This property ensures a clear error if used before initialization. + + +#### `get_client` + +```python +get_client(self, client_id: str) -> OAuthClientInformationFull | None +``` + +Get client information by ID. This is generally the random ID +provided to the DCR client during registration, not the upstream client ID. + +For unregistered clients, returns None (which will raise an error in the SDK). +CIMD clients (URL-based client IDs) are looked up and cached automatically. + + +#### `register_client` + +```python +register_client(self, client_info: OAuthClientInformationFull) -> None +``` + +Register a client locally + +When a client registers, we create a ProxyDCRClient that is more +forgiving about validating redirect URIs, since the DCR client's +redirect URI will likely be localhost or unknown to the proxied IDP. The +proxied IDP only knows about this server's fixed redirect URI. + + +#### `authorize` + +```python +authorize(self, client: OAuthClientInformationFull, params: AuthorizationParams) -> str +``` + +Start OAuth transaction and route through consent interstitial. + +Flow: +1. Validate client's resource matches server's resource URL (security check) +2. Store transaction with client details and PKCE (if forwarding) +3. Return local /consent URL; browser visits consent first +4. Consent handler redirects to upstream IdP if approved/already approved + +If consent is disabled (require_authorization_consent=False), skip the consent screen +and redirect directly to the upstream IdP. + + +#### `load_authorization_code` + +```python +load_authorization_code(self, client: OAuthClientInformationFull, authorization_code: str) -> AuthorizationCode | None +``` + +Load authorization code for validation. + +Look up our client code and return authorization code object +with PKCE challenge for validation. + + +#### `exchange_authorization_code` + +```python +exchange_authorization_code(self, client: OAuthClientInformationFull, authorization_code: AuthorizationCode) -> OAuthToken +``` + +Exchange authorization code for FastMCP-issued tokens. + +Implements the token factory pattern: +1. Retrieves upstream tokens from stored authorization code +2. Extracts user identity from upstream token +3. Encrypts and stores upstream tokens +4. Issues FastMCP-signed JWT tokens +5. Returns FastMCP tokens (NOT upstream tokens) + +PKCE validation is handled by the MCP framework before this method is called. + + +#### `load_refresh_token` + +```python +load_refresh_token(self, client: OAuthClientInformationFull, refresh_token: str) -> RefreshToken | None +``` + +Load refresh token metadata from distributed storage. + +Looks up by token hash and reconstructs the RefreshToken object. +Validates that the token belongs to the requesting client. + + +#### `exchange_refresh_token` + +```python +exchange_refresh_token(self, client: OAuthClientInformationFull, refresh_token: RefreshToken, scopes: list[str]) -> OAuthToken +``` + +Exchange FastMCP refresh token for new FastMCP access token. + +Implements two-tier refresh: +1. Verify FastMCP refresh token +2. Look up upstream token via JTI mapping +3. Refresh upstream token with upstream provider +4. Update stored upstream token +5. Issue new FastMCP access token +6. Keep same FastMCP refresh token (unless upstream rotates) + + +#### `load_access_token` + +```python +load_access_token(self, token: str) -> AccessToken | None +``` + +Validate FastMCP JWT by swapping for upstream token. + +This implements the token swap pattern: +1. Verify FastMCP JWT signature (proves it's our token) +2. Look up upstream token via JTI mapping +3. Decrypt upstream token +4. Validate upstream token with provider (GitHub API, JWT validation, etc.) +5. Return upstream validation result + +The FastMCP JWT is a reference token - all authorization data comes +from validating the upstream token via the TokenVerifier. + + +#### `revoke_token` + +```python +revoke_token(self, token: AccessToken | RefreshToken) -> None +``` + +Revoke token locally and with upstream server if supported. + +For refresh tokens, removes from local storage by hash. +For all tokens, attempts upstream revocation if endpoint is configured. +Access token JTI mappings expire via TTL. + + +#### `get_routes` + +```python +get_routes(self, mcp_path: str | None = None) -> list[Route] +``` + +Get OAuth routes with custom handlers for better error UX. + +This method creates standard OAuth routes and replaces: +- /authorize endpoint: Enhanced error responses for unregistered clients +- /token endpoint: OAuth 2.1 compliant error codes + +**Args:** +- `mcp_path`: The path where the MCP endpoint is mounted (e.g., "/mcp") +This is used to advertise the resource URL in metadata. + diff --git a/docs/python-sdk/fastmcp-server-auth-oauth_proxy-ui.mdx b/docs/python-sdk/fastmcp-server-auth-oauth_proxy-ui.mdx new file mode 100644 index 000000000..fdbd2eb50 --- /dev/null +++ b/docs/python-sdk/fastmcp-server-auth-oauth_proxy-ui.mdx @@ -0,0 +1,50 @@ +--- +title: ui +sidebarTitle: ui +--- + +# `fastmcp.server.auth.oauth_proxy.ui` + + +OAuth Proxy UI Generation Functions. + +This module contains HTML generation functions for consent and error pages. + + +## Functions + +### `create_consent_html` + +```python +create_consent_html(client_id: str, redirect_uri: str, scopes: list[str], txn_id: str, csrf_token: str, client_name: str | None = None, title: str = 'Application Access Request', server_name: str | None = None, server_icon_url: str | None = None, server_website_url: str | None = None, client_website_url: str | None = None, csp_policy: str | None = None, is_cimd_client: bool = False, cimd_domain: str | None = None) -> str +``` + + +Create a styled HTML consent page for OAuth authorization requests. + +**Args:** +- `csp_policy`: Content Security Policy override. +If None, uses the built-in CSP policy with appropriate directives. +If empty string "", disables CSP entirely (no meta tag is rendered). +If a non-empty string, uses that as the CSP policy value. + + +### `create_error_html` + +```python +create_error_html(error_title: str, error_message: str, error_details: dict[str, str] | None = None, server_name: str | None = None, server_icon_url: str | None = None) -> str +``` + + +Create a styled HTML error page for OAuth errors. + +**Args:** +- `error_title`: The error title (e.g., "OAuth Error", "Authorization Failed") +- `error_message`: The main error message to display +- `error_details`: Optional dictionary of error details to show (e.g., `{"Error Code"\: "invalid_client"}`) +- `server_name`: Optional server name to display +- `server_icon_url`: Optional URL to server icon/logo + +**Returns:** +- Complete HTML page as a string + diff --git a/docs/python-sdk/fastmcp-server-auth-oidc_proxy.mdx b/docs/python-sdk/fastmcp-server-auth-oidc_proxy.mdx new file mode 100644 index 000000000..183380ed9 --- /dev/null +++ b/docs/python-sdk/fastmcp-server-auth-oidc_proxy.mdx @@ -0,0 +1,82 @@ +--- +title: oidc_proxy +sidebarTitle: oidc_proxy +--- + +# `fastmcp.server.auth.oidc_proxy` + + +OIDC Proxy Provider for FastMCP. + +This provider acts as a transparent proxy to an upstream OIDC compliant Authorization +Server. It leverages the OAuthProxy class to handle Dynamic Client Registration and +forwarding of all OAuth flows. + +This implementation is based on: + OpenID Connect Discovery 1.0 - https://openid.net/specs/openid-connect-discovery-1_0.html + OAuth 2.0 Authorization Server Metadata - https://datatracker.ietf.org/doc/html/rfc8414 + + +## Classes + +### `OIDCConfiguration` + + +OIDC Configuration. + + +**Methods:** + +#### `get_oidc_configuration` + +```python +get_oidc_configuration(cls, config_url: AnyHttpUrl) -> Self +``` + +Get the OIDC configuration for the specified config URL. + +**Args:** +- `config_url`: The OIDC config URL +- `strict`: The strict flag for the configuration +- `timeout_seconds`: HTTP request timeout in seconds + + +### `OIDCProxy` + + +OAuth provider that wraps OAuthProxy to provide configuration via an OIDC configuration URL. + +This provider makes it easier to add OAuth protection for any upstream provider +that is OIDC compliant. + + +**Methods:** + +#### `get_oidc_configuration` + +```python +get_oidc_configuration(self, config_url: AnyHttpUrl, strict: bool | None, timeout_seconds: int | None) -> OIDCConfiguration +``` + +Gets the OIDC configuration for the specified configuration URL. + +**Args:** +- `config_url`: The OIDC configuration URL +- `strict`: The strict flag for the configuration +- `timeout_seconds`: HTTP request timeout in seconds + + +#### `get_token_verifier` + +```python +get_token_verifier(self) -> TokenVerifier +``` + +Creates the token verifier for the specified OIDC configuration and arguments. + +**Args:** +- `algorithm`: Optional token verifier algorithm +- `audience`: Optional token verifier audience +- `required_scopes`: Optional token verifier required_scopes +- `timeout_seconds`: HTTP request timeout in seconds + diff --git a/docs/python-sdk/fastmcp-server-auth-providers-__init__.mdx b/docs/python-sdk/fastmcp-server-auth-providers-__init__.mdx new file mode 100644 index 000000000..9de7cce8a --- /dev/null +++ b/docs/python-sdk/fastmcp-server-auth-providers-__init__.mdx @@ -0,0 +1,8 @@ +--- +title: __init__ +sidebarTitle: __init__ +--- + +# `fastmcp.server.auth.providers` + +*This module is empty or contains only private/internal implementations.* diff --git a/docs/python-sdk/fastmcp-server-auth-providers-auth0.mdx b/docs/python-sdk/fastmcp-server-auth-providers-auth0.mdx new file mode 100644 index 000000000..140ddd193 --- /dev/null +++ b/docs/python-sdk/fastmcp-server-auth-providers-auth0.mdx @@ -0,0 +1,41 @@ +--- +title: auth0 +sidebarTitle: auth0 +--- + +# `fastmcp.server.auth.providers.auth0` + + +Auth0 OAuth provider for FastMCP. + +This module provides a complete Auth0 integration that's ready to use with +just the configuration URL, client ID, client secret, audience, and base URL. + +Example: + ```python + from fastmcp import FastMCP + from fastmcp.server.auth.providers.auth0 import Auth0Provider + + # Simple Auth0 OAuth protection + auth = Auth0Provider( + config_url="https://auth0.config.url", + client_id="your-auth0-client-id", + client_secret="your-auth0-client-secret", + audience="your-auth0-api-audience", + base_url="http://localhost:8000", + ) + + mcp = FastMCP("My Protected Server", auth=auth) + ``` + + +## Classes + +### `Auth0Provider` + + +An Auth0 provider implementation for FastMCP. + +This provider is a complete Auth0 integration that's ready to use with +just the configuration URL, client ID, client secret, audience, and base URL. + diff --git a/docs/python-sdk/fastmcp-server-auth-providers-aws.mdx b/docs/python-sdk/fastmcp-server-auth-providers-aws.mdx new file mode 100644 index 000000000..5803d4f62 --- /dev/null +++ b/docs/python-sdk/fastmcp-server-auth-providers-aws.mdx @@ -0,0 +1,82 @@ +--- +title: aws +sidebarTitle: aws +--- + +# `fastmcp.server.auth.providers.aws` + + +AWS Cognito OAuth provider for FastMCP. + +This module provides a complete AWS Cognito OAuth integration that's ready to use +with a user pool ID, domain prefix, client ID and client secret. It handles all +the complexity of AWS Cognito's OAuth flow, token validation, and user management. + +Example: + ```python + from fastmcp import FastMCP + from fastmcp.server.auth.providers.aws_cognito import AWSCognitoProvider + + # Simple AWS Cognito OAuth protection + auth = AWSCognitoProvider( + user_pool_id="your-user-pool-id", + aws_region="eu-central-1", + client_id="your-cognito-client-id", + client_secret="your-cognito-client-secret" + ) + + mcp = FastMCP("My Protected Server", auth=auth) + ``` + + +## Classes + +### `AWSCognitoTokenVerifier` + + +Token verifier that filters claims to Cognito-specific subset. + + +**Methods:** + +#### `verify_token` + +```python +verify_token(self, token: str) -> AccessToken | None +``` + +Verify token and filter claims to Cognito-specific subset. + + +### `AWSCognitoProvider` + + +Complete AWS Cognito OAuth provider for FastMCP. + +This provider makes it trivial to add AWS Cognito OAuth protection to any +FastMCP server using OIDC Discovery. Just provide your Cognito User Pool details, +client credentials, and a base URL, and you're ready to go. + +Features: +- Automatic OIDC Discovery from AWS Cognito User Pool +- Automatic JWT token validation via Cognito's public keys +- Cognito-specific claim filtering (sub, username, cognito:groups) +- Support for Cognito User Pools + + +**Methods:** + +#### `get_token_verifier` + +```python +get_token_verifier(self) -> TokenVerifier +``` + +Creates a Cognito-specific token verifier with claim filtering. + +**Args:** +- `algorithm`: Optional token verifier algorithm +- `audience`: Optional token verifier audience +- `required_scopes`: Optional token verifier required_scopes +- `timeout_seconds`: HTTP request timeout in seconds + diff --git a/docs/python-sdk/fastmcp-server-auth-providers-azure.mdx b/docs/python-sdk/fastmcp-server-auth-providers-azure.mdx new file mode 100644 index 000000000..4d3140c4a --- /dev/null +++ b/docs/python-sdk/fastmcp-server-auth-providers-azure.mdx @@ -0,0 +1,182 @@ +--- +title: azure +sidebarTitle: azure +--- + +# `fastmcp.server.auth.providers.azure` + + +Azure (Microsoft Entra) OAuth provider for FastMCP. + +This provider implements Azure/Microsoft Entra ID OAuth authentication +using the OAuth Proxy pattern for non-DCR OAuth flows. + + +## Functions + +### `EntraOBOToken` + +```python +EntraOBOToken(scopes: list[str]) -> str +``` + + +Exchange the user's Entra token for a downstream API token via OBO. + +This dependency performs a Microsoft Entra On-Behalf-Of (OBO) token exchange, +allowing your MCP server to call downstream APIs (like Microsoft Graph) on +behalf of the authenticated user. + +**Args:** +- `scopes`: The scopes to request for the downstream API. For Microsoft Graph, +use scopes like ["https\://graph.microsoft.com/Mail.Read"] or +["https\://graph.microsoft.com/.default"]. + +**Returns:** +- A dependency that resolves to the downstream API access token string + +**Raises:** +- `ImportError`: If fastmcp[azure] is not installed +- `RuntimeError`: If no access token is available, provider is not Azure, +or OBO exchange fails + + +## Classes + +### `AzureProvider` + + +Azure (Microsoft Entra) OAuth provider for FastMCP. + +This provider implements Azure/Microsoft Entra ID authentication using the +OAuth Proxy pattern. It supports both organizational accounts and personal +Microsoft accounts depending on the tenant configuration. + +Scope Handling: +- required_scopes: Provide unprefixed scope names (e.g., ["read", "write"]) + → Automatically prefixed with identifier_uri during initialization + → Validated on all tokens and advertised to MCP clients +- additional_authorize_scopes: Provide full format (e.g., ["User.Read"]) + → NOT prefixed, NOT validated, NOT advertised to clients + → Used to request Microsoft Graph or other upstream API permissions + +Features: +- OAuth proxy to Azure/Microsoft identity platform +- JWT validation using tenant issuer and JWKS +- Supports tenant configurations: specific tenant ID, "organizations", or "consumers" +- Custom API scopes and Microsoft Graph scopes in a single provider + +Setup: +1. Create an App registration in Azure Portal +2. Configure Web platform redirect URI: http://localhost:8000/auth/callback (or your custom path) +3. Add an Application ID URI under "Expose an API" (defaults to api://{client_id}) +4. Add custom scopes (e.g., "read", "write") under "Expose an API" +5. Set access token version to 2 in the App manifest: "requestedAccessTokenVersion": 2 +6. Create a client secret +7. Get Application (client) ID, Directory (tenant) ID, and client secret + + +**Methods:** + +#### `authorize` + +```python +authorize(self, client: OAuthClientInformationFull, params: AuthorizationParams) -> str +``` + +Start OAuth transaction and redirect to Azure AD. + +Override parent's authorize method to filter out the 'resource' parameter +which is not supported by Azure AD v2.0 endpoints. The v2.0 endpoints use +scopes to determine the resource/audience instead of a separate parameter. + +**Args:** +- `client`: OAuth client information +- `params`: Authorization parameters from the client + +**Returns:** +- Authorization URL to redirect the user to Azure AD + + +#### `get_obo_credential` + +```python +get_obo_credential(self, user_assertion: str) -> OnBehalfOfCredential +``` + +Get a cached or new OnBehalfOfCredential for OBO token exchange. + +Credentials are cached by user assertion so the Azure SDK's internal +token cache can avoid redundant OBO exchanges when the same user +calls multiple tools with the same scopes. + +**Args:** +- `user_assertion`: The user's access token to exchange via OBO. + +**Returns:** +- A configured OnBehalfOfCredential ready for get_token() calls. + +**Raises:** +- `ImportError`: If azure-identity is not installed (requires fastmcp[azure]). + + +#### `close_obo_credentials` + +```python +close_obo_credentials(self) -> None +``` + +Close all cached OBO credentials. + + +### `AzureJWTVerifier` + + +JWT verifier pre-configured for Azure AD / Microsoft Entra ID. + +Auto-configures JWKS URI, issuer, audience, and scope handling from your +Azure app registration details. Designed for Managed Identity and other +token-verification-only scenarios where AzureProvider's full OAuth proxy +isn't needed. + +Handles Azure's scope format automatically: +- Validates tokens using short-form scopes (what Azure puts in ``scp`` claims) +- Advertises full-URI scopes in OAuth metadata (what clients need to request) + +Example:: + + from fastmcp.server.auth import RemoteAuthProvider + from fastmcp.server.auth.providers.azure import AzureJWTVerifier + from pydantic import AnyHttpUrl + + verifier = AzureJWTVerifier( + client_id="your-client-id", + tenant_id="your-tenant-id", + required_scopes=["access_as_user"], + ) + + auth = RemoteAuthProvider( + token_verifier=verifier, + authorization_servers=[ + AnyHttpUrl("https://login.microsoftonline.com/your-tenant-id/v2.0") + ], + base_url="https://my-server.com", + ) + + +**Methods:** + +#### `scopes_supported` + +```python +scopes_supported(self) -> list[str] +``` + +Return scopes with Azure URI prefix for OAuth metadata. + +Azure tokens contain short-form scopes (e.g., ``read``) in the ``scp`` +claim, but clients must request full URI scopes (e.g., +``api://client-id/read``) from the Azure authorization endpoint. This +property returns the full-URI form for OAuth metadata while +``required_scopes`` retains the short form for token validation. + diff --git a/docs/python-sdk/fastmcp-server-auth-providers-debug.mdx b/docs/python-sdk/fastmcp-server-auth-providers-debug.mdx new file mode 100644 index 000000000..8ed3e6b87 --- /dev/null +++ b/docs/python-sdk/fastmcp-server-auth-providers-debug.mdx @@ -0,0 +1,70 @@ +--- +title: debug +sidebarTitle: debug +--- + +# `fastmcp.server.auth.providers.debug` + + +Debug token verifier for testing and special cases. + +This module provides a flexible token verifier that delegates validation +to a custom callable. Useful for testing, development, or scenarios where +standard verification isn't possible (like opaque tokens without introspection). + +Example: + ```python + from fastmcp import FastMCP + from fastmcp.server.auth.providers.debug import DebugTokenVerifier + + # Accept all tokens (default - useful for testing) + auth = DebugTokenVerifier() + + # Custom sync validation logic + auth = DebugTokenVerifier(validate=lambda token: token.startswith("valid-")) + + # Custom async validation logic + async def check_cache(token: str) -> bool: + return await redis.exists(f"token:{token}") + + auth = DebugTokenVerifier(validate=check_cache) + + mcp = FastMCP("My Server", auth=auth) + ``` + + +## Classes + +### `DebugTokenVerifier` + + +Token verifier with custom validation logic. + +This verifier delegates token validation to a user-provided callable. +By default, it accepts all non-empty tokens (useful for testing). + +Use cases: +- Testing: Accept any token without real verification +- Development: Custom validation logic for prototyping +- Opaque tokens: When you have tokens with no introspection endpoint + +WARNING: This bypasses standard security checks. Only use in controlled +environments or when you understand the security implications. + + +**Methods:** + +#### `verify_token` + +```python +verify_token(self, token: str) -> AccessToken | None +``` + +Verify token using custom validation logic. + +**Args:** +- `token`: The token string to validate + +**Returns:** +- AccessToken if validation succeeds, None otherwise + diff --git a/docs/python-sdk/fastmcp-server-auth-providers-descope.mdx b/docs/python-sdk/fastmcp-server-auth-providers-descope.mdx new file mode 100644 index 000000000..3436aa5c3 --- /dev/null +++ b/docs/python-sdk/fastmcp-server-auth-providers-descope.mdx @@ -0,0 +1,60 @@ +--- +title: descope +sidebarTitle: descope +--- + +# `fastmcp.server.auth.providers.descope` + + +Descope authentication provider for FastMCP. + +This module provides DescopeProvider - a complete authentication solution that integrates +with Descope's OAuth 2.1 and OpenID Connect services, supporting Dynamic Client Registration (DCR) +for seamless MCP client authentication. + + +## Classes + +### `DescopeProvider` + + +Descope metadata provider for DCR (Dynamic Client Registration). + +This provider implements Descope integration using metadata forwarding. +This is the recommended approach for Descope DCR +as it allows Descope to handle the OAuth flow directly while FastMCP acts +as a resource server. + +IMPORTANT SETUP REQUIREMENTS: + +1. Create an MCP Server in Descope Console: + - Go to the [MCP Servers page](https://app.descope.com/mcp-servers) of the Descope Console + - Create a new MCP Server + - Ensure that **Dynamic Client Registration (DCR)** is enabled + - Note your Well-Known URL + +2. Note your Well-Known URL: + - Save your Well-Known URL from [MCP Server Settings](https://app.descope.com/mcp-servers) + - Format: ``https://.../v1/apps/agentic/P.../M.../.well-known/openid-configuration`` + +For detailed setup instructions, see: +https://docs.descope.com/identity-federation/inbound-apps/creating-inbound-apps#method-2-dynamic-client-registration-dcr + + +**Methods:** + +#### `get_routes` + +```python +get_routes(self, mcp_path: str | None = None) -> list[Route] +``` + +Get OAuth routes including Descope authorization server metadata forwarding. + +This returns the standard protected resource routes plus an authorization server +metadata endpoint that forwards Descope's OAuth metadata to clients. + +**Args:** +- `mcp_path`: The path where the MCP endpoint is mounted (e.g., "/mcp") +This is used to advertise the resource URL in metadata. + diff --git a/docs/python-sdk/fastmcp-server-auth-providers-discord.mdx b/docs/python-sdk/fastmcp-server-auth-providers-discord.mdx new file mode 100644 index 000000000..61b024b63 --- /dev/null +++ b/docs/python-sdk/fastmcp-server-auth-providers-discord.mdx @@ -0,0 +1,66 @@ +--- +title: discord +sidebarTitle: discord +--- + +# `fastmcp.server.auth.providers.discord` + + +Discord OAuth provider for FastMCP. + +This module provides a complete Discord OAuth integration that's ready to use +with just a client ID and client secret. It handles all the complexity of +Discord's OAuth flow, token validation, and user management. + +Example: + ```python + from fastmcp import FastMCP + from fastmcp.server.auth.providers.discord import DiscordProvider + + # Simple Discord OAuth protection + auth = DiscordProvider( + client_id="your-discord-client-id", + client_secret="your-discord-client-secret" + ) + + mcp = FastMCP("My Protected Server", auth=auth) + ``` + + +## Classes + +### `DiscordTokenVerifier` + + +Token verifier for Discord OAuth tokens. + +Discord OAuth tokens are opaque (not JWTs), so we verify them +by calling Discord's tokeninfo API to check if they're valid and get user info. + + +**Methods:** + +#### `verify_token` + +```python +verify_token(self, token: str) -> AccessToken | None +``` + +Verify Discord OAuth token by calling Discord's tokeninfo API. + + +### `DiscordProvider` + + +Complete Discord OAuth provider for FastMCP. + +This provider makes it trivial to add Discord OAuth protection to any +FastMCP server. Just provide your Discord OAuth app credentials and +a base URL, and you're ready to go. + +Features: +- Transparent OAuth proxy to Discord +- Automatic token validation via Discord's API +- User information extraction from Discord APIs +- Minimal configuration required + diff --git a/docs/python-sdk/fastmcp-server-auth-providers-github.mdx b/docs/python-sdk/fastmcp-server-auth-providers-github.mdx new file mode 100644 index 000000000..66a808136 --- /dev/null +++ b/docs/python-sdk/fastmcp-server-auth-providers-github.mdx @@ -0,0 +1,66 @@ +--- +title: github +sidebarTitle: github +--- + +# `fastmcp.server.auth.providers.github` + + +GitHub OAuth provider for FastMCP. + +This module provides a complete GitHub OAuth integration that's ready to use +with just a client ID and client secret. It handles all the complexity of +GitHub's OAuth flow, token validation, and user management. + +Example: + ```python + from fastmcp import FastMCP + from fastmcp.server.auth.providers.github import GitHubProvider + + # Simple GitHub OAuth protection + auth = GitHubProvider( + client_id="your-github-client-id", + client_secret="your-github-client-secret" + ) + + mcp = FastMCP("My Protected Server", auth=auth) + ``` + + +## Classes + +### `GitHubTokenVerifier` + + +Token verifier for GitHub OAuth tokens. + +GitHub OAuth tokens are opaque (not JWTs), so we verify them +by calling GitHub's API to check if they're valid and get user info. + + +**Methods:** + +#### `verify_token` + +```python +verify_token(self, token: str) -> AccessToken | None +``` + +Verify GitHub OAuth token by calling GitHub API. + + +### `GitHubProvider` + + +Complete GitHub OAuth provider for FastMCP. + +This provider makes it trivial to add GitHub OAuth protection to any +FastMCP server. Just provide your GitHub OAuth app credentials and +a base URL, and you're ready to go. + +Features: +- Transparent OAuth proxy to GitHub +- Automatic token validation via GitHub API +- User information extraction +- Minimal configuration required + diff --git a/docs/python-sdk/fastmcp-server-auth-providers-google.mdx b/docs/python-sdk/fastmcp-server-auth-providers-google.mdx new file mode 100644 index 000000000..880488438 --- /dev/null +++ b/docs/python-sdk/fastmcp-server-auth-providers-google.mdx @@ -0,0 +1,66 @@ +--- +title: google +sidebarTitle: google +--- + +# `fastmcp.server.auth.providers.google` + + +Google OAuth provider for FastMCP. + +This module provides a complete Google OAuth integration that's ready to use +with just a client ID and client secret. It handles all the complexity of +Google's OAuth flow, token validation, and user management. + +Example: + ```python + from fastmcp import FastMCP + from fastmcp.server.auth.providers.google import GoogleProvider + + # Simple Google OAuth protection + auth = GoogleProvider( + client_id="your-google-client-id.apps.googleusercontent.com", + client_secret="your-google-client-secret" + ) + + mcp = FastMCP("My Protected Server", auth=auth) + ``` + + +## Classes + +### `GoogleTokenVerifier` + + +Token verifier for Google OAuth tokens. + +Google OAuth tokens are opaque (not JWTs), so we verify them +by calling Google's tokeninfo API to check if they're valid and get user info. + + +**Methods:** + +#### `verify_token` + +```python +verify_token(self, token: str) -> AccessToken | None +``` + +Verify Google OAuth token by calling Google's tokeninfo API. + + +### `GoogleProvider` + + +Complete Google OAuth provider for FastMCP. + +This provider makes it trivial to add Google OAuth protection to any +FastMCP server. Just provide your Google OAuth app credentials and +a base URL, and you're ready to go. + +Features: +- Transparent OAuth proxy to Google +- Automatic token validation via Google's tokeninfo API +- User information extraction from Google APIs +- Minimal configuration required + diff --git a/docs/python-sdk/fastmcp-server-auth-providers-in_memory.mdx b/docs/python-sdk/fastmcp-server-auth-providers-in_memory.mdx new file mode 100644 index 000000000..c4ee4cc14 --- /dev/null +++ b/docs/python-sdk/fastmcp-server-auth-providers-in_memory.mdx @@ -0,0 +1,96 @@ +--- +title: in_memory +sidebarTitle: in_memory +--- + +# `fastmcp.server.auth.providers.in_memory` + +## Classes + +### `InMemoryOAuthProvider` + + +An in-memory OAuth provider for testing purposes. +It simulates the OAuth 2.1 flow locally without external calls. + + +**Methods:** + +#### `get_client` + +```python +get_client(self, client_id: str) -> OAuthClientInformationFull | None +``` + +#### `register_client` + +```python +register_client(self, client_info: OAuthClientInformationFull) -> None +``` + +#### `authorize` + +```python +authorize(self, client: OAuthClientInformationFull, params: AuthorizationParams) -> str +``` + +Simulates user authorization and generates an authorization code. +Returns a redirect URI with the code and state. + + +#### `load_authorization_code` + +```python +load_authorization_code(self, client: OAuthClientInformationFull, authorization_code: str) -> AuthorizationCode | None +``` + +#### `exchange_authorization_code` + +```python +exchange_authorization_code(self, client: OAuthClientInformationFull, authorization_code: AuthorizationCode) -> OAuthToken +``` + +#### `load_refresh_token` + +```python +load_refresh_token(self, client: OAuthClientInformationFull, refresh_token: str) -> RefreshToken | None +``` + +#### `exchange_refresh_token` + +```python +exchange_refresh_token(self, client: OAuthClientInformationFull, refresh_token: RefreshToken, scopes: list[str]) -> OAuthToken +``` + +#### `load_access_token` + +```python +load_access_token(self, token: str) -> AccessToken | None +``` + +#### `verify_token` + +```python +verify_token(self, token: str) -> AccessToken | None +``` + +Verify a bearer token and return access info if valid. + +This method implements the TokenVerifier protocol by delegating +to our existing load_access_token method. + +**Args:** +- `token`: The token string to validate + +**Returns:** +- AccessToken object if valid, None if invalid or expired + + +#### `revoke_token` + +```python +revoke_token(self, token: AccessToken | RefreshToken) -> None +``` + +Revokes an access or refresh token and its counterpart. + diff --git a/docs/python-sdk/fastmcp-server-auth-providers-introspection.mdx b/docs/python-sdk/fastmcp-server-auth-providers-introspection.mdx new file mode 100644 index 000000000..811737e34 --- /dev/null +++ b/docs/python-sdk/fastmcp-server-auth-providers-introspection.mdx @@ -0,0 +1,82 @@ +--- +title: introspection +sidebarTitle: introspection +--- + +# `fastmcp.server.auth.providers.introspection` + + +OAuth 2.0 Token Introspection (RFC 7662) provider for FastMCP. + +This module provides token verification for opaque tokens using the OAuth 2.0 +Token Introspection protocol defined in RFC 7662. It allows FastMCP servers to +validate tokens issued by authorization servers that don't use JWT format. + +Example: + ```python + from fastmcp import FastMCP + from fastmcp.server.auth.providers.introspection import IntrospectionTokenVerifier + + # Verify opaque tokens via RFC 7662 introspection + verifier = IntrospectionTokenVerifier( + introspection_url="https://auth.example.com/oauth/introspect", + client_id="your-client-id", + client_secret="your-client-secret", + required_scopes=["read", "write"] + ) + + mcp = FastMCP("My Protected Server", auth=verifier) + ``` + + +## Classes + +### `IntrospectionTokenVerifier` + + +OAuth 2.0 Token Introspection verifier (RFC 7662). + +This verifier validates opaque tokens by calling an OAuth 2.0 token introspection +endpoint. Unlike JWT verification which is stateless, token introspection requires +a network call to the authorization server for each token validation. + +The verifier authenticates to the introspection endpoint using either: +- HTTP Basic Auth (client_secret_basic, default): credentials in Authorization header +- POST body authentication (client_secret_post): credentials in request body + +Both methods are specified in RFC 6749 (OAuth 2.0) and RFC 7662 (Token Introspection). + +Use this when: +- Your authorization server issues opaque (non-JWT) tokens +- You need to validate tokens from Auth0, Okta, Keycloak, or other OAuth servers +- Your tokens require real-time revocation checking +- Your authorization server supports RFC 7662 introspection + +Caching is disabled by default to preserve real-time revocation semantics. +Set ``cache_ttl_seconds`` to enable caching and reduce load on the +introspection endpoint (e.g., ``cache_ttl_seconds=300`` for 5 minutes). + + +**Methods:** + +#### `verify_token` + +```python +verify_token(self, token: str) -> AccessToken | None +``` + +Verify a bearer token using OAuth 2.0 Token Introspection (RFC 7662). + +This method makes a POST request to the introspection endpoint with the token, +authenticated using the configured client authentication method (client_secret_basic +or client_secret_post). + +Results are cached in-memory to reduce load on the introspection endpoint. +Cache TTL and size are configurable via constructor parameters. + +**Args:** +- `token`: The opaque token string to validate + +**Returns:** +- AccessToken object if valid and active, None if invalid, inactive, or expired + diff --git a/docs/python-sdk/fastmcp-server-auth-providers-jwt.mdx b/docs/python-sdk/fastmcp-server-auth-providers-jwt.mdx new file mode 100644 index 000000000..6ba9054c2 --- /dev/null +++ b/docs/python-sdk/fastmcp-server-auth-providers-jwt.mdx @@ -0,0 +1,146 @@ +--- +title: jwt +sidebarTitle: jwt +--- + +# `fastmcp.server.auth.providers.jwt` + + +TokenVerifier implementations for FastMCP. + +## Classes + +### `JWKData` + + +JSON Web Key data structure. + + +### `JWKSData` + + +JSON Web Key Set data structure. + + +### `RSAKeyPair` + + +RSA key pair for JWT testing. + + +**Methods:** + +#### `generate` + +```python +generate(cls) -> RSAKeyPair +``` + +Generate an RSA key pair for testing. + +**Returns:** +- Generated key pair + + +#### `create_token` + +```python +create_token(self, subject: str = 'fastmcp-user', issuer: str = 'https://fastmcp.example.com', audience: str | list[str] | None = None, scopes: list[str] | None = None, expires_in_seconds: int = 3600, additional_claims: dict[str, Any] | None = None, kid: str | None = None) -> str +``` + +Generate a test JWT token for testing purposes. + +**Args:** +- `subject`: Subject claim (usually user ID) +- `issuer`: Issuer claim +- `audience`: Audience claim - can be a string or list of strings (optional) +- `scopes`: List of scopes to include +- `expires_in_seconds`: Token expiration time in seconds +- `additional_claims`: Any additional claims to include +- `kid`: Key ID to include in header + + +### `JWTVerifier` + + +JWT token verifier supporting both asymmetric (RSA/ECDSA) and symmetric (HMAC) algorithms. + +This verifier validates JWT tokens using various signing algorithms: +- **Asymmetric algorithms** (RS256/384/512, ES256/384/512, PS256/384/512): + Uses public/private key pairs. Ideal for external clients and services where + only the authorization server has the private key. +- **Symmetric algorithms** (HS256/384/512): Uses a shared secret for both + signing and verification. Perfect for internal microservices and trusted + environments where the secret can be securely shared. + +Use this when: +- You have JWT tokens issued by an external service (asymmetric) +- You need JWKS support for automatic key rotation (asymmetric) +- You have internal microservices sharing a secret key (symmetric) +- Your tokens contain standard OAuth scopes and claims + + +**Methods:** + +#### `load_access_token` + +```python +load_access_token(self, token: str) -> AccessToken | None +``` + +Validate a JWT bearer token and return an AccessToken when the token is valid. + +**Args:** +- `token`: The JWT bearer token string to validate. + +**Returns:** +- AccessToken | None: An AccessToken populated from token claims if the token is valid; `None` if the token is expired, has an invalid signature or format, fails issuer/audience/scope validation, or any other validation error occurs. + + +#### `verify_token` + +```python +verify_token(self, token: str) -> AccessToken | None +``` + +Verify a bearer token and return access info if valid. + +This method implements the TokenVerifier protocol by delegating +to our existing load_access_token method. + +**Args:** +- `token`: The JWT token string to validate + +**Returns:** +- AccessToken object if valid, None if invalid or expired + + +### `StaticTokenVerifier` + + +Simple static token verifier for testing and development. + +This verifier validates tokens against a predefined dictionary of valid token +strings and their associated claims. When a token string matches a key in the +dictionary, the verifier returns the corresponding claims as if the token was +validated by a real authorization server. + +Use this when: +- You're developing or testing locally without a real OAuth server +- You need predictable tokens for automated testing +- You want to simulate different users/scopes without complex setup +- You're prototyping and need simple API key-style authentication + +WARNING: Never use this in production - tokens are stored in plain text! + + +**Methods:** + +#### `verify_token` + +```python +verify_token(self, token: str) -> AccessToken | None +``` + +Verify token against static token dictionary. + diff --git a/docs/python-sdk/fastmcp-server-auth-providers-oci.mdx b/docs/python-sdk/fastmcp-server-auth-providers-oci.mdx new file mode 100644 index 000000000..b88c7c49e --- /dev/null +++ b/docs/python-sdk/fastmcp-server-auth-providers-oci.mdx @@ -0,0 +1,97 @@ +--- +title: oci +sidebarTitle: oci +--- + +# `fastmcp.server.auth.providers.oci` + + +OCI OIDC provider for FastMCP. + +The pull request for the provider is submitted to fastmcp. + +This module provides OIDC Implementation to integrate MCP servers with OCI. +You only need OCI Identity Domain's discovery URL, client ID, client secret, and base URL. + +Post Authentication, you get OCI IAM domain access token. That is not authorized to invoke OCI control plane. +You need to exchange the IAM domain access token for OCI UPST token to invoke OCI control plane APIs. +The sample code below has get_oci_signer function that returns OCI TokenExchangeSigner object. +You can use the signer object to create OCI service object. + +Example: + ```python + from fastmcp import FastMCP + from fastmcp.server.auth.providers.oci import OCIProvider + from fastmcp.server.dependencies import get_access_token + from fastmcp.utilities.logging import get_logger + + import os + + import oci + from oci.auth.signers import TokenExchangeSigner + + logger = get_logger(__name__) + + # Load configuration from environment + config_url = os.environ.get("OCI_CONFIG_URL") # OCI IAM Domain OIDC discovery URL + client_id = os.environ.get("OCI_CLIENT_ID") # Client ID configured for the OCI IAM Domain Integrated Application + client_secret = os.environ.get("OCI_CLIENT_SECRET") # Client secret configured for the OCI IAM Domain Integrated Application + iam_guid = os.environ.get("OCI_IAM_GUID") # IAM GUID configured for the OCI IAM Domain + + # Simple OCI OIDC protection + auth = OCIProvider( + config_url=config_url, # config URL is the OCI IAM Domain OIDC discovery URL + client_id=client_id, # This is same as the client ID configured for the OCI IAM Domain Integrated Application + client_secret=client_secret, # This is same as the client secret configured for the OCI IAM Domain Integrated Application + required_scopes=["openid", "profile", "email"], + redirect_path="/auth/callback", + base_url="http://localhost:8000", + ) + + # NOTE: For production use, replace this with a thread-safe cache implementation + # such as threading.Lock-protected dict or a proper caching library + _global_token_cache = {} # In memory cache for OCI session token signer + + def get_oci_signer() -> TokenExchangeSigner: + + authntoken = get_access_token() + tokenID = authntoken.claims.get("jti") + token = authntoken.token + + # Check if the signer exists for the token ID in memory cache + cached_signer = _global_token_cache.get(tokenID) + logger.debug(f"Global cached signer: {cached_signer}") + if cached_signer: + logger.debug(f"Using globally cached signer for token ID: {tokenID}") + return cached_signer + + # If the signer is not yet created for the token then create new OCI signer object + logger.debug(f"Creating new signer for token ID: {tokenID}") + signer = TokenExchangeSigner( + jwt_or_func=token, + oci_domain_id=iam_guid.split(".")[0] if iam_guid else None, # This is same as IAM GUID configured for the OCI IAM Domain + client_id=client_id, # This is same as the client ID configured for the OCI IAM Domain Integrated Application + client_secret=client_secret, # This is same as the client secret configured for the OCI IAM Domain Integrated Application + ) + logger.debug(f"Signer {signer} created for token ID: {tokenID}") + + #Cache the signer object in memory cache + _global_token_cache[tokenID] = signer + logger.debug(f"Signer cached for token ID: {tokenID}") + + return signer + + mcp = FastMCP("My Protected Server", auth=auth) + ``` + + +## Classes + +### `OCIProvider` + + +An OCI IAM Domain provider implementation for FastMCP. + +This provider is a complete OCI integration that's ready to use with +just the configuration URL, client ID, client secret, and base URL. + diff --git a/docs/python-sdk/fastmcp-server-auth-providers-propelauth.mdx b/docs/python-sdk/fastmcp-server-auth-providers-propelauth.mdx new file mode 100644 index 000000000..3b31b00d8 --- /dev/null +++ b/docs/python-sdk/fastmcp-server-auth-providers-propelauth.mdx @@ -0,0 +1,69 @@ +--- +title: propelauth +sidebarTitle: propelauth +--- + +# `fastmcp.server.auth.providers.propelauth` + + +PropelAuth authentication provider for FastMCP. + +Example: + ```python + from fastmcp import FastMCP + from fastmcp.server.auth.providers.propelauth import PropelAuthProvider + + auth = PropelAuthProvider( + auth_url="https://auth.yourdomain.com", + introspection_client_id="your-client-id", + introspection_client_secret="your-client-secret", + base_url="https://your-fastmcp-server.com", + required_scopes=["read:user_data"], + ) + + mcp = FastMCP("My App", auth=auth) + ``` + + +## Classes + +### `PropelAuthTokenIntrospectionOverrides` + +### `PropelAuthProvider` + + +PropelAuth resource server provider using OAuth 2.1 token introspection. + +This provider validates access tokens via PropelAuth's introspection endpoint +and forwards authorization server metadata for OAuth discovery. + +For detailed setup instructions, see: +https://docs.propelauth.com/mcp-authentication/overview + + +**Methods:** + +#### `get_routes` + +```python +get_routes(self, mcp_path: str | None = None) -> list[Route] +``` + +Get routes for this provider. + +Includes the standard routes from the RemoteAuthProvider (protected resource metadata routes (RFC 9728)), +and creates an authorization server metadata route that forwards to PropelAuth's route + +**Args:** +- `mcp_path`: The path where the MCP endpoint is mounted (e.g., "/mcp") +This is used to advertise the resource URL in metadata. + + +#### `verify_token` + +```python +verify_token(self, token: str) -> AccessToken | None +``` + +Verify token and check the ``aud`` claim against the configured resource. + diff --git a/docs/python-sdk/fastmcp-server-auth-providers-scalekit.mdx b/docs/python-sdk/fastmcp-server-auth-providers-scalekit.mdx new file mode 100644 index 000000000..1aa125c6c --- /dev/null +++ b/docs/python-sdk/fastmcp-server-auth-providers-scalekit.mdx @@ -0,0 +1,61 @@ +--- +title: scalekit +sidebarTitle: scalekit +--- + +# `fastmcp.server.auth.providers.scalekit` + + +Scalekit authentication provider for FastMCP. + +This module provides ScalekitProvider - a complete authentication solution that integrates +with Scalekit's OAuth 2.1 and OpenID Connect services, supporting Resource Server +authentication for seamless MCP client authentication. + + +## Classes + +### `ScalekitProvider` + + +Scalekit resource server provider for OAuth 2.1 authentication. + +This provider implements Scalekit integration using resource server pattern. +FastMCP acts as a protected resource server that validates access tokens issued +by Scalekit's authorization server. + +IMPORTANT SETUP REQUIREMENTS: + +1. Create an MCP Server in Scalekit Dashboard: + - Go to your [Scalekit Dashboard](https://app.scalekit.com/) + - Navigate to MCP Servers section + - Register a new MCP Server with appropriate scopes + - Ensure the Resource Identifier matches exactly what you configure as MCP URL + - Note the Resource ID + +2. Environment Configuration: + - Set SCALEKIT_ENVIRONMENT_URL (e.g., https://your-env.scalekit.com) + - Set SCALEKIT_RESOURCE_ID from your created resource + - Set BASE_URL to your FastMCP server's public URL + +For detailed setup instructions, see: +https://docs.scalekit.com/mcp/overview/ + + +**Methods:** + +#### `get_routes` + +```python +get_routes(self, mcp_path: str | None = None) -> list[Route] +``` + +Get OAuth routes including Scalekit authorization server metadata forwarding. + +This returns the standard protected resource routes plus an authorization server +metadata endpoint that forwards Scalekit's OAuth metadata to clients. + +**Args:** +- `mcp_path`: The path where the MCP endpoint is mounted (e.g., "/mcp") +This is used to advertise the resource URL in metadata. + diff --git a/docs/python-sdk/fastmcp-server-auth-providers-supabase.mdx b/docs/python-sdk/fastmcp-server-auth-providers-supabase.mdx new file mode 100644 index 000000000..c44deecae --- /dev/null +++ b/docs/python-sdk/fastmcp-server-auth-providers-supabase.mdx @@ -0,0 +1,67 @@ +--- +title: supabase +sidebarTitle: supabase +--- + +# `fastmcp.server.auth.providers.supabase` + + +Supabase authentication provider for FastMCP. + +This module provides SupabaseProvider - a complete authentication solution that integrates +with Supabase Auth's JWT verification, supporting Dynamic Client Registration (DCR) +for seamless MCP client authentication. + + +## Classes + +### `SupabaseProvider` + + +Supabase metadata provider for DCR (Dynamic Client Registration). + +This provider implements Supabase Auth integration using metadata forwarding. +This approach allows Supabase to handle the OAuth flow directly while FastMCP acts +as a resource server, verifying JWTs issued by Supabase Auth. + +IMPORTANT SETUP REQUIREMENTS: + +1. Supabase Project Setup: + - Create a Supabase project at https://supabase.com + - Note your project URL (e.g., "https://abc123.supabase.co") + - Configure your JWT algorithm in Supabase Auth settings (HS256, RS256, or ES256) + - Asymmetric keys (RS256/ES256) are recommended for production + +2. JWT Verification: + - FastMCP verifies JWTs using the JWKS endpoint at {project_url}{auth_route}/.well-known/jwks.json + - JWTs are issued by {project_url}{auth_route} + - Default auth_route is "/auth/v1" (can be customized for self-hosted setups) + - Tokens are cached for up to 10 minutes by Supabase's edge servers + - Algorithm must match your Supabase Auth configuration + +3. Authorization: + - Supabase uses Row Level Security (RLS) policies for database authorization + - OAuth-level scopes are an upcoming feature in Supabase Auth + - Both approaches will be supported once scope handling is available + +For detailed setup instructions, see: +https://supabase.com/docs/guides/auth/jwts + + +**Methods:** + +#### `get_routes` + +```python +get_routes(self, mcp_path: str | None = None) -> list[Route] +``` + +Get OAuth routes including Supabase authorization server metadata forwarding. + +This returns the standard protected resource routes plus an authorization server +metadata endpoint that forwards Supabase's OAuth metadata to clients. + +**Args:** +- `mcp_path`: The path where the MCP endpoint is mounted (e.g., "/mcp") +This is used to advertise the resource URL in metadata. + diff --git a/docs/python-sdk/fastmcp-server-auth-providers-workos.mdx b/docs/python-sdk/fastmcp-server-auth-providers-workos.mdx new file mode 100644 index 000000000..cb263d9ec --- /dev/null +++ b/docs/python-sdk/fastmcp-server-auth-providers-workos.mdx @@ -0,0 +1,102 @@ +--- +title: workos +sidebarTitle: workos +--- + +# `fastmcp.server.auth.providers.workos` + + +WorkOS authentication providers for FastMCP. + +This module provides two WorkOS authentication strategies: + +1. WorkOSProvider - OAuth proxy for WorkOS Connect applications (non-DCR) +2. AuthKitProvider - DCR-compliant provider for WorkOS AuthKit + +Choose based on your WorkOS setup and authentication requirements. + + +## Classes + +### `WorkOSTokenVerifier` + + +Token verifier for WorkOS OAuth tokens. + +WorkOS AuthKit tokens are opaque, so we verify them by calling +the /oauth2/userinfo endpoint to check validity and get user info. + + +**Methods:** + +#### `verify_token` + +```python +verify_token(self, token: str) -> AccessToken | None +``` + +Verify WorkOS OAuth token by calling userinfo endpoint. + + +### `WorkOSProvider` + + +Complete WorkOS OAuth provider for FastMCP. + +This provider implements WorkOS AuthKit OAuth using the OAuth Proxy pattern. +It provides OAuth2 authentication for users through WorkOS Connect applications. + +Features: +- Transparent OAuth proxy to WorkOS AuthKit +- Automatic token validation via userinfo endpoint +- User information extraction from ID tokens +- Support for standard OAuth scopes (openid, profile, email) + +Setup Requirements: +1. Create a WorkOS Connect application in your dashboard +2. Note your AuthKit domain (e.g., "https://your-app.authkit.app") +3. Configure redirect URI as: http://localhost:8000/auth/callback +4. Note your Client ID and Client Secret + + +### `AuthKitProvider` + + +AuthKit metadata provider for DCR (Dynamic Client Registration). + +This provider implements AuthKit integration using metadata forwarding +instead of OAuth proxying. This is the recommended approach for WorkOS DCR +as it allows WorkOS to handle the OAuth flow directly while FastMCP acts +as a resource server. + +IMPORTANT SETUP REQUIREMENTS: + +1. Enable Dynamic Client Registration in WorkOS Dashboard: + - Go to Applications → Configuration + - Toggle "Dynamic Client Registration" to enabled + +2. Configure your FastMCP server URL as a callback: + - Add your server URL to the Redirects tab in WorkOS dashboard + - Example: https://your-fastmcp-server.com/oauth2/callback + +For detailed setup instructions, see: +https://workos.com/docs/authkit/mcp/integrating/token-verification + + +**Methods:** + +#### `get_routes` + +```python +get_routes(self, mcp_path: str | None = None) -> list[Route] +``` + +Get OAuth routes including AuthKit authorization server metadata forwarding. + +This returns the standard protected resource routes plus an authorization server +metadata endpoint that forwards AuthKit's OAuth metadata to clients. + +**Args:** +- `mcp_path`: The path where the MCP endpoint is mounted (e.g., "/mcp") +This is used to advertise the resource URL in metadata. + diff --git a/docs/python-sdk/fastmcp-server-auth-redirect_validation.mdx b/docs/python-sdk/fastmcp-server-auth-redirect_validation.mdx new file mode 100644 index 000000000..65155a160 --- /dev/null +++ b/docs/python-sdk/fastmcp-server-auth-redirect_validation.mdx @@ -0,0 +1,63 @@ +--- +title: redirect_validation +sidebarTitle: redirect_validation +--- + +# `fastmcp.server.auth.redirect_validation` + + +Utilities for validating client redirect URIs in OAuth flows. + +This module provides secure redirect URI validation with wildcard support, +protecting against userinfo-based bypass attacks like http://localhost@evil.com. + + +## Functions + +### `matches_allowed_pattern` + +```python +matches_allowed_pattern(uri: str, pattern: str) -> bool +``` + + +Securely check if a URI matches an allowed pattern with wildcard support. + +This function parses both the URI and pattern as URLs, comparing each +component separately to prevent bypass attacks like userinfo injection. + +Patterns support wildcards: +- http://localhost:* matches any localhost port +- http://127.0.0.1:* matches any 127.0.0.1 port +- https://*.example.com/* matches any subdomain of example.com +- https://app.example.com/auth/* matches any path under /auth/ + +Security: Rejects URIs with userinfo (user:pass@host) which could bypass +naive string matching (e.g., http://localhost@evil.com). + +**Args:** +- `uri`: The redirect URI to validate +- `pattern`: The allowed pattern (may contain wildcards) + +**Returns:** +- True if the URI matches the pattern + + +### `validate_redirect_uri` + +```python +validate_redirect_uri(redirect_uri: str | AnyUrl | None, allowed_patterns: list[str] | None) -> bool +``` + + +Validate a redirect URI against allowed patterns. + +**Args:** +- `redirect_uri`: The redirect URI to validate +- `allowed_patterns`: List of allowed patterns. If None, all URIs are allowed (for DCR compatibility). + If empty list, no URIs are allowed. + To restrict to localhost only, explicitly pass DEFAULT_LOCALHOST_PATTERNS. + +**Returns:** +- True if the redirect URI is allowed + diff --git a/docs/python-sdk/fastmcp-server-auth-ssrf.mdx b/docs/python-sdk/fastmcp-server-auth-ssrf.mdx new file mode 100644 index 000000000..c54ac5000 --- /dev/null +++ b/docs/python-sdk/fastmcp-server-auth-ssrf.mdx @@ -0,0 +1,172 @@ +--- +title: ssrf +sidebarTitle: ssrf +--- + +# `fastmcp.server.auth.ssrf` + + +SSRF-safe HTTP utilities for FastMCP. + +This module provides SSRF-protected HTTP fetching with: +- DNS resolution and IP validation before requests +- DNS pinning to prevent rebinding TOCTOU attacks +- Support for both CIMD and JWKS fetches + + +## Functions + +### `format_ip_for_url` + +```python +format_ip_for_url(ip_str: str) -> str +``` + + +Format IP address for use in URL (bracket IPv6 addresses). + +IPv6 addresses must be bracketed in URLs to distinguish the address from +the port separator. For example: https://[2001:db8::1]:443/path + +**Args:** +- `ip_str`: IP address string + +**Returns:** +- IP string suitable for URL (IPv6 addresses are bracketed) + + +### `is_ip_allowed` + +```python +is_ip_allowed(ip_str: str) -> bool +``` + + +Check if an IP address is allowed (must be globally routable unicast). + +Uses ip.is_global which catches: +- Private (10.x, 172.16-31.x, 192.168.x) +- Loopback (127.x, ::1) +- Link-local (169.254.x, fe80::) - includes AWS metadata! +- Reserved, unspecified +- RFC6598 Carrier-Grade NAT (100.64.0.0/10) - can point to internal networks + +Additionally blocks multicast addresses (not caught by is_global). + +**Args:** +- `ip_str`: IP address string to check + +**Returns:** +- True if the IP is allowed (public unicast internet), False if blocked + + +### `resolve_hostname` + +```python +resolve_hostname(hostname: str, port: int = 443) -> list[str] +``` + + +Resolve hostname to IP addresses using DNS. + +**Args:** +- `hostname`: Hostname to resolve +- `port`: Port number (used for getaddrinfo) + +**Returns:** +- List of resolved IP addresses + +**Raises:** +- `SSRFError`: If resolution fails + + +### `validate_url` + +```python +validate_url(url: str, require_path: bool = False) -> ValidatedURL +``` + + +Validate URL for SSRF and resolve to IPs. + +**Args:** +- `url`: URL to validate +- `require_path`: If True, require non-root path (for CIMD) + +**Returns:** +- ValidatedURL with resolved IPs + +**Raises:** +- `SSRFError`: If URL is invalid or resolves to blocked IPs + + +### `ssrf_safe_fetch` + +```python +ssrf_safe_fetch(url: str) -> bytes +``` + + +Fetch URL with comprehensive SSRF protection and DNS pinning. + +Security measures: +1. HTTPS only +2. DNS resolution with IP validation +3. Connects to validated IP directly (DNS pinning prevents rebinding) +4. Response size limit +5. Redirects disabled +6. Overall timeout + +**Args:** +- `url`: URL to fetch +- `require_path`: If True, require non-root path +- `max_size`: Maximum response size in bytes (default 5KB) +- `timeout`: Per-operation timeout in seconds +- `overall_timeout`: Overall timeout for entire operation + +**Returns:** +- Response body as bytes + +**Raises:** +- `SSRFError`: If SSRF validation fails +- `SSRFFetchError`: If fetch fails + + +### `ssrf_safe_fetch_response` + +```python +ssrf_safe_fetch_response(url: str) -> SSRFFetchResponse +``` + + +Fetch URL with SSRF protection and return response metadata. + +This is equivalent to :func:`ssrf_safe_fetch` but returns response headers +and status code, and supports conditional request headers. + + +## Classes + +### `SSRFError` + + +Raised when an SSRF protection check fails. + + +### `SSRFFetchError` + + +Raised when SSRF-safe fetch fails. + + +### `ValidatedURL` + + +A URL that has been validated for SSRF with resolved IPs. + + +### `SSRFFetchResponse` + + +Response payload from an SSRF-safe fetch. + diff --git a/docs/python-sdk/fastmcp-server-context.mdx b/docs/python-sdk/fastmcp-server-context.mdx new file mode 100644 index 000000000..58a916faf --- /dev/null +++ b/docs/python-sdk/fastmcp-server-context.mdx @@ -0,0 +1,745 @@ +--- +title: context +sidebarTitle: context +--- + +# `fastmcp.server.context` + +## Functions + +### `set_transport` + +```python +set_transport(transport: TransportType) -> Token[TransportType | None] +``` + + +Set the current transport type. Returns token for reset. + + +### `reset_transport` + +```python +reset_transport(token: Token[TransportType | None]) -> None +``` + + +Reset transport to previous value. + + +### `set_context` + +```python +set_context(context: Context) -> Generator[Context, None, None] +``` + +## Classes + +### `LogData` + + +Data object for passing log arguments to client-side handlers. + +This provides an interface to match the Python standard library logging, +for compatibility with structured logging. + + +### `Context` + + +Context object providing access to MCP capabilities. + +This provides a cleaner interface to MCP's RequestContext functionality. +It gets injected into tool and resource functions that request it via type hints. + +To use context in a tool function, add a parameter with the Context type annotation: + +```python +@server.tool +async def my_tool(x: int, ctx: Context) -> str: + # Log messages to the client + await ctx.info(f"Processing {x}") + await ctx.debug("Debug info") + await ctx.warning("Warning message") + await ctx.error("Error message") + + # Report progress + await ctx.report_progress(50, 100, "Processing") + + # Access resources + data = await ctx.read_resource("resource://data") + + # Get request info + request_id = ctx.request_id + client_id = ctx.client_id + + # Manage state across the session (persists across requests) + await ctx.set_state("key", "value") + value = await ctx.get_state("key") + + # Store non-serializable values for the current request only + await ctx.set_state("client", http_client, serializable=False) + + return str(x) +``` + +State Management: +Context provides session-scoped state that persists across requests within +the same MCP session. State is automatically keyed by session, ensuring +isolation between different clients. + +State set during `on_initialize` middleware will persist to subsequent tool +calls when using the same session object (STDIO, SSE, single-server HTTP). +For distributed/serverless HTTP deployments where different machines handle +the init and tool calls, state is isolated by the mcp-session-id header. + +The context parameter name can be anything as long as it's annotated with Context. +The context is optional - tools that don't need it can omit the parameter. + + +**Methods:** + +#### `is_background_task` + +```python +is_background_task(self) -> bool +``` + +True when this context is running in a background task (Docket worker). + +When True, certain operations like elicit() and sample() will use +task-aware implementations that can pause the task and wait for +client input. + + +#### `task_id` + +```python +task_id(self) -> str | None +``` + +Get the background task ID if running in a background task. + +Returns None if not running in a background task context. + + +#### `origin_request_id` + +```python +origin_request_id(self) -> str | None +``` + +Get the request ID that originated this execution, if available. + +In foreground request mode, this is the current request_id. +In background task mode, this is the request_id captured when the task +was submitted, if one was available. + + +#### `fastmcp` + +```python +fastmcp(self) -> FastMCP +``` + +Get the FastMCP instance. + + +#### `request_context` + +```python +request_context(self) -> RequestContext[ServerSession, Any, Request] | None +``` + +Access to the underlying request context. + +Returns None when the MCP session has not been established yet. +Returns the full RequestContext once the MCP session is available. + +For HTTP request access in middleware, use `get_http_request()` from fastmcp.server.dependencies, +which works whether or not the MCP session is available. + +Example in middleware: +```python +async def on_request(self, context, call_next): + ctx = context.fastmcp_context + if ctx.request_context: + # MCP session available - can access session_id, request_id, etc. + session_id = ctx.session_id + else: + # MCP session not available yet - use HTTP helpers + from fastmcp.server.dependencies import get_http_request + request = get_http_request() + return await call_next(context) +``` + + +#### `lifespan_context` + +```python +lifespan_context(self) -> dict[str, Any] +``` + +Access the server's lifespan context. + +Returns the context dict yielded by the server's lifespan function. +Returns an empty dict if no lifespan was configured or if the MCP +session is not yet established. + +In background tasks (Docket workers), where request_context is not +available, falls back to reading from the FastMCP server's lifespan +result directly. + +Example: +```python +@server.tool +def my_tool(ctx: Context) -> str: + db = ctx.lifespan_context.get("db") + if db: + return db.query("SELECT 1") + return "No database connection" +``` + + +#### `report_progress` + +```python +report_progress(self, progress: float, total: float | None = None, message: str | None = None) -> None +``` + +Report progress for the current operation. + +Works in both foreground (MCP progress notifications) and background +(Docket task execution) contexts. + +**Args:** +- `progress`: Current progress value e.g. 24 +- `total`: Optional total value e.g. 100 +- `message`: Optional status message describing current progress + + +#### `list_resources` + +```python +list_resources(self) -> list[SDKResource] +``` + +List all available resources from the server. + +**Returns:** +- List of Resource objects available on the server + + +#### `list_prompts` + +```python +list_prompts(self) -> list[SDKPrompt] +``` + +List all available prompts from the server. + +**Returns:** +- List of Prompt objects available on the server + + +#### `get_prompt` + +```python +get_prompt(self, name: str, arguments: dict[str, Any] | None = None) -> GetPromptResult +``` + +Get a prompt by name with optional arguments. + +**Args:** +- `name`: The name of the prompt to get +- `arguments`: Optional arguments to pass to the prompt + +**Returns:** +- The prompt result + + +#### `read_resource` + +```python +read_resource(self, uri: str | AnyUrl) -> ResourceResult +``` + +Read a resource by URI. + +**Args:** +- `uri`: Resource URI to read + +**Returns:** +- ResourceResult with contents + + +#### `log` + +```python +log(self, message: str, level: LoggingLevel | None = None, logger_name: str | None = None, extra: Mapping[str, Any] | None = None) -> None +``` + +Send a log message to the client. + +Messages sent to Clients are also logged to the `fastmcp.server.context.to_client` logger with a level of `DEBUG`. + +**Args:** +- `message`: Log message +- `level`: Optional log level. One of "debug", "info", "notice", "warning", "error", "critical", +"alert", or "emergency". Default is "info". +- `logger_name`: Optional logger name +- `extra`: Optional mapping for additional arguments + + +#### `transport` + +```python +transport(self) -> TransportType | None +``` + +Get the current transport type. + +Returns the transport type used to run this server: "stdio", "sse", +or "streamable-http". Returns None if called outside of a server context. + + +#### `client_supports_extension` + +```python +client_supports_extension(self, extension_id: str) -> bool +``` + +Check whether the connected client supports a given MCP extension. + +Inspects the ``extensions`` extra field on ``ClientCapabilities`` +sent by the client during initialization. + +Returns ``False`` when no session is available (e.g., outside a +request context) or when the client did not advertise the extension. + +Example:: + + from fastmcp.server.apps import UI_EXTENSION_ID + + @mcp.tool + async def my_tool(ctx: Context) -> str: + if ctx.client_supports_extension(UI_EXTENSION_ID): + return "UI-capable client" + return "text-only client" + + +#### `client_id` + +```python +client_id(self) -> str | None +``` + +Get the client ID if available. + + +#### `request_id` + +```python +request_id(self) -> str +``` + +Get the unique ID for this request. + +Raises RuntimeError if MCP request context is not available. + + +#### `session_id` + +```python +session_id(self) -> str +``` + +Get the MCP session ID for ALL transports. + +Returns the session ID that can be used as a key for session-based +data storage (e.g., Redis) to share data between tool calls within +the same client session. + +**Returns:** +- The session ID for StreamableHTTP transports, or a generated ID +- for other transports. + + +#### `session` + +```python +session(self) -> ServerSession +``` + +Access to the underlying session for advanced usage. + +In request mode: Returns the session from the active request context. +In background task mode: Returns the session stored at Context creation. + +Raises RuntimeError if no session is available. + + +#### `debug` + +```python +debug(self, message: str, logger_name: str | None = None, extra: Mapping[str, Any] | None = None) -> None +``` + +Send a `DEBUG`-level message to the connected MCP Client. + +Messages sent to Clients are also logged to the `fastmcp.server.context.to_client` logger with a level of `DEBUG`. + + +#### `info` + +```python +info(self, message: str, logger_name: str | None = None, extra: Mapping[str, Any] | None = None) -> None +``` + +Send a `INFO`-level message to the connected MCP Client. + +Messages sent to Clients are also logged to the `fastmcp.server.context.to_client` logger with a level of `DEBUG`. + + +#### `warning` + +```python +warning(self, message: str, logger_name: str | None = None, extra: Mapping[str, Any] | None = None) -> None +``` + +Send a `WARNING`-level message to the connected MCP Client. + +Messages sent to Clients are also logged to the `fastmcp.server.context.to_client` logger with a level of `DEBUG`. + + +#### `error` + +```python +error(self, message: str, logger_name: str | None = None, extra: Mapping[str, Any] | None = None) -> None +``` + +Send a `ERROR`-level message to the connected MCP Client. + +Messages sent to Clients are also logged to the `fastmcp.server.context.to_client` logger with a level of `DEBUG`. + + +#### `list_roots` + +```python +list_roots(self) -> list[Root] +``` + +List the roots available to the server, as indicated by the client. + + +#### `send_notification` + +```python +send_notification(self, notification: mcp.types.ServerNotificationType) -> None +``` + +Send a notification to the client immediately. + +**Args:** +- `notification`: An MCP notification instance (e.g., ToolListChangedNotification()) + + +#### `close_sse_stream` + +```python +close_sse_stream(self) -> None +``` + +Close the current response stream to trigger client reconnection. + +When using StreamableHTTP transport with an EventStore configured, this +method gracefully closes the HTTP connection for the current request. +The client will automatically reconnect (after `retry_interval` milliseconds) +and resume receiving events from where it left off via the EventStore. + +This is useful for long-running operations to avoid load balancer timeouts. +Instead of holding a connection open for minutes, you can periodically close +and let the client reconnect. + + +#### `sample_step` + +```python +sample_step(self, messages: str | Sequence[str | SamplingMessage]) -> SampleStep +``` + +Make a single LLM sampling call. + +This is a stateless function that makes exactly one LLM call and optionally +executes any requested tools. Use this for fine-grained control over the +sampling loop. + +**Args:** +- `messages`: The message(s) to send. Can be a string, list of strings, +or list of SamplingMessage objects. +- `system_prompt`: Optional system prompt for the LLM. +- `temperature`: Optional sampling temperature. +- `max_tokens`: Maximum tokens to generate. Defaults to 512. +- `model_preferences`: Optional model preferences. +- `tools`: Optional list of tools the LLM can use. +- `tool_choice`: Tool choice mode ("auto", "required", or "none"). +- `execute_tools`: If True (default), execute tool calls and append results +to history. If False, return immediately with tool_calls available +in the step for manual execution. +- `mask_error_details`: If True, mask detailed error messages from tool +execution. When None (default), uses the global settings value. +Tools can raise ToolError to bypass masking. +- `tool_concurrency`: Controls parallel execution of tools\: +- None (default)\: Sequential execution (one at a time) +- 0\: Unlimited parallel execution +- N > 0\: Execute at most N tools concurrently +If any tool has sequential=True, all tools execute sequentially +regardless of this setting. + +**Returns:** +- SampleStep containing: +- - .response: The raw LLM response +- - .history: Messages including input, assistant response, and tool results +- - .is_tool_use: True if the LLM requested tool execution +- - .tool_calls: List of tool calls (if any) +- - .text: The text content (if any) + + +#### `sample` + +```python +sample(self, messages: str | Sequence[str | SamplingMessage]) -> SamplingResult[ResultT] +``` + +Overload: With result_type, returns SamplingResult[ResultT]. + + +#### `sample` + +```python +sample(self, messages: str | Sequence[str | SamplingMessage]) -> SamplingResult[str] +``` + +Overload: Without result_type, returns SamplingResult[str]. + + +#### `sample` + +```python +sample(self, messages: str | Sequence[str | SamplingMessage]) -> SamplingResult[ResultT] | SamplingResult[str] +``` + +Send a sampling request to the client and await the response. + +This method runs to completion automatically. When tools are provided, +it executes a tool loop: if the LLM returns a tool use request, the tools +are executed and the results are sent back to the LLM. This continues +until the LLM provides a final text response. + +When result_type is specified, a synthetic `final_response` tool is +created. The LLM calls this tool to provide the structured response, +which is validated against the result_type and returned as `.result`. + +For fine-grained control over the sampling loop, use sample_step() instead. + +**Args:** +- `messages`: The message(s) to send. Can be a string, list of strings, +or list of SamplingMessage objects. +- `system_prompt`: Optional system prompt for the LLM. +- `temperature`: Optional sampling temperature. +- `max_tokens`: Maximum tokens to generate. Defaults to 512. +- `model_preferences`: Optional model preferences. +- `tools`: Optional list of tools the LLM can use. Accepts plain +functions or SamplingTools. +- `result_type`: Optional type for structured output. When specified, +a synthetic `final_response` tool is created and the LLM's +response is validated against this type. +- `mask_error_details`: If True, mask detailed error messages from tool +execution. When None (default), uses the global settings value. +Tools can raise ToolError to bypass masking. +- `tool_concurrency`: Controls parallel execution of tools\: +- None (default)\: Sequential execution (one at a time) +- 0\: Unlimited parallel execution +- N > 0\: Execute at most N tools concurrently +If any tool has sequential=True, all tools execute sequentially +regardless of this setting. + +**Returns:** +- SamplingResult[T] containing: +- - .text: The text representation (raw text or JSON for structured) +- - .result: The typed result (str for text, parsed object for structured) +- - .history: All messages exchanged during sampling + + +#### `elicit` + +```python +elicit(self, message: str, response_type: None) -> AcceptedElicitation[dict[str, Any]] | DeclinedElicitation | CancelledElicitation +``` + +#### `elicit` + +```python +elicit(self, message: str, response_type: type[T]) -> AcceptedElicitation[T] | DeclinedElicitation | CancelledElicitation +``` + +#### `elicit` + +```python +elicit(self, message: str, response_type: list[str]) -> AcceptedElicitation[str] | DeclinedElicitation | CancelledElicitation +``` + +#### `elicit` + +```python +elicit(self, message: str, response_type: dict[str, dict[str, str]]) -> AcceptedElicitation[str] | DeclinedElicitation | CancelledElicitation +``` + +#### `elicit` + +```python +elicit(self, message: str, response_type: list[list[str]]) -> AcceptedElicitation[list[str]] | DeclinedElicitation | CancelledElicitation +``` + +#### `elicit` + +```python +elicit(self, message: str, response_type: list[dict[str, dict[str, str]]]) -> AcceptedElicitation[list[str]] | DeclinedElicitation | CancelledElicitation +``` + +#### `elicit` + +```python +elicit(self, message: str, response_type: type[T] | list[str] | dict[str, dict[str, str]] | list[list[str]] | list[dict[str, dict[str, str]]] | None = None) -> AcceptedElicitation[T] | AcceptedElicitation[dict[str, Any]] | AcceptedElicitation[str] | AcceptedElicitation[list[str]] | DeclinedElicitation | CancelledElicitation +``` + +Send an elicitation request to the client and await the response. + +Call this method at any time to request additional information from +the user through the client. The client must support elicitation, +or the request will error. + +Note that the MCP protocol only supports simple object schemas with +primitive types. You can provide a dataclass, TypedDict, or BaseModel to +comply. If you provide a primitive type, an object schema with a single +"value" field will be generated for the MCP interaction and +automatically deconstructed into the primitive type upon response. + +If the response_type is None, the generated schema will be that of an +empty object in order to comply with the MCP protocol requirements. +Clients must send an empty object ("{}")in response. + +**Args:** +- `message`: A human-readable message explaining what information is needed +- `response_type`: The type of the response, which should be a primitive +type or dataclass or BaseModel. If it is a primitive type, an +object schema with a single "value" field will be generated. + + +#### `set_state` + +```python +set_state(self, key: str, value: Any) -> None +``` + +Set a value in the state store. + +By default, values are stored in the session-scoped state store and +persist across requests within the same MCP session. Values must be +JSON-serializable (dicts, lists, strings, numbers, etc.). + +For non-serializable values (e.g., HTTP clients, database connections), +pass ``serializable=False``. These values are stored in a request-scoped +dict and only live for the current MCP request (tool call, resource +read, or prompt render). They will not be available in subsequent +requests. + +The key is automatically prefixed with the session identifier. + + +#### `get_state` + +```python +get_state(self, key: str) -> Any +``` + +Get a value from the state store. + +Checks request-scoped state first (set with ``serializable=False``), +then falls back to the session-scoped state store. + +Returns None if the key is not found. + + +#### `delete_state` + +```python +delete_state(self, key: str) -> None +``` + +Delete a value from the state store. + +Removes from both request-scoped and session-scoped stores. + + +#### `enable_components` + +```python +enable_components(self) -> None +``` + +Enable components matching criteria for this session only. + +Session rules override global transforms. Rules accumulate - each call +adds a new rule to the session. Later marks override earlier ones +(Visibility transform semantics). + +Sends notifications to this session only: ToolListChangedNotification, +ResourceListChangedNotification, and PromptListChangedNotification. + +**Args:** +- `names`: Component names or URIs to match. +- `keys`: Component keys to match (e.g., {"tool\:my_tool@v1"}). +- `version`: Component version spec to match. +- `tags`: Tags to match (component must have at least one). +- `components`: Component types to match (e.g., {"tool", "prompt"}). +- `match_all`: If True, matches all components regardless of other criteria. + + +#### `disable_components` + +```python +disable_components(self) -> None +``` + +Disable components matching criteria for this session only. + +Session rules override global transforms. Rules accumulate - each call +adds a new rule to the session. Later marks override earlier ones +(Visibility transform semantics). + +Sends notifications to this session only: ToolListChangedNotification, +ResourceListChangedNotification, and PromptListChangedNotification. + +**Args:** +- `names`: Component names or URIs to match. +- `keys`: Component keys to match (e.g., {"tool\:my_tool@v1"}). +- `version`: Component version spec to match. +- `tags`: Tags to match (component must have at least one). +- `components`: Component types to match (e.g., {"tool", "prompt"}). +- `match_all`: If True, matches all components regardless of other criteria. + + +#### `reset_visibility` + +```python +reset_visibility(self) -> None +``` + +Clear all session visibility rules. + +Use this to reset session visibility back to global defaults. + +Sends notifications to this session only: ToolListChangedNotification, +ResourceListChangedNotification, and PromptListChangedNotification. + diff --git a/docs/python-sdk/fastmcp-server-dependencies.mdx b/docs/python-sdk/fastmcp-server-dependencies.mdx new file mode 100644 index 000000000..60439e182 --- /dev/null +++ b/docs/python-sdk/fastmcp-server-dependencies.mdx @@ -0,0 +1,616 @@ +--- +title: dependencies +sidebarTitle: dependencies +--- + +# `fastmcp.server.dependencies` + + +Dependency injection for FastMCP. + +DI features (Depends, CurrentContext, CurrentFastMCP) work without pydocket +using the uncalled-for DI engine. Only task-related dependencies (CurrentDocket, +CurrentWorker) and background task execution require fastmcp[tasks]. + + +## Functions + +### `get_task_context` + +```python +get_task_context() -> TaskContextInfo | None +``` + + +Get the current task context if running inside a background task worker. + +This function extracts task information from the Docket execution context. +Returns None if not running in a task context (e.g., foreground execution). + +**Returns:** +- TaskContextInfo with task_id and session_id, or None if not in a task. + + +### `register_task_session` + +```python +register_task_session(session_id: str, session: ServerSession) -> None +``` + + +Register a session for Context access in background tasks. + +Called automatically when a task is submitted to Docket. The session is +stored as a weakref so it doesn't prevent garbage collection when the +client disconnects. + +**Args:** +- `session_id`: The session identifier +- `session`: The ServerSession instance + + +### `get_task_session` + +```python +get_task_session(session_id: str) -> ServerSession | None +``` + + +Get a registered session by ID if still alive. + +**Args:** +- `session_id`: The session identifier + +**Returns:** +- The ServerSession if found and alive, None otherwise + + +### `is_docket_available` + +```python +is_docket_available() -> bool +``` + + +Check if pydocket is installed. + + +### `require_docket` + +```python +require_docket(feature: str) -> None +``` + + +Raise ImportError with install instructions if docket not available. + +**Args:** +- `feature`: Description of what requires docket (e.g., "`task=True`", + "CurrentDocket()"). Will be included in the error message. + + +### `transform_context_annotations` + +```python +transform_context_annotations(fn: Callable[..., Any]) -> Callable[..., Any] +``` + + +Transform ctx: Context into ctx: Context = CurrentContext(). + +Transforms ALL params typed as Context to use Docket's DI system, +unless they already have a Dependency-based default (like CurrentContext()). + +This unifies the legacy type annotation DI with Docket's Depends() system, +allowing both patterns to work through a single resolution path. + +Note: Only POSITIONAL_OR_KEYWORD parameters are reordered (params with defaults +after those without). KEYWORD_ONLY parameters keep their position since Python +allows them to have defaults in any order. + +**Args:** +- `fn`: Function to transform + +**Returns:** +- Function with modified signature (same function object, updated __signature__) + + +### `get_context` + +```python +get_context() -> Context +``` + + +Get the current FastMCP Context instance directly. + + +### `get_server` + +```python +get_server() -> FastMCP +``` + + +Get the current FastMCP server instance directly. + +**Returns:** +- The active FastMCP server + +**Raises:** +- `RuntimeError`: If no server in context + + +### `get_http_request` + +```python +get_http_request() -> Request +``` + + +Get the current HTTP request. + +Tries MCP SDK's request_ctx first, then falls back to FastMCP's HTTP context. + + +### `get_http_headers` + +```python +get_http_headers(include_all: bool = False, include: set[str] | None = None) -> dict[str, str] +``` + + +Extract headers from the current HTTP request if available. + +Never raises an exception, even if there is no active HTTP request (in which case +an empty dict is returned). + +By default, strips problematic headers like `content-length` and `authorization` +that cause issues if forwarded to downstream services. If `include_all` is True, +all headers are returned. + +The `include` parameter allows specific headers to be included even if they would +normally be excluded. This is useful for proxy transports that need to forward +authorization headers to upstream MCP servers. + + +### `get_access_token` + +```python +get_access_token() -> AccessToken | None +``` + + +Get the FastMCP access token from the current context. + +This function first tries to get the token from the current HTTP request's scope, +which is more reliable for long-lived connections where the SDK's auth_context_var +may become stale after token refresh. Falls back to the SDK's context var if no +request is available. In background tasks (Docket workers), falls back to the +token snapshot stored in Redis at task submission time. + +**Returns:** +- The access token if an authenticated user is available, None otherwise. + + +### `without_injected_parameters` + +```python +without_injected_parameters(fn: Callable[..., Any]) -> Callable[..., Any] +``` + + +Create a wrapper function without injected parameters. + +Returns a wrapper that excludes Context and Docket dependency parameters, +making it safe to use with Pydantic TypeAdapter for schema generation and +validation. The wrapper internally handles all dependency resolution and +Context injection when called. + +Handles: +- Legacy Context injection (always works) +- Depends() injection (always works - uses docket or vendored DI engine) + +**Args:** +- `fn`: Original function with Context and/or dependencies + +**Returns:** +- Async wrapper function without injected parameters + + +### `resolve_dependencies` + +```python +resolve_dependencies(fn: Callable[..., Any], arguments: dict[str, Any]) -> AsyncGenerator[dict[str, Any], None] +``` + + +Resolve dependencies for a FastMCP function. + +This function: +1. Filters out any dependency parameter names from user arguments (security) +2. Resolves Depends() parameters via the DI system + +The filtering prevents external callers from overriding injected parameters by +providing values for dependency parameter names. This is a security feature. + +Note: Context injection is handled via transform_context_annotations() which +converts `ctx: Context` to `ctx: Context = Depends(get_context)` at registration +time, so all injection goes through the unified DI system. + +**Args:** +- `fn`: The function to resolve dependencies for +- `arguments`: User arguments (may contain keys that match dependency names, + which will be filtered out) + + +### `CurrentContext` + +```python +CurrentContext() -> Context +``` + + +Get the current FastMCP Context instance. + +This dependency provides access to the active FastMCP Context for the +current MCP operation (tool/resource/prompt call). + +**Returns:** +- A dependency that resolves to the active Context instance + +**Raises:** +- `RuntimeError`: If no active context found (during resolution) + + +### `OptionalCurrentContext` + +```python +OptionalCurrentContext() -> Context | None +``` + + +Get the current FastMCP Context, or None when no context is active. + + +### `CurrentDocket` + +```python +CurrentDocket() -> Docket +``` + + +Get the current Docket instance managed by FastMCP. + +This dependency provides access to the Docket instance that FastMCP +automatically creates for background task scheduling. + +**Returns:** +- A dependency that resolves to the active Docket instance + +**Raises:** +- `RuntimeError`: If not within a FastMCP server context +- `ImportError`: If fastmcp[tasks] not installed + + +### `CurrentWorker` + +```python +CurrentWorker() -> Worker +``` + + +Get the current Docket Worker instance managed by FastMCP. + +This dependency provides access to the Worker instance that FastMCP +automatically creates for background task processing. + +**Returns:** +- A dependency that resolves to the active Worker instance + +**Raises:** +- `RuntimeError`: If not within a FastMCP server context +- `ImportError`: If fastmcp[tasks] not installed + + +### `CurrentFastMCP` + +```python +CurrentFastMCP() -> FastMCP +``` + + +Get the current FastMCP server instance. + +This dependency provides access to the active FastMCP server. + +**Returns:** +- A dependency that resolves to the active FastMCP server + +**Raises:** +- `RuntimeError`: If no server in context (during resolution) + + +### `CurrentRequest` + +```python +CurrentRequest() -> Request +``` + + +Get the current HTTP request. + +This dependency provides access to the Starlette Request object for the +current HTTP request. Only available when running over HTTP transports +(SSE or Streamable HTTP). + +**Returns:** +- A dependency that resolves to the active Starlette Request + +**Raises:** +- `RuntimeError`: If no HTTP request in context (e.g., STDIO transport) + + +### `CurrentHeaders` + +```python +CurrentHeaders() -> dict[str, str] +``` + + +Get the current HTTP request headers. + +This dependency provides access to the HTTP headers for the current request, +including the authorization header. Returns an empty dictionary when no HTTP +request is available, making it safe to use in code that might run over any +transport. + +**Returns:** +- A dependency that resolves to a dictionary of header name -> value + + +### `CurrentAccessToken` + +```python +CurrentAccessToken() -> AccessToken +``` + + +Get the current access token for the authenticated user. + +This dependency provides access to the AccessToken for the current +authenticated request. Raises an error if no authentication is present. + +**Returns:** +- A dependency that resolves to the active AccessToken + +**Raises:** +- `RuntimeError`: If no authenticated user (use get_access_token() for optional) + + +### `TokenClaim` + +```python +TokenClaim(name: str) -> str +``` + + +Get a specific claim from the access token. + +This dependency extracts a single claim value from the current access token. +It's useful for getting user identifiers, roles, or other token claims +without needing the full token object. + +**Args:** +- `name`: The name of the claim to extract (e.g., "oid", "sub", "email") + +**Returns:** +- A dependency that resolves to the claim value as a string + +**Raises:** +- `RuntimeError`: If no access token is available or claim is missing + + +## Classes + +### `TaskContextInfo` + + +Information about the current background task context. + +Returned by ``get_task_context()`` when running inside a Docket worker. +Contains identifiers needed to communicate with the MCP session. + + +### `ProgressLike` + + +Protocol for progress tracking interface. + +Defines the common interface between InMemoryProgress (server context) +and Docket's Progress (worker context). + + +**Methods:** + +#### `current` + +```python +current(self) -> int | None +``` + +Current progress value. + + +#### `total` + +```python +total(self) -> int +``` + +Total/target progress value. + + +#### `message` + +```python +message(self) -> str | None +``` + +Current progress message. + + +#### `set_total` + +```python +set_total(self, total: int) -> None +``` + +Set the total/target value for progress tracking. + + +#### `increment` + +```python +increment(self, amount: int = 1) -> None +``` + +Atomically increment the current progress value. + + +#### `set_message` + +```python +set_message(self, message: str | None) -> None +``` + +Update the progress status message. + + +### `InMemoryProgress` + + +In-memory progress tracker for immediate tool execution. + +Provides the same interface as Docket's Progress but stores state in memory +instead of Redis. Useful for testing and immediate execution where +progress doesn't need to be observable across processes. + + +**Methods:** + +#### `current` + +```python +current(self) -> int | None +``` + +#### `total` + +```python +total(self) -> int +``` + +#### `message` + +```python +message(self) -> str | None +``` + +#### `set_total` + +```python +set_total(self, total: int) -> None +``` + +Set the total/target value for progress tracking. + + +#### `increment` + +```python +increment(self, amount: int = 1) -> None +``` + +Atomically increment the current progress value. + + +#### `set_message` + +```python +set_message(self, message: str | None) -> None +``` + +Update the progress status message. + + +### `Progress` + + +FastMCP Progress dependency that works in both server and worker contexts. + +Handles three execution modes: +- In Docket worker: Uses the execution's progress (observable via Redis) +- In FastMCP server with Docket: Falls back to in-memory progress +- In FastMCP server without Docket: Uses in-memory progress + +This allows tools to use Progress() regardless of whether they're called +immediately or as background tasks, and regardless of whether pydocket +is installed. + + +**Methods:** + +#### `current` + +```python +current(self) -> int | None +``` + +Current progress value. + + +#### `total` + +```python +total(self) -> int +``` + +Total/target progress value. + + +#### `message` + +```python +message(self) -> str | None +``` + +Current progress message. + + +#### `set_total` + +```python +set_total(self, total: int) -> None +``` + +Set the total/target value for progress tracking. + + +#### `increment` + +```python +increment(self, amount: int = 1) -> None +``` + +Atomically increment the current progress value. + + +#### `set_message` + +```python +set_message(self, message: str | None) -> None +``` + +Update the progress status message. + diff --git a/docs/python-sdk/fastmcp-server-elicitation.mdx b/docs/python-sdk/fastmcp-server-elicitation.mdx new file mode 100644 index 000000000..85f140c6e --- /dev/null +++ b/docs/python-sdk/fastmcp-server-elicitation.mdx @@ -0,0 +1,145 @@ +--- +title: elicitation +sidebarTitle: elicitation +--- + +# `fastmcp.server.elicitation` + +## Functions + +### `parse_elicit_response_type` + +```python +parse_elicit_response_type(response_type: Any) -> ElicitConfig +``` + + +Parse response_type into schema and handling configuration. + +Supports multiple syntaxes: +- None: Empty object schema, expect empty response +- dict: `{"low": {"title": "..."}}` -> single-select titled enum +- list patterns: + - `[["a", "b"]]` -> multi-select untitled + - `[{"low": {...}}]` -> multi-select titled + - `["a", "b"]` -> single-select untitled +- `list[X]` type annotation: multi-select with type +- Scalar types (bool, int, float, str, Literal, Enum): single value +- Other types (dataclass, BaseModel): use directly + + +### `handle_elicit_accept` + +```python +handle_elicit_accept(config: ElicitConfig, content: Any) -> AcceptedElicitation[Any] +``` + + +Handle an accepted elicitation response. + +**Args:** +- `config`: The elicitation configuration from parse_elicit_response_type +- `content`: The response content from the client + +**Returns:** +- AcceptedElicitation with the extracted/validated data + + +### `get_elicitation_schema` + +```python +get_elicitation_schema(response_type: type[T]) -> dict[str, Any] +``` + + +Get the schema for an elicitation response. + +**Args:** +- `response_type`: The type of the response + + +### `validate_elicitation_json_schema` + +```python +validate_elicitation_json_schema(schema: dict[str, Any]) -> None +``` + + +Validate that a JSON schema follows MCP elicitation requirements. + +This ensures the schema is compatible with MCP elicitation requirements: +- Must be an object schema +- Must only contain primitive field types (string, number, integer, boolean) +- Must be flat (no nested objects or arrays of objects) +- Allows const fields (for Literal types) and enum fields (for Enum types) +- Only primitive types and their nullable variants are allowed + +**Args:** +- `schema`: The JSON schema to validate + +**Raises:** +- `TypeError`: If the schema doesn't meet MCP elicitation requirements + + +## Classes + +### `ElicitationJsonSchema` + + +Custom JSON schema generator for MCP elicitation that always inlines enums. + +MCP elicitation requires inline enum schemas without $ref/$defs references. +This generator ensures enums are always generated inline for compatibility. +Optionally adds enumNames for better UI display when available. + + +**Methods:** + +#### `generate_inner` + +```python +generate_inner(self, schema: core_schema.CoreSchema) -> JsonSchemaValue +``` + +Override to prevent ref generation for enums and handle list schemas. + + +#### `list_schema` + +```python +list_schema(self, schema: core_schema.ListSchema) -> JsonSchemaValue +``` + +Generate schema for list types, detecting enum items for multi-select. + + +#### `enum_schema` + +```python +enum_schema(self, schema: core_schema.EnumSchema) -> JsonSchemaValue +``` + +Generate inline enum schema. + +Always generates enum pattern: `{"enum": [value, ...]}` +Titled enums are handled separately via dict-based syntax in ctx.elicit(). + + +### `AcceptedElicitation` + + +Result when user accepts the elicitation. + + +### `ScalarElicitationType` + +### `ElicitConfig` + + +Configuration for an elicitation request. + +**Attributes:** +- `schema`: The JSON schema to send to the client +- `response_type`: The type to validate responses with (None for raw schemas) +- `is_raw`: True if schema was built directly (extract "value" from response) + diff --git a/docs/python-sdk/fastmcp-server-event_store.mdx b/docs/python-sdk/fastmcp-server-event_store.mdx new file mode 100644 index 000000000..004e94405 --- /dev/null +++ b/docs/python-sdk/fastmcp-server-event_store.mdx @@ -0,0 +1,78 @@ +--- +title: event_store +sidebarTitle: event_store +--- + +# `fastmcp.server.event_store` + + +EventStore implementation backed by AsyncKeyValue. + +This module provides an EventStore implementation that enables SSE polling/resumability +for Streamable HTTP transports. Events are stored using the key_value package's +AsyncKeyValue protocol, allowing users to configure any compatible backend +(in-memory, Redis, etc.) following the same pattern as ResponseCachingMiddleware. + + +## Classes + +### `EventEntry` + + +Stored event entry. + + +### `StreamEventList` + + +List of event IDs for a stream. + + +### `EventStore` + + +EventStore implementation backed by AsyncKeyValue. + +Enables SSE polling/resumability by storing events that can be replayed +when clients reconnect. Works with any AsyncKeyValue backend (memory, Redis, etc.) +following the same pattern as ResponseCachingMiddleware and OAuthProxy. + +**Args:** +- `storage`: AsyncKeyValue backend. Defaults to MemoryStore. +- `max_events_per_stream`: Maximum events to retain per stream. Default 100. +- `ttl`: Event TTL in seconds. Default 3600 (1 hour). Set to None for no expiration. + + +**Methods:** + +#### `store_event` + +```python +store_event(self, stream_id: StreamId, message: JSONRPCMessage | None) -> EventId +``` + +Store an event and return its ID. + +**Args:** +- `stream_id`: ID of the stream the event belongs to +- `message`: The JSON-RPC message to store, or None for priming events + +**Returns:** +- The generated event ID for the stored event + + +#### `replay_events_after` + +```python +replay_events_after(self, last_event_id: EventId, send_callback: EventCallback) -> StreamId | None +``` + +Replay events that occurred after the specified event ID. + +**Args:** +- `last_event_id`: The ID of the last event the client received +- `send_callback`: A callback function to send events to the client + +**Returns:** +- The stream ID of the replayed events, or None if the event ID was not found + diff --git a/docs/python-sdk/fastmcp-server-http.mdx b/docs/python-sdk/fastmcp-server-http.mdx new file mode 100644 index 000000000..9b2fe758d --- /dev/null +++ b/docs/python-sdk/fastmcp-server-http.mdx @@ -0,0 +1,106 @@ +--- +title: http +sidebarTitle: http +--- + +# `fastmcp.server.http` + +## Functions + +### `set_http_request` + +```python +set_http_request(request: Request) -> Generator[Request, None, None] +``` + +### `create_base_app` + +```python +create_base_app(routes: list[BaseRoute], middleware: list[Middleware], debug: bool = False, lifespan: Callable | None = None) -> StarletteWithLifespan +``` + + +Create a base Starlette app with common middleware and routes. + +**Args:** +- `routes`: List of routes to include in the app +- `middleware`: List of middleware to include in the app +- `debug`: Whether to enable debug mode +- `lifespan`: Optional lifespan manager for the app + +**Returns:** +- A Starlette application + + +### `create_sse_app` + +```python +create_sse_app(server: FastMCP[LifespanResultT], message_path: str, sse_path: str, auth: AuthProvider | None = None, debug: bool = False, routes: list[BaseRoute] | None = None, middleware: list[Middleware] | None = None) -> StarletteWithLifespan +``` + + +Return an instance of the SSE server app. + +**Args:** +- `server`: The FastMCP server instance +- `message_path`: Path for SSE messages +- `sse_path`: Path for SSE connections +- `auth`: Optional authentication provider (AuthProvider) +- `debug`: Whether to enable debug mode +- `routes`: Optional list of custom routes +- `middleware`: Optional list of middleware + +Returns: + A Starlette application with RequestContextMiddleware + + +### `create_streamable_http_app` + +```python +create_streamable_http_app(server: FastMCP[LifespanResultT], streamable_http_path: str, event_store: EventStore | None = None, retry_interval: int | None = None, auth: AuthProvider | None = None, json_response: bool = False, stateless_http: bool = False, debug: bool = False, routes: list[BaseRoute] | None = None, middleware: list[Middleware] | None = None) -> StarletteWithLifespan +``` + + +Return an instance of the StreamableHTTP server app. + +**Args:** +- `server`: The FastMCP server instance +- `streamable_http_path`: Path for StreamableHTTP connections +- `event_store`: Optional event store for SSE polling/resumability +- `retry_interval`: Optional retry interval in milliseconds for SSE polling. +Controls how quickly clients should reconnect after server-initiated +disconnections. Requires event_store to be set. Defaults to SDK default. +- `auth`: Optional authentication provider (AuthProvider) +- `json_response`: Whether to use JSON response format +- `stateless_http`: Whether to use stateless mode (new transport per request) +- `debug`: Whether to enable debug mode +- `routes`: Optional list of custom routes +- `middleware`: Optional list of middleware + +**Returns:** +- A Starlette application with StreamableHTTP support + + +## Classes + +### `StreamableHTTPASGIApp` + + +ASGI application wrapper for Streamable HTTP server transport. + + +### `StarletteWithLifespan` + +**Methods:** + +#### `lifespan` + +```python +lifespan(self) -> Lifespan[Starlette] +``` + +### `RequestContextMiddleware` + + +Middleware that stores each request in a ContextVar and sets transport type. + diff --git a/docs/python-sdk/fastmcp-server-lifespan.mdx b/docs/python-sdk/fastmcp-server-lifespan.mdx new file mode 100644 index 000000000..08a67ddd9 --- /dev/null +++ b/docs/python-sdk/fastmcp-server-lifespan.mdx @@ -0,0 +1,101 @@ +--- +title: lifespan +sidebarTitle: lifespan +--- + +# `fastmcp.server.lifespan` + + +Composable lifespans for FastMCP servers. + +This module provides a `@lifespan` decorator for creating composable server lifespans +that can be combined using the `|` operator. + +Example: + ```python + from fastmcp import FastMCP + from fastmcp.server.lifespan import lifespan + + @lifespan + async def db_lifespan(server): + conn = await connect_db() + yield {"db": conn} + await conn.close() + + @lifespan + async def cache_lifespan(server): + cache = await connect_cache() + yield {"cache": cache} + await cache.close() + + mcp = FastMCP("server", lifespan=db_lifespan | cache_lifespan) + ``` + +To compose with existing `@asynccontextmanager` lifespans, wrap them explicitly: + + ```python + from contextlib import asynccontextmanager + from fastmcp.server.lifespan import lifespan, ContextManagerLifespan + + @asynccontextmanager + async def legacy_lifespan(server): + yield {"legacy": True} + + @lifespan + async def new_lifespan(server): + yield {"new": True} + + # Wrap the legacy lifespan explicitly + combined = ContextManagerLifespan(legacy_lifespan) | new_lifespan + ``` + + +## Functions + +### `lifespan` + +```python +lifespan(fn: LifespanFn) -> Lifespan +``` + + +Decorator to create a composable lifespan. + +Use this decorator on an async generator function to make it composable +with other lifespans using the `|` operator. + +**Args:** +- `fn`: An async generator function that takes a FastMCP server and yields +a dict for the lifespan context. + +**Returns:** +- A composable Lifespan wrapper. + + +## Classes + +### `Lifespan` + + +Composable lifespan wrapper. + +Wraps an async generator function and enables composition via the `|` operator. +The wrapped function should yield a dict that becomes part of the lifespan context. + + +### `ContextManagerLifespan` + + +Lifespan wrapper for already-wrapped context manager functions. + +Use this for functions already decorated with @asynccontextmanager. + + +### `ComposedLifespan` + + +Two lifespans composed together. + +Enters the left lifespan first, then the right. Exits in reverse order. +Results are shallow-merged into a single dict. + diff --git a/docs/python-sdk/fastmcp-server-low_level.mdx b/docs/python-sdk/fastmcp-server-low_level.mdx new file mode 100644 index 000000000..78acc7225 --- /dev/null +++ b/docs/python-sdk/fastmcp-server-low_level.mdx @@ -0,0 +1,108 @@ +--- +title: low_level +sidebarTitle: low_level +--- + +# `fastmcp.server.low_level` + +## Classes + +### `MiddlewareServerSession` + + +ServerSession that routes initialization requests through FastMCP middleware. + + +**Methods:** + +#### `fastmcp` + +```python +fastmcp(self) -> FastMCP +``` + +Get the FastMCP instance. + + +#### `client_supports_extension` + +```python +client_supports_extension(self, extension_id: str) -> bool +``` + +Check if the connected client supports a given MCP extension. + +Inspects the ``extensions`` extra field on ``ClientCapabilities`` +sent by the client during initialization. + + +### `LowLevelServer` + +**Methods:** + +#### `fastmcp` + +```python +fastmcp(self) -> FastMCP +``` + +Get the FastMCP instance. + + +#### `create_initialization_options` + +```python +create_initialization_options(self, notification_options: NotificationOptions | None = None, experimental_capabilities: dict[str, dict[str, Any]] | None = None, **kwargs: Any) -> InitializationOptions +``` + +#### `get_capabilities` + +```python +get_capabilities(self, notification_options: NotificationOptions, experimental_capabilities: dict[str, dict[str, Any]]) -> mcp.types.ServerCapabilities +``` + +Override to set capabilities.tasks as a first-class field per SEP-1686. + +This ensures task capabilities appear in capabilities.tasks instead of +capabilities.experimental.tasks, which is required by the MCP spec and +enables proper task detection by clients like VS Code Copilot 1.107+. + + +#### `run` + +```python +run(self, read_stream: MemoryObjectReceiveStream[SessionMessage | Exception], write_stream: MemoryObjectSendStream[SessionMessage], initialization_options: InitializationOptions, raise_exceptions: bool = False, stateless: bool = False) +``` + +Overrides the run method to use the MiddlewareServerSession. + + +#### `read_resource` + +```python +read_resource(self) -> Callable[[Callable[[AnyUrl], Awaitable[mcp.types.ReadResourceResult | mcp.types.CreateTaskResult]]], Callable[[AnyUrl], Awaitable[mcp.types.ReadResourceResult | mcp.types.CreateTaskResult]]] +``` + +Decorator for registering a read_resource handler with CreateTaskResult support. + +The MCP SDK's read_resource decorator does not support returning CreateTaskResult +for background task execution. This decorator wraps the result in ServerResult. + +This decorator can be removed once the MCP SDK adds native CreateTaskResult support +for resources. + + +#### `get_prompt` + +```python +get_prompt(self) -> Callable[[Callable[[str, dict[str, Any] | None], Awaitable[mcp.types.GetPromptResult | mcp.types.CreateTaskResult]]], Callable[[str, dict[str, Any] | None], Awaitable[mcp.types.GetPromptResult | mcp.types.CreateTaskResult]]] +``` + +Decorator for registering a get_prompt handler with CreateTaskResult support. + +The MCP SDK's get_prompt decorator does not support returning CreateTaskResult +for background task execution. This decorator wraps the result in ServerResult. + +This decorator can be removed once the MCP SDK adds native CreateTaskResult support +for prompts. + diff --git a/docs/python-sdk/fastmcp-server-middleware-__init__.mdx b/docs/python-sdk/fastmcp-server-middleware-__init__.mdx new file mode 100644 index 000000000..8583b1df9 --- /dev/null +++ b/docs/python-sdk/fastmcp-server-middleware-__init__.mdx @@ -0,0 +1,8 @@ +--- +title: __init__ +sidebarTitle: __init__ +--- + +# `fastmcp.server.middleware` + +*This module is empty or contains only private/internal implementations.* diff --git a/docs/python-sdk/fastmcp-server-middleware-authorization.mdx b/docs/python-sdk/fastmcp-server-middleware-authorization.mdx new file mode 100644 index 000000000..5bf859a09 --- /dev/null +++ b/docs/python-sdk/fastmcp-server-middleware-authorization.mdx @@ -0,0 +1,116 @@ +--- +title: authorization +sidebarTitle: authorization +--- + +# `fastmcp.server.middleware.authorization` + + +Authorization middleware for FastMCP. + +This module provides middleware-based authorization using callable auth checks. +AuthMiddleware applies auth checks globally to all components on the server. + +Example: + ```python + from fastmcp import FastMCP + from fastmcp.server.auth import require_scopes, restrict_tag + from fastmcp.server.middleware import AuthMiddleware + + # Require specific scope for all components + mcp = FastMCP(middleware=[ + AuthMiddleware(auth=require_scopes("api")) + ]) + + # Tag-based: components tagged "admin" require "admin" scope + mcp = FastMCP(middleware=[ + AuthMiddleware(auth=restrict_tag("admin", scopes=["admin"])) + ]) + ``` + + +## Classes + +### `AuthMiddleware` + + +Global authorization middleware using callable checks. + +This middleware applies auth checks to all components (tools, resources, +prompts) on the server. It uses the same callable API as component-level +auth checks. + +The middleware: +- Filters tools/resources/prompts from list responses based on auth checks +- Checks auth before tool execution, resource read, and prompt render +- Skips all auth checks for STDIO transport (no OAuth concept) + +**Args:** +- `auth`: A single auth check function or list of check functions. +All checks must pass for authorization to succeed (AND logic). + + +**Methods:** + +#### `on_list_tools` + +```python +on_list_tools(self, context: MiddlewareContext[mt.ListToolsRequest], call_next: CallNext[mt.ListToolsRequest, Sequence[Tool]]) -> Sequence[Tool] +``` + +Filter tools/list response based on auth checks. + + +#### `on_call_tool` + +```python +on_call_tool(self, context: MiddlewareContext[mt.CallToolRequestParams], call_next: CallNext[mt.CallToolRequestParams, ToolResult]) -> ToolResult +``` + +Check auth before tool execution. + + +#### `on_list_resources` + +```python +on_list_resources(self, context: MiddlewareContext[mt.ListResourcesRequest], call_next: CallNext[mt.ListResourcesRequest, Sequence[Resource]]) -> Sequence[Resource] +``` + +Filter resources/list response based on auth checks. + + +#### `on_read_resource` + +```python +on_read_resource(self, context: MiddlewareContext[mt.ReadResourceRequestParams], call_next: CallNext[mt.ReadResourceRequestParams, ResourceResult]) -> ResourceResult +``` + +Check auth before resource read. + + +#### `on_list_resource_templates` + +```python +on_list_resource_templates(self, context: MiddlewareContext[mt.ListResourceTemplatesRequest], call_next: CallNext[mt.ListResourceTemplatesRequest, Sequence[ResourceTemplate]]) -> Sequence[ResourceTemplate] +``` + +Filter resource templates/list response based on auth checks. + + +#### `on_list_prompts` + +```python +on_list_prompts(self, context: MiddlewareContext[mt.ListPromptsRequest], call_next: CallNext[mt.ListPromptsRequest, Sequence[Prompt]]) -> Sequence[Prompt] +``` + +Filter prompts/list response based on auth checks. + + +#### `on_get_prompt` + +```python +on_get_prompt(self, context: MiddlewareContext[mt.GetPromptRequestParams], call_next: CallNext[mt.GetPromptRequestParams, PromptResult]) -> PromptResult +``` + +Check auth before prompt render. + diff --git a/docs/python-sdk/fastmcp-server-middleware-caching.mdx b/docs/python-sdk/fastmcp-server-middleware-caching.mdx new file mode 100644 index 000000000..66b86999d --- /dev/null +++ b/docs/python-sdk/fastmcp-server-middleware-caching.mdx @@ -0,0 +1,221 @@ +--- +title: caching +sidebarTitle: caching +--- + +# `fastmcp.server.middleware.caching` + + +A middleware for response caching. + +## Classes + +### `CachableResourceContent` + + +A wrapper for ResourceContent that can be cached. + + +### `CachableResourceResult` + + +A wrapper for ResourceResult that can be cached. + + +**Methods:** + +#### `get_size` + +```python +get_size(self) -> int +``` + +#### `wrap` + +```python +wrap(cls, value: ResourceResult) -> Self +``` + +#### `unwrap` + +```python +unwrap(self) -> ResourceResult +``` + +### `CachableToolResult` + +**Methods:** + +#### `wrap` + +```python +wrap(cls, value: ToolResult) -> Self +``` + +#### `unwrap` + +```python +unwrap(self) -> ToolResult +``` + +### `CachableMessage` + + +A wrapper for Message that can be cached. + + +### `CachablePromptResult` + + +A wrapper for PromptResult that can be cached. + + +**Methods:** + +#### `get_size` + +```python +get_size(self) -> int +``` + +#### `wrap` + +```python +wrap(cls, value: PromptResult) -> Self +``` + +#### `unwrap` + +```python +unwrap(self) -> PromptResult +``` + +### `SharedMethodSettings` + + +Shared config for a cache method. + + +### `ListToolsSettings` + + +Configuration options for Tool-related caching. + + +### `ListResourcesSettings` + + +Configuration options for Resource-related caching. + + +### `ListPromptsSettings` + + +Configuration options for Prompt-related caching. + + +### `CallToolSettings` + + +Configuration options for Tool-related caching. + + +### `ReadResourceSettings` + + +Configuration options for Resource-related caching. + + +### `GetPromptSettings` + + +Configuration options for Prompt-related caching. + + +### `ResponseCachingStatistics` + +### `ResponseCachingMiddleware` + + +The response caching middleware offers a simple way to cache responses to mcp methods. The Middleware +supports cache invalidation via notifications from the server. The Middleware implements TTL-based caching +but cache implementations may offer additional features like LRU eviction, size limits, and more. + +When items are retrieved from the cache they will no longer be the original objects, but rather no-op objects +this means that response caching may not be compatible with other middleware that expects original subclasses. + +Notes: +- Caches `tools/call`, `resources/read`, `prompts/get`, `tools/list`, `resources/list`, and `prompts/list` requests. +- Cache keys are derived from method name and arguments. + + +**Methods:** + +#### `on_list_tools` + +```python +on_list_tools(self, context: MiddlewareContext[mcp.types.ListToolsRequest], call_next: CallNext[mcp.types.ListToolsRequest, Sequence[Tool]]) -> Sequence[Tool] +``` + +List tools from the cache, if caching is enabled, and the result is in the cache. Otherwise, +otherwise call the next middleware and store the result in the cache if caching is enabled. + + +#### `on_list_resources` + +```python +on_list_resources(self, context: MiddlewareContext[mcp.types.ListResourcesRequest], call_next: CallNext[mcp.types.ListResourcesRequest, Sequence[Resource]]) -> Sequence[Resource] +``` + +List resources from the cache, if caching is enabled, and the result is in the cache. Otherwise, +otherwise call the next middleware and store the result in the cache if caching is enabled. + + +#### `on_list_prompts` + +```python +on_list_prompts(self, context: MiddlewareContext[mcp.types.ListPromptsRequest], call_next: CallNext[mcp.types.ListPromptsRequest, Sequence[Prompt]]) -> Sequence[Prompt] +``` + +List prompts from the cache, if caching is enabled, and the result is in the cache. Otherwise, +otherwise call the next middleware and store the result in the cache if caching is enabled. + + +#### `on_call_tool` + +```python +on_call_tool(self, context: MiddlewareContext[mcp.types.CallToolRequestParams], call_next: CallNext[mcp.types.CallToolRequestParams, ToolResult]) -> ToolResult +``` + +Call a tool from the cache, if caching is enabled, and the result is in the cache. Otherwise, +otherwise call the next middleware and store the result in the cache if caching is enabled. + + +#### `on_read_resource` + +```python +on_read_resource(self, context: MiddlewareContext[mcp.types.ReadResourceRequestParams], call_next: CallNext[mcp.types.ReadResourceRequestParams, ResourceResult]) -> ResourceResult +``` + +Read a resource from the cache, if caching is enabled, and the result is in the cache. Otherwise, +otherwise call the next middleware and store the result in the cache if caching is enabled. + + +#### `on_get_prompt` + +```python +on_get_prompt(self, context: MiddlewareContext[mcp.types.GetPromptRequestParams], call_next: CallNext[mcp.types.GetPromptRequestParams, PromptResult]) -> PromptResult +``` + +Get a prompt from the cache, if caching is enabled, and the result is in the cache. Otherwise, +otherwise call the next middleware and store the result in the cache if caching is enabled. + + +#### `statistics` + +```python +statistics(self) -> ResponseCachingStatistics +``` + +Get the statistics for the cache. + diff --git a/docs/python-sdk/fastmcp-server-middleware-dereference.mdx b/docs/python-sdk/fastmcp-server-middleware-dereference.mdx new file mode 100644 index 000000000..57c5edf88 --- /dev/null +++ b/docs/python-sdk/fastmcp-server-middleware-dereference.mdx @@ -0,0 +1,35 @@ +--- +title: dereference +sidebarTitle: dereference +--- + +# `fastmcp.server.middleware.dereference` + + +Middleware that dereferences $ref in JSON schemas before sending to clients. + +## Classes + +### `DereferenceRefsMiddleware` + + +Dereferences $ref in component schemas before sending to clients. + +Some MCP clients (e.g., VS Code Copilot) don't handle JSON Schema $ref +properly. This middleware inlines all $ref definitions so schemas are +self-contained. Enabled by default via ``FastMCP(dereference_schemas=True)``. + + +**Methods:** + +#### `on_list_tools` + +```python +on_list_tools(self, context: MiddlewareContext[mt.ListToolsRequest], call_next: CallNext[mt.ListToolsRequest, Sequence[Tool]]) -> Sequence[Tool] +``` + +#### `on_list_resource_templates` + +```python +on_list_resource_templates(self, context: MiddlewareContext[mt.ListResourceTemplatesRequest], call_next: CallNext[mt.ListResourceTemplatesRequest, Sequence[ResourceTemplate]]) -> Sequence[ResourceTemplate] +``` diff --git a/docs/python-sdk/fastmcp-server-middleware-error_handling.mdx b/docs/python-sdk/fastmcp-server-middleware-error_handling.mdx new file mode 100644 index 000000000..3089f4d2c --- /dev/null +++ b/docs/python-sdk/fastmcp-server-middleware-error_handling.mdx @@ -0,0 +1,60 @@ +--- +title: error_handling +sidebarTitle: error_handling +--- + +# `fastmcp.server.middleware.error_handling` + + +Error handling middleware for consistent error responses and tracking. + +## Classes + +### `ErrorHandlingMiddleware` + + +Middleware that provides consistent error handling and logging. + +Catches exceptions, logs them appropriately, and converts them to +proper MCP error responses. Also tracks error patterns for monitoring. + + +**Methods:** + +#### `on_message` + +```python +on_message(self, context: MiddlewareContext, call_next: CallNext) -> Any +``` + +Handle errors for all messages. + + +#### `get_error_stats` + +```python +get_error_stats(self) -> dict[str, int] +``` + +Get error statistics for monitoring. + + +### `RetryMiddleware` + + +Middleware that implements automatic retry logic for failed requests. + +Retries requests that fail with transient errors, using exponential +backoff to avoid overwhelming the server or external dependencies. + + +**Methods:** + +#### `on_request` + +```python +on_request(self, context: MiddlewareContext, call_next: CallNext) -> Any +``` + +Implement retry logic for requests. + diff --git a/docs/python-sdk/fastmcp-server-middleware-logging.mdx b/docs/python-sdk/fastmcp-server-middleware-logging.mdx new file mode 100644 index 000000000..10f6933a1 --- /dev/null +++ b/docs/python-sdk/fastmcp-server-middleware-logging.mdx @@ -0,0 +1,58 @@ +--- +title: logging +sidebarTitle: logging +--- + +# `fastmcp.server.middleware.logging` + + +Comprehensive logging middleware for FastMCP servers. + +## Functions + +### `default_serializer` + +```python +default_serializer(data: Any) -> str +``` + + +The default serializer for Payloads in the logging middleware. + + +## Classes + +### `BaseLoggingMiddleware` + + +Base class for logging middleware. + + +**Methods:** + +#### `on_message` + +```python +on_message(self, context: MiddlewareContext[Any], call_next: CallNext[Any, Any]) -> Any +``` + +Log messages for configured methods. + + +### `LoggingMiddleware` + + +Middleware that provides comprehensive request and response logging. + +Logs all MCP messages with configurable detail levels. Useful for debugging, +monitoring, and understanding server usage patterns. + + +### `StructuredLoggingMiddleware` + + +Middleware that provides structured JSON logging for better log analysis. + +Outputs structured logs that are easier to parse and analyze with log +aggregation tools like ELK stack, Splunk, or cloud logging services. + diff --git a/docs/python-sdk/fastmcp-server-middleware-middleware.mdx b/docs/python-sdk/fastmcp-server-middleware-middleware.mdx new file mode 100644 index 000000000..04a87f554 --- /dev/null +++ b/docs/python-sdk/fastmcp-server-middleware-middleware.mdx @@ -0,0 +1,112 @@ +--- +title: middleware +sidebarTitle: middleware +--- + +# `fastmcp.server.middleware.middleware` + +## Functions + +### `make_middleware_wrapper` + +```python +make_middleware_wrapper(middleware: Middleware, call_next: CallNext[T, R]) -> CallNext[T, R] +``` + + +Create a wrapper that applies a single middleware to a context. The +closure bakes in the middleware and call_next function, so it can be +passed to other functions that expect a call_next function. + + +## Classes + +### `CallNext` + +### `MiddlewareContext` + + +Unified context for all middleware operations. + + +**Methods:** + +#### `copy` + +```python +copy(self, **kwargs: Any) -> MiddlewareContext[T] +``` + +### `Middleware` + + +Base class for FastMCP middleware with dispatching hooks. + + +**Methods:** + +#### `on_message` + +```python +on_message(self, context: MiddlewareContext[Any], call_next: CallNext[Any, Any]) -> Any +``` + +#### `on_request` + +```python +on_request(self, context: MiddlewareContext[mt.Request[Any, Any]], call_next: CallNext[mt.Request[Any, Any], Any]) -> Any +``` + +#### `on_notification` + +```python +on_notification(self, context: MiddlewareContext[mt.Notification[Any, Any]], call_next: CallNext[mt.Notification[Any, Any], Any]) -> Any +``` + +#### `on_initialize` + +```python +on_initialize(self, context: MiddlewareContext[mt.InitializeRequest], call_next: CallNext[mt.InitializeRequest, mt.InitializeResult | None]) -> mt.InitializeResult | None +``` + +#### `on_call_tool` + +```python +on_call_tool(self, context: MiddlewareContext[mt.CallToolRequestParams], call_next: CallNext[mt.CallToolRequestParams, ToolResult]) -> ToolResult +``` + +#### `on_read_resource` + +```python +on_read_resource(self, context: MiddlewareContext[mt.ReadResourceRequestParams], call_next: CallNext[mt.ReadResourceRequestParams, ResourceResult]) -> ResourceResult +``` + +#### `on_get_prompt` + +```python +on_get_prompt(self, context: MiddlewareContext[mt.GetPromptRequestParams], call_next: CallNext[mt.GetPromptRequestParams, PromptResult]) -> PromptResult +``` + +#### `on_list_tools` + +```python +on_list_tools(self, context: MiddlewareContext[mt.ListToolsRequest], call_next: CallNext[mt.ListToolsRequest, Sequence[Tool]]) -> Sequence[Tool] +``` + +#### `on_list_resources` + +```python +on_list_resources(self, context: MiddlewareContext[mt.ListResourcesRequest], call_next: CallNext[mt.ListResourcesRequest, Sequence[Resource]]) -> Sequence[Resource] +``` + +#### `on_list_resource_templates` + +```python +on_list_resource_templates(self, context: MiddlewareContext[mt.ListResourceTemplatesRequest], call_next: CallNext[mt.ListResourceTemplatesRequest, Sequence[ResourceTemplate]]) -> Sequence[ResourceTemplate] +``` + +#### `on_list_prompts` + +```python +on_list_prompts(self, context: MiddlewareContext[mt.ListPromptsRequest], call_next: CallNext[mt.ListPromptsRequest, Sequence[Prompt]]) -> Sequence[Prompt] +``` diff --git a/docs/python-sdk/fastmcp-server-middleware-ping.mdx b/docs/python-sdk/fastmcp-server-middleware-ping.mdx new file mode 100644 index 000000000..7ff39d339 --- /dev/null +++ b/docs/python-sdk/fastmcp-server-middleware-ping.mdx @@ -0,0 +1,32 @@ +--- +title: ping +sidebarTitle: ping +--- + +# `fastmcp.server.middleware.ping` + + +Ping middleware for keeping client connections alive. + +## Classes + +### `PingMiddleware` + + +Middleware that sends periodic pings to keep client connections alive. + +Starts a background ping task on first message from each session. The task +sends server-to-client pings at the configured interval until the session +ends. + + +**Methods:** + +#### `on_message` + +```python +on_message(self, context: MiddlewareContext, call_next: CallNext) -> Any +``` + +Start ping task on first message from a session. + diff --git a/docs/python-sdk/fastmcp-server-middleware-rate_limiting.mdx b/docs/python-sdk/fastmcp-server-middleware-rate_limiting.mdx new file mode 100644 index 000000000..0ac2c263f --- /dev/null +++ b/docs/python-sdk/fastmcp-server-middleware-rate_limiting.mdx @@ -0,0 +1,97 @@ +--- +title: rate_limiting +sidebarTitle: rate_limiting +--- + +# `fastmcp.server.middleware.rate_limiting` + + +Rate limiting middleware for protecting FastMCP servers from abuse. + +## Classes + +### `RateLimitError` + + +Error raised when rate limit is exceeded. + + +### `TokenBucketRateLimiter` + + +Token bucket implementation for rate limiting. + + +**Methods:** + +#### `consume` + +```python +consume(self, tokens: int = 1) -> bool +``` + +Try to consume tokens from the bucket. + +**Args:** +- `tokens`: Number of tokens to consume + +**Returns:** +- True if tokens were available and consumed, False otherwise + + +### `SlidingWindowRateLimiter` + + +Sliding window rate limiter implementation. + + +**Methods:** + +#### `is_allowed` + +```python +is_allowed(self) -> bool +``` + +Check if a request is allowed. + + +### `RateLimitingMiddleware` + + +Middleware that implements rate limiting to prevent server abuse. + +Uses a token bucket algorithm by default, allowing for burst traffic +while maintaining a sustainable long-term rate. + + +**Methods:** + +#### `on_request` + +```python +on_request(self, context: MiddlewareContext, call_next: CallNext) -> Any +``` + +Apply rate limiting to requests. + + +### `SlidingWindowRateLimitingMiddleware` + + +Middleware that implements sliding window rate limiting. + +Uses a sliding window approach which provides more precise rate limiting +but uses more memory to track individual request timestamps. + + +**Methods:** + +#### `on_request` + +```python +on_request(self, context: MiddlewareContext, call_next: CallNext) -> Any +``` + +Apply sliding window rate limiting to requests. + diff --git a/docs/python-sdk/fastmcp-server-middleware-response_limiting.mdx b/docs/python-sdk/fastmcp-server-middleware-response_limiting.mdx new file mode 100644 index 000000000..0f344100b --- /dev/null +++ b/docs/python-sdk/fastmcp-server-middleware-response_limiting.mdx @@ -0,0 +1,32 @@ +--- +title: response_limiting +sidebarTitle: response_limiting +--- + +# `fastmcp.server.middleware.response_limiting` + + +Response limiting middleware for controlling tool response sizes. + +## Classes + +### `ResponseLimitingMiddleware` + + +Middleware that limits the response size of tool calls. + +Intercepts tool call responses and enforces size limits. If a response +exceeds the limit, it extracts text content, truncates it, and returns +a single TextContent block. + + +**Methods:** + +#### `on_call_tool` + +```python +on_call_tool(self, context: MiddlewareContext[mt.CallToolRequestParams], call_next: CallNext[mt.CallToolRequestParams, ToolResult]) -> ToolResult +``` + +Intercept tool calls and limit response size. + diff --git a/docs/python-sdk/fastmcp-server-middleware-timing.mdx b/docs/python-sdk/fastmcp-server-middleware-timing.mdx new file mode 100644 index 000000000..533ff5de8 --- /dev/null +++ b/docs/python-sdk/fastmcp-server-middleware-timing.mdx @@ -0,0 +1,105 @@ +--- +title: timing +sidebarTitle: timing +--- + +# `fastmcp.server.middleware.timing` + + +Timing middleware for measuring and logging request performance. + +## Classes + +### `TimingMiddleware` + + +Middleware that logs the execution time of requests. + +Only measures and logs timing for request messages (not notifications). +Provides insights into performance characteristics of your MCP server. + + +**Methods:** + +#### `on_request` + +```python +on_request(self, context: MiddlewareContext, call_next: CallNext) -> Any +``` + +Time request execution and log the results. + + +### `DetailedTimingMiddleware` + + +Enhanced timing middleware with per-operation breakdowns. + +Provides detailed timing information for different types of MCP operations, +allowing you to identify performance bottlenecks in specific operations. + + +**Methods:** + +#### `on_call_tool` + +```python +on_call_tool(self, context: MiddlewareContext, call_next: CallNext) -> Any +``` + +Time tool execution. + + +#### `on_read_resource` + +```python +on_read_resource(self, context: MiddlewareContext, call_next: CallNext) -> Any +``` + +Time resource reading. + + +#### `on_get_prompt` + +```python +on_get_prompt(self, context: MiddlewareContext, call_next: CallNext) -> Any +``` + +Time prompt retrieval. + + +#### `on_list_tools` + +```python +on_list_tools(self, context: MiddlewareContext, call_next: CallNext) -> Any +``` + +Time tool listing. + + +#### `on_list_resources` + +```python +on_list_resources(self, context: MiddlewareContext, call_next: CallNext) -> Any +``` + +Time resource listing. + + +#### `on_list_resource_templates` + +```python +on_list_resource_templates(self, context: MiddlewareContext, call_next: CallNext) -> Any +``` + +Time resource template listing. + + +#### `on_list_prompts` + +```python +on_list_prompts(self, context: MiddlewareContext, call_next: CallNext) -> Any +``` + +Time prompt listing. + diff --git a/docs/python-sdk/fastmcp-server-middleware-tool_injection.mdx b/docs/python-sdk/fastmcp-server-middleware-tool_injection.mdx new file mode 100644 index 000000000..6c9c01346 --- /dev/null +++ b/docs/python-sdk/fastmcp-server-middleware-tool_injection.mdx @@ -0,0 +1,91 @@ +--- +title: tool_injection +sidebarTitle: tool_injection +--- + +# `fastmcp.server.middleware.tool_injection` + + +A middleware for injecting tools into the MCP server context. + +## Functions + +### `list_prompts` + +```python +list_prompts(context: Context) -> list[Prompt] +``` + + +List prompts available on the server. + + +### `get_prompt` + +```python +get_prompt(context: Context, name: Annotated[str, 'The name of the prompt to render.'], arguments: Annotated[dict[str, Any] | None, 'The arguments to pass to the prompt.'] = None) -> mcp.types.GetPromptResult +``` + + +Render a prompt available on the server. + + +### `list_resources` + +```python +list_resources(context: Context) -> list[mcp.types.Resource] +``` + + +List resources available on the server. + + +### `read_resource` + +```python +read_resource(context: Context, uri: Annotated[AnyUrl | str, 'The URI of the resource to read.']) -> ResourceResult +``` + + +Read a resource available on the server. + + +## Classes + +### `ToolInjectionMiddleware` + + +A middleware for injecting tools into the context. + + +**Methods:** + +#### `on_list_tools` + +```python +on_list_tools(self, context: MiddlewareContext[mcp.types.ListToolsRequest], call_next: CallNext[mcp.types.ListToolsRequest, Sequence[Tool]]) -> Sequence[Tool] +``` + +Inject tools into the response. + + +#### `on_call_tool` + +```python +on_call_tool(self, context: MiddlewareContext[mcp.types.CallToolRequestParams], call_next: CallNext[mcp.types.CallToolRequestParams, ToolResult]) -> ToolResult +``` + +Intercept tool calls to injected tools. + + +### `PromptToolMiddleware` + + +A middleware for injecting prompts as tools into the context. + + +### `ResourceToolMiddleware` + + +A middleware for injecting resources as tools into the context. + diff --git a/docs/python-sdk/fastmcp-server-mixins-__init__.mdx b/docs/python-sdk/fastmcp-server-mixins-__init__.mdx new file mode 100644 index 000000000..d35f9fc06 --- /dev/null +++ b/docs/python-sdk/fastmcp-server-mixins-__init__.mdx @@ -0,0 +1,9 @@ +--- +title: __init__ +sidebarTitle: __init__ +--- + +# `fastmcp.server.mixins` + + +Server mixins for FastMCP. diff --git a/docs/python-sdk/fastmcp-server-mixins-lifespan.mdx b/docs/python-sdk/fastmcp-server-mixins-lifespan.mdx new file mode 100644 index 000000000..9d0eec22e --- /dev/null +++ b/docs/python-sdk/fastmcp-server-mixins-lifespan.mdx @@ -0,0 +1,30 @@ +--- +title: lifespan +sidebarTitle: lifespan +--- + +# `fastmcp.server.mixins.lifespan` + + +Lifespan and Docket task infrastructure for FastMCP Server. + +## Classes + +### `LifespanMixin` + + +Mixin providing lifespan and Docket task infrastructure for FastMCP. + + +**Methods:** + +#### `docket` + +```python +docket(self: FastMCP) -> Docket | None +``` + +Get the Docket instance if Docket support is enabled. + +Returns None if Docket is not enabled or server hasn't been started yet. + diff --git a/docs/python-sdk/fastmcp-server-mixins-mcp_operations.mdx b/docs/python-sdk/fastmcp-server-mixins-mcp_operations.mdx new file mode 100644 index 000000000..0b6bef529 --- /dev/null +++ b/docs/python-sdk/fastmcp-server-mixins-mcp_operations.mdx @@ -0,0 +1,23 @@ +--- +title: mcp_operations +sidebarTitle: mcp_operations +--- + +# `fastmcp.server.mixins.mcp_operations` + + +MCP protocol handler setup and wire-format handlers for FastMCP Server. + +## Classes + +### `MCPOperationsMixin` + + +Mixin providing MCP protocol handler setup and wire-format handlers. + +Note: Methods registered with SDK decorators (e.g., _list_tools_mcp, _call_tool_mcp) +cannot use `self: FastMCP` type hints because the SDK's `get_type_hints()` fails +to resolve FastMCP at runtime (it's only available under TYPE_CHECKING). When +type hints fail to resolve, the SDK falls back to calling handlers with no arguments. +These methods use untyped `self` to avoid this issue. + diff --git a/docs/python-sdk/fastmcp-server-mixins-transport.mdx b/docs/python-sdk/fastmcp-server-mixins-transport.mdx new file mode 100644 index 000000000..c5cc4e2fd --- /dev/null +++ b/docs/python-sdk/fastmcp-server-mixins-transport.mdx @@ -0,0 +1,131 @@ +--- +title: transport +sidebarTitle: transport +--- + +# `fastmcp.server.mixins.transport` + + +Transport-related methods for FastMCP Server. + +## Classes + +### `TransportMixin` + + +Mixin providing transport-related methods for FastMCP. + +Includes HTTP/stdio/SSE transport handling and custom HTTP routes. + + +**Methods:** + +#### `run_async` + +```python +run_async(self: FastMCP, transport: Transport | None = None, show_banner: bool | None = None, **transport_kwargs: Any) -> None +``` + +Run the FastMCP server asynchronously. + +**Args:** +- `transport`: Transport protocol to use ("stdio", "http", "sse", or "streamable-http") +- `show_banner`: Whether to display the server banner. If None, uses the +FASTMCP_SHOW_SERVER_BANNER setting (default\: True). + + +#### `run` + +```python +run(self: FastMCP, transport: Transport | None = None, show_banner: bool | None = None, **transport_kwargs: Any) -> None +``` + +Run the FastMCP server. Note this is a synchronous function. + +**Args:** +- `transport`: Transport protocol to use ("http", "stdio", "sse", or "streamable-http") +- `show_banner`: Whether to display the server banner. If None, uses the +FASTMCP_SHOW_SERVER_BANNER setting (default\: True). + + +#### `custom_route` + +```python +custom_route(self: FastMCP, path: str, methods: list[str], name: str | None = None, include_in_schema: bool = True) -> Callable[[Callable[[Request], Awaitable[Response]]], Callable[[Request], Awaitable[Response]]] +``` + +Decorator to register a custom HTTP route on the FastMCP server. + +Allows adding arbitrary HTTP endpoints outside the standard MCP protocol, +which can be useful for OAuth callbacks, health checks, or admin APIs. +The handler function must be an async function that accepts a Starlette +Request and returns a Response. + +**Args:** +- `path`: URL path for the route (e.g., "/auth/callback") +- `methods`: List of HTTP methods to support (e.g., ["GET", "POST"]) +- `name`: Optional name for the route (to reference this route with +Starlette's reverse URL lookup feature) +- `include_in_schema`: Whether to include in OpenAPI schema, defaults to True + + +#### `run_stdio_async` + +```python +run_stdio_async(self: FastMCP, show_banner: bool = True, log_level: str | None = None, stateless: bool = False) -> None +``` + +Run the server using stdio transport. + +**Args:** +- `show_banner`: Whether to display the server banner +- `log_level`: Log level for the server +- `stateless`: Whether to run in stateless mode (no session initialization) + + +#### `run_http_async` + +```python +run_http_async(self: FastMCP, show_banner: bool = True, transport: Literal['http', 'streamable-http', 'sse'] = 'http', host: str | None = None, port: int | None = None, log_level: str | None = None, path: str | None = None, uvicorn_config: dict[str, Any] | None = None, middleware: list[ASGIMiddleware] | None = None, json_response: bool | None = None, stateless_http: bool | None = None, stateless: bool | None = None) -> None +``` + +Run the server using HTTP transport. + +**Args:** +- `transport`: Transport protocol to use - "http" (default), "streamable-http", or "sse" +- `host`: Host address to bind to (defaults to settings.host) +- `port`: Port to bind to (defaults to settings.port) +- `log_level`: Log level for the server (defaults to settings.log_level) +- `path`: Path for the endpoint (defaults to settings.streamable_http_path or settings.sse_path) +- `uvicorn_config`: Additional configuration for the Uvicorn server +- `middleware`: A list of middleware to apply to the app +- `json_response`: Whether to use JSON response format (defaults to settings.json_response) +- `stateless_http`: Whether to use stateless HTTP (defaults to settings.stateless_http) +- `stateless`: Alias for stateless_http for CLI consistency + + +#### `http_app` + +```python +http_app(self: FastMCP, path: str | None = None, middleware: list[ASGIMiddleware] | None = None, json_response: bool | None = None, stateless_http: bool | None = None, transport: Literal['http', 'streamable-http', 'sse'] = 'http', event_store: EventStore | None = None, retry_interval: int | None = None) -> StarletteWithLifespan +``` + +Create a Starlette app using the specified HTTP transport. + +**Args:** +- `path`: The path for the HTTP endpoint +- `middleware`: A list of middleware to apply to the app +- `json_response`: Whether to use JSON response format +- `stateless_http`: Whether to use stateless mode (new transport per request) +- `transport`: Transport protocol to use - "http", "streamable-http", or "sse" +- `event_store`: Optional event store for SSE polling/resumability. When set, +enables clients to reconnect and resume receiving events after +server-initiated disconnections. Only used with streamable-http transport. +- `retry_interval`: Optional retry interval in milliseconds for SSE polling. +Controls how quickly clients should reconnect after server-initiated +disconnections. Requires event_store to be set. Only used with +streamable-http transport. + +**Returns:** +- A Starlette application configured with the specified transport + diff --git a/docs/python-sdk/fastmcp-server-openapi-__init__.mdx b/docs/python-sdk/fastmcp-server-openapi-__init__.mdx new file mode 100644 index 000000000..af9cd5517 --- /dev/null +++ b/docs/python-sdk/fastmcp-server-openapi-__init__.mdx @@ -0,0 +1,27 @@ +--- +title: __init__ +sidebarTitle: __init__ +--- + +# `fastmcp.server.openapi` + + +OpenAPI server implementation for FastMCP. + +.. deprecated:: + This module is deprecated. Import from fastmcp.server.providers.openapi instead. + +The recommended approach is to use OpenAPIProvider with FastMCP: + + from fastmcp import FastMCP + from fastmcp.server.providers.openapi import OpenAPIProvider + import httpx + + client = httpx.AsyncClient(base_url="https://api.example.com") + provider = OpenAPIProvider(openapi_spec=spec, client=client) + + mcp = FastMCP("My API Server") + mcp.add_provider(provider) + +FastMCPOpenAPI is still available but deprecated. + diff --git a/docs/python-sdk/fastmcp-server-openapi-components.mdx b/docs/python-sdk/fastmcp-server-openapi-components.mdx new file mode 100644 index 000000000..320cc7092 --- /dev/null +++ b/docs/python-sdk/fastmcp-server-openapi-components.mdx @@ -0,0 +1,12 @@ +--- +title: components +sidebarTitle: components +--- + +# `fastmcp.server.openapi.components` + + +OpenAPI component implementations - backwards compatibility stub. + +This module is deprecated. Import from fastmcp.server.providers.openapi instead. + diff --git a/docs/python-sdk/fastmcp-server-openapi-routing.mdx b/docs/python-sdk/fastmcp-server-openapi-routing.mdx new file mode 100644 index 000000000..650a4a497 --- /dev/null +++ b/docs/python-sdk/fastmcp-server-openapi-routing.mdx @@ -0,0 +1,13 @@ +--- +title: routing +sidebarTitle: routing +--- + +# `fastmcp.server.openapi.routing` + + +Route mapping logic for OpenAPI operations. + +.. deprecated:: + This module is deprecated. Import from fastmcp.server.providers.openapi instead. + diff --git a/docs/python-sdk/fastmcp-server-openapi-server.mdx b/docs/python-sdk/fastmcp-server-openapi-server.mdx new file mode 100644 index 000000000..4f751e090 --- /dev/null +++ b/docs/python-sdk/fastmcp-server-openapi-server.mdx @@ -0,0 +1,43 @@ +--- +title: server +sidebarTitle: server +--- + +# `fastmcp.server.openapi.server` + + +FastMCPOpenAPI - backwards compatibility wrapper. + +This class is deprecated. Use FastMCP with OpenAPIProvider instead: + + from fastmcp import FastMCP + from fastmcp.server.providers.openapi import OpenAPIProvider + import httpx + + client = httpx.AsyncClient(base_url="https://api.example.com") + provider = OpenAPIProvider(openapi_spec=spec, client=client) + mcp = FastMCP("My API Server", providers=[provider]) + + +## Classes + +### `FastMCPOpenAPI` + + +FastMCP server implementation that creates components from an OpenAPI schema. + +.. deprecated:: + Use FastMCP with OpenAPIProvider instead. This class will be + removed in a future version. + +Example (deprecated): + ```python + from fastmcp.server.openapi import FastMCPOpenAPI + import httpx + + server = FastMCPOpenAPI( + openapi_spec=spec, + client=httpx.AsyncClient(), + ) + ``` + diff --git a/docs/python-sdk/fastmcp-server-providers-__init__.mdx b/docs/python-sdk/fastmcp-server-providers-__init__.mdx new file mode 100644 index 000000000..b7addb653 --- /dev/null +++ b/docs/python-sdk/fastmcp-server-providers-__init__.mdx @@ -0,0 +1,34 @@ +--- +title: __init__ +sidebarTitle: __init__ +--- + +# `fastmcp.server.providers` + + +Providers for dynamic MCP components. + +This module provides the `Provider` abstraction for providing tools, +resources, and prompts dynamically at runtime. + +Example: + ```python + from fastmcp import FastMCP + from fastmcp.server.providers import Provider + from fastmcp.tools import Tool + + class DatabaseProvider(Provider): + def __init__(self, db_url: str): + self.db = Database(db_url) + + async def _list_tools(self) -> list[Tool]: + rows = await self.db.fetch("SELECT * FROM tools") + return [self._make_tool(row) for row in rows] + + async def _get_tool(self, name: str) -> Tool | None: + row = await self.db.fetchone("SELECT * FROM tools WHERE name = ?", name) + return self._make_tool(row) if row else None + + mcp = FastMCP("Server", providers=[DatabaseProvider(db_url)]) + ``` + diff --git a/docs/python-sdk/fastmcp-server-providers-aggregate.mdx b/docs/python-sdk/fastmcp-server-providers-aggregate.mdx new file mode 100644 index 000000000..e0a8103da --- /dev/null +++ b/docs/python-sdk/fastmcp-server-providers-aggregate.mdx @@ -0,0 +1,83 @@ +--- +title: aggregate +sidebarTitle: aggregate +--- + +# `fastmcp.server.providers.aggregate` + + +AggregateProvider for combining multiple providers into one. + +This module provides `AggregateProvider`, a utility class that presents +multiple providers as a single unified provider. Useful when you want to +combine custom providers without creating a full FastMCP server. + +Example: + ```python + from fastmcp.server.providers import AggregateProvider + + # Combine multiple providers into one + combined = AggregateProvider() + combined.add_provider(provider1) + combined.add_provider(provider2, namespace="api") # Tools become "api_foo" + + # Use like any other provider + tools = await combined.list_tools() + ``` + + +## Classes + +### `AggregateProvider` + + +Utility provider that combines multiple providers into one. + +Components are aggregated from all providers. For get_* operations, +providers are queried in parallel and the highest version is returned. + +When adding providers with a namespace, wrap_transform() is used to apply +the Namespace transform. This means namespace transformation is handled +by the wrapped provider, not by AggregateProvider. + +Errors from individual providers are logged and skipped (graceful degradation). + + +**Methods:** + +#### `add_provider` + +```python +add_provider(self, provider: Provider) -> None +``` + +Add a provider with optional namespace. + +If the provider is a FastMCP server, it's automatically wrapped in +FastMCPProvider to ensure middleware is invoked correctly. + +**Args:** +- `provider`: The provider to add. +- `namespace`: Optional namespace prefix. When set\: +- Tools become "namespace_toolname" +- Resources become "protocol\://namespace/path" +- Prompts become "namespace_promptname" + + +#### `get_tasks` + +```python +get_tasks(self) -> Sequence[FastMCPComponent] +``` + +Get all task-eligible components from all providers. + + +#### `lifespan` + +```python +lifespan(self) -> AsyncIterator[None] +``` + +Combine lifespans of all providers. + diff --git a/docs/python-sdk/fastmcp-server-providers-base.mdx b/docs/python-sdk/fastmcp-server-providers-base.mdx new file mode 100644 index 000000000..09d02595b --- /dev/null +++ b/docs/python-sdk/fastmcp-server-providers-base.mdx @@ -0,0 +1,306 @@ +--- +title: base +sidebarTitle: base +--- + +# `fastmcp.server.providers.base` + + +Base Provider class for dynamic MCP components. + +This module provides the `Provider` abstraction for providing tools, +resources, and prompts dynamically at runtime. + +Example: + ```python + from fastmcp import FastMCP + from fastmcp.server.providers import Provider + from fastmcp.tools import Tool + + class DatabaseProvider(Provider): + def __init__(self, db_url: str): + super().__init__() + self.db = Database(db_url) + + async def _list_tools(self) -> list[Tool]: + rows = await self.db.fetch("SELECT * FROM tools") + return [self._make_tool(row) for row in rows] + + async def _get_tool(self, name: str) -> Tool | None: + row = await self.db.fetchone("SELECT * FROM tools WHERE name = ?", name) + return self._make_tool(row) if row else None + + mcp = FastMCP("Server", providers=[DatabaseProvider(db_url)]) + ``` + + +## Classes + +### `Provider` + + +Base class for dynamic component providers. + +Subclass and override whichever methods you need. Default implementations +return empty lists / None, so you only need to implement what your provider +supports. + + +**Methods:** + +#### `transforms` + +```python +transforms(self) -> list[Transform] +``` + +All transforms applied to components from this provider. + + +#### `add_transform` + +```python +add_transform(self, transform: Transform) -> None +``` + +Add a transform to this provider. + +Transforms modify components (tools, resources, prompts) as they flow +through the provider. They're applied in order - first added is innermost. + +**Args:** +- `transform`: The transform to add. + + +#### `wrap_transform` + +```python +wrap_transform(self, transform: Transform) -> Provider +``` + +Return a new provider with this transform applied (immutable). + +Unlike add_transform() which mutates this provider, wrap_transform() +returns a new provider that wraps this one. The original provider +is unchanged. + +This is useful when you want to apply transforms without side effects, +such as adding the same provider to multiple aggregators with different +namespaces. + +**Args:** +- `transform`: The transform to apply. + +**Returns:** +- A new provider that wraps this one with the transform applied. + + +#### `list_tools` + +```python +list_tools(self) -> Sequence[Tool] +``` + +List tools with all transforms applied. + +Applies transforms sequentially: base → transforms (in order). +Each transform receives the result from the previous transform. +Components may be marked as disabled but are NOT filtered here - +filtering happens at the server level to allow session transforms to override. + +**Returns:** +- Transformed sequence of tools (including disabled ones). + + +#### `get_tool` + +```python +get_tool(self, name: str, version: VersionSpec | None = None) -> Tool | None +``` + +Get tool by transformed name with all transforms applied. + +Note: This method does NOT filter disabled components. The Server +(FastMCP) performs enabled filtering after all transforms complete, +allowing session-level transforms to override provider-level disables. + +**Args:** +- `name`: The transformed tool name to look up. +- `version`: Optional version filter. If None, returns highest version. + +**Returns:** +- The tool if found (may be marked disabled), None if not found. + + +#### `list_resources` + +```python +list_resources(self) -> Sequence[Resource] +``` + +List resources with all transforms applied. + +Components may be marked as disabled but are NOT filtered here. + + +#### `get_resource` + +```python +get_resource(self, uri: str, version: VersionSpec | None = None) -> Resource | None +``` + +Get resource by transformed URI with all transforms applied. + +Note: This method does NOT filter disabled components. The Server +(FastMCP) performs enabled filtering after all transforms complete. + +**Args:** +- `uri`: The transformed resource URI to look up. +- `version`: Optional version filter. If None, returns highest version. + +**Returns:** +- The resource if found (may be marked disabled), None if not found. + + +#### `list_resource_templates` + +```python +list_resource_templates(self) -> Sequence[ResourceTemplate] +``` + +List resource templates with all transforms applied. + +Components may be marked as disabled but are NOT filtered here. + + +#### `get_resource_template` + +```python +get_resource_template(self, uri: str, version: VersionSpec | None = None) -> ResourceTemplate | None +``` + +Get resource template by transformed URI with all transforms applied. + +Note: This method does NOT filter disabled components. The Server +(FastMCP) performs enabled filtering after all transforms complete. + +**Args:** +- `uri`: The transformed template URI to look up. +- `version`: Optional version filter. If None, returns highest version. + +**Returns:** +- The template if found (may be marked disabled), None if not found. + + +#### `list_prompts` + +```python +list_prompts(self) -> Sequence[Prompt] +``` + +List prompts with all transforms applied. + +Components may be marked as disabled but are NOT filtered here. + + +#### `get_prompt` + +```python +get_prompt(self, name: str, version: VersionSpec | None = None) -> Prompt | None +``` + +Get prompt by transformed name with all transforms applied. + +Note: This method does NOT filter disabled components. The Server +(FastMCP) performs enabled filtering after all transforms complete. + +**Args:** +- `name`: The transformed prompt name to look up. +- `version`: Optional version filter. If None, returns highest version. + +**Returns:** +- The prompt if found (may be marked disabled), None if not found. + + +#### `get_tasks` + +```python +get_tasks(self) -> Sequence[FastMCPComponent] +``` + +Return components that should be registered as background tasks. + +Override to customize which components are task-eligible. +Default calls list_* methods, applies provider transforms, and filters +for components with task_config.mode != 'forbidden'. + +Used by the server during startup to register functions with Docket. + + +#### `lifespan` + +```python +lifespan(self) -> AsyncIterator[None] +``` + +User-overridable lifespan for custom setup and teardown. + +Override this method to perform provider-specific initialization +like opening database connections, setting up external resources, +or other state management needed for the provider's lifetime. + +The lifespan scope matches the server's lifespan - code before yield +runs at startup, code after yield runs at shutdown. + + +#### `enable` + +```python +enable(self) -> Self +``` + +Enable components matching all specified criteria. + +Adds a visibility transform that marks matching components as enabled. +Later transforms override earlier ones, so enable after disable makes +the component enabled. + +With only=True, switches to allowlist mode - first disables everything, +then enables matching components. + +**Args:** +- `names`: Component names or URIs to enable. +- `keys`: Component keys to enable (e.g., {"tool\:my_tool@v1"}). +- `version`: Component version spec to enable (e.g., VersionSpec(eq="v1") or +VersionSpec(gte="v2")). Unversioned components will not match. +- `tags`: Enable components with these tags. +- `components`: Component types to include (e.g., {"tool", "prompt"}). +- `only`: If True, ONLY enable matching components (allowlist mode). + +**Returns:** +- Self for method chaining. + + +#### `disable` + +```python +disable(self) -> Self +``` + +Disable components matching all specified criteria. + +Adds a visibility transform that marks matching components as disabled. +Components can be re-enabled by calling enable() with matching criteria +(the later transform wins). + +**Args:** +- `names`: Component names or URIs to disable. +- `keys`: Component keys to disable (e.g., {"tool\:my_tool@v1"}). +- `version`: Component version spec to disable (e.g., VersionSpec(eq="v1") or +VersionSpec(gte="v2")). Unversioned components will not match. +- `tags`: Disable components with these tags. +- `components`: Component types to include (e.g., {"tool", "prompt"}). + +**Returns:** +- Self for method chaining. + diff --git a/docs/python-sdk/fastmcp-server-providers-fastmcp_provider.mdx b/docs/python-sdk/fastmcp-server-providers-fastmcp_provider.mdx new file mode 100644 index 000000000..84d60da3d --- /dev/null +++ b/docs/python-sdk/fastmcp-server-providers-fastmcp_provider.mdx @@ -0,0 +1,238 @@ +--- +title: fastmcp_provider +sidebarTitle: fastmcp_provider +--- + +# `fastmcp.server.providers.fastmcp_provider` + + +FastMCPProvider for wrapping FastMCP servers as providers. + +This module provides the `FastMCPProvider` class that wraps a FastMCP server +and exposes its components through the Provider interface. + +It also provides FastMCPProvider* component classes that delegate execution to +the wrapped server's middleware, ensuring middleware runs when components are +executed. + + +## Classes + +### `FastMCPProviderTool` + + +Tool that delegates execution to a wrapped server's middleware. + +When `run()` is called, this tool invokes the wrapped server's +`_call_tool_middleware()` method, ensuring the server's middleware +chain is executed. + + +**Methods:** + +#### `wrap` + +```python +wrap(cls, server: Any, tool: Tool) -> FastMCPProviderTool +``` + +Wrap a Tool to delegate execution to the server's middleware. + + +#### `run` + +```python +run(self, arguments: dict[str, Any]) -> ToolResult +``` + +Delegate to child server's call_tool() without task_meta. + +This is called when the tool is used within a TransformedTool +forwarding function or other contexts where task_meta is not available. + + +#### `get_span_attributes` + +```python +get_span_attributes(self) -> dict[str, Any] +``` + +### `FastMCPProviderResource` + + +Resource that delegates reading to a wrapped server's read_resource(). + +When `read()` is called, this resource invokes the wrapped server's +`read_resource()` method, ensuring the server's middleware chain is executed. + + +**Methods:** + +#### `wrap` + +```python +wrap(cls, server: Any, resource: Resource) -> FastMCPProviderResource +``` + +Wrap a Resource to delegate reading to the server's middleware. + + +#### `get_span_attributes` + +```python +get_span_attributes(self) -> dict[str, Any] +``` + +### `FastMCPProviderPrompt` + + +Prompt that delegates rendering to a wrapped server's render_prompt(). + +When `render()` is called, this prompt invokes the wrapped server's +`render_prompt()` method, ensuring the server's middleware chain is executed. + + +**Methods:** + +#### `wrap` + +```python +wrap(cls, server: Any, prompt: Prompt) -> FastMCPProviderPrompt +``` + +Wrap a Prompt to delegate rendering to the server's middleware. + + +#### `render` + +```python +render(self, arguments: dict[str, Any] | None = None) -> PromptResult +``` + +Delegate to child server's render_prompt() without task_meta. + +This is called when the prompt is used within a transformed context +or other contexts where task_meta is not available. + + +#### `get_span_attributes` + +```python +get_span_attributes(self) -> dict[str, Any] +``` + +### `FastMCPProviderResourceTemplate` + + +Resource template that creates FastMCPProviderResources. + +When `create_resource()` is called, this template creates a +FastMCPProviderResource that will invoke the wrapped server's middleware +when read. + + +**Methods:** + +#### `wrap` + +```python +wrap(cls, server: Any, template: ResourceTemplate) -> FastMCPProviderResourceTemplate +``` + +Wrap a ResourceTemplate to create FastMCPProviderResources. + + +#### `create_resource` + +```python +create_resource(self, uri: str, params: dict[str, Any]) -> Resource +``` + +Create a FastMCPProviderResource for the given URI. + +The `uri` is the external/transformed URI (e.g., with namespace prefix). +We use `_original_uri_template` with `params` to construct the internal +URI that the nested server understands. + + +#### `read` + +```python +read(self, arguments: dict[str, Any]) -> str | bytes | ResourceResult +``` + +Read the resource content for background task execution. + +Reads the resource via the wrapped server and returns the ResourceResult. +This method is called by Docket during background task execution. + + +#### `register_with_docket` + +```python +register_with_docket(self, docket: Docket) -> None +``` + +No-op: the child's actual template is registered via get_tasks(). + + +#### `add_to_docket` + +```python +add_to_docket(self, docket: Docket, params: dict[str, Any], **kwargs: Any) -> Execution +``` + +Schedule this template for background execution via docket. + +The child's FunctionResourceTemplate.fn is registered (via get_tasks), +and it expects splatted **kwargs, so we splat params here. + + +#### `get_span_attributes` + +```python +get_span_attributes(self) -> dict[str, Any] +``` + +### `FastMCPProvider` + + +Provider that wraps a FastMCP server. + +This provider enables mounting one FastMCP server onto another, exposing +the mounted server's tools, resources, and prompts through the parent +server. + +Components returned by this provider are wrapped in FastMCPProvider* +classes that delegate execution to the wrapped server's middleware chain. +This ensures middleware runs when components are executed. + + +**Methods:** + +#### `get_tasks` + +```python +get_tasks(self) -> Sequence[FastMCPComponent] +``` + +Return task-eligible components from the mounted server. + +Returns the child's ACTUAL components (not wrapped) so their actual +functions get registered with Docket. Gets components with child +server's transforms applied, then applies this provider's transforms +for correct registration keys. + + +#### `lifespan` + +```python +lifespan(self) -> AsyncIterator[None] +``` + +Start the mounted server's user lifespan. + +This starts only the wrapped server's user-defined lifespan, NOT its +full _lifespan_manager() (which includes Docket). The parent server's +Docket handles all background tasks. + diff --git a/docs/python-sdk/fastmcp-server-providers-filesystem.mdx b/docs/python-sdk/fastmcp-server-providers-filesystem.mdx new file mode 100644 index 000000000..d5b589e1e --- /dev/null +++ b/docs/python-sdk/fastmcp-server-providers-filesystem.mdx @@ -0,0 +1,54 @@ +--- +title: filesystem +sidebarTitle: filesystem +--- + +# `fastmcp.server.providers.filesystem` + + +FileSystemProvider for filesystem-based component discovery. + +FileSystemProvider scans a directory for Python files, imports them, and +registers any Tool, Resource, ResourceTemplate, or Prompt objects found. + +Components are created using the standalone decorators from fastmcp.tools, +fastmcp.resources, and fastmcp.prompts: + +Example: + ```python + # In mcp/tools.py + from fastmcp.tools import tool + + @tool + def greet(name: str) -> str: + return f"Hello, {name}!" + + # In main.py + from pathlib import Path + + from fastmcp import FastMCP + from fastmcp.server.providers import FileSystemProvider + + mcp = FastMCP("MyServer", providers=[FileSystemProvider(Path(__file__).parent / "mcp")]) + ``` + + +## Classes + +### `FileSystemProvider` + + +Provider that discovers components from the filesystem. + +Scans a directory for Python files and registers any Tool, Resource, +ResourceTemplate, or Prompt objects found. Components are created using +the standalone decorators: +- @tool from fastmcp.tools +- @resource from fastmcp.resources +- @prompt from fastmcp.prompts + +**Args:** +- `root`: Root directory to scan. Defaults to current directory. +- `reload`: If True, re-scan files on every request (dev mode). +Defaults to False (scan once at init, cache results). + diff --git a/docs/python-sdk/fastmcp-server-providers-filesystem_discovery.mdx b/docs/python-sdk/fastmcp-server-providers-filesystem_discovery.mdx new file mode 100644 index 000000000..060398177 --- /dev/null +++ b/docs/python-sdk/fastmcp-server-providers-filesystem_discovery.mdx @@ -0,0 +1,104 @@ +--- +title: filesystem_discovery +sidebarTitle: filesystem_discovery +--- + +# `fastmcp.server.providers.filesystem_discovery` + + +File discovery and module import utilities for filesystem-based routing. + +This module provides functions to: +1. Discover Python files in a directory tree +2. Import modules (as packages if __init__.py exists, else directly) +3. Extract decorated components (Tool, Resource, Prompt objects) from imported modules + + +## Functions + +### `discover_files` + +```python +discover_files(root: Path) -> list[Path] +``` + + +Recursively discover all Python files under a directory. + +Excludes __init__.py files (they're for package structure, not components). + +**Args:** +- `root`: Root directory to scan. + +**Returns:** +- List of .py file paths, sorted for deterministic order. + + +### `import_module_from_file` + +```python +import_module_from_file(file_path: Path) -> ModuleType +``` + + +Import a Python file as a module. + +If the file is part of a package (directory has __init__.py), imports +it as a proper package member (relative imports work). Otherwise, +imports directly using spec_from_file_location. + +**Args:** +- `file_path`: Path to the Python file. + +**Returns:** +- The imported module. + +**Raises:** +- `ImportError`: If the module cannot be imported. + + +### `extract_components` + +```python +extract_components(module: ModuleType) -> list[FastMCPComponent] +``` + + +Extract all MCP components from a module. + +Scans all module attributes for instances of Tool, Resource, +ResourceTemplate, or Prompt objects created by standalone decorators, +or functions decorated with @tool/@resource/@prompt that have __fastmcp__ metadata. + +**Args:** +- `module`: The imported module to scan. + +**Returns:** +- List of component objects (Tool, Resource, ResourceTemplate, Prompt). + + +### `discover_and_import` + +```python +discover_and_import(root: Path) -> DiscoveryResult +``` + + +Discover files, import modules, and extract components. + +This is the main entry point for filesystem-based discovery. + +**Args:** +- `root`: Root directory to scan. + +**Returns:** +- DiscoveryResult with components and any failed files. + + +## Classes + +### `DiscoveryResult` + + +Result of filesystem discovery. + diff --git a/docs/python-sdk/fastmcp-server-providers-local_provider-__init__.mdx b/docs/python-sdk/fastmcp-server-providers-local_provider-__init__.mdx new file mode 100644 index 000000000..5fe082a63 --- /dev/null +++ b/docs/python-sdk/fastmcp-server-providers-local_provider-__init__.mdx @@ -0,0 +1,13 @@ +--- +title: __init__ +sidebarTitle: __init__ +--- + +# `fastmcp.server.providers.local_provider` + + +LocalProvider for locally-defined MCP components. + +This module provides the `LocalProvider` class that manages tools, resources, +templates, and prompts registered via decorators or direct methods. + diff --git a/docs/python-sdk/fastmcp-server-providers-local_provider-decorators-__init__.mdx b/docs/python-sdk/fastmcp-server-providers-local_provider-decorators-__init__.mdx new file mode 100644 index 000000000..d6009a6de --- /dev/null +++ b/docs/python-sdk/fastmcp-server-providers-local_provider-decorators-__init__.mdx @@ -0,0 +1,13 @@ +--- +title: __init__ +sidebarTitle: __init__ +--- + +# `fastmcp.server.providers.local_provider.decorators` + + +Decorator mixins for LocalProvider. + +This module provides mixin classes that add decorator functionality +to LocalProvider for tools, resources, templates, and prompts. + diff --git a/docs/python-sdk/fastmcp-server-providers-local_provider-decorators-prompts.mdx b/docs/python-sdk/fastmcp-server-providers-local_provider-decorators-prompts.mdx new file mode 100644 index 000000000..e7d7d68f9 --- /dev/null +++ b/docs/python-sdk/fastmcp-server-providers-local_provider-decorators-prompts.mdx @@ -0,0 +1,81 @@ +--- +title: prompts +sidebarTitle: prompts +--- + +# `fastmcp.server.providers.local_provider.decorators.prompts` + + +Prompt decorator mixin for LocalProvider. + +This module provides the PromptDecoratorMixin class that adds prompt +registration functionality to LocalProvider. + + +## Classes + +### `PromptDecoratorMixin` + + +Mixin class providing prompt decorator functionality for LocalProvider. + +This mixin contains all methods related to: +- Prompt registration via add_prompt() +- Prompt decorator (@provider.prompt) + + +**Methods:** + +#### `add_prompt` + +```python +add_prompt(self: LocalProvider, prompt: Prompt | Callable[..., Any]) -> Prompt +``` + +Add a prompt to this provider's storage. + +Accepts either a Prompt object or a decorated function with __fastmcp__ metadata. + + +#### `prompt` + +```python +prompt(self: LocalProvider, name_or_fn: F) -> F +``` + +#### `prompt` + +```python +prompt(self: LocalProvider, name_or_fn: str | None = None) -> Callable[[F], F] +``` + +#### `prompt` + +```python +prompt(self: LocalProvider, name_or_fn: str | AnyFunction | None = None) -> Callable[[AnyFunction], FunctionPrompt] | FunctionPrompt | partial[Callable[[AnyFunction], FunctionPrompt] | FunctionPrompt] +``` + +Decorator to register a prompt. + +This decorator supports multiple calling patterns: +- @provider.prompt (without parentheses) +- @provider.prompt() (with empty parentheses) +- @provider.prompt("custom_name") (with name as first argument) +- @provider.prompt(name="custom_name") (with name as keyword argument) +- provider.prompt(function, name="custom_name") (direct function call) + +**Args:** +- `name_or_fn`: Either a function (when used as @prompt), a string name, or None +- `name`: Optional name for the prompt (keyword-only, alternative to name_or_fn) +- `title`: Optional title for the prompt +- `description`: Optional description of what the prompt does +- `icons`: Optional icons for the prompt +- `tags`: Optional set of tags for categorizing the prompt +- `enabled`: Whether the prompt is enabled (default True). If False, adds to blocklist. +- `meta`: Optional meta information about the prompt +- `task`: Optional task configuration for background execution +- `auth`: Optional authorization checks for the prompt + +**Returns:** +- The registered FunctionPrompt or a decorator function. + diff --git a/docs/python-sdk/fastmcp-server-providers-local_provider-decorators-resources.mdx b/docs/python-sdk/fastmcp-server-providers-local_provider-decorators-resources.mdx new file mode 100644 index 000000000..70c67d91c --- /dev/null +++ b/docs/python-sdk/fastmcp-server-providers-local_provider-decorators-resources.mdx @@ -0,0 +1,77 @@ +--- +title: resources +sidebarTitle: resources +--- + +# `fastmcp.server.providers.local_provider.decorators.resources` + + +Resource decorator mixin for LocalProvider. + +This module provides the ResourceDecoratorMixin class that adds resource +and template registration functionality to LocalProvider. + + +## Classes + +### `ResourceDecoratorMixin` + + +Mixin class providing resource decorator functionality for LocalProvider. + +This mixin contains all methods related to: +- Resource registration via add_resource() +- Resource template registration via add_template() +- Resource decorator (@provider.resource) + + +**Methods:** + +#### `add_resource` + +```python +add_resource(self: LocalProvider, resource: Resource | ResourceTemplate | Callable[..., Any]) -> Resource | ResourceTemplate +``` + +Add a resource to this provider's storage. + +Accepts either a Resource/ResourceTemplate object or a decorated function with __fastmcp__ metadata. + + +#### `add_template` + +```python +add_template(self: LocalProvider, template: ResourceTemplate) -> ResourceTemplate +``` + +Add a resource template to this provider's storage. + + +#### `resource` + +```python +resource(self: LocalProvider, uri: str) -> Callable[[F], F] +``` + +Decorator to register a function as a resource. + +If the URI contains parameters (e.g. "resource://{param}") or the function +has parameters, it will be registered as a template resource. + +**Args:** +- `uri`: URI for the resource (e.g. "resource\://my-resource" or "resource\://{param}") +- `name`: Optional name for the resource +- `title`: Optional title for the resource +- `description`: Optional description of the resource +- `icons`: Optional icons for the resource +- `mime_type`: Optional MIME type for the resource +- `tags`: Optional set of tags for categorizing the resource +- `enabled`: Whether the resource is enabled (default True). If False, adds to blocklist. +- `annotations`: Optional annotations about the resource's behavior +- `meta`: Optional meta information about the resource +- `task`: Optional task configuration for background execution +- `auth`: Optional authorization checks for the resource + +**Returns:** +- A decorator function. + diff --git a/docs/python-sdk/fastmcp-server-providers-local_provider-decorators-tools.mdx b/docs/python-sdk/fastmcp-server-providers-local_provider-decorators-tools.mdx new file mode 100644 index 000000000..efeae3661 --- /dev/null +++ b/docs/python-sdk/fastmcp-server-providers-local_provider-decorators-tools.mdx @@ -0,0 +1,84 @@ +--- +title: tools +sidebarTitle: tools +--- + +# `fastmcp.server.providers.local_provider.decorators.tools` + + +Tool decorator mixin for LocalProvider. + +This module provides the ToolDecoratorMixin class that adds tool +registration functionality to LocalProvider. + + +## Classes + +### `ToolDecoratorMixin` + + +Mixin class providing tool decorator functionality for LocalProvider. + +This mixin contains all methods related to: +- Tool registration via add_tool() +- Tool decorator (@provider.tool) + + +**Methods:** + +#### `add_tool` + +```python +add_tool(self: LocalProvider, tool: Tool | Callable[..., Any]) -> Tool +``` + +Add a tool to this provider's storage. + +Accepts either a Tool object or a decorated function with __fastmcp__ metadata. + + +#### `tool` + +```python +tool(self: LocalProvider, name_or_fn: F) -> F +``` + +#### `tool` + +```python +tool(self: LocalProvider, name_or_fn: str | None = None) -> Callable[[F], F] +``` + +#### `tool` + +```python +tool(self: LocalProvider, name_or_fn: str | AnyFunction | None = None) -> Callable[[AnyFunction], FunctionTool] | FunctionTool | partial[Callable[[AnyFunction], FunctionTool] | FunctionTool] +``` + +Decorator to register a tool. + +This decorator supports multiple calling patterns: +- @provider.tool (without parentheses) +- @provider.tool() (with empty parentheses) +- @provider.tool("custom_name") (with name as first argument) +- @provider.tool(name="custom_name") (with name as keyword argument) +- provider.tool(function, name="custom_name") (direct function call) + +**Args:** +- `name_or_fn`: Either a function (when used as @tool), a string name, or None +- `name`: Optional name for the tool (keyword-only, alternative to name_or_fn) +- `title`: Optional title for the tool +- `description`: Optional description of what the tool does +- `icons`: Optional icons for the tool +- `tags`: Optional set of tags for categorizing the tool +- `output_schema`: Optional JSON schema for the tool's output +- `annotations`: Optional annotations about the tool's behavior +- `exclude_args`: Optional list of argument names to exclude from the tool schema +- `meta`: Optional meta information about the tool +- `enabled`: Whether the tool is enabled (default True). If False, adds to blocklist. +- `task`: Optional task configuration for background execution +- `serializer`: Deprecated. Return ToolResult from your tools for full control over serialization. + +**Returns:** +- The registered FunctionTool or a decorator function. + diff --git a/docs/python-sdk/fastmcp-server-providers-local_provider-local_provider.mdx b/docs/python-sdk/fastmcp-server-providers-local_provider-local_provider.mdx new file mode 100644 index 000000000..f3bc03205 --- /dev/null +++ b/docs/python-sdk/fastmcp-server-providers-local_provider-local_provider.mdx @@ -0,0 +1,125 @@ +--- +title: local_provider +sidebarTitle: local_provider +--- + +# `fastmcp.server.providers.local_provider.local_provider` + + +LocalProvider for locally-defined MCP components. + +This module provides the `LocalProvider` class that manages tools, resources, +templates, and prompts registered via decorators or direct methods. + +LocalProvider can be used standalone and attached to multiple servers: + +```python +from fastmcp.server.providers import LocalProvider + +# Create a reusable provider with tools +provider = LocalProvider() + +@provider.tool +def greet(name: str) -> str: + return f"Hello, {name}!" + +# Attach to any server +from fastmcp import FastMCP +server1 = FastMCP("Server1", providers=[provider]) +server2 = FastMCP("Server2", providers=[provider]) +``` + + +## Classes + +### `LocalProvider` + + +Provider for locally-defined components. + +Supports decorator-based registration (`@provider.tool`, `@provider.resource`, +`@provider.prompt`) and direct object registration methods. + +When used standalone, LocalProvider uses default settings. When attached +to a FastMCP server via the server's decorators, server-level settings +like `_tool_serializer` and `_support_tasks_by_default` are injected. + + +**Methods:** + +#### `remove_tool` + +```python +remove_tool(self, name: str, version: str | None = None) -> None +``` + +Remove tool(s) from this provider's storage. + +**Args:** +- `name`: The tool name. +- `version`: If None, removes ALL versions. If specified, removes only that version. + +**Raises:** +- `KeyError`: If no matching tool is found. + + +#### `remove_resource` + +```python +remove_resource(self, uri: str, version: str | None = None) -> None +``` + +Remove resource(s) from this provider's storage. + +**Args:** +- `uri`: The resource URI. +- `version`: If None, removes ALL versions. If specified, removes only that version. + +**Raises:** +- `KeyError`: If no matching resource is found. + + +#### `remove_template` + +```python +remove_template(self, uri_template: str, version: str | None = None) -> None +``` + +Remove resource template(s) from this provider's storage. + +**Args:** +- `uri_template`: The template URI pattern. +- `version`: If None, removes ALL versions. If specified, removes only that version. + +**Raises:** +- `KeyError`: If no matching template is found. + + +#### `remove_prompt` + +```python +remove_prompt(self, name: str, version: str | None = None) -> None +``` + +Remove prompt(s) from this provider's storage. + +**Args:** +- `name`: The prompt name. +- `version`: If None, removes ALL versions. If specified, removes only that version. + +**Raises:** +- `KeyError`: If no matching prompt is found. + + +#### `get_tasks` + +```python +get_tasks(self) -> Sequence[FastMCPComponent] +``` + +Return components eligible for background task execution. + +Returns components that have task_config.mode != 'forbidden'. +This includes both FunctionTool/Resource/Prompt instances created via +decorators and custom Tool/Resource/Prompt subclasses. + diff --git a/docs/python-sdk/fastmcp-server-providers-openapi-__init__.mdx b/docs/python-sdk/fastmcp-server-providers-openapi-__init__.mdx new file mode 100644 index 000000000..bd79a038b --- /dev/null +++ b/docs/python-sdk/fastmcp-server-providers-openapi-__init__.mdx @@ -0,0 +1,23 @@ +--- +title: __init__ +sidebarTitle: __init__ +--- + +# `fastmcp.server.providers.openapi` + + +OpenAPI provider for FastMCP. + +This module provides OpenAPI integration for FastMCP through the Provider pattern. + +Example: + ```python + from fastmcp import FastMCP + from fastmcp.server.providers.openapi import OpenAPIProvider + import httpx + + client = httpx.AsyncClient(base_url="https://api.example.com") + provider = OpenAPIProvider(openapi_spec=spec, client=client) + mcp = FastMCP("API Server", providers=[provider]) + ``` + diff --git a/docs/python-sdk/fastmcp-server-providers-openapi-components.mdx b/docs/python-sdk/fastmcp-server-providers-openapi-components.mdx new file mode 100644 index 000000000..94f0b7b6a --- /dev/null +++ b/docs/python-sdk/fastmcp-server-providers-openapi-components.mdx @@ -0,0 +1,62 @@ +--- +title: components +sidebarTitle: components +--- + +# `fastmcp.server.providers.openapi.components` + + +OpenAPI component classes: Tool, Resource, and ResourceTemplate. + +## Classes + +### `OpenAPITool` + + +Tool implementation for OpenAPI endpoints. + + +**Methods:** + +#### `run` + +```python +run(self, arguments: dict[str, Any]) -> ToolResult +``` + +Execute the HTTP request using RequestDirector. + + +### `OpenAPIResource` + + +Resource implementation for OpenAPI endpoints. + + +**Methods:** + +#### `read` + +```python +read(self) -> ResourceResult +``` + +Fetch the resource data by making an HTTP request. + + +### `OpenAPIResourceTemplate` + + +Resource template implementation for OpenAPI endpoints. + + +**Methods:** + +#### `create_resource` + +```python +create_resource(self, uri: str, params: dict[str, Any], context: Context | None = None) -> Resource +``` + +Create a resource with the given parameters. + diff --git a/docs/python-sdk/fastmcp-server-providers-openapi-provider.mdx b/docs/python-sdk/fastmcp-server-providers-openapi-provider.mdx new file mode 100644 index 000000000..5d74c19ae --- /dev/null +++ b/docs/python-sdk/fastmcp-server-providers-openapi-provider.mdx @@ -0,0 +1,40 @@ +--- +title: provider +sidebarTitle: provider +--- + +# `fastmcp.server.providers.openapi.provider` + + +OpenAPIProvider for creating MCP components from OpenAPI specifications. + +## Classes + +### `OpenAPIProvider` + + +Provider that creates MCP components from an OpenAPI specification. + +Components are created eagerly during initialization by parsing the OpenAPI +spec. Each component makes HTTP calls to the described API endpoints. + + +**Methods:** + +#### `lifespan` + +```python +lifespan(self) -> AsyncIterator[None] +``` + +Manage the lifecycle of the auto-created httpx client. + + +#### `get_tasks` + +```python +get_tasks(self) -> Sequence[FastMCPComponent] +``` + +Return empty list - OpenAPI components don't support tasks. + diff --git a/docs/python-sdk/fastmcp-server-providers-openapi-routing.mdx b/docs/python-sdk/fastmcp-server-providers-openapi-routing.mdx new file mode 100644 index 000000000..c35ca5886 --- /dev/null +++ b/docs/python-sdk/fastmcp-server-providers-openapi-routing.mdx @@ -0,0 +1,23 @@ +--- +title: routing +sidebarTitle: routing +--- + +# `fastmcp.server.providers.openapi.routing` + + +Route mapping logic for OpenAPI operations. + +## Classes + +### `MCPType` + + +Type of FastMCP component to create from a route. + + +### `RouteMap` + + +Mapping configuration for HTTP routes to FastMCP component types. + diff --git a/docs/python-sdk/fastmcp-server-providers-proxy.mdx b/docs/python-sdk/fastmcp-server-providers-proxy.mdx new file mode 100644 index 000000000..4c64d8566 --- /dev/null +++ b/docs/python-sdk/fastmcp-server-providers-proxy.mdx @@ -0,0 +1,317 @@ +--- +title: proxy +sidebarTitle: proxy +--- + +# `fastmcp.server.providers.proxy` + + +ProxyProvider for proxying to remote MCP servers. + +This module provides the `ProxyProvider` class that proxies components from +a remote MCP server via a client factory. It also provides proxy component +classes that forward execution to remote servers. + + +## Functions + +### `default_proxy_roots_handler` + +```python +default_proxy_roots_handler(context: RequestContext[ClientSession, LifespanContextT]) -> RootsList +``` + + +Forward list roots request from remote server to proxy's connected clients. + + +### `default_proxy_sampling_handler` + +```python +default_proxy_sampling_handler(messages: list[mcp.types.SamplingMessage], params: mcp.types.CreateMessageRequestParams, context: RequestContext[ClientSession, LifespanContextT]) -> mcp.types.CreateMessageResult +``` + + +Forward sampling request from remote server to proxy's connected clients. + + +### `default_proxy_elicitation_handler` + +```python +default_proxy_elicitation_handler(message: str, response_type: type, params: mcp.types.ElicitRequestParams, context: RequestContext[ClientSession, LifespanContextT]) -> ElicitResult +``` + + +Forward elicitation request from remote server to proxy's connected clients. + + +### `default_proxy_log_handler` + +```python +default_proxy_log_handler(message: LogMessage) -> None +``` + + +Forward log notification from remote server to proxy's connected clients. + + +### `default_proxy_progress_handler` + +```python +default_proxy_progress_handler(progress: float, total: float | None, message: str | None) -> None +``` + + +Forward progress notification from remote server to proxy's connected clients. + + +## Classes + +### `ProxyTool` + + +A Tool that represents and executes a tool on a remote server. + + +**Methods:** + +#### `model_copy` + +```python +model_copy(self, **kwargs: Any) -> ProxyTool +``` + +Override to preserve _backend_name when name changes. + + +#### `from_mcp_tool` + +```python +from_mcp_tool(cls, client_factory: ClientFactoryT, mcp_tool: mcp.types.Tool) -> ProxyTool +``` + +Factory method to create a ProxyTool from a raw MCP tool schema. + + +#### `run` + +```python +run(self, arguments: dict[str, Any], context: Context | None = None) -> ToolResult +``` + +Executes the tool by making a call through the client. + + +#### `get_span_attributes` + +```python +get_span_attributes(self) -> dict[str, Any] +``` + +### `ProxyResource` + + +A Resource that represents and reads a resource from a remote server. + + +**Methods:** + +#### `model_copy` + +```python +model_copy(self, **kwargs: Any) -> ProxyResource +``` + +Override to preserve _backend_uri when uri changes. + + +#### `from_mcp_resource` + +```python +from_mcp_resource(cls, client_factory: ClientFactoryT, mcp_resource: mcp.types.Resource) -> ProxyResource +``` + +Factory method to create a ProxyResource from a raw MCP resource schema. + + +#### `read` + +```python +read(self) -> ResourceResult +``` + +Read the resource content from the remote server. + + +#### `get_span_attributes` + +```python +get_span_attributes(self) -> dict[str, Any] +``` + +### `ProxyTemplate` + + +A ResourceTemplate that represents and creates resources from a remote server template. + + +**Methods:** + +#### `model_copy` + +```python +model_copy(self, **kwargs: Any) -> ProxyTemplate +``` + +Override to preserve _backend_uri_template when uri_template changes. + + +#### `from_mcp_template` + +```python +from_mcp_template(cls, client_factory: ClientFactoryT, mcp_template: mcp.types.ResourceTemplate) -> ProxyTemplate +``` + +Factory method to create a ProxyTemplate from a raw MCP template schema. + + +#### `create_resource` + +```python +create_resource(self, uri: str, params: dict[str, Any], context: Context | None = None) -> ProxyResource +``` + +Create a resource from the template by calling the remote server. + + +#### `get_span_attributes` + +```python +get_span_attributes(self) -> dict[str, Any] +``` + +### `ProxyPrompt` + + +A Prompt that represents and renders a prompt from a remote server. + + +**Methods:** + +#### `model_copy` + +```python +model_copy(self, **kwargs: Any) -> ProxyPrompt +``` + +Override to preserve _backend_name when name changes. + + +#### `from_mcp_prompt` + +```python +from_mcp_prompt(cls, client_factory: ClientFactoryT, mcp_prompt: mcp.types.Prompt) -> ProxyPrompt +``` + +Factory method to create a ProxyPrompt from a raw MCP prompt schema. + + +#### `render` + +```python +render(self, arguments: dict[str, Any]) -> PromptResult +``` + +Render the prompt by making a call through the client. + + +#### `get_span_attributes` + +```python +get_span_attributes(self) -> dict[str, Any] +``` + +### `ProxyProvider` + + +Provider that proxies to a remote MCP server via a client factory. + +This provider fetches components from a remote server and returns Proxy* +component instances that forward execution to the remote server. + +All components returned by this provider have task_config.mode="forbidden" +because tasks cannot be executed through a proxy. + + +**Methods:** + +#### `get_tasks` + +```python +get_tasks(self) -> Sequence[FastMCPComponent] +``` + +Return empty list since proxy components don't support tasks. + +Override the base implementation to avoid calling list_tools() during +server lifespan initialization, which would open the client before any +context is set. All Proxy* components have task_config.mode="forbidden". + + +### `FastMCPProxy` + + +A FastMCP server that acts as a proxy to a remote MCP-compliant server. + +This is a convenience wrapper that creates a FastMCP server with a +ProxyProvider. For more control, use FastMCP with add_provider(ProxyProvider(...)). + + +### `ProxyClient` + + +A proxy client that forwards advanced interactions between a remote MCP server and the proxy's connected clients. + +Supports forwarding roots, sampling, elicitation, logging, and progress. + + +### `StatefulProxyClient` + + +A proxy client that provides a stateful client factory for the proxy server. + +The stateful proxy client bound its copy to the server session. +And it will be disconnected when the session is exited. + +This is useful to proxy a stateful mcp server such as the Playwright MCP server. +Note that it is essential to ensure that the proxy server itself is also stateful. + +Because session reuse means the receive-loop task inherits a stale +``request_ctx`` ContextVar snapshot, the default proxy handlers are +replaced with versions that restore the ContextVar before forwarding. +``ProxyTool.run`` stashes the current ``RequestContext`` in +``_proxy_rc_ref`` before each backend call, and the handlers consult +it to detect (and correct) staleness. + + +**Methods:** + +#### `clear` + +```python +clear(self) +``` + +Clear all cached clients and force disconnect them. + + +#### `new_stateful` + +```python +new_stateful(self) -> Client[ClientTransportT] +``` + +Create a new stateful proxy client instance with the same configuration. + +Use this method as the client factory for stateful proxy server. + diff --git a/docs/python-sdk/fastmcp-server-providers-skills-__init__.mdx b/docs/python-sdk/fastmcp-server-providers-skills-__init__.mdx new file mode 100644 index 000000000..c3f296111 --- /dev/null +++ b/docs/python-sdk/fastmcp-server-providers-skills-__init__.mdx @@ -0,0 +1,32 @@ +--- +title: __init__ +sidebarTitle: __init__ +--- + +# `fastmcp.server.providers.skills` + + +Skills providers for exposing agent skills as MCP resources. + +This module provides a two-layer architecture for skill discovery: + +- **SkillProvider**: Handles a single skill folder, exposing its files as resources. +- **SkillsDirectoryProvider**: Scans a directory, creates a SkillProvider per folder. +- **Vendor providers**: Platform-specific providers for Claude, Cursor, VS Code, Codex, + Gemini, Goose, Copilot, and OpenCode. + +Example: + ```python + from pathlib import Path + from fastmcp import FastMCP + from fastmcp.server.providers.skills import ClaudeSkillsProvider, SkillProvider + + mcp = FastMCP("Skills Server") + + # Load a single skill + mcp.add_provider(SkillProvider(Path.home() / ".claude/skills/pdf-processing")) + + # Or load all skills in a directory + mcp.add_provider(ClaudeSkillsProvider()) # Uses ~/.claude/skills/ + ``` + diff --git a/docs/python-sdk/fastmcp-server-providers-skills-claude_provider.mdx b/docs/python-sdk/fastmcp-server-providers-skills-claude_provider.mdx new file mode 100644 index 000000000..30ed2c7c7 --- /dev/null +++ b/docs/python-sdk/fastmcp-server-providers-skills-claude_provider.mdx @@ -0,0 +1,25 @@ +--- +title: claude_provider +sidebarTitle: claude_provider +--- + +# `fastmcp.server.providers.skills.claude_provider` + + +Claude-specific skills provider for Claude Code skills. + +## Classes + +### `ClaudeSkillsProvider` + + +Provider for Claude Code skills from ~/.claude/skills/. + +A convenience subclass that sets the default root to Claude's skills location. + +**Args:** +- `reload`: If True, re-scan on every request. Defaults to False. +- `supporting_files`: How supporting files are exposed\: +- "template"\: Accessed via ResourceTemplate, hidden from list_resources(). +- "resources"\: Each file exposed as individual Resource in list_resources(). + diff --git a/docs/python-sdk/fastmcp-server-providers-skills-directory_provider.mdx b/docs/python-sdk/fastmcp-server-providers-skills-directory_provider.mdx new file mode 100644 index 000000000..bf68a00e3 --- /dev/null +++ b/docs/python-sdk/fastmcp-server-providers-skills-directory_provider.mdx @@ -0,0 +1,31 @@ +--- +title: directory_provider +sidebarTitle: directory_provider +--- + +# `fastmcp.server.providers.skills.directory_provider` + + +Directory scanning provider for discovering multiple skills. + +## Classes + +### `SkillsDirectoryProvider` + + +Provider that scans directories and creates a SkillProvider per skill folder. + +This extends AggregateProvider to combine multiple SkillProviders into one. +Each subdirectory containing a main file (default: SKILL.md) becomes a skill. +Can scan multiple root directories - if a skill name appears in multiple roots, +the first one found wins. + +**Args:** +- `roots`: Root directory(ies) containing skill folders. Can be a single path +or a sequence of paths. +- `reload`: If True, re-discover skills on each request. Defaults to False. +- `main_file_name`: Name of the main skill file. Defaults to "SKILL.md". +- `supporting_files`: How supporting files are exposed in child SkillProviders\: +- "template"\: Accessed via ResourceTemplate, hidden from list_resources(). +- "resources"\: Each file exposed as individual Resource in list_resources(). + diff --git a/docs/python-sdk/fastmcp-server-providers-skills-skill_provider.mdx b/docs/python-sdk/fastmcp-server-providers-skills-skill_provider.mdx new file mode 100644 index 000000000..c1ab56d9d --- /dev/null +++ b/docs/python-sdk/fastmcp-server-providers-skills-skill_provider.mdx @@ -0,0 +1,121 @@ +--- +title: skill_provider +sidebarTitle: skill_provider +--- + +# `fastmcp.server.providers.skills.skill_provider` + + +Basic skill provider for handling a single skill folder. + +## Classes + +### `SkillResource` + + +A resource representing a skill's main file or manifest. + + +**Methods:** + +#### `get_meta` + +```python +get_meta(self) -> dict[str, Any] +``` + +#### `read` + +```python +read(self) -> str | bytes | ResourceResult +``` + +Read the resource content. + + +### `SkillFileTemplate` + + +A template for accessing files within a skill. + + +**Methods:** + +#### `read` + +```python +read(self, arguments: dict[str, Any]) -> str | bytes | ResourceResult +``` + +Read a file from the skill directory. + + +#### `create_resource` + +```python +create_resource(self, uri: str, params: dict[str, Any]) -> Resource +``` + +Create a resource for the given URI and parameters. + +Note: This is not typically used since _read() handles file reading directly. +Provided for compatibility with the ResourceTemplate interface. + + +### `SkillFileResource` + + +A resource representing a specific file within a skill. + + +**Methods:** + +#### `get_meta` + +```python +get_meta(self) -> dict[str, Any] +``` + +#### `read` + +```python +read(self) -> str | bytes | ResourceResult +``` + +Read the file content. + + +### `SkillProvider` + + +Provider that exposes a single skill folder as MCP resources. + +Each skill folder must contain a main file (default: SKILL.md) and may +contain additional supporting files. + +Exposes: +- A Resource for the main file (skill://{name}/SKILL.md) +- A Resource for the synthetic manifest (skill://{name}/_manifest) +- Supporting files via ResourceTemplate or Resources (configurable) + +**Args:** +- `skill_path`: Path to the skill directory. +- `main_file_name`: Name of the main skill file. Defaults to "SKILL.md". +- `supporting_files`: How supporting files (everything except main file and +manifest) are exposed to clients\: +- "template"\: Accessed via ResourceTemplate, hidden from list_resources(). + Clients discover files by reading the manifest first. +- "resources"\: Each file exposed as individual Resource in list_resources(). + Full enumeration upfront. + + +**Methods:** + +#### `skill_info` + +```python +skill_info(self) -> SkillInfo +``` + +Get the loaded skill info. + diff --git a/docs/python-sdk/fastmcp-server-providers-skills-vendor_providers.mdx b/docs/python-sdk/fastmcp-server-providers-skills-vendor_providers.mdx new file mode 100644 index 000000000..a5a724953 --- /dev/null +++ b/docs/python-sdk/fastmcp-server-providers-skills-vendor_providers.mdx @@ -0,0 +1,56 @@ +--- +title: vendor_providers +sidebarTitle: vendor_providers +--- + +# `fastmcp.server.providers.skills.vendor_providers` + + +Vendor-specific skills providers for various AI coding platforms. + +## Classes + +### `CursorSkillsProvider` + + +Cursor skills from ~/.cursor/skills/. + + +### `VSCodeSkillsProvider` + + +VS Code skills from ~/.copilot/skills/. + + +### `CodexSkillsProvider` + + +Codex skills from /etc/codex/skills/ and ~/.codex/skills/. + +Scans both system-level and user-level directories. System skills take +precedence if duplicates exist. + + +### `GeminiSkillsProvider` + + +Gemini skills from ~/.gemini/skills/. + + +### `GooseSkillsProvider` + + +Goose skills from ~/.config/agents/skills/. + + +### `CopilotSkillsProvider` + + +GitHub Copilot skills from ~/.copilot/skills/. + + +### `OpenCodeSkillsProvider` + + +OpenCode skills from ~/.config/opencode/skills/. + diff --git a/docs/python-sdk/fastmcp-server-providers-wrapped_provider.mdx b/docs/python-sdk/fastmcp-server-providers-wrapped_provider.mdx new file mode 100644 index 000000000..22fc90b40 --- /dev/null +++ b/docs/python-sdk/fastmcp-server-providers-wrapped_provider.mdx @@ -0,0 +1,13 @@ +--- +title: wrapped_provider +sidebarTitle: wrapped_provider +--- + +# `fastmcp.server.providers.wrapped_provider` + + +WrappedProvider for immutable transform composition. + +This module provides `_WrappedProvider`, an internal class that wraps a provider +with an additional transform. Created by `Provider.wrap_transform()`. + diff --git a/docs/python-sdk/fastmcp-server-proxy.mdx b/docs/python-sdk/fastmcp-server-proxy.mdx new file mode 100644 index 000000000..a9200635c --- /dev/null +++ b/docs/python-sdk/fastmcp-server-proxy.mdx @@ -0,0 +1,14 @@ +--- +title: proxy +sidebarTitle: proxy +--- + +# `fastmcp.server.proxy` + + +Backwards compatibility - import from fastmcp.server.providers.proxy instead. + +This module re-exports all proxy-related classes from their new location +at fastmcp.server.providers.proxy. Direct imports from this module are +deprecated and will be removed in a future version. + diff --git a/docs/python-sdk/fastmcp-server-sampling-__init__.mdx b/docs/python-sdk/fastmcp-server-sampling-__init__.mdx new file mode 100644 index 000000000..0b0533971 --- /dev/null +++ b/docs/python-sdk/fastmcp-server-sampling-__init__.mdx @@ -0,0 +1,9 @@ +--- +title: __init__ +sidebarTitle: __init__ +--- + +# `fastmcp.server.sampling` + + +Sampling module for FastMCP servers. diff --git a/docs/python-sdk/fastmcp-server-sampling-run.mdx b/docs/python-sdk/fastmcp-server-sampling-run.mdx new file mode 100644 index 000000000..c09ad42d5 --- /dev/null +++ b/docs/python-sdk/fastmcp-server-sampling-run.mdx @@ -0,0 +1,203 @@ +--- +title: run +sidebarTitle: run +--- + +# `fastmcp.server.sampling.run` + + +Sampling types and helper functions for FastMCP servers. + +## Functions + +### `determine_handler_mode` + +```python +determine_handler_mode(context: Context, needs_tools: bool) -> bool +``` + + +Determine whether to use fallback handler or client for sampling. + +**Args:** +- `context`: The MCP context. +- `needs_tools`: Whether the sampling request requires tool support. + +**Returns:** +- True if fallback handler should be used, False to use client. + +**Raises:** +- `ValueError`: If client lacks required capability and no fallback configured. + + +### `call_sampling_handler` + +```python +call_sampling_handler(context: Context, messages: list[SamplingMessage]) -> CreateMessageResult | CreateMessageResultWithTools +``` + + +Make LLM call using the fallback handler. + +Note: This function expects the caller (sample_step) to have validated that +sampling_handler is set via determine_handler_mode(). The checks below are +safeguards against internal misuse. + + +### `execute_tools` + +```python +execute_tools(tool_calls: list[ToolUseContent], tool_map: dict[str, SamplingTool], mask_error_details: bool = False, tool_concurrency: int | None = None) -> list[ToolResultContent] +``` + + +Execute tool calls and return results. + +**Args:** +- `tool_calls`: List of tool use requests from the LLM. +- `tool_map`: Mapping from tool name to SamplingTool. +- `mask_error_details`: If True, mask detailed error messages from tool execution. +When masked, only generic error messages are returned to the LLM. +Tools can explicitly raise ToolError to bypass masking when they want +to provide specific error messages to the LLM. +- `tool_concurrency`: Controls parallel execution of tools\: +- None (default)\: Sequential execution (one at a time) +- 0\: Unlimited parallel execution +- N > 0\: Execute at most N tools concurrently +If any tool has sequential=True, all tools execute sequentially +regardless of this setting. + +**Returns:** +- List of tool result content blocks in the same order as tool_calls. + + +### `prepare_messages` + +```python +prepare_messages(messages: str | Sequence[str | SamplingMessage]) -> list[SamplingMessage] +``` + + +Convert various message formats to a list of SamplingMessage objects. + + +### `prepare_tools` + +```python +prepare_tools(tools: Sequence[SamplingTool | FunctionTool | TransformedTool | Callable[..., Any]] | None) -> list[SamplingTool] | None +``` + + +Convert tools to SamplingTool objects. + +Accepts SamplingTool instances, FunctionTool instances, TransformedTool instances, +or plain callable functions. FunctionTool and TransformedTool are converted using +from_callable_tool(), while plain functions use from_function(). + +**Args:** +- `tools`: Sequence of tools to prepare. Can be SamplingTool, FunctionTool, +TransformedTool, or plain callable functions. + +**Returns:** +- List of SamplingTool instances, or None if tools is None. + + +### `extract_tool_calls` + +```python +extract_tool_calls(response: CreateMessageResult | CreateMessageResultWithTools) -> list[ToolUseContent] +``` + + +Extract tool calls from a response. + + +### `create_final_response_tool` + +```python +create_final_response_tool(result_type: type) -> SamplingTool +``` + + +Create a synthetic 'final_response' tool for structured output. + +This tool is used to capture structured responses from the LLM. +The tool's schema is derived from the result_type. + + +### `sample_step_impl` + +```python +sample_step_impl(context: Context, messages: str | Sequence[str | SamplingMessage]) -> SampleStep +``` + + +Implementation of Context.sample_step(). + +Make a single LLM sampling call. This is a stateless function that makes +exactly one LLM call and optionally executes any requested tools. + + +### `sample_impl` + +```python +sample_impl(context: Context, messages: str | Sequence[str | SamplingMessage]) -> SamplingResult[ResultT] +``` + + +Implementation of Context.sample(). + +Send a sampling request to the client and await the response. This method +runs to completion automatically, executing a tool loop until the LLM +provides a final text response. + + +## Classes + +### `SamplingResult` + + +Result of a sampling operation. + +**Attributes:** +- `text`: The text representation of the result (raw text or JSON for structured). +- `result`: The typed result (str for text, parsed object for structured output). +- `history`: All messages exchanged during sampling. + + +### `SampleStep` + + +Result of a single sampling call. + +Represents what the LLM returned in this step plus the message history. + + +**Methods:** + +#### `is_tool_use` + +```python +is_tool_use(self) -> bool +``` + +True if the LLM is requesting tool execution. + + +#### `text` + +```python +text(self) -> str | None +``` + +Extract text from the response, if available. + + +#### `tool_calls` + +```python +tool_calls(self) -> list[ToolUseContent] +``` + +Get the list of tool calls from the response. + diff --git a/docs/python-sdk/fastmcp-server-sampling-sampling_tool.mdx b/docs/python-sdk/fastmcp-server-sampling-sampling_tool.mdx new file mode 100644 index 000000000..cac91d36e --- /dev/null +++ b/docs/python-sdk/fastmcp-server-sampling-sampling_tool.mdx @@ -0,0 +1,101 @@ +--- +title: sampling_tool +sidebarTitle: sampling_tool +--- + +# `fastmcp.server.sampling.sampling_tool` + + +SamplingTool for use during LLM sampling requests. + +## Classes + +### `SamplingTool` + + +A tool that can be used during LLM sampling. + +SamplingTools bundle a tool's schema (name, description, parameters) with +an executor function, enabling servers to execute agentic workflows where +the LLM can request tool calls during sampling. + +In most cases, pass functions directly to ctx.sample(): + + def search(query: str) -> str: + '''Search the web.''' + return web_search(query) + + result = await context.sample( + messages="Find info about Python", + tools=[search], # Plain functions work directly + ) + +Create a SamplingTool explicitly when you need custom name/description: + + tool = SamplingTool.from_function(search, name="web_search") + + +**Methods:** + +#### `run` + +```python +run(self, arguments: dict[str, Any] | None = None) -> Any +``` + +Execute the tool with the given arguments. + +**Args:** +- `arguments`: Dictionary of arguments to pass to the tool function. + +**Returns:** +- The result of executing the tool function. + + +#### `from_function` + +```python +from_function(cls, fn: Callable[..., Any]) -> SamplingTool +``` + +Create a SamplingTool from a function. + +The function's signature is analyzed to generate a JSON schema for +the tool's parameters. Type hints are used to determine parameter types. + +**Args:** +- `fn`: The function to create a tool from. +- `name`: Optional name override. Defaults to the function's name. +- `description`: Optional description override. Defaults to the function's docstring. +- `sequential`: If True, this tool requires sequential execution and prevents +parallel execution of all tools in the batch. Set to True for tools +with shared state, file writes, or other operations that cannot run +concurrently. Defaults to False. + +**Returns:** +- A SamplingTool wrapping the function. + +**Raises:** +- `ValueError`: If the function is a lambda without a name override. + + +#### `from_callable_tool` + +```python +from_callable_tool(cls, tool: FunctionTool | TransformedTool) -> SamplingTool +``` + +Create a SamplingTool from a FunctionTool or TransformedTool. + +Reuses existing server tools in sampling contexts. For TransformedTool, +the tool's .run() method is used to ensure proper argument transformation, +and the ToolResult is automatically unwrapped. + +**Args:** +- `tool`: A FunctionTool or TransformedTool to convert. +- `name`: Optional name override. Defaults to tool.name. +- `description`: Optional description override. Defaults to tool.description. + +**Raises:** +- `TypeError`: If the tool is not a FunctionTool or TransformedTool. + diff --git a/docs/python-sdk/fastmcp-server-server.mdx b/docs/python-sdk/fastmcp-server-server.mdx new file mode 100644 index 000000000..dbd0ad15a --- /dev/null +++ b/docs/python-sdk/fastmcp-server-server.mdx @@ -0,0 +1,910 @@ +--- +title: server +sidebarTitle: server +--- + +# `fastmcp.server.server` + + +FastMCP - A more ergonomic interface for MCP servers. + +## Functions + +### `default_lifespan` + +```python +default_lifespan(server: FastMCP[LifespanResultT]) -> AsyncIterator[Any] +``` + + +Default lifespan context manager that does nothing. + +**Args:** +- `server`: The server instance this lifespan is managing + +**Returns:** +- An empty dictionary as the lifespan result. + + +### `create_proxy` + +```python +create_proxy(target: Client[ClientTransportT] | ClientTransport | FastMCP[Any] | FastMCP1Server | AnyUrl | Path | MCPConfig | dict[str, Any] | str, **settings: Any) -> FastMCPProxy +``` + + +Create a FastMCP proxy server for the given target. + +This is the recommended way to create a proxy server. For lower-level control, +use `FastMCPProxy` or `ProxyProvider` directly from `fastmcp.server.providers.proxy`. + +**Args:** +- `target`: The backend to proxy to. Can be\: +- A Client instance (connected or disconnected) +- A ClientTransport +- A FastMCP server instance +- A URL string or AnyUrl +- A Path to a server script +- An MCPConfig or dict +- `**settings`: Additional settings passed to FastMCPProxy (name, etc.) + +**Returns:** +- A FastMCPProxy server that proxies to the target. + + +## Classes + +### `StateValue` + + +Wrapper for stored context state values. + + +### `FastMCP` + +**Methods:** + +#### `name` + +```python +name(self) -> str +``` + +#### `instructions` + +```python +instructions(self) -> str | None +``` + +#### `instructions` + +```python +instructions(self, value: str | None) -> None +``` + +#### `version` + +```python +version(self) -> str | None +``` + +#### `website_url` + +```python +website_url(self) -> str | None +``` + +#### `icons` + +```python +icons(self) -> list[mcp.types.Icon] +``` + +#### `local_provider` + +```python +local_provider(self) -> LocalProvider +``` + +The server's local provider, which stores directly-registered components. + +Use this to remove components: + + mcp.local_provider.remove_tool("my_tool") + mcp.local_provider.remove_resource("data://info") + mcp.local_provider.remove_prompt("my_prompt") + + +#### `add_middleware` + +```python +add_middleware(self, middleware: Middleware) -> None +``` + +#### `add_provider` + +```python +add_provider(self, provider: Provider) -> None +``` + +Add a provider for dynamic tools, resources, and prompts. + +Providers are queried in registration order. The first provider to return +a non-None result wins. Static components (registered via decorators) +always take precedence over providers. + +**Args:** +- `provider`: A Provider instance that will provide components dynamically. +- `namespace`: Optional namespace prefix. When set\: +- Tools become "namespace_toolname" +- Resources become "protocol\://namespace/path" +- Prompts become "namespace_promptname" + + +#### `get_tasks` + +```python +get_tasks(self) -> Sequence[FastMCPComponent] +``` + +Get task-eligible components with all transforms applied. + +Overrides AggregateProvider.get_tasks() to apply server-level transforms +after aggregation. AggregateProvider handles provider-level namespacing. + + +#### `add_transform` + +```python +add_transform(self, transform: Transform) -> None +``` + +Add a server-level transform. + +Server-level transforms are applied after all providers are aggregated. +They transform tools, resources, and prompts from ALL providers. + +**Args:** +- `transform`: The transform to add. + + +#### `add_tool_transformation` + +```python +add_tool_transformation(self, tool_name: str, transformation: ToolTransformConfig) -> None +``` + +Add a tool transformation. + +.. deprecated:: + Use ``add_transform(ToolTransform({...}))`` instead. + + +#### `remove_tool_transformation` + +```python +remove_tool_transformation(self, _tool_name: str) -> None +``` + +Remove a tool transformation. + +.. deprecated:: + Tool transformations are now immutable. Use enable/disable controls instead. + + +#### `list_tools` + +```python +list_tools(self) -> Sequence[Tool] +``` + +List all enabled tools from providers. + +Overrides Provider.list_tools() to add visibility filtering, auth filtering, +and middleware execution. Returns all versions (no deduplication). +Protocol handlers deduplicate for MCP wire format. + + +#### `get_tool` + +```python +get_tool(self, name: str, version: VersionSpec | None = None) -> Tool | None +``` + +Get a tool by name, filtering disabled tools. + +Overrides Provider.get_tool() to add visibility filtering after all +transforms (including session-level) have been applied. This ensures +session transforms can override provider-level disables. + +**Args:** +- `name`: The tool name. +- `version`: Version filter (None returns highest version). + +**Returns:** +- The tool if found and enabled, None otherwise. + + +#### `list_resources` + +```python +list_resources(self) -> Sequence[Resource] +``` + +List all enabled resources from providers. + +Overrides Provider.list_resources() to add visibility filtering, auth filtering, +and middleware execution. Returns all versions (no deduplication). +Protocol handlers deduplicate for MCP wire format. + + +#### `get_resource` + +```python +get_resource(self, uri: str, version: VersionSpec | None = None) -> Resource | None +``` + +Get a resource by URI, filtering disabled resources. + +Overrides Provider.get_resource() to add visibility filtering after all +transforms (including session-level) have been applied. + +**Args:** +- `uri`: The resource URI. +- `version`: Version filter (None returns highest version). + +**Returns:** +- The resource if found and enabled, None otherwise. + + +#### `list_resource_templates` + +```python +list_resource_templates(self) -> Sequence[ResourceTemplate] +``` + +List all enabled resource templates from providers. + +Overrides Provider.list_resource_templates() to add visibility filtering, +auth filtering, and middleware execution. Returns all versions (no deduplication). +Protocol handlers deduplicate for MCP wire format. + + +#### `get_resource_template` + +```python +get_resource_template(self, uri: str, version: VersionSpec | None = None) -> ResourceTemplate | None +``` + +Get a resource template by URI, filtering disabled templates. + +Overrides Provider.get_resource_template() to add visibility filtering after +all transforms (including session-level) have been applied. + +**Args:** +- `uri`: The template URI. +- `version`: Version filter (None returns highest version). + +**Returns:** +- The template if found and enabled, None otherwise. + + +#### `list_prompts` + +```python +list_prompts(self) -> Sequence[Prompt] +``` + +List all enabled prompts from providers. + +Overrides Provider.list_prompts() to add visibility filtering, auth filtering, +and middleware execution. Returns all versions (no deduplication). +Protocol handlers deduplicate for MCP wire format. + + +#### `get_prompt` + +```python +get_prompt(self, name: str, version: VersionSpec | None = None) -> Prompt | None +``` + +Get a prompt by name, filtering disabled prompts. + +Overrides Provider.get_prompt() to add visibility filtering after all +transforms (including session-level) have been applied. + +**Args:** +- `name`: The prompt name. +- `version`: Version filter (None returns highest version). + +**Returns:** +- The prompt if found and enabled, None otherwise. + + +#### `call_tool` + +```python +call_tool(self, name: str, arguments: dict[str, Any] | None = None) -> ToolResult +``` + +#### `call_tool` + +```python +call_tool(self, name: str, arguments: dict[str, Any] | None = None) -> mcp.types.CreateTaskResult +``` + +#### `call_tool` + +```python +call_tool(self, name: str, arguments: dict[str, Any] | None = None) -> ToolResult | mcp.types.CreateTaskResult +``` + +Call a tool by name. + +This is the public API for executing tools. By default, middleware is applied. + +**Args:** +- `name`: The tool name +- `arguments`: Tool arguments (optional) +- `version`: Specific version to call. If None, calls highest version. +- `run_middleware`: If True (default), apply the middleware chain. +Set to False when called from middleware to avoid re-applying. +- `task_meta`: If provided, execute as a background task and return +CreateTaskResult. If None (default), execute synchronously and +return ToolResult. + +**Returns:** +- ToolResult when task_meta is None. +- CreateTaskResult when task_meta is provided. + +**Raises:** +- `NotFoundError`: If tool not found or disabled +- `ToolError`: If tool execution fails +- `ValidationError`: If arguments fail validation + + +#### `read_resource` + +```python +read_resource(self, uri: str) -> ResourceResult +``` + +#### `read_resource` + +```python +read_resource(self, uri: str) -> mcp.types.CreateTaskResult +``` + +#### `read_resource` + +```python +read_resource(self, uri: str) -> ResourceResult | mcp.types.CreateTaskResult +``` + +Read a resource by URI. + +This is the public API for reading resources. By default, middleware is applied. +Checks concrete resources first, then templates. + +**Args:** +- `uri`: The resource URI +- `version`: Specific version to read. If None, reads highest version. +- `run_middleware`: If True (default), apply the middleware chain. +Set to False when called from middleware to avoid re-applying. +- `task_meta`: If provided, execute as a background task and return +CreateTaskResult. If None (default), execute synchronously and +return ResourceResult. + +**Returns:** +- ResourceResult when task_meta is None. +- CreateTaskResult when task_meta is provided. + +**Raises:** +- `NotFoundError`: If resource not found or disabled +- `ResourceError`: If resource read fails + + +#### `render_prompt` + +```python +render_prompt(self, name: str, arguments: dict[str, Any] | None = None) -> PromptResult +``` + +#### `render_prompt` + +```python +render_prompt(self, name: str, arguments: dict[str, Any] | None = None) -> mcp.types.CreateTaskResult +``` + +#### `render_prompt` + +```python +render_prompt(self, name: str, arguments: dict[str, Any] | None = None) -> PromptResult | mcp.types.CreateTaskResult +``` + +Render a prompt by name. + +This is the public API for rendering prompts. By default, middleware is applied. +Use get_prompt() to retrieve the prompt definition without rendering. + +**Args:** +- `name`: The prompt name +- `arguments`: Prompt arguments (optional) +- `version`: Specific version to render. If None, renders highest version. +- `run_middleware`: If True (default), apply the middleware chain. +Set to False when called from middleware to avoid re-applying. +- `task_meta`: If provided, execute as a background task and return +CreateTaskResult. If None (default), execute synchronously and +return PromptResult. + +**Returns:** +- PromptResult when task_meta is None. +- CreateTaskResult when task_meta is provided. + +**Raises:** +- `NotFoundError`: If prompt not found or disabled +- `PromptError`: If prompt rendering fails + + +#### `add_tool` + +```python +add_tool(self, tool: Tool | Callable[..., Any]) -> Tool +``` + +Add a tool to the server. + +The tool function can optionally request a Context object by adding a parameter +with the Context type annotation. See the @tool decorator for examples. + +**Args:** +- `tool`: The Tool instance or @tool-decorated function to register + +**Returns:** +- The tool instance that was added to the server. + + +#### `remove_tool` + +```python +remove_tool(self, name: str, version: str | None = None) -> None +``` + +Remove tool(s) from the server. + +.. deprecated:: + Use ``mcp.local_provider.remove_tool(name)`` instead. + +**Args:** +- `name`: The name of the tool to remove. +- `version`: If None, removes ALL versions. If specified, removes only that version. + +**Raises:** +- `NotFoundError`: If no matching tool is found. + + +#### `tool` + +```python +tool(self, name_or_fn: F) -> F +``` + +#### `tool` + +```python +tool(self, name_or_fn: str | None = None) -> Callable[[F], F] +``` + +#### `tool` + +```python +tool(self, name_or_fn: str | AnyFunction | None = None) -> Callable[[AnyFunction], FunctionTool] | FunctionTool | partial[Callable[[AnyFunction], FunctionTool] | FunctionTool] +``` + +Decorator to register a tool. + +Tools can optionally request a Context object by adding a parameter with the +Context type annotation. The context provides access to MCP capabilities like +logging, progress reporting, and resource access. + +This decorator supports multiple calling patterns: +- @server.tool (without parentheses) +- @server.tool (with empty parentheses) +- @server.tool("custom_name") (with name as first argument) +- @server.tool(name="custom_name") (with name as keyword argument) +- server.tool(function, name="custom_name") (direct function call) + +**Args:** +- `name_or_fn`: Either a function (when used as @tool), a string name, or None +- `name`: Optional name for the tool (keyword-only, alternative to name_or_fn) +- `description`: Optional description of what the tool does +- `tags`: Optional set of tags for categorizing the tool +- `output_schema`: Optional JSON schema for the tool's output +- `annotations`: Optional annotations about the tool's behavior +- `exclude_args`: Optional list of argument names to exclude from the tool schema. +Deprecated\: Use `Depends()` for dependency injection instead. +- `meta`: Optional meta information about the tool + +**Examples:** + +Register a tool with a custom name: +```python +@server.tool +def my_tool(x: int) -> str: + return str(x) + +# Register a tool with a custom name +@server.tool +def my_tool(x: int) -> str: + return str(x) + +@server.tool("custom_name") +def my_tool(x: int) -> str: + return str(x) + +@server.tool(name="custom_name") +def my_tool(x: int) -> str: + return str(x) + +# Direct function call +server.tool(my_function, name="custom_name") +``` + + +#### `add_resource` + +```python +add_resource(self, resource: Resource | Callable[..., Any]) -> Resource | ResourceTemplate +``` + +Add a resource to the server. + +**Args:** +- `resource`: A Resource instance or @resource-decorated function to add + +**Returns:** +- The resource instance that was added to the server. + + +#### `add_template` + +```python +add_template(self, template: ResourceTemplate) -> ResourceTemplate +``` + +Add a resource template to the server. + +**Args:** +- `template`: A ResourceTemplate instance to add + +**Returns:** +- The template instance that was added to the server. + + +#### `resource` + +```python +resource(self, uri: str) -> Callable[[F], F] +``` + +Decorator to register a function as a resource. + +The function will be called when the resource is read to generate its content. +The function can return: +- str for text content +- bytes for binary content +- other types will be converted to JSON + +Resources can optionally request a Context object by adding a parameter with the +Context type annotation. The context provides access to MCP capabilities like +logging, progress reporting, and session information. + +If the URI contains parameters (e.g. "resource://{param}") or the function +has parameters, it will be registered as a template resource. + +**Args:** +- `uri`: URI for the resource (e.g. "resource\://my-resource" or "resource\://{param}") +- `name`: Optional name for the resource +- `description`: Optional description of the resource +- `mime_type`: Optional MIME type for the resource +- `tags`: Optional set of tags for categorizing the resource +- `annotations`: Optional annotations about the resource's behavior +- `meta`: Optional meta information about the resource + +**Examples:** + +Register a resource with a custom name: +```python +@server.resource("resource://my-resource") +def get_data() -> str: + return "Hello, world!" + +@server.resource("resource://my-resource") +async get_data() -> str: + data = await fetch_data() + return f"Hello, world! {data}" + +@server.resource("resource://{city}/weather") +def get_weather(city: str) -> str: + return f"Weather for {city}" + +@server.resource("resource://{city}/weather") +async def get_weather_with_context(city: str, ctx: Context) -> str: + await ctx.info(f"Fetching weather for {city}") + return f"Weather for {city}" + +@server.resource("resource://{city}/weather") +async def get_weather(city: str) -> str: + data = await fetch_weather(city) + return f"Weather for {city}: {data}" +``` + + +#### `add_prompt` + +```python +add_prompt(self, prompt: Prompt | Callable[..., Any]) -> Prompt +``` + +Add a prompt to the server. + +**Args:** +- `prompt`: A Prompt instance or @prompt-decorated function to add + +**Returns:** +- The prompt instance that was added to the server. + + +#### `prompt` + +```python +prompt(self, name_or_fn: F) -> F +``` + +#### `prompt` + +```python +prompt(self, name_or_fn: str | None = None) -> Callable[[F], F] +``` + +#### `prompt` + +```python +prompt(self, name_or_fn: str | AnyFunction | None = None) -> Callable[[AnyFunction], FunctionPrompt] | FunctionPrompt | partial[Callable[[AnyFunction], FunctionPrompt] | FunctionPrompt] +``` + +Decorator to register a prompt. + + Prompts can optionally request a Context object by adding a parameter with the + Context type annotation. The context provides access to MCP capabilities like + logging, progress reporting, and session information. + + This decorator supports multiple calling patterns: + - @server.prompt (without parentheses) + - @server.prompt() (with empty parentheses) + - @server.prompt("custom_name") (with name as first argument) + - @server.prompt(name="custom_name") (with name as keyword argument) + - server.prompt(function, name="custom_name") (direct function call) + + Args: + name_or_fn: Either a function (when used as @prompt), a string name, or None + name: Optional name for the prompt (keyword-only, alternative to name_or_fn) + description: Optional description of what the prompt does + tags: Optional set of tags for categorizing the prompt + meta: Optional meta information about the prompt + + Examples: + + ```python + @server.prompt + def analyze_table(table_name: str) -> list[Message]: + schema = read_table_schema(table_name) + return [ + { + "role": "user", + "content": f"Analyze this schema: +{schema}" + } + ] + + @server.prompt() + async def analyze_with_context(table_name: str, ctx: Context) -> list[Message]: + await ctx.info(f"Analyzing table {table_name}") + schema = read_table_schema(table_name) + return [ + { + "role": "user", + "content": f"Analyze this schema: +{schema}" + } + ] + + @server.prompt("custom_name") + async def analyze_file(path: str) -> list[Message]: + content = await read_file(path) + return [ + { + "role": "user", + "content": { + "type": "resource", + "resource": { + "uri": f"file://{path}", + "text": content + } + } + } + ] + + @server.prompt(name="custom_name") + def another_prompt(data: str) -> list[Message]: + return [{"role": "user", "content": data}] + + # Direct function call + server.prompt(my_function, name="custom_name") + ``` + + +#### `mount` + +```python +mount(self, server: FastMCP[LifespanResultT], namespace: str | None = None, as_proxy: bool | None = None, tool_names: dict[str, str] | None = None, prefix: str | None = None) -> None +``` + +Mount another FastMCP server on this server with an optional namespace. + +Unlike importing (with import_server), mounting establishes a dynamic connection +between servers. When a client interacts with a mounted server's objects through +the parent server, requests are forwarded to the mounted server in real-time. +This means changes to the mounted server are immediately reflected when accessed +through the parent. + +When a server is mounted with a namespace: +- Tools from the mounted server are accessible with namespaced names. + Example: If server has a tool named "get_weather", it will be available as "namespace_get_weather". +- Resources are accessible with namespaced URIs. + Example: If server has a resource with URI "weather://forecast", it will be available as + "weather://namespace/forecast". +- Templates are accessible with namespaced URI templates. + Example: If server has a template with URI "weather://location/{id}", it will be available + as "weather://namespace/location/{id}". +- Prompts are accessible with namespaced names. + Example: If server has a prompt named "weather_prompt", it will be available as + "namespace_weather_prompt". + +When a server is mounted without a namespace (namespace=None), its tools, resources, templates, +and prompts are accessible with their original names. Multiple servers can be mounted +without namespaces, and they will be tried in order until a match is found. + +The mounted server's lifespan is executed when the parent server starts, and its +middleware chain is invoked for all operations (tool calls, resource reads, prompts). + +**Args:** +- `server`: The FastMCP server to mount. +- `namespace`: Optional namespace to use for the mounted server's objects. If None, +the server's objects are accessible with their original names. +- `as_proxy`: Deprecated. Mounted servers now always have their lifespan and +middleware invoked. To create a proxy server, use create_proxy() +explicitly before mounting. +- `tool_names`: Optional mapping of original tool names to custom names. Use this +to override namespaced names. Keys are the original tool names from the +mounted server. +- `prefix`: Deprecated. Use namespace instead. + + +#### `import_server` + +```python +import_server(self, server: FastMCP[LifespanResultT], prefix: str | None = None) -> None +``` + +Import the MCP objects from another FastMCP server into this one, +optionally with a given prefix. + +.. deprecated:: + Use :meth:`mount` instead. ``import_server`` will be removed in a + future version. + +Note that when a server is *imported*, its objects are immediately +registered to the importing server. This is a one-time operation and +future changes to the imported server will not be reflected in the +importing server. Server-level configurations and lifespans are not imported. + +When a server is imported with a prefix: +- The tools are imported with prefixed names + Example: If server has a tool named "get_weather", it will be + available as "prefix_get_weather" +- The resources are imported with prefixed URIs using the new format + Example: If server has a resource with URI "weather://forecast", it will + be available as "weather://prefix/forecast" +- The templates are imported with prefixed URI templates using the new format + Example: If server has a template with URI "weather://location/{id}", it will + be available as "weather://prefix/location/{id}" +- The prompts are imported with prefixed names + Example: If server has a prompt named "weather_prompt", it will be available as + "prefix_weather_prompt" + +When a server is imported without a prefix (prefix=None), its tools, resources, +templates, and prompts are imported with their original names. + +**Args:** +- `server`: The FastMCP server to import +- `prefix`: Optional prefix to use for the imported server's objects. If None, +objects are imported with their original names. + + +#### `from_openapi` + +```python +from_openapi(cls, openapi_spec: dict[str, Any], client: httpx.AsyncClient | None = None, name: str = 'OpenAPI Server', route_maps: list[RouteMap] | None = None, route_map_fn: OpenAPIRouteMapFn | None = None, mcp_component_fn: OpenAPIComponentFn | None = None, mcp_names: dict[str, str] | None = None, tags: set[str] | None = None, validate_output: bool = True, **settings: Any) -> Self +``` + +Create a FastMCP server from an OpenAPI specification. + +**Args:** +- `openapi_spec`: OpenAPI schema as a dictionary +- `client`: Optional httpx AsyncClient for making HTTP requests. +If not provided, a default client is created using the first +server URL from the OpenAPI spec with a 30-second timeout. +- `name`: Name for the MCP server +- `route_maps`: Optional list of RouteMap objects defining route mappings +- `route_map_fn`: Optional callable for advanced route type mapping +- `mcp_component_fn`: Optional callable for component customization +- `mcp_names`: Optional dictionary mapping operationId to component names +- `tags`: Optional set of tags to add to all components +- `validate_output`: If True (default), tools use the output schema +extracted from the OpenAPI spec for response validation. If +False, a permissive schema is used instead, allowing any +response structure while still returning structured JSON. +- `**settings`: Additional settings passed to FastMCP + +**Returns:** +- A FastMCP server with an OpenAPIProvider attached. + + +#### `from_fastapi` + +```python +from_fastapi(cls, app: Any, name: str | None = None, route_maps: list[RouteMap] | None = None, route_map_fn: OpenAPIRouteMapFn | None = None, mcp_component_fn: OpenAPIComponentFn | None = None, mcp_names: dict[str, str] | None = None, httpx_client_kwargs: dict[str, Any] | None = None, tags: set[str] | None = None, **settings: Any) -> Self +``` + +Create a FastMCP server from a FastAPI application. + +**Args:** +- `app`: FastAPI application instance +- `name`: Name for the MCP server (defaults to app.title) +- `route_maps`: Optional list of RouteMap objects defining route mappings +- `route_map_fn`: Optional callable for advanced route type mapping +- `mcp_component_fn`: Optional callable for component customization +- `mcp_names`: Optional dictionary mapping operationId to component names +- `httpx_client_kwargs`: Optional kwargs passed to httpx.AsyncClient. +Use this to configure timeout and other client settings. +- `tags`: Optional set of tags to add to all components +- `**settings`: Additional settings passed to FastMCP + +**Returns:** +- A FastMCP server with an OpenAPIProvider attached. + + +#### `as_proxy` + +```python +as_proxy(cls, backend: Client[ClientTransportT] | ClientTransport | FastMCP[Any] | FastMCP1Server | AnyUrl | Path | MCPConfig | dict[str, Any] | str, **settings: Any) -> FastMCPProxy +``` + +Create a FastMCP proxy server for the given backend. + +.. deprecated:: + Use :func:`fastmcp.server.create_proxy` instead. + This method will be removed in a future version. + +The `backend` argument can be either an existing `fastmcp.client.Client` +instance or any value accepted as the `transport` argument of +`fastmcp.client.Client`. This mirrors the convenience of the +`fastmcp.client.Client` constructor. + + +#### `generate_name` + +```python +generate_name(cls, name: str | None = None) -> str +``` diff --git a/docs/python-sdk/fastmcp-server-tasks-__init__.mdx b/docs/python-sdk/fastmcp-server-tasks-__init__.mdx new file mode 100644 index 000000000..9c9f5e88e --- /dev/null +++ b/docs/python-sdk/fastmcp-server-tasks-__init__.mdx @@ -0,0 +1,12 @@ +--- +title: __init__ +sidebarTitle: __init__ +--- + +# `fastmcp.server.tasks` + + +MCP SEP-1686 background tasks support. + +This module implements protocol-level background task execution for MCP servers. + diff --git a/docs/python-sdk/fastmcp-server-tasks-capabilities.mdx b/docs/python-sdk/fastmcp-server-tasks-capabilities.mdx new file mode 100644 index 000000000..03b1102dd --- /dev/null +++ b/docs/python-sdk/fastmcp-server-tasks-capabilities.mdx @@ -0,0 +1,29 @@ +--- +title: capabilities +sidebarTitle: capabilities +--- + +# `fastmcp.server.tasks.capabilities` + + +SEP-1686 task capabilities declaration. + +## Functions + +### `get_task_capabilities` + +```python +get_task_capabilities() -> ServerTasksCapability | None +``` + + +Return the SEP-1686 task capabilities. + +Returns task capabilities as a first-class ServerCapabilities field, +declaring support for list, cancel, and request operations per SEP-1686. + +Returns None if pydocket is not installed (no task support). + +Note: prompts/resources are passed via extra_data since the SDK types +don't include them yet (FastMCP supports them ahead of the spec). + diff --git a/docs/python-sdk/fastmcp-server-tasks-config.mdx b/docs/python-sdk/fastmcp-server-tasks-config.mdx new file mode 100644 index 000000000..0dc2bf4ba --- /dev/null +++ b/docs/python-sdk/fastmcp-server-tasks-config.mdx @@ -0,0 +1,96 @@ +--- +title: config +sidebarTitle: config +--- + +# `fastmcp.server.tasks.config` + + +TaskConfig for MCP SEP-1686 background task execution modes. + +This module defines the configuration for how tools, resources, and prompts +handle task-augmented execution as specified in SEP-1686. + + +## Classes + +### `TaskMeta` + + +Metadata for task-augmented execution requests. + +When passed to call_tool/read_resource/get_prompt, signals that +the operation should be submitted as a background task. + +**Attributes:** +- `ttl`: Client-requested TTL in milliseconds. If None, uses server default. +- `fn_key`: Docket routing key. Auto-derived from component name if None. + + +### `TaskConfig` + + +Configuration for MCP background task execution (SEP-1686). + +Controls how a component handles task-augmented requests: + +- "forbidden": Component does not support task execution. Clients must not + request task augmentation; server returns -32601 if they do. +- "optional": Component supports both synchronous and task execution. + Client may request task augmentation or call normally. +- "required": Component requires task execution. Clients must request task + augmentation; server returns -32601 if they don't. + + +**Methods:** + +#### `from_bool` + +```python +from_bool(cls, value: bool) -> TaskConfig +``` + +Convert boolean task flag to TaskConfig. + +**Args:** +- `value`: True for "optional" mode, False for "forbidden" mode. + +**Returns:** +- TaskConfig with appropriate mode. + + +#### `supports_tasks` + +```python +supports_tasks(self) -> bool +``` + +Check if this component supports task execution. + +**Returns:** +- True if mode is "optional" or "required", False if "forbidden". + + +#### `validate_function` + +```python +validate_function(self, fn: Callable[..., Any], name: str) -> None +``` + +Validate that function is compatible with this task config. + +Task execution requires: +1. fastmcp[tasks] to be installed (pydocket) +2. Async functions + +Raises ImportError if mode is "optional" or "required" but pydocket +is not installed. Raises ValueError if function is synchronous. + +**Args:** +- `fn`: The function to validate (handles callable classes and staticmethods). +- `name`: Name for error messages. + +**Raises:** +- `ImportError`: If task execution is enabled but pydocket not installed. +- `ValueError`: If task execution is enabled but function is sync. + diff --git a/docs/python-sdk/fastmcp-server-tasks-elicitation.mdx b/docs/python-sdk/fastmcp-server-tasks-elicitation.mdx new file mode 100644 index 000000000..cc6f3dea2 --- /dev/null +++ b/docs/python-sdk/fastmcp-server-tasks-elicitation.mdx @@ -0,0 +1,96 @@ +--- +title: elicitation +sidebarTitle: elicitation +--- + +# `fastmcp.server.tasks.elicitation` + + +Background task elicitation support (SEP-1686). + +This module provides elicitation capabilities for background tasks running +in Docket workers. Unlike regular MCP requests, background tasks don't have +an active request context, so elicitation requires special handling: + +1. Set task status to "input_required" via Redis +2. Send notifications/tasks/status with elicitation metadata +3. Wait for client to send input via tasks/sendInput +4. Resume task execution with the provided input + +This uses the public MCP SDK APIs where possible, with minimal use of +internal APIs for background task coordination. + + +## Functions + +### `elicit_for_task` + +```python +elicit_for_task(task_id: str, session: ServerSession | None, message: str, schema: dict[str, Any], fastmcp: FastMCP) -> mcp.types.ElicitResult +``` + + +Send an elicitation request from a background task. + +This function handles the complexity of eliciting user input when running +in a Docket worker context where there's no active MCP request. + +**Args:** +- `task_id`: The background task ID +- `session`: The MCP ServerSession for this task +- `message`: The message to display to the user +- `schema`: The JSON schema for the expected response +- `fastmcp`: The FastMCP server instance + +**Returns:** +- ElicitResult containing the user's response + +**Raises:** +- `RuntimeError`: If Docket is not available +- `McpError`: If the elicitation request fails + + +### `relay_elicitation` + +```python +relay_elicitation(session: ServerSession, session_id: str, task_id: str, elicitation: dict[str, Any], fastmcp: FastMCP) -> None +``` + + +Relay elicitation from a background task worker to the client. + +Called by the notification subscriber when it detects an input_required +notification with elicitation metadata. Sends a standard elicitation/create +request to the client session, then uses handle_task_input() to push the +response to Redis so the blocked worker can resume. + +**Args:** +- `session`: MCP ServerSession +- `session_id`: Session identifier +- `task_id`: Background task ID +- `elicitation`: Elicitation metadata (message, requestedSchema) +- `fastmcp`: FastMCP server instance + + +### `handle_task_input` + +```python +handle_task_input(task_id: str, session_id: str, action: str, content: dict[str, Any] | None, fastmcp: FastMCP) -> bool +``` + + +Handle input sent to a background task via tasks/sendInput. + +This is called when a client sends input in response to an elicitation +request from a background task. + +**Args:** +- `task_id`: The background task ID +- `session_id`: The MCP session ID +- `action`: The elicitation action ("accept", "decline", "cancel") +- `content`: The response content (for "accept" action) +- `fastmcp`: The FastMCP server instance + +**Returns:** +- True if the input was successfully stored, False otherwise + diff --git a/docs/python-sdk/fastmcp-server-tasks-handlers.mdx b/docs/python-sdk/fastmcp-server-tasks-handlers.mdx new file mode 100644 index 000000000..31f228f14 --- /dev/null +++ b/docs/python-sdk/fastmcp-server-tasks-handlers.mdx @@ -0,0 +1,41 @@ +--- +title: handlers +sidebarTitle: handlers +--- + +# `fastmcp.server.tasks.handlers` + + +SEP-1686 task execution handlers. + +Handles queuing tool/prompt/resource executions to Docket as background tasks. + + +## Functions + +### `submit_to_docket` + +```python +submit_to_docket(task_type: Literal['tool', 'resource', 'template', 'prompt'], key: str, component: Tool | Resource | ResourceTemplate | Prompt, arguments: dict[str, Any] | None = None, task_meta: TaskMeta | None = None) -> mcp.types.CreateTaskResult +``` + + +Submit any component to Docket for background execution (SEP-1686). + +Unified handler for all component types. Called by component's internal +methods (_run, _read, _render) when task metadata is present and mode allows. + +Queues the component's method to Docket, stores raw return values, +and converts to MCP types on retrieval. + +**Args:** +- `task_type`: Component type for task key construction +- `key`: The component key as seen by MCP layer (with namespace prefix) +- `component`: The component instance (Tool, Resource, ResourceTemplate, Prompt) +- `arguments`: Arguments/params (None for Resource which has no args) +- `task_meta`: Task execution metadata. If task_meta.ttl is provided, it +overrides the server default (docket.execution_ttl). + +**Returns:** +- Task stub with proper Task object + diff --git a/docs/python-sdk/fastmcp-server-tasks-keys.mdx b/docs/python-sdk/fastmcp-server-tasks-keys.mdx new file mode 100644 index 000000000..a274d3c1d --- /dev/null +++ b/docs/python-sdk/fastmcp-server-tasks-keys.mdx @@ -0,0 +1,89 @@ +--- +title: keys +sidebarTitle: keys +--- + +# `fastmcp.server.tasks.keys` + + +Task key management for SEP-1686 background tasks. + +Task keys encode security scoping and metadata in the Docket key format: + `{session_id}:{client_task_id}:{task_type}:{component_identifier}` + +This format provides: +- Session-based security scoping (prevents cross-session access) +- Task type identification (tool/prompt/resource) +- Component identification (name or URI for result conversion) + + +## Functions + +### `build_task_key` + +```python +build_task_key(session_id: str, client_task_id: str, task_type: str, component_identifier: str) -> str +``` + + +Build Docket task key with embedded metadata. + +Format: `{session_id}:{client_task_id}:{task_type}:{component_identifier}` + +The component_identifier is URI-encoded to handle special characters (colons, slashes, etc.). + +**Args:** +- `session_id`: Session ID for security scoping +- `client_task_id`: Client-provided task ID +- `task_type`: Type of task ("tool", "prompt", "resource") +- `component_identifier`: Tool name, prompt name, or resource URI + +**Returns:** +- Encoded task key for Docket + +**Examples:** + +>>> build_task_key("session123", "task456", "tool", "my_tool") +'session123:task456:tool:my_tool' +>>> build_task_key("session123", "task456", "resource", "file://data.txt") +'session123:task456:resource:file%3A%2F%2Fdata.txt' + + +### `parse_task_key` + +```python +parse_task_key(task_key: str) -> dict[str, str] +``` + + +Parse Docket task key to extract metadata. + +**Args:** +- `task_key`: Encoded task key from Docket + +**Returns:** +- Dict with keys: session_id, client_task_id, task_type, component_identifier + +**Examples:** + +>>> parse_task_key("session123:task456:tool:my_tool") +`{'session_id': 'session123', 'client_task_id': 'task456', 'task_type': 'tool', 'component_identifier': 'my_tool'}` +>>> parse_task_key("session123:task456:resource:file%3A%2F%2Fdata.txt") +`{'session_id': 'session123', 'client_task_id': 'task456', 'task_type': 'resource', 'component_identifier': 'file://data.txt'}` + + +### `get_client_task_id_from_key` + +```python +get_client_task_id_from_key(task_key: str) -> str +``` + + +Extract just the client task ID from a task key. + +**Args:** +- `task_key`: Full encoded task key + +**Returns:** +- Client-provided task ID (second segment) + diff --git a/docs/python-sdk/fastmcp-server-tasks-notifications.mdx b/docs/python-sdk/fastmcp-server-tasks-notifications.mdx new file mode 100644 index 000000000..217b4b6ac --- /dev/null +++ b/docs/python-sdk/fastmcp-server-tasks-notifications.mdx @@ -0,0 +1,113 @@ +--- +title: notifications +sidebarTitle: notifications +--- + +# `fastmcp.server.tasks.notifications` + + +Distributed notification queue for background task events (SEP-1686). + +Enables distributed Docket workers to send MCP notifications to clients +without holding session references. Workers push to a Redis queue, +the MCP server process subscribes and forwards to the client's session. + +Pattern: Fire-and-forward with retry +- One queue per session_id +- LPUSH/BRPOP for reliable ordered delivery +- Retry up to 3 times on delivery failure, then discard +- TTL-based expiration for stale messages + +Note: Docket's execution.subscribe() handles task state/progress events via +Redis Pub/Sub. This module handles elicitation-specific notifications that +require reliable delivery (input_required prompts, cancel signals). + + +## Functions + +### `push_notification` + +```python +push_notification(session_id: str, notification: dict[str, Any], docket: Docket) -> None +``` + + +Push notification to session's queue (called from Docket worker). + +Used for elicitation-specific notifications (input_required, cancel) +that need reliable delivery across distributed processes. + +**Args:** +- `session_id`: Target session's identifier +- `notification`: MCP notification dict (method, params, _meta) +- `docket`: Docket instance for Redis access + + +### `notification_subscriber_loop` + +```python +notification_subscriber_loop(session_id: str, session: ServerSession, docket: Docket, fastmcp: FastMCP) -> None +``` + + +Subscribe to notification queue and forward to session. + +Runs in the MCP server process. Bridges distributed workers to clients. + +This loop: +1. Maintains a heartbeat (active subscriber marker for debugging) +2. Blocks on BRPOP waiting for notifications +3. Forwards notifications to the client's session +4. Retries failed deliveries, then discards (no dead-letter queue) + +**Args:** +- `session_id`: Session identifier to subscribe to +- `session`: MCP ServerSession for sending notifications +- `docket`: Docket instance for Redis access +- `fastmcp`: FastMCP server instance (for elicitation relay) + + +### `ensure_subscriber_running` + +```python +ensure_subscriber_running(session_id: str, session: ServerSession, docket: Docket, fastmcp: FastMCP) -> None +``` + + +Start notification subscriber if not already running (idempotent). + +Subscriber is created on first task submission and cleaned up on disconnect. +Safe to call multiple times for the same session. + +**Args:** +- `session_id`: Session identifier +- `session`: MCP ServerSession +- `docket`: Docket instance +- `fastmcp`: FastMCP server instance (for elicitation relay) + + +### `stop_subscriber` + +```python +stop_subscriber(session_id: str) -> None +``` + + +Stop notification subscriber for a session. + +Called when session disconnects. Pending messages remain in queue +for delivery if client reconnects (with TTL expiration). + +**Args:** +- `session_id`: Session identifier + + +### `get_subscriber_count` + +```python +get_subscriber_count() -> int +``` + + +Get number of active subscribers (for monitoring). + diff --git a/docs/python-sdk/fastmcp-server-tasks-requests.mdx b/docs/python-sdk/fastmcp-server-tasks-requests.mdx new file mode 100644 index 000000000..5cde802fc --- /dev/null +++ b/docs/python-sdk/fastmcp-server-tasks-requests.mdx @@ -0,0 +1,91 @@ +--- +title: requests +sidebarTitle: requests +--- + +# `fastmcp.server.tasks.requests` + + +SEP-1686 task request handlers. + +Handles MCP task protocol requests: tasks/get, tasks/result, tasks/list, tasks/cancel. +These handlers query and manage existing tasks (contrast with handlers.py which creates tasks). + +This module requires fastmcp[tasks] (pydocket). It is only imported when docket is available. + + +## Functions + +### `tasks_get_handler` + +```python +tasks_get_handler(server: FastMCP, params: dict[str, Any]) -> GetTaskResult +``` + + +Handle MCP 'tasks/get' request (SEP-1686). + +**Args:** +- `server`: FastMCP server instance +- `params`: Request params containing taskId + +**Returns:** +- Task status response with spec-compliant fields + + +### `tasks_result_handler` + +```python +tasks_result_handler(server: FastMCP, params: dict[str, Any]) -> Any +``` + + +Handle MCP 'tasks/result' request (SEP-1686). + +Converts raw task return values to MCP types based on task type. + +**Args:** +- `server`: FastMCP server instance +- `params`: Request params containing taskId + +**Returns:** +- MCP result (CallToolResult, GetPromptResult, or ReadResourceResult) + + +### `tasks_list_handler` + +```python +tasks_list_handler(server: FastMCP, params: dict[str, Any]) -> ListTasksResult +``` + + +Handle MCP 'tasks/list' request (SEP-1686). + +Note: With client-side tracking, this returns minimal info. + +**Args:** +- `server`: FastMCP server instance +- `params`: Request params (cursor, limit) + +**Returns:** +- Response with tasks list and pagination + + +### `tasks_cancel_handler` + +```python +tasks_cancel_handler(server: FastMCP, params: dict[str, Any]) -> CancelTaskResult +``` + + +Handle MCP 'tasks/cancel' request (SEP-1686). + +Cancels a running task, transitioning it to cancelled state. + +**Args:** +- `server`: FastMCP server instance +- `params`: Request params containing taskId + +**Returns:** +- Task status response showing cancelled state + diff --git a/docs/python-sdk/fastmcp-server-tasks-routing.mdx b/docs/python-sdk/fastmcp-server-tasks-routing.mdx new file mode 100644 index 000000000..435d62775 --- /dev/null +++ b/docs/python-sdk/fastmcp-server-tasks-routing.mdx @@ -0,0 +1,37 @@ +--- +title: routing +sidebarTitle: routing +--- + +# `fastmcp.server.tasks.routing` + + +Task routing helper for MCP components. + +Provides unified task mode enforcement and docket routing logic. + + +## Functions + +### `check_background_task` + +```python +check_background_task(component: Tool | Resource | ResourceTemplate | Prompt, task_type: TaskType, arguments: dict[str, Any] | None = None, task_meta: TaskMeta | None = None) -> mcp.types.CreateTaskResult | None +``` + + +Check task mode and submit to background if requested. + +**Args:** +- `component`: The MCP component +- `task_type`: Type of task ("tool", "resource", "template", "prompt") +- `arguments`: Arguments for tool/prompt/template execution +- `task_meta`: Task execution metadata. If provided, execute as background task. + +**Returns:** +- CreateTaskResult if submitted to docket, None for sync execution + +**Raises:** +- `McpError`: If mode="required" but no task metadata, or mode="forbidden" + but task metadata is present + diff --git a/docs/python-sdk/fastmcp-server-tasks-subscriptions.mdx b/docs/python-sdk/fastmcp-server-tasks-subscriptions.mdx new file mode 100644 index 000000000..2fd2e3cd4 --- /dev/null +++ b/docs/python-sdk/fastmcp-server-tasks-subscriptions.mdx @@ -0,0 +1,38 @@ +--- +title: subscriptions +sidebarTitle: subscriptions +--- + +# `fastmcp.server.tasks.subscriptions` + + +Task subscription helpers for sending MCP notifications (SEP-1686). + +Subscribes to Docket execution state changes and sends notifications/tasks/status +to clients when their tasks change state. + +This module requires fastmcp[tasks] (pydocket). It is only imported when docket is available. + + +## Functions + +### `subscribe_to_task_updates` + +```python +subscribe_to_task_updates(task_id: str, task_key: str, session: ServerSession, docket: Docket, poll_interval_ms: int = 5000) -> None +``` + + +Subscribe to Docket execution events and send MCP notifications. + +Per SEP-1686 lines 436-444, servers MAY send notifications/tasks/status +when task state changes. This is an optional optimization that reduces +client polling frequency. + +**Args:** +- `task_id`: Client-visible task ID (server-generated UUID) +- `task_key`: Internal Docket execution key (includes session, type, component) +- `session`: MCP ServerSession for sending notifications +- `docket`: Docket instance for subscribing to execution events +- `poll_interval_ms`: Poll interval in milliseconds to include in notifications + diff --git a/docs/python-sdk/fastmcp-server-telemetry.mdx b/docs/python-sdk/fastmcp-server-telemetry.mdx new file mode 100644 index 000000000..09d2b0d76 --- /dev/null +++ b/docs/python-sdk/fastmcp-server-telemetry.mdx @@ -0,0 +1,56 @@ +--- +title: telemetry +sidebarTitle: telemetry +--- + +# `fastmcp.server.telemetry` + + +Server-side telemetry helpers. + +## Functions + +### `get_auth_span_attributes` + +```python +get_auth_span_attributes() -> dict[str, str] +``` + + +Get auth attributes for the current request, if authenticated. + + +### `get_session_span_attributes` + +```python +get_session_span_attributes() -> dict[str, str] +``` + + +Get session attributes for the current request. + + +### `server_span` + +```python +server_span(name: str, method: str, server_name: str, component_type: str, component_key: str, resource_uri: str | None = None) -> Generator[Span, None, None] +``` + + +Create a SERVER span with standard MCP attributes and auth context. + +Automatically records any exception on the span and sets error status. + + +### `delegate_span` + +```python +delegate_span(name: str, provider_type: str, component_key: str) -> Generator[Span, None, None] +``` + + +Create an INTERNAL span for provider delegation. + +Used by FastMCPProvider when delegating to mounted servers. +Automatically records any exception on the span and sets error status. + diff --git a/docs/python-sdk/fastmcp-server-transforms-__init__.mdx b/docs/python-sdk/fastmcp-server-transforms-__init__.mdx new file mode 100644 index 000000000..f98150302 --- /dev/null +++ b/docs/python-sdk/fastmcp-server-transforms-__init__.mdx @@ -0,0 +1,193 @@ +--- +title: __init__ +sidebarTitle: __init__ +--- + +# `fastmcp.server.transforms` + + +Transform system for component transformations. + +Transforms modify components (tools, resources, prompts). List operations use a pure +function pattern where transforms receive sequences and return transformed sequences. +Get operations use a middleware pattern with `call_next` to chain lookups. + +Unlike middleware (which operates on requests), transforms are observable by the +system for task registration, tag filtering, and component introspection. + +Example: + ```python + from fastmcp import FastMCP + from fastmcp.server.transforms import Namespace + + server = FastMCP("Server") + mount = server.mount(other_server) + mount.add_transform(Namespace("api")) # Tools become api_toolname + ``` + + +## Classes + +### `GetToolNext` + + +Protocol for get_tool call_next functions. + + +### `GetResourceNext` + + +Protocol for get_resource call_next functions. + + +### `GetResourceTemplateNext` + + +Protocol for get_resource_template call_next functions. + + +### `GetPromptNext` + + +Protocol for get_prompt call_next functions. + + +### `Transform` + + +Base class for component transformations. + +List operations use a pure function pattern: transforms receive sequences +and return transformed sequences. Get operations use a middleware pattern +with `call_next` to chain lookups. + + +**Methods:** + +#### `list_tools` + +```python +list_tools(self, tools: Sequence[Tool]) -> Sequence[Tool] +``` + +List tools with transformation applied. + +**Args:** +- `tools`: Sequence of tools to transform. + +**Returns:** +- Transformed sequence of tools. + + +#### `get_tool` + +```python +get_tool(self, name: str, call_next: GetToolNext) -> Tool | None +``` + +Get a tool by name. + +**Args:** +- `name`: The requested tool name (may be transformed). +- `call_next`: Callable to get tool from downstream. +- `version`: Optional version filter to apply. + +**Returns:** +- The tool if found, None otherwise. + + +#### `list_resources` + +```python +list_resources(self, resources: Sequence[Resource]) -> Sequence[Resource] +``` + +List resources with transformation applied. + +**Args:** +- `resources`: Sequence of resources to transform. + +**Returns:** +- Transformed sequence of resources. + + +#### `get_resource` + +```python +get_resource(self, uri: str, call_next: GetResourceNext) -> Resource | None +``` + +Get a resource by URI. + +**Args:** +- `uri`: The requested resource URI (may be transformed). +- `call_next`: Callable to get resource from downstream. +- `version`: Optional version filter to apply. + +**Returns:** +- The resource if found, None otherwise. + + +#### `list_resource_templates` + +```python +list_resource_templates(self, templates: Sequence[ResourceTemplate]) -> Sequence[ResourceTemplate] +``` + +List resource templates with transformation applied. + +**Args:** +- `templates`: Sequence of resource templates to transform. + +**Returns:** +- Transformed sequence of resource templates. + + +#### `get_resource_template` + +```python +get_resource_template(self, uri: str, call_next: GetResourceTemplateNext) -> ResourceTemplate | None +``` + +Get a resource template by URI. + +**Args:** +- `uri`: The requested template URI (may be transformed). +- `call_next`: Callable to get template from downstream. +- `version`: Optional version filter to apply. + +**Returns:** +- The resource template if found, None otherwise. + + +#### `list_prompts` + +```python +list_prompts(self, prompts: Sequence[Prompt]) -> Sequence[Prompt] +``` + +List prompts with transformation applied. + +**Args:** +- `prompts`: Sequence of prompts to transform. + +**Returns:** +- Transformed sequence of prompts. + + +#### `get_prompt` + +```python +get_prompt(self, name: str, call_next: GetPromptNext) -> Prompt | None +``` + +Get a prompt by name. + +**Args:** +- `name`: The requested prompt name (may be transformed). +- `call_next`: Callable to get prompt from downstream. +- `version`: Optional version filter to apply. + +**Returns:** +- The prompt if found, None otherwise. + diff --git a/docs/python-sdk/fastmcp-server-transforms-catalog.mdx b/docs/python-sdk/fastmcp-server-transforms-catalog.mdx new file mode 100644 index 000000000..1dd2cfe4a --- /dev/null +++ b/docs/python-sdk/fastmcp-server-transforms-catalog.mdx @@ -0,0 +1,220 @@ +--- +title: catalog +sidebarTitle: catalog +--- + +# `fastmcp.server.transforms.catalog` + + +Base class for transforms that need to read the real component catalog. + +Some transforms replace ``list_tools()`` output with synthetic components +(e.g. a search interface) while still needing access to the *real* +(auth-filtered) catalog at call time. ``CatalogTransform`` provides the +bypass machinery so subclasses can call ``get_tool_catalog()`` without +triggering their own replacement logic. + +Re-entrancy problem +------------------- + +When a synthetic tool handler calls ``get_tool_catalog()``, that calls +``ctx.fastmcp.list_tools()`` which re-enters the transform pipeline — +including *this* transform's ``list_tools()``. If the subclass overrides +``list_tools()`` directly, the re-entrant call would hit the subclass's +replacement logic again (returning synthetic tools instead of the real +catalog). A ``super()`` call can't prevent this because Python can't +short-circuit a method after ``super()`` returns. + +Solution: ``CatalogTransform`` owns ``list_tools()`` and uses a +per-instance ``ContextVar`` to detect re-entrant calls. During bypass, +it passes through to the base ``Transform.list_tools()`` (a no-op). +Otherwise, it delegates to ``transform_tools()`` — the subclass hook +where replacement logic lives. Same pattern for resources, prompts, +and resource templates. + +This is *not* the same as the ``Provider._list_tools()`` convention +(which produces raw components with no arguments). ``transform_tools()`` +receives the current catalog and returns a transformed version. The +distinct name avoids confusion between the two patterns. + +Usage:: + + class MyTransform(CatalogTransform): + async def transform_tools(self, tools): + return [self._make_search_tool()] + + def _make_search_tool(self): + async def search(ctx: Context = None): + real_tools = await self.get_tool_catalog(ctx) + ... + return Tool.from_function(fn=search, name="search") + + +## Classes + +### `CatalogTransform` + + +Transform that needs access to the real component catalog. + +Subclasses override ``transform_tools()`` / ``transform_resources()`` +/ ``transform_prompts()`` / ``transform_resource_templates()`` +instead of the ``list_*()`` methods. The base class owns +``list_*()`` and handles re-entrant bypass automatically — subclasses +never see re-entrant calls from ``get_*_catalog()``. + +The ``get_*_catalog()`` methods fetch the real (auth-filtered) catalog +by temporarily setting a bypass flag so that this transform's +``list_*()`` passes through without calling the subclass hook. + + +**Methods:** + +#### `list_tools` + +```python +list_tools(self, tools: Sequence[Tool]) -> Sequence[Tool] +``` + +#### `list_resources` + +```python +list_resources(self, resources: Sequence[Resource]) -> Sequence[Resource] +``` + +#### `list_resource_templates` + +```python +list_resource_templates(self, templates: Sequence[ResourceTemplate]) -> Sequence[ResourceTemplate] +``` + +#### `list_prompts` + +```python +list_prompts(self, prompts: Sequence[Prompt]) -> Sequence[Prompt] +``` + +#### `transform_tools` + +```python +transform_tools(self, tools: Sequence[Tool]) -> Sequence[Tool] +``` + +Transform the tool catalog. + +Override this method to replace, filter, or augment the tool listing. +The default implementation passes through unchanged. + +Do NOT override ``list_tools()`` directly — the base class uses it +to handle re-entrant bypass when ``get_tool_catalog()`` reads the +real catalog. + + +#### `transform_resources` + +```python +transform_resources(self, resources: Sequence[Resource]) -> Sequence[Resource] +``` + +Transform the resource catalog. + +Override this method to replace, filter, or augment the resource listing. +The default implementation passes through unchanged. + +Do NOT override ``list_resources()`` directly — the base class uses it +to handle re-entrant bypass when ``get_resource_catalog()`` reads the +real catalog. + + +#### `transform_resource_templates` + +```python +transform_resource_templates(self, templates: Sequence[ResourceTemplate]) -> Sequence[ResourceTemplate] +``` + +Transform the resource template catalog. + +Override this method to replace, filter, or augment the template listing. +The default implementation passes through unchanged. + +Do NOT override ``list_resource_templates()`` directly — the base class +uses it to handle re-entrant bypass when +``get_resource_template_catalog()`` reads the real catalog. + + +#### `transform_prompts` + +```python +transform_prompts(self, prompts: Sequence[Prompt]) -> Sequence[Prompt] +``` + +Transform the prompt catalog. + +Override this method to replace, filter, or augment the prompt listing. +The default implementation passes through unchanged. + +Do NOT override ``list_prompts()`` directly — the base class uses it +to handle re-entrant bypass when ``get_prompt_catalog()`` reads the +real catalog. + + +#### `get_tool_catalog` + +```python +get_tool_catalog(self, ctx: Context) -> Sequence[Tool] +``` + +Fetch the real tool catalog, bypassing this transform. + +**Args:** +- `ctx`: The current request context. +- `run_middleware`: Whether to run middleware on the inner call. +Defaults to True because this is typically called from a +tool handler where list_tools middleware has not yet run. + + +#### `get_resource_catalog` + +```python +get_resource_catalog(self, ctx: Context) -> Sequence[Resource] +``` + +Fetch the real resource catalog, bypassing this transform. + +**Args:** +- `ctx`: The current request context. +- `run_middleware`: Whether to run middleware on the inner call. +Defaults to True because this is typically called from a +tool handler where list_resources middleware has not yet run. + + +#### `get_prompt_catalog` + +```python +get_prompt_catalog(self, ctx: Context) -> Sequence[Prompt] +``` + +Fetch the real prompt catalog, bypassing this transform. + +**Args:** +- `ctx`: The current request context. +- `run_middleware`: Whether to run middleware on the inner call. +Defaults to True because this is typically called from a +tool handler where list_prompts middleware has not yet run. + + +#### `get_resource_template_catalog` + +```python +get_resource_template_catalog(self, ctx: Context) -> Sequence[ResourceTemplate] +``` + +Fetch the real resource template catalog, bypassing this transform. + +**Args:** +- `ctx`: The current request context. +- `run_middleware`: Whether to run middleware on the inner call. +Defaults to True because this is typically called from a +tool handler where list_resource_templates middleware has +not yet run. + diff --git a/docs/python-sdk/fastmcp-server-transforms-namespace.mdx b/docs/python-sdk/fastmcp-server-transforms-namespace.mdx new file mode 100644 index 000000000..9f590356d --- /dev/null +++ b/docs/python-sdk/fastmcp-server-transforms-namespace.mdx @@ -0,0 +1,96 @@ +--- +title: namespace +sidebarTitle: namespace +--- + +# `fastmcp.server.transforms.namespace` + + +Namespace transform for prefixing component names. + +## Classes + +### `Namespace` + + +Prefixes component names with a namespace. + +- Tools: name → namespace_name +- Prompts: name → namespace_name +- Resources: protocol://path → protocol://namespace/path +- Resource Templates: same as resources + + +**Methods:** + +#### `list_tools` + +```python +list_tools(self, tools: Sequence[Tool]) -> Sequence[Tool] +``` + +Prefix tool names with namespace. + + +#### `get_tool` + +```python +get_tool(self, name: str, call_next: GetToolNext) -> Tool | None +``` + +Get tool by namespaced name. + + +#### `list_resources` + +```python +list_resources(self, resources: Sequence[Resource]) -> Sequence[Resource] +``` + +Add namespace path segment to resource URIs. + + +#### `get_resource` + +```python +get_resource(self, uri: str, call_next: GetResourceNext) -> Resource | None +``` + +Get resource by namespaced URI. + + +#### `list_resource_templates` + +```python +list_resource_templates(self, templates: Sequence[ResourceTemplate]) -> Sequence[ResourceTemplate] +``` + +Add namespace path segment to template URIs. + + +#### `get_resource_template` + +```python +get_resource_template(self, uri: str, call_next: GetResourceTemplateNext) -> ResourceTemplate | None +``` + +Get resource template by namespaced URI. + + +#### `list_prompts` + +```python +list_prompts(self, prompts: Sequence[Prompt]) -> Sequence[Prompt] +``` + +Prefix prompt names with namespace. + + +#### `get_prompt` + +```python +get_prompt(self, name: str, call_next: GetPromptNext) -> Prompt | None +``` + +Get prompt by namespaced name. + diff --git a/docs/python-sdk/fastmcp-server-transforms-prompts_as_tools.mdx b/docs/python-sdk/fastmcp-server-transforms-prompts_as_tools.mdx new file mode 100644 index 000000000..f1656c263 --- /dev/null +++ b/docs/python-sdk/fastmcp-server-transforms-prompts_as_tools.mdx @@ -0,0 +1,59 @@ +--- +title: prompts_as_tools +sidebarTitle: prompts_as_tools +--- + +# `fastmcp.server.transforms.prompts_as_tools` + + +Transform that exposes prompts as tools. + +This transform generates tools for listing and getting prompts, enabling +clients that only support tools to access prompt functionality. + +Example: + ```python + from fastmcp import FastMCP + from fastmcp.server.transforms import PromptsAsTools + + mcp = FastMCP("Server") + mcp.add_transform(PromptsAsTools(mcp)) + # Now has list_prompts and get_prompt tools + ``` + + +## Classes + +### `PromptsAsTools` + + +Transform that adds tools for listing and getting prompts. + +Generates two tools: +- `list_prompts`: Lists all prompts from the provider +- `get_prompt`: Gets a specific prompt with optional arguments + +The transform captures a provider reference at construction and queries it +for prompts when the generated tools are called. When used with FastMCP, +the provider's auth and visibility filtering is automatically applied. + + +**Methods:** + +#### `list_tools` + +```python +list_tools(self, tools: Sequence[Tool]) -> Sequence[Tool] +``` + +Add prompt tools to the tool list. + + +#### `get_tool` + +```python +get_tool(self, name: str, call_next: GetToolNext) -> Tool | None +``` + +Get a tool by name, including generated prompt tools. + diff --git a/docs/python-sdk/fastmcp-server-transforms-resources_as_tools.mdx b/docs/python-sdk/fastmcp-server-transforms-resources_as_tools.mdx new file mode 100644 index 000000000..3b46e875c --- /dev/null +++ b/docs/python-sdk/fastmcp-server-transforms-resources_as_tools.mdx @@ -0,0 +1,59 @@ +--- +title: resources_as_tools +sidebarTitle: resources_as_tools +--- + +# `fastmcp.server.transforms.resources_as_tools` + + +Transform that exposes resources as tools. + +This transform generates tools for listing and reading resources, enabling +clients that only support tools to access resource functionality. + +Example: + ```python + from fastmcp import FastMCP + from fastmcp.server.transforms import ResourcesAsTools + + mcp = FastMCP("Server") + mcp.add_transform(ResourcesAsTools(mcp)) + # Now has list_resources and read_resource tools + ``` + + +## Classes + +### `ResourcesAsTools` + + +Transform that adds tools for listing and reading resources. + +Generates two tools: +- `list_resources`: Lists all resources and templates from the provider +- `read_resource`: Reads a resource by URI + +The transform captures a provider reference at construction and queries it +for resources when the generated tools are called. When used with FastMCP, +the provider's auth and visibility filtering is automatically applied. + + +**Methods:** + +#### `list_tools` + +```python +list_tools(self, tools: Sequence[Tool]) -> Sequence[Tool] +``` + +Add resource tools to the tool list. + + +#### `get_tool` + +```python +get_tool(self, name: str, call_next: GetToolNext) -> Tool | None +``` + +Get a tool by name, including generated resource tools. + diff --git a/docs/python-sdk/fastmcp-server-transforms-search-__init__.mdx b/docs/python-sdk/fastmcp-server-transforms-search-__init__.mdx new file mode 100644 index 000000000..80b71d226 --- /dev/null +++ b/docs/python-sdk/fastmcp-server-transforms-search-__init__.mdx @@ -0,0 +1,23 @@ +--- +title: __init__ +sidebarTitle: __init__ +--- + +# `fastmcp.server.transforms.search` + + +Search transforms for tool discovery. + +Search transforms collapse a large tool catalog into a search interface, +letting LLMs discover tools on demand instead of seeing the full list. + +Example: + ```python + from fastmcp import FastMCP + from fastmcp.server.transforms.search import RegexSearchTransform + + mcp = FastMCP("Server") + mcp.add_transform(RegexSearchTransform()) + # list_tools now returns only search_tools + call_tool + ``` + diff --git a/docs/python-sdk/fastmcp-server-transforms-search-base.mdx b/docs/python-sdk/fastmcp-server-transforms-search-base.mdx new file mode 100644 index 000000000..7ecd3b5f2 --- /dev/null +++ b/docs/python-sdk/fastmcp-server-transforms-search-base.mdx @@ -0,0 +1,105 @@ +--- +title: base +sidebarTitle: base +--- + +# `fastmcp.server.transforms.search.base` + + +Base class for search transforms. + +Search transforms replace ``list_tools()`` output with a small set of +synthetic tools — a search tool and a call-tool proxy — so LLMs can +discover tools on demand instead of receiving the full catalog. + +All concrete search transforms (``RegexSearchTransform``, +``BM25SearchTransform``, etc.) inherit from ``BaseSearchTransform`` and +implement ``_make_search_tool()`` and ``_search()`` to provide their +specific search strategy. + +Example:: + + from fastmcp import FastMCP + from fastmcp.server.transforms.search import RegexSearchTransform + + mcp = FastMCP("Server") + + @mcp.tool + def add(a: int, b: int) -> int: ... + + @mcp.tool + def multiply(x: float, y: float) -> float: ... + + # Clients now see only ``search_tools`` and ``call_tool``. + # The original tools are discoverable via search. + mcp.add_transform(RegexSearchTransform()) + + +## Functions + +### `serialize_tools_for_output_json` + +```python +serialize_tools_for_output_json(tools: Sequence[Tool]) -> list[dict[str, Any]] +``` + + +Serialize tools to the same dict format as ``list_tools`` output. + + +### `serialize_tools_for_output_markdown` + +```python +serialize_tools_for_output_markdown(tools: Sequence[Tool]) -> str +``` + + +Serialize tools to compact markdown, using ~65-70% fewer tokens than JSON. + + +## Classes + +### `BaseSearchTransform` + + +Replace the tool listing with a search interface. + +When this transform is active, ``list_tools()`` returns only: + +* Any tools listed in ``always_visible`` (pinned). +* A **search tool** that finds tools matching a query. +* A **call_tool** proxy that executes tools discovered via search. + +Hidden tools remain callable — ``get_tool()`` delegates unknown +names downstream, so direct calls and the call-tool proxy both work. + +Search results respect the full auth pipeline: middleware, visibility +transforms, and component-level auth checks all apply. + +**Args:** +- `max_results`: Maximum number of tools returned per search. +- `always_visible`: Tool names that stay in the ``list_tools`` +output alongside the synthetic search/call tools. +- `search_tool_name`: Name of the generated search tool. +- `call_tool_name`: Name of the generated call-tool proxy. + + +**Methods:** + +#### `transform_tools` + +```python +transform_tools(self, tools: Sequence[Tool]) -> Sequence[Tool] +``` + +Replace the catalog with pinned + synthetic search/call tools. + + +#### `get_tool` + +```python +get_tool(self, name: str, call_next: GetToolNext) -> Tool | None +``` + +Intercept synthetic tool names; delegate everything else. + diff --git a/docs/python-sdk/fastmcp-server-transforms-search-bm25.mdx b/docs/python-sdk/fastmcp-server-transforms-search-bm25.mdx new file mode 100644 index 000000000..d5264f46a --- /dev/null +++ b/docs/python-sdk/fastmcp-server-transforms-search-bm25.mdx @@ -0,0 +1,20 @@ +--- +title: bm25 +sidebarTitle: bm25 +--- + +# `fastmcp.server.transforms.search.bm25` + + +BM25-based search transform. + +## Classes + +### `BM25SearchTransform` + + +Search transform using BM25 Okapi relevance ranking. + +Maintains an in-memory index that is lazily rebuilt when the tool +catalog changes (detected via a hash of tool names). + diff --git a/docs/python-sdk/fastmcp-server-transforms-search-regex.mdx b/docs/python-sdk/fastmcp-server-transforms-search-regex.mdx new file mode 100644 index 000000000..e36c8d25e --- /dev/null +++ b/docs/python-sdk/fastmcp-server-transforms-search-regex.mdx @@ -0,0 +1,20 @@ +--- +title: regex +sidebarTitle: regex +--- + +# `fastmcp.server.transforms.search.regex` + + +Regex-based search transform. + +## Classes + +### `RegexSearchTransform` + + +Search transform using regex pattern matching. + +Tools are matched against their name, description, and parameter +information using ``re.search`` with ``re.IGNORECASE``. + diff --git a/docs/python-sdk/fastmcp-server-transforms-tool_transform.mdx b/docs/python-sdk/fastmcp-server-transforms-tool_transform.mdx new file mode 100644 index 000000000..d911f4819 --- /dev/null +++ b/docs/python-sdk/fastmcp-server-transforms-tool_transform.mdx @@ -0,0 +1,40 @@ +--- +title: tool_transform +sidebarTitle: tool_transform +--- + +# `fastmcp.server.transforms.tool_transform` + + +Transform for applying tool transformations. + +## Classes + +### `ToolTransform` + + +Applies tool transformations to modify tool schemas. + +Wraps ToolTransformConfig to apply argument renames, schema changes, +hidden arguments, and other transformations at the transform level. + + +**Methods:** + +#### `list_tools` + +```python +list_tools(self, tools: Sequence[Tool]) -> Sequence[Tool] +``` + +Apply transforms to matching tools. + + +#### `get_tool` + +```python +get_tool(self, name: str, call_next: GetToolNext) -> Tool | None +``` + +Get tool by transformed name. + diff --git a/docs/python-sdk/fastmcp-server-transforms-version_filter.mdx b/docs/python-sdk/fastmcp-server-transforms-version_filter.mdx new file mode 100644 index 000000000..7902c0a0a --- /dev/null +++ b/docs/python-sdk/fastmcp-server-transforms-version_filter.mdx @@ -0,0 +1,89 @@ +--- +title: version_filter +sidebarTitle: version_filter +--- + +# `fastmcp.server.transforms.version_filter` + + +Version filter transform for filtering components by version range. + +## Classes + +### `VersionFilter` + + +Filters components by version range. + +When applied to a provider or server, components within the version range +are visible, and unversioned components are included by default. Within +that filtered set, the highest version of each component is exposed to +clients (standard deduplication behavior). Set +``include_unversioned=False`` to exclude unversioned components. + +Parameters mirror comparison operators for clarity: + + # Versions < 3.0 (v1 and v2) + server.add_transform(VersionFilter(version_lt="3.0")) + + # Versions >= 2.0 and < 3.0 (only v2.x) + server.add_transform(VersionFilter(version_gte="2.0", version_lt="3.0")) + +Works with any version string - PEP 440 (1.0, 2.0) or dates (2025-01-01). + +**Args:** +- `version_gte`: Versions >= this value pass through. +- `version_lt`: Versions < this value pass through. +- `include_unversioned`: Whether unversioned components (``version=None``) +should pass through the filter. Defaults to True. + + +**Methods:** + +#### `list_tools` + +```python +list_tools(self, tools: Sequence[Tool]) -> Sequence[Tool] +``` + +#### `get_tool` + +```python +get_tool(self, name: str, call_next: GetToolNext) -> Tool | None +``` + +#### `list_resources` + +```python +list_resources(self, resources: Sequence[Resource]) -> Sequence[Resource] +``` + +#### `get_resource` + +```python +get_resource(self, uri: str, call_next: GetResourceNext) -> Resource | None +``` + +#### `list_resource_templates` + +```python +list_resource_templates(self, templates: Sequence[ResourceTemplate]) -> Sequence[ResourceTemplate] +``` + +#### `get_resource_template` + +```python +get_resource_template(self, uri: str, call_next: GetResourceTemplateNext) -> ResourceTemplate | None +``` + +#### `list_prompts` + +```python +list_prompts(self, prompts: Sequence[Prompt]) -> Sequence[Prompt] +``` + +#### `get_prompt` + +```python +get_prompt(self, name: str, call_next: GetPromptNext) -> Prompt | None +``` diff --git a/docs/python-sdk/fastmcp-server-transforms-visibility.mdx b/docs/python-sdk/fastmcp-server-transforms-visibility.mdx new file mode 100644 index 000000000..772cddc97 --- /dev/null +++ b/docs/python-sdk/fastmcp-server-transforms-visibility.mdx @@ -0,0 +1,261 @@ +--- +title: visibility +sidebarTitle: visibility +--- + +# `fastmcp.server.transforms.visibility` + + +Visibility transform for marking component visibility state. + +Each Visibility instance marks components via internal metadata. Multiple +visibility transforms can be stacked - later transforms override earlier ones. +Final filtering happens at the Provider level. + + +## Functions + +### `is_enabled` + +```python +is_enabled(component: FastMCPComponent) -> bool +``` + + +Check if component is enabled. + +Returns True if: +- No visibility mark exists (default is enabled) +- Visibility mark is True + +Returns False if visibility mark is False. + +**Args:** +- `component`: Component to check. + +**Returns:** +- True if component should be enabled/visible to clients. + + +### `get_visibility_rules` + +```python +get_visibility_rules(context: Context) -> list[dict[str, Any]] +``` + + +Load visibility rule dicts from session state. + + +### `save_visibility_rules` + +```python +save_visibility_rules(context: Context, rules: list[dict[str, Any]]) -> None +``` + + +Save visibility rule dicts to session state and send notifications. + +**Args:** +- `context`: The context to save rules for. +- `rules`: The visibility rules to save. +- `components`: Optional hint about which component types are affected. +If None, sends notifications for all types (safe default). +If provided, only sends notifications for specified types. + + +### `create_visibility_transforms` + +```python +create_visibility_transforms(rules: list[dict[str, Any]]) -> list[Visibility] +``` + + +Convert rule dicts to Visibility transforms. + + +### `get_session_transforms` + +```python +get_session_transforms(context: Context) -> list[Visibility] +``` + + +Get session-specific Visibility transforms from state store. + + +### `enable_components` + +```python +enable_components(context: Context) -> None +``` + + +Enable components matching criteria for this session only. + +Session rules override global transforms. Rules accumulate - each call +adds a new rule to the session. Later marks override earlier ones +(Visibility transform semantics). + +Sends notifications to this session only: ToolListChangedNotification, +ResourceListChangedNotification, and PromptListChangedNotification. + +**Args:** +- `context`: The context for this session. +- `names`: Component names or URIs to match. +- `keys`: Component keys to match (e.g., {"tool\:my_tool@v1"}). +- `version`: Component version spec to match. +- `tags`: Tags to match (component must have at least one). +- `components`: Component types to match (e.g., {"tool", "prompt"}). +- `match_all`: If True, matches all components regardless of other criteria. + + +### `disable_components` + +```python +disable_components(context: Context) -> None +``` + + +Disable components matching criteria for this session only. + +Session rules override global transforms. Rules accumulate - each call +adds a new rule to the session. Later marks override earlier ones +(Visibility transform semantics). + +Sends notifications to this session only: ToolListChangedNotification, +ResourceListChangedNotification, and PromptListChangedNotification. + +**Args:** +- `context`: The context for this session. +- `names`: Component names or URIs to match. +- `keys`: Component keys to match (e.g., {"tool\:my_tool@v1"}). +- `version`: Component version spec to match. +- `tags`: Tags to match (component must have at least one). +- `components`: Component types to match (e.g., {"tool", "prompt"}). +- `match_all`: If True, matches all components regardless of other criteria. + + +### `reset_visibility` + +```python +reset_visibility(context: Context) -> None +``` + + +Clear all session visibility rules. + +Use this to reset session visibility back to global defaults. + +Sends notifications to this session only: ToolListChangedNotification, +ResourceListChangedNotification, and PromptListChangedNotification. + +**Args:** +- `context`: The context for this session. + + +### `apply_session_transforms` + +```python +apply_session_transforms(components: Sequence[ComponentT]) -> Sequence[ComponentT] +``` + + +Apply session-specific visibility transforms to components. + +This helper applies session-level enable/disable rules by marking +components with their visibility state. Session transforms override +global transforms due to mark-based semantics (later marks win). + +**Args:** +- `components`: The components to apply session transforms to. + +**Returns:** +- The components with session transforms applied. + + +## Classes + +### `Visibility` + + +Sets visibility state on matching components. + +Does NOT filter inline - just marks components with visibility state. +Later transforms in the chain can override earlier marks. +Final filtering happens at the Provider level after all transforms run. + + +**Methods:** + +#### `list_tools` + +```python +list_tools(self, tools: Sequence[Tool]) -> Sequence[Tool] +``` + +Mark tools by visibility state. + + +#### `get_tool` + +```python +get_tool(self, name: str, call_next: GetToolNext) -> Tool | None +``` + +Mark tool if found. + + +#### `list_resources` + +```python +list_resources(self, resources: Sequence[Resource]) -> Sequence[Resource] +``` + +Mark resources by visibility state. + + +#### `get_resource` + +```python +get_resource(self, uri: str, call_next: GetResourceNext) -> Resource | None +``` + +Mark resource if found. + + +#### `list_resource_templates` + +```python +list_resource_templates(self, templates: Sequence[ResourceTemplate]) -> Sequence[ResourceTemplate] +``` + +Mark resource templates by visibility state. + + +#### `get_resource_template` + +```python +get_resource_template(self, uri: str, call_next: GetResourceTemplateNext) -> ResourceTemplate | None +``` + +Mark resource template if found. + + +#### `list_prompts` + +```python +list_prompts(self, prompts: Sequence[Prompt]) -> Sequence[Prompt] +``` + +Mark prompts by visibility state. + + +#### `get_prompt` + +```python +get_prompt(self, name: str, call_next: GetPromptNext) -> Prompt | None +``` + +Mark prompt if found. + diff --git a/docs/python-sdk/fastmcp-settings.mdx b/docs/python-sdk/fastmcp-settings.mdx new file mode 100644 index 000000000..eeb1156f8 --- /dev/null +++ b/docs/python-sdk/fastmcp-settings.mdx @@ -0,0 +1,48 @@ +--- +title: settings +sidebarTitle: settings +--- + +# `fastmcp.settings` + +## Classes + +### `DocketSettings` + + +Docket worker configuration. + + +### `Settings` + + +FastMCP settings. + + +**Methods:** + +#### `get_setting` + +```python +get_setting(self, attr: str) -> Any +``` + +Get a setting. If the setting contains one or more `__`, it will be +treated as a nested setting. + + +#### `set_setting` + +```python +set_setting(self, attr: str, value: Any) -> None +``` + +Set a setting. If the setting contains one or more `__`, it will be +treated as a nested setting. + + +#### `normalize_log_level` + +```python +normalize_log_level(cls, v) +``` diff --git a/docs/python-sdk/fastmcp-telemetry.mdx b/docs/python-sdk/fastmcp-telemetry.mdx new file mode 100644 index 000000000..757e41fb9 --- /dev/null +++ b/docs/python-sdk/fastmcp-telemetry.mdx @@ -0,0 +1,95 @@ +--- +title: telemetry +sidebarTitle: telemetry +--- + +# `fastmcp.telemetry` + + +OpenTelemetry instrumentation for FastMCP. + +This module provides native OpenTelemetry integration for FastMCP servers and clients. +It uses only the opentelemetry-api package, so telemetry is a no-op unless the user +installs an OpenTelemetry SDK and configures exporters. + +Example usage with SDK: + ```python + from opentelemetry import trace + from opentelemetry.sdk.trace import TracerProvider + from opentelemetry.sdk.trace.export import ConsoleSpanExporter, SimpleSpanProcessor + + # Configure the SDK (user responsibility) + provider = TracerProvider() + provider.add_span_processor(SimpleSpanProcessor(ConsoleSpanExporter())) + trace.set_tracer_provider(provider) + + # Now FastMCP will emit traces + from fastmcp import FastMCP + mcp = FastMCP("my-server") + ``` + + +## Functions + +### `get_tracer` + +```python +get_tracer(version: str | None = None) -> Tracer +``` + + +Get the FastMCP tracer for creating spans. + +**Args:** +- `version`: Optional version string for the instrumentation + +**Returns:** +- A tracer instance. Returns a no-op tracer if no SDK is configured. + + +### `inject_trace_context` + +```python +inject_trace_context(meta: dict[str, Any] | None = None) -> dict[str, Any] | None +``` + + +Inject current trace context into a meta dict for MCP request propagation. + +**Args:** +- `meta`: Optional existing meta dict to merge with trace context + +**Returns:** +- A new dict containing the original meta (if any) plus trace context keys, +- or None if no trace context to inject and meta was None + + +### `record_span_error` + +```python +record_span_error(span: Span, exception: BaseException) -> None +``` + + +Record an exception on a span and set error status. + + +### `extract_trace_context` + +```python +extract_trace_context(meta: dict[str, Any] | None) -> Context +``` + + +Extract trace context from an MCP request meta dict. + +If already in a valid trace (e.g., from HTTP propagation), the existing +trace context is preserved and meta is not used. + +**Args:** +- `meta`: The meta dict from an MCP request (ctx.request_context.meta) + +**Returns:** +- An OpenTelemetry Context with the extracted trace context, +- or the current context if no trace context found or already in a trace + diff --git a/docs/python-sdk/fastmcp-tools-__init__.mdx b/docs/python-sdk/fastmcp-tools-__init__.mdx new file mode 100644 index 000000000..5b7c8b04d --- /dev/null +++ b/docs/python-sdk/fastmcp-tools-__init__.mdx @@ -0,0 +1,8 @@ +--- +title: __init__ +sidebarTitle: __init__ +--- + +# `fastmcp.tools` + +*This module is empty or contains only private/internal implementations.* diff --git a/docs/python-sdk/fastmcp-tools-function_parsing.mdx b/docs/python-sdk/fastmcp-tools-function_parsing.mdx new file mode 100644 index 000000000..f9cd7f28e --- /dev/null +++ b/docs/python-sdk/fastmcp-tools-function_parsing.mdx @@ -0,0 +1,21 @@ +--- +title: function_parsing +sidebarTitle: function_parsing +--- + +# `fastmcp.tools.function_parsing` + + +Function introspection and schema generation for FastMCP tools. + +## Classes + +### `ParsedFunction` + +**Methods:** + +#### `from_function` + +```python +from_function(cls, fn: Callable[..., Any], exclude_args: list[str] | None = None, validate: bool = True, wrap_non_object_output_schema: bool = True) -> ParsedFunction +``` diff --git a/docs/python-sdk/fastmcp-tools-function_tool.mdx b/docs/python-sdk/fastmcp-tools-function_tool.mdx new file mode 100644 index 000000000..d25c6ecf8 --- /dev/null +++ b/docs/python-sdk/fastmcp-tools-function_tool.mdx @@ -0,0 +1,108 @@ +--- +title: function_tool +sidebarTitle: function_tool +--- + +# `fastmcp.tools.function_tool` + + +Standalone @tool decorator for FastMCP. + +## Functions + +### `tool` + +```python +tool(name_or_fn: str | Callable[..., Any] | None = None) -> Any +``` + + +Standalone decorator to mark a function as an MCP tool. + +Returns the original function with metadata attached. Register with a server +using mcp.add_tool(). + + +## Classes + +### `DecoratedTool` + + +Protocol for functions decorated with @tool. + + +### `ToolMeta` + + +Metadata attached to functions by the @tool decorator. + + +### `FunctionTool` + +**Methods:** + +#### `to_mcp_tool` + +```python +to_mcp_tool(self, **overrides: Any) -> mcp.types.Tool +``` + +Convert the FastMCP tool to an MCP tool. + +Extends the base implementation to add task execution mode if enabled. + + +#### `from_function` + +```python +from_function(cls, fn: Callable[..., Any]) -> FunctionTool +``` + +Create a FunctionTool from a function. + +**Args:** +- `fn`: The function to wrap +- `metadata`: ToolMeta object with all configuration. If provided, +individual parameters must not be passed. +- `name, title, etc.`: Individual parameters for backwards compatibility. +Cannot be used together with metadata parameter. + + +#### `run` + +```python +run(self, arguments: dict[str, Any]) -> ToolResult +``` + +Run the tool with arguments. + + +#### `register_with_docket` + +```python +register_with_docket(self, docket: Docket) -> None +``` + +Register this tool with docket for background execution. + +FunctionTool registers the underlying function, which has the user's +Depends parameters for docket to resolve. + + +#### `add_to_docket` + +```python +add_to_docket(self, docket: Docket, arguments: dict[str, Any], **kwargs: Any) -> Execution +``` + +Schedule this tool for background execution via docket. + +FunctionTool splats the arguments dict since .fn expects **kwargs. + +**Args:** +- `docket`: The Docket instance +- `arguments`: Tool arguments +- `fn_key`: Function lookup key in Docket registry (defaults to self.key) +- `task_key`: Redis storage key for the result +- `**kwargs`: Additional kwargs passed to docket.add() + diff --git a/docs/python-sdk/fastmcp-tools-tool.mdx b/docs/python-sdk/fastmcp-tools-tool.mdx new file mode 100644 index 000000000..0394bf4a5 --- /dev/null +++ b/docs/python-sdk/fastmcp-tools-tool.mdx @@ -0,0 +1,116 @@ +--- +title: tool +sidebarTitle: tool +--- + +# `fastmcp.tools.tool` + +## Functions + +### `default_serializer` + +```python +default_serializer(data: Any) -> str +``` + +## Classes + +### `ToolResult` + +**Methods:** + +#### `to_mcp_result` + +```python +to_mcp_result(self) -> list[ContentBlock] | tuple[list[ContentBlock], dict[str, Any]] | CallToolResult +``` + +### `Tool` + + +Internal tool registration info. + + +**Methods:** + +#### `to_mcp_tool` + +```python +to_mcp_tool(self, **overrides: Any) -> MCPTool +``` + +Convert the FastMCP tool to an MCP tool. + + +#### `from_function` + +```python +from_function(cls, fn: Callable[..., Any]) -> FunctionTool +``` + +Create a Tool from a function. + + +#### `run` + +```python +run(self, arguments: dict[str, Any]) -> ToolResult +``` + +Run the tool with arguments. + +This method is not implemented in the base Tool class and must be +implemented by subclasses. + +`run()` can EITHER return a list of ContentBlocks, or a tuple of +(list of ContentBlocks, dict of structured output). + + +#### `convert_result` + +```python +convert_result(self, raw_value: Any) -> ToolResult +``` + +Convert a raw result to ToolResult. + +Handles ToolResult passthrough and converts raw values using the tool's +attributes (serializer, output_schema) for proper conversion. + + +#### `register_with_docket` + +```python +register_with_docket(self, docket: Docket) -> None +``` + +Register this tool with docket for background execution. + + +#### `add_to_docket` + +```python +add_to_docket(self, docket: Docket, arguments: dict[str, Any], **kwargs: Any) -> Execution +``` + +Schedule this tool for background execution via docket. + +**Args:** +- `docket`: The Docket instance +- `arguments`: Tool arguments +- `fn_key`: Function lookup key in Docket registry (defaults to self.key) +- `task_key`: Redis storage key for the result +- `**kwargs`: Additional kwargs passed to docket.add() + + +#### `from_tool` + +```python +from_tool(cls, tool: Tool | Callable[..., Any]) -> TransformedTool +``` + +#### `get_span_attributes` + +```python +get_span_attributes(self) -> dict[str, Any] +``` diff --git a/docs/python-sdk/fastmcp-tools-tool_transform.mdx b/docs/python-sdk/fastmcp-tools-tool_transform.mdx new file mode 100644 index 000000000..84a1b66cf --- /dev/null +++ b/docs/python-sdk/fastmcp-tools-tool_transform.mdx @@ -0,0 +1,311 @@ +--- +title: tool_transform +sidebarTitle: tool_transform +--- + +# `fastmcp.tools.tool_transform` + +## Functions + +### `forward` + +```python +forward(**kwargs: Any) -> ToolResult +``` + + +Forward to parent tool with argument transformation applied. + +This function can only be called from within a transformed tool's custom +function. It applies argument transformation (renaming, validation) before +calling the parent tool. + +For example, if the parent tool has args `x` and `y`, but the transformed +tool has args `a` and `b`, and an `transform_args` was provided that maps `x` to +`a` and `y` to `b`, then `forward(a=1, b=2)` will call the parent tool with +`x=1` and `y=2`. + +**Args:** +- `**kwargs`: Arguments to forward to the parent tool (using transformed names). + +**Returns:** +- The ToolResult from the parent tool execution. + +**Raises:** +- `RuntimeError`: If called outside a transformed tool context. +- `TypeError`: If provided arguments don't match the transformed schema. + + +### `forward_raw` + +```python +forward_raw(**kwargs: Any) -> ToolResult +``` + + +Forward directly to parent tool without transformation. + +This function bypasses all argument transformation and validation, calling the parent +tool directly with the provided arguments. Use this when you need to call the parent +with its original parameter names and structure. + +For example, if the parent tool has args `x` and `y`, then `forward_raw(x=1, +y=2)` will call the parent tool with `x=1` and `y=2`. + +**Args:** +- `**kwargs`: Arguments to pass directly to the parent tool (using original names). + +**Returns:** +- The ToolResult from the parent tool execution. + +**Raises:** +- `RuntimeError`: If called outside a transformed tool context. + + +### `apply_transformations_to_tools` + +```python +apply_transformations_to_tools(tools: dict[str, Tool], transformations: dict[str, ToolTransformConfig]) -> dict[str, Tool] +``` + + +Apply a list of transformations to a list of tools. Tools that do not have any transformations +are left unchanged. + +Note: tools dict is keyed by prefixed key (e.g., "tool:my_tool"), +but transformations are keyed by tool name (e.g., "my_tool"). + + +## Classes + +### `ArgTransform` + + +Configuration for transforming a parent tool's argument. + +This class allows fine-grained control over how individual arguments are transformed +when creating a new tool from an existing one. You can rename arguments, change their +descriptions, add default values, or hide them from clients while passing constants. + +**Attributes:** +- `name`: New name for the argument. Use None to keep original name, or ... for no change. +- `description`: New description for the argument. Use None to remove description, or ... for no change. +- `default`: New default value for the argument. Use ... for no change. +- `default_factory`: Callable that returns a default value. Cannot be used with default. +- `type`: New type for the argument. Use ... for no change. +- `hide`: If True, hide this argument from clients but pass a constant value to parent. +- `required`: If True, make argument required (remove default). Use ... for no change. +- `examples`: Examples for the argument. Use ... for no change. + +**Examples:** + +Rename argument 'old_name' to 'new_name' +```python +ArgTransform(name="new_name") +``` + +Change description only +```python +ArgTransform(description="Updated description") +``` + +Add a default value (makes argument optional) +```python +ArgTransform(default=42) +``` + +Add a default factory (makes argument optional) +```python +ArgTransform(default_factory=lambda: time.time()) +``` + +Change the type +```python +ArgTransform(type=str) +``` + +Hide the argument entirely from clients +```python +ArgTransform(hide=True) +``` + +Hide argument but pass a constant value to parent +```python +ArgTransform(hide=True, default="constant_value") +``` + +Hide argument but pass a factory-generated value to parent +```python +ArgTransform(hide=True, default_factory=lambda: uuid.uuid4().hex) +``` + +Make an optional parameter required (removes any default) +```python +ArgTransform(required=True) +``` + +Combine multiple transformations +```python +ArgTransform(name="new_name", description="New desc", default=None, type=int) +``` + + +### `ArgTransformConfig` + + +A model for requesting a single argument transform. + + +**Methods:** + +#### `to_arg_transform` + +```python +to_arg_transform(self) -> ArgTransform +``` + +Convert the argument transform to a FastMCP argument transform. + + +### `TransformedTool` + + +A tool that is transformed from another tool. + +This class represents a tool that has been created by transforming another tool. +It supports argument renaming, schema modification, custom function injection, +structured output control, and provides context for the forward() and forward_raw() functions. + +The transformation can be purely schema-based (argument renaming, dropping, etc.) +or can include a custom function that uses forward() to call the parent tool +with transformed arguments. Output schemas and structured outputs are automatically +inherited from the parent tool but can be overridden or disabled. + +**Attributes:** +- `parent_tool`: The original tool that this tool was transformed from. +- `fn`: The function to execute when this tool is called (either the forwarding +function for pure transformations or a custom user function). +- `forwarding_fn`: Internal function that handles argument transformation and +validation when forward() is called from custom functions. + + +**Methods:** + +#### `run` + +```python +run(self, arguments: dict[str, Any]) -> ToolResult +``` + +Run the tool with context set for forward() functions. + +This method executes the tool's function while setting up the context +that allows forward() and forward_raw() to work correctly within custom +functions. + +**Args:** +- `arguments`: Dictionary of arguments to pass to the tool's function. + +**Returns:** +- ToolResult object containing content and optional structured output. + + +#### `from_tool` + +```python +from_tool(cls, tool: Tool | Callable[..., Any], name: str | None = None, version: str | NotSetT | None = NotSet, title: str | NotSetT | None = NotSet, description: str | NotSetT | None = NotSet, tags: set[str] | None = None, transform_fn: Callable[..., Any] | None = None, transform_args: dict[str, ArgTransform] | None = None, annotations: ToolAnnotations | NotSetT | None = NotSet, output_schema: dict[str, Any] | NotSetT | None = NotSet, serializer: Callable[[Any], str] | NotSetT | None = NotSet, meta: dict[str, Any] | NotSetT | None = NotSet) -> TransformedTool +``` + +Create a transformed tool from a parent tool. + +**Args:** +- `tool`: The parent tool to transform. +- `transform_fn`: Optional custom function. Can use forward() and forward_raw() +to call the parent tool. Functions with **kwargs receive transformed +argument names. +- `name`: New name for the tool. Defaults to parent tool's name. +- `version`: New version for the tool. Defaults to parent tool's version. +- `title`: New title for the tool. Defaults to parent tool's title. +- `transform_args`: Optional transformations for parent tool arguments. +Only specified arguments are transformed, others pass through unchanged\: +- Simple rename (str) +- Complex transformation (rename/description/default/drop) (ArgTransform) +- Drop the argument (None) +- `description`: New description. Defaults to parent's description. +- `tags`: New tags. Defaults to parent's tags. +- `annotations`: New annotations. Defaults to parent's annotations. +- `output_schema`: Control output schema for structured outputs\: +- None (default)\: Inherit from transform_fn if available, then parent tool +- dict\: Use custom output schema +- False\: Disable output schema and structured outputs +- `serializer`: Deprecated. Return ToolResult from your tools for full control over serialization. +- `meta`: Control meta information\: +- NotSet (default)\: Inherit from parent tool +- dict\: Use custom meta information +- None\: Remove meta information + +**Returns:** +- TransformedTool with the specified transformations. + +**Examples:** + +# Transform specific arguments only +```python +Tool.from_tool(parent, transform_args={"old": "new"}) # Others unchanged +``` + +# Custom function with partial transforms +```python +async def custom(x: int, y: int) -> str: + result = await forward(x=x, y=y) + return f"Custom: {result}" + +Tool.from_tool(parent, transform_fn=custom, transform_args={"a": "x", "b": "y"}) +``` + +# Using **kwargs (gets all args, transformed and untransformed) +```python +async def flexible(**kwargs) -> str: + result = await forward(**kwargs) + return f"Got: {kwargs}" + +Tool.from_tool(parent, transform_fn=flexible, transform_args={"a": "x"}) +``` + +# Control structured outputs and schemas +```python +# Custom output schema +Tool.from_tool(parent, output_schema={ + "type": "object", + "properties": {"status": {"type": "string"}} +}) + +# Disable structured outputs +Tool.from_tool(parent, output_schema=None) + +# Return ToolResult for full control +async def custom_output(**kwargs) -> ToolResult: + result = await forward(**kwargs) + return ToolResult( + content=[TextContent(text="Summary")], + structured_content={"processed": True} + ) +``` + + +### `ToolTransformConfig` + + +Provides a way to transform a tool. + + +**Methods:** + +#### `apply` + +```python +apply(self, tool: Tool) -> TransformedTool +``` + +Create a TransformedTool from a provided tool and this transformation configuration. + diff --git a/docs/python-sdk/fastmcp-utilities-__init__.mdx b/docs/python-sdk/fastmcp-utilities-__init__.mdx new file mode 100644 index 000000000..12e12b4ed --- /dev/null +++ b/docs/python-sdk/fastmcp-utilities-__init__.mdx @@ -0,0 +1,9 @@ +--- +title: __init__ +sidebarTitle: __init__ +--- + +# `fastmcp.utilities` + + +FastMCP utility modules. diff --git a/docs/python-sdk/fastmcp-utilities-async_utils.mdx b/docs/python-sdk/fastmcp-utilities-async_utils.mdx new file mode 100644 index 000000000..cfd0cd7ab --- /dev/null +++ b/docs/python-sdk/fastmcp-utilities-async_utils.mdx @@ -0,0 +1,44 @@ +--- +title: async_utils +sidebarTitle: async_utils +--- + +# `fastmcp.utilities.async_utils` + + +Async utilities for FastMCP. + +## Functions + +### `call_sync_fn_in_threadpool` + +```python +call_sync_fn_in_threadpool(fn: Callable[..., Any], *args: Any, **kwargs: Any) -> Any +``` + + +Call a sync function in a threadpool to avoid blocking the event loop. + +Uses anyio.to_thread.run_sync which properly propagates contextvars, +making this safe for functions that depend on context (like dependency injection). + + +### `gather` + +```python +gather(*awaitables: Awaitable[T]) -> list[T] | list[T | BaseException] +``` + + +Run awaitables concurrently and return results in order. + +Uses anyio TaskGroup for structured concurrency. + +**Args:** +- `*awaitables`: Awaitables to run concurrently +- `return_exceptions`: If True, exceptions are returned in results. + If False, first exception cancels all and raises. + +**Returns:** +- List of results in the same order as input awaitables. + diff --git a/docs/python-sdk/fastmcp-utilities-auth.mdx b/docs/python-sdk/fastmcp-utilities-auth.mdx new file mode 100644 index 000000000..c2d23b9a5 --- /dev/null +++ b/docs/python-sdk/fastmcp-utilities-auth.mdx @@ -0,0 +1,67 @@ +--- +title: auth +sidebarTitle: auth +--- + +# `fastmcp.utilities.auth` + + +Authentication utility helpers. + +## Functions + +### `decode_jwt_header` + +```python +decode_jwt_header(token: str) -> dict[str, Any] +``` + + +Decode JWT header without signature verification. + +Useful for extracting the key ID (kid) for JWKS lookup. + +**Args:** +- `token`: JWT token string (header.payload.signature) + +**Returns:** +- Decoded header as a dictionary + +**Raises:** +- `ValueError`: If token is not a valid JWT format + + +### `decode_jwt_payload` + +```python +decode_jwt_payload(token: str) -> dict[str, Any] +``` + + +Decode JWT payload without signature verification. + +Use only for tokens received directly from trusted sources (e.g., IdP token endpoints). + +**Args:** +- `token`: JWT token string (header.payload.signature) + +**Returns:** +- Decoded payload as a dictionary + +**Raises:** +- `ValueError`: If token is not a valid JWT format + + +### `parse_scopes` + +```python +parse_scopes(value: Any) -> list[str] | None +``` + + +Parse scopes from environment variables or settings values. + +Accepts either a JSON array string, a comma- or space-separated string, +a list of strings, or ``None``. Returns a list of scopes or ``None`` if +no value is provided. + diff --git a/docs/python-sdk/fastmcp-utilities-cli.mdx b/docs/python-sdk/fastmcp-utilities-cli.mdx new file mode 100644 index 000000000..52f2addff --- /dev/null +++ b/docs/python-sdk/fastmcp-utilities-cli.mdx @@ -0,0 +1,48 @@ +--- +title: cli +sidebarTitle: cli +--- + +# `fastmcp.utilities.cli` + +## Functions + +### `is_already_in_uv_subprocess` + +```python +is_already_in_uv_subprocess() -> bool +``` + + +Check if we're already running in a FastMCP uv subprocess. + + +### `load_and_merge_config` + +```python +load_and_merge_config(server_spec: str | None, **cli_overrides) -> tuple[MCPServerConfig, str] +``` + + +Load config from server_spec and apply CLI overrides. + +This consolidates the config parsing logic that was duplicated across +run, inspect, and dev commands. + +**Args:** +- `server_spec`: Python file, config file, URL, or None to auto-detect +- `cli_overrides`: CLI arguments that override config values + +**Returns:** +- Tuple of (MCPServerConfig, resolved_server_spec) + + +### `log_server_banner` + +```python +log_server_banner(server: FastMCP[Any]) -> None +``` + + +Creates and logs a formatted banner with server information and logo. + diff --git a/docs/python-sdk/fastmcp-utilities-components.mdx b/docs/python-sdk/fastmcp-utilities-components.mdx new file mode 100644 index 000000000..eba2517c2 --- /dev/null +++ b/docs/python-sdk/fastmcp-utilities-components.mdx @@ -0,0 +1,148 @@ +--- +title: components +sidebarTitle: components +--- + +# `fastmcp.utilities.components` + +## Functions + +### `get_fastmcp_metadata` + +```python +get_fastmcp_metadata(meta: dict[str, Any] | None) -> FastMCPMeta +``` + + +Extract FastMCP metadata from a component's meta dict. + +Handles both the current `fastmcp` namespace and the legacy `_fastmcp` +namespace for compatibility with older FastMCP servers. + + +## Classes + +### `FastMCPMeta` + +### `FastMCPComponent` + + +Base class for FastMCP tools, prompts, resources, and resource templates. + + +**Methods:** + +#### `make_key` + +```python +make_key(cls, identifier: str) -> str +``` + +Construct the lookup key for this component type. + +**Args:** +- `identifier`: The raw identifier (name for tools/prompts, uri for resources) + +**Returns:** +- A prefixed key like "tool:name" or "resource:uri" + + +#### `key` + +```python +key(self) -> str +``` + +The globally unique lookup key for this component. + +Format: "{key_prefix}:{identifier}@{version}" or "{key_prefix}:{identifier}@" +e.g. "tool:my_tool@v2", "tool:my_tool@", "resource:file://x.txt@" + +The @ suffix is ALWAYS present to enable unambiguous parsing of keys +(URIs may contain @ characters, so we always include the delimiter). + +Subclasses should override this to use their specific identifier. +Base implementation uses name. + + +#### `get_meta` + +```python +get_meta(self) -> dict[str, Any] +``` + +Get the meta information about the component. + +Returns a dict that always includes a `fastmcp` key containing: +- `tags`: sorted list of component tags +- `version`: component version (only if set) + +Internal keys (prefixed with `_`) are stripped from the fastmcp namespace. + + +#### `enable` + +```python +enable(self) -> None +``` + +Removed in 3.0. Use server.enable(keys=[...]) instead. + + +#### `disable` + +```python +disable(self) -> None +``` + +Removed in 3.0. Use server.disable(keys=[...]) instead. + + +#### `copy` + +```python +copy(self) -> Self +``` + +Create a copy of the component. + + +#### `register_with_docket` + +```python +register_with_docket(self, docket: Docket) -> None +``` + +Register this component with docket for background execution. + +No-ops if task_config.mode is "forbidden". Subclasses override to +register their callable (self.run, self.read, self.render, or self.fn). + + +#### `add_to_docket` + +```python +add_to_docket(self, docket: Docket, *args: Any, **kwargs: Any) -> Execution +``` + +Schedule this component for background execution via docket. + +Subclasses override this to handle their specific calling conventions: +- Tool: add_to_docket(docket, arguments: dict, **kwargs) +- Resource: add_to_docket(docket, **kwargs) +- ResourceTemplate: add_to_docket(docket, params: dict, **kwargs) +- Prompt: add_to_docket(docket, arguments: dict | None, **kwargs) + +The **kwargs are passed through to docket.add() (e.g., key=task_key). + + +#### `get_span_attributes` + +```python +get_span_attributes(self) -> dict[str, Any] +``` + +Return span attributes for telemetry. + +Subclasses should call super() and merge their specific attributes. + diff --git a/docs/python-sdk/fastmcp-utilities-exceptions.mdx b/docs/python-sdk/fastmcp-utilities-exceptions.mdx new file mode 100644 index 000000000..5794f185e --- /dev/null +++ b/docs/python-sdk/fastmcp-utilities-exceptions.mdx @@ -0,0 +1,20 @@ +--- +title: exceptions +sidebarTitle: exceptions +--- + +# `fastmcp.utilities.exceptions` + +## Functions + +### `iter_exc` + +```python +iter_exc(group: BaseExceptionGroup) +``` + +### `get_catch_handlers` + +```python +get_catch_handlers() -> Mapping[type[BaseException] | Iterable[type[BaseException]], Callable[[BaseExceptionGroup[Any]], Any]] +``` diff --git a/docs/python-sdk/fastmcp-utilities-http.mdx b/docs/python-sdk/fastmcp-utilities-http.mdx new file mode 100644 index 000000000..d274477c5 --- /dev/null +++ b/docs/python-sdk/fastmcp-utilities-http.mdx @@ -0,0 +1,18 @@ +--- +title: http +sidebarTitle: http +--- + +# `fastmcp.utilities.http` + +## Functions + +### `find_available_port` + +```python +find_available_port() -> int +``` + + +Find an available port by letting the OS assign one. + diff --git a/docs/python-sdk/fastmcp-utilities-inspect.mdx b/docs/python-sdk/fastmcp-utilities-inspect.mdx new file mode 100644 index 000000000..a813eb51e --- /dev/null +++ b/docs/python-sdk/fastmcp-utilities-inspect.mdx @@ -0,0 +1,143 @@ +--- +title: inspect +sidebarTitle: inspect +--- + +# `fastmcp.utilities.inspect` + + +Utilities for inspecting FastMCP instances. + +## Functions + +### `inspect_fastmcp_v2` + +```python +inspect_fastmcp_v2(mcp: FastMCP[Any]) -> FastMCPInfo +``` + + +Extract information from a FastMCP v2.x instance. + +**Args:** +- `mcp`: The FastMCP v2.x instance to inspect + +**Returns:** +- FastMCPInfo dataclass containing the extracted information + + +### `inspect_fastmcp_v1` + +```python +inspect_fastmcp_v1(mcp: FastMCP1x) -> FastMCPInfo +``` + + +Extract information from a FastMCP v1.x instance using a Client. + +**Args:** +- `mcp`: The FastMCP v1.x instance to inspect + +**Returns:** +- FastMCPInfo dataclass containing the extracted information + + +### `inspect_fastmcp` + +```python +inspect_fastmcp(mcp: FastMCP[Any] | FastMCP1x) -> FastMCPInfo +``` + + +Extract information from a FastMCP instance into a dataclass. + +This function automatically detects whether the instance is FastMCP v1.x or v2.x +and uses the appropriate extraction method. + +**Args:** +- `mcp`: The FastMCP instance to inspect (v1.x or v2.x) + +**Returns:** +- FastMCPInfo dataclass containing the extracted information + + +### `format_fastmcp_info` + +```python +format_fastmcp_info(info: FastMCPInfo) -> bytes +``` + + +Format FastMCPInfo as FastMCP-specific JSON. + +This includes FastMCP-specific fields like tags, enabled, annotations, etc. + + +### `format_mcp_info` + +```python +format_mcp_info(mcp: FastMCP[Any] | FastMCP1x) -> bytes +``` + + +Format server info as standard MCP protocol JSON. + +Uses Client to get the standard MCP protocol format with camelCase fields. +Includes version metadata at the top level. + + +### `format_info` + +```python +format_info(mcp: FastMCP[Any] | FastMCP1x, format: InspectFormat | Literal['fastmcp', 'mcp'], info: FastMCPInfo | None = None) -> bytes +``` + + +Format server information according to the specified format. + +**Args:** +- `mcp`: The FastMCP instance +- `format`: Output format ("fastmcp" or "mcp") +- `info`: Pre-extracted FastMCPInfo (optional, will be extracted if not provided) + +**Returns:** +- JSON bytes in the requested format + + +## Classes + +### `ToolInfo` + + +Information about a tool. + + +### `PromptInfo` + + +Information about a prompt. + + +### `ResourceInfo` + + +Information about a resource. + + +### `TemplateInfo` + + +Information about a resource template. + + +### `FastMCPInfo` + + +Information extracted from a FastMCP instance. + + +### `InspectFormat` + + +Output format for inspect command. + diff --git a/docs/python-sdk/fastmcp-utilities-json_schema.mdx b/docs/python-sdk/fastmcp-utilities-json_schema.mdx new file mode 100644 index 000000000..e08643cb9 --- /dev/null +++ b/docs/python-sdk/fastmcp-utilities-json_schema.mdx @@ -0,0 +1,79 @@ +--- +title: json_schema +sidebarTitle: json_schema +--- + +# `fastmcp.utilities.json_schema` + +## Functions + +### `dereference_refs` + +```python +dereference_refs(schema: dict[str, Any]) -> dict[str, Any] +``` + + +Resolve all $ref references in a JSON schema by inlining definitions. + +This function resolves $ref references that point to $defs, replacing them +with the actual definition content while preserving sibling keywords (like +description, default, examples) that Pydantic places alongside $ref. + +This is necessary because some MCP clients (e.g., VS Code Copilot) don't +properly handle $ref in tool input schemas. + +For self-referencing/circular schemas where full dereferencing is not possible, +this function falls back to resolving only the root-level $ref while preserving +$defs for nested references. + +**Args:** +- `schema`: JSON schema dict that may contain $ref references + +**Returns:** +- A new schema dict with $ref resolved where possible and $defs removed +- when no longer needed + + +### `resolve_root_ref` + +```python +resolve_root_ref(schema: dict[str, Any]) -> dict[str, Any] +``` + + +Resolve $ref at root level to meet MCP spec requirements. + +MCP specification requires outputSchema to have "type": "object" at the root level. +When Pydantic generates schemas for self-referential models, it uses $ref at the +root level pointing to $defs. This function resolves such references by inlining +the referenced definition while preserving $defs for nested references. + +**Args:** +- `schema`: JSON schema dict that may have $ref at root level + +**Returns:** +- A new schema dict with root-level $ref resolved, or the original schema +- if no resolution is needed + + +### `compress_schema` + +```python +compress_schema(schema: dict[str, Any], prune_params: list[str] | None = None, prune_additional_properties: bool = False, prune_titles: bool = False, dereference: bool = False) -> dict[str, Any] +``` + + +Compress and optimize a JSON schema for MCP compatibility. + +**Args:** +- `schema`: The schema to compress +- `prune_params`: List of parameter names to remove from properties +- `prune_additional_properties`: Whether to remove additionalProperties\: false. +Defaults to False to maintain MCP client compatibility, as some clients +(e.g., Claude) require additionalProperties\: false for strict validation. +- `prune_titles`: Whether to remove title fields from the schema +- `dereference`: Whether to dereference $ref by inlining definitions. +Defaults to False; dereferencing is typically handled by +middleware at serve-time instead. + diff --git a/docs/python-sdk/fastmcp-utilities-json_schema_type.mdx b/docs/python-sdk/fastmcp-utilities-json_schema_type.mdx new file mode 100644 index 000000000..b1137e7de --- /dev/null +++ b/docs/python-sdk/fastmcp-utilities-json_schema_type.mdx @@ -0,0 +1,110 @@ +--- +title: json_schema_type +sidebarTitle: json_schema_type +--- + +# `fastmcp.utilities.json_schema_type` + + +Convert JSON Schema to Python types with validation. + +The json_schema_to_type function converts a JSON Schema into a Python type that can be used +for validation with Pydantic. It supports: + +- Basic types (string, number, integer, boolean, null) +- Complex types (arrays, objects) +- Format constraints (date-time, email, uri) +- Numeric constraints (minimum, maximum, multipleOf) +- String constraints (minLength, maxLength, pattern) +- Array constraints (minItems, maxItems, uniqueItems) +- Object properties with defaults +- References and recursive schemas +- Enums and constants +- Union types + +Example: + ```python + schema = { + "type": "object", + "properties": { + "name": {"type": "string", "minLength": 1}, + "age": {"type": "integer", "minimum": 0}, + "email": {"type": "string", "format": "email"} + }, + "required": ["name", "age"] + } + + # Name is optional and will be inferred from schema's "title" property if not provided + Person = json_schema_to_type(schema) + # Creates a validated dataclass with name, age, and optional email fields + ``` + + +## Functions + +### `json_schema_to_type` + +```python +json_schema_to_type(schema: Mapping[str, Any], name: str | None = None) -> type +``` + + +Convert JSON schema to appropriate Python type with validation. + +**Args:** +- `schema`: A JSON Schema dictionary defining the type structure and validation rules +- `name`: Optional name for object schemas. Only allowed when schema type is "object". +If not provided for objects, name will be inferred from schema's "title" +property or default to "Root". + +**Returns:** +- A Python type (typically a dataclass for objects) with Pydantic validation + +**Raises:** +- `ValueError`: If a name is provided for a non-object schema + +**Examples:** + +Create a dataclass from an object schema: +```python +schema = { + "type": "object", + "title": "Person", + "properties": { + "name": {"type": "string", "minLength": 1}, + "age": {"type": "integer", "minimum": 0}, + "email": {"type": "string", "format": "email"} + }, + "required": ["name", "age"] +} + +Person = json_schema_to_type(schema) +# Creates a dataclass with name, age, and optional email fields: +# @dataclass +# class Person: +# name: str +# age: int +# email: str | None = None +``` +Person(name="John", age=30) + +Create a scalar type with constraints: +```python +schema = { + "type": "string", + "minLength": 3, + "pattern": "^[A-Z][a-z]+$" +} + +NameType = json_schema_to_type(schema) +# Creates Annotated[str, StringConstraints(min_length=3, pattern="^[A-Z][a-z]+$")] + +@dataclass +class Name: + name: NameType +``` + + +## Classes + +### `JSONSchema` diff --git a/docs/python-sdk/fastmcp-utilities-lifespan.mdx b/docs/python-sdk/fastmcp-utilities-lifespan.mdx new file mode 100644 index 000000000..912cbfad6 --- /dev/null +++ b/docs/python-sdk/fastmcp-utilities-lifespan.mdx @@ -0,0 +1,36 @@ +--- +title: lifespan +sidebarTitle: lifespan +--- + +# `fastmcp.utilities.lifespan` + + +Lifespan utilities for combining async context manager lifespans. + +## Functions + +### `combine_lifespans` + +```python +combine_lifespans(*lifespans: Callable[[AppT], AbstractAsyncContextManager[Mapping[str, Any] | None]]) -> Callable[[AppT], AbstractAsyncContextManager[dict[str, Any]]] +``` + + +Combine multiple lifespans into a single lifespan. + +Useful when mounting FastMCP into FastAPI and you need to run +both your app's lifespan and the MCP server's lifespan. + +Works with both FastAPI-style lifespans (yield None) and FastMCP-style +lifespans (yield dict). Results are merged; later lifespans override +earlier ones on key conflicts. + +Lifespans are entered in order and exited in reverse order (LIFO). + +**Args:** +- `*lifespans`: Lifespan context manager factories to combine. + +**Returns:** +- A combined lifespan context manager factory. + diff --git a/docs/python-sdk/fastmcp-utilities-logging.mdx b/docs/python-sdk/fastmcp-utilities-logging.mdx new file mode 100644 index 000000000..2b5fea4ae --- /dev/null +++ b/docs/python-sdk/fastmcp-utilities-logging.mdx @@ -0,0 +1,58 @@ +--- +title: logging +sidebarTitle: logging +--- + +# `fastmcp.utilities.logging` + + +Logging utilities for FastMCP. + +## Functions + +### `get_logger` + +```python +get_logger(name: str) -> logging.Logger +``` + + +Get a logger nested under FastMCP namespace. + +**Args:** +- `name`: the name of the logger, which will be prefixed with 'FastMCP.' + +**Returns:** +- a configured logger instance + + +### `configure_logging` + +```python +configure_logging(level: Literal['DEBUG', 'INFO', 'WARNING', 'ERROR', 'CRITICAL'] | int = 'INFO', logger: logging.Logger | None = None, enable_rich_tracebacks: bool | None = None, **rich_kwargs: Any) -> None +``` + + +Configure logging for FastMCP. + +**Args:** +- `logger`: the logger to configure +- `level`: the log level to use +- `rich_kwargs`: the parameters to use for creating RichHandler + + +### `temporary_log_level` + +```python +temporary_log_level(level: str | None, logger: logging.Logger | None = None, enable_rich_tracebacks: bool | None = None, **rich_kwargs: Any) +``` + + +Context manager to temporarily set log level and restore it afterwards. + +**Args:** +- `level`: The temporary log level to set (e.g., "DEBUG", "INFO") +- `logger`: Optional logger to configure (defaults to FastMCP logger) +- `enable_rich_tracebacks`: Whether to enable rich tracebacks +- `**rich_kwargs`: Additional parameters for RichHandler + diff --git a/docs/python-sdk/fastmcp-utilities-mcp_server_config-__init__.mdx b/docs/python-sdk/fastmcp-utilities-mcp_server_config-__init__.mdx new file mode 100644 index 000000000..bc8fc9500 --- /dev/null +++ b/docs/python-sdk/fastmcp-utilities-mcp_server_config-__init__.mdx @@ -0,0 +1,13 @@ +--- +title: __init__ +sidebarTitle: __init__ +--- + +# `fastmcp.utilities.mcp_server_config` + + +FastMCP Configuration module. + +This module provides versioned configuration support for FastMCP servers. +The current version is v1, which is re-exported here for convenience. + diff --git a/docs/python-sdk/fastmcp-utilities-mcp_server_config-v1-__init__.mdx b/docs/python-sdk/fastmcp-utilities-mcp_server_config-v1-__init__.mdx new file mode 100644 index 000000000..d29664280 --- /dev/null +++ b/docs/python-sdk/fastmcp-utilities-mcp_server_config-v1-__init__.mdx @@ -0,0 +1,8 @@ +--- +title: __init__ +sidebarTitle: __init__ +--- + +# `fastmcp.utilities.mcp_server_config.v1` + +*This module is empty or contains only private/internal implementations.* diff --git a/docs/python-sdk/fastmcp-utilities-mcp_server_config-v1-environments-__init__.mdx b/docs/python-sdk/fastmcp-utilities-mcp_server_config-v1-environments-__init__.mdx new file mode 100644 index 000000000..01f147482 --- /dev/null +++ b/docs/python-sdk/fastmcp-utilities-mcp_server_config-v1-environments-__init__.mdx @@ -0,0 +1,9 @@ +--- +title: __init__ +sidebarTitle: __init__ +--- + +# `fastmcp.utilities.mcp_server_config.v1.environments` + + +Environment configuration for MCP servers. diff --git a/docs/python-sdk/fastmcp-utilities-mcp_server_config-v1-environments-base.mdx b/docs/python-sdk/fastmcp-utilities-mcp_server_config-v1-environments-base.mdx new file mode 100644 index 000000000..f59bb18b1 --- /dev/null +++ b/docs/python-sdk/fastmcp-utilities-mcp_server_config-v1-environments-base.mdx @@ -0,0 +1,43 @@ +--- +title: base +sidebarTitle: base +--- + +# `fastmcp.utilities.mcp_server_config.v1.environments.base` + +## Classes + +### `Environment` + + +Base class for environment configuration. + + +**Methods:** + +#### `build_command` + +```python +build_command(self, command: list[str]) -> list[str] +``` + +Build the full command with environment setup. + +**Args:** +- `command`: Base command to wrap with environment setup + +**Returns:** +- Full command ready for subprocess execution + + +#### `prepare` + +```python +prepare(self, output_dir: Path | None = None) -> None +``` + +Prepare the environment (optional, can be no-op). + +**Args:** +- `output_dir`: Directory for persistent environment setup + diff --git a/docs/python-sdk/fastmcp-utilities-mcp_server_config-v1-environments-uv.mdx b/docs/python-sdk/fastmcp-utilities-mcp_server_config-v1-environments-uv.mdx new file mode 100644 index 000000000..e5a2d6a11 --- /dev/null +++ b/docs/python-sdk/fastmcp-utilities-mcp_server_config-v1-environments-uv.mdx @@ -0,0 +1,45 @@ +--- +title: uv +sidebarTitle: uv +--- + +# `fastmcp.utilities.mcp_server_config.v1.environments.uv` + +## Classes + +### `UVEnvironment` + + +Configuration for Python environment setup. + + +**Methods:** + +#### `build_command` + +```python +build_command(self, command: list[str]) -> list[str] +``` + +Build complete uv run command with environment args and command to execute. + +**Args:** +- `command`: Command to execute (e.g., ["fastmcp", "run", "server.py"]) + +**Returns:** +- Complete command ready for subprocess.run, including "uv" prefix if needed. +- If no environment configuration is set, returns the command unchanged. + + +#### `prepare` + +```python +prepare(self, output_dir: Path | None = None) -> None +``` + +Prepare the Python environment using uv. + +**Args:** +- `output_dir`: Directory where the persistent uv project will be created. + If None, creates a temporary directory for ephemeral use. + diff --git a/docs/python-sdk/fastmcp-utilities-mcp_server_config-v1-mcp_server_config.mdx b/docs/python-sdk/fastmcp-utilities-mcp_server_config-v1-mcp_server_config.mdx new file mode 100644 index 000000000..460f1f83d --- /dev/null +++ b/docs/python-sdk/fastmcp-utilities-mcp_server_config-v1-mcp_server_config.mdx @@ -0,0 +1,235 @@ +--- +title: mcp_server_config +sidebarTitle: mcp_server_config +--- + +# `fastmcp.utilities.mcp_server_config.v1.mcp_server_config` + + +FastMCP Configuration File Support. + +This module provides support for fastmcp.json configuration files that allow +users to specify server settings in a declarative format instead of using +command-line arguments. + + +## Functions + +### `generate_schema` + +```python +generate_schema(output_path: Path | str | None = None) -> dict[str, Any] | None +``` + + +Generate JSON schema for fastmcp.json files. + +This is used to create the schema file that IDEs can use for +validation and auto-completion. + +**Args:** +- `output_path`: Optional path to write the schema to. If provided, + writes the schema and returns None. If not provided, + returns the schema as a dictionary. + +**Returns:** +- JSON schema as a dictionary if output_path is None, otherwise None + + +## Classes + +### `Deployment` + + +Configuration for server deployment and runtime settings. + + +**Methods:** + +#### `apply_runtime_settings` + +```python +apply_runtime_settings(self, config_path: Path | None = None) -> None +``` + +Apply runtime settings like environment variables and working directory. + +**Args:** +- `config_path`: Path to config file for resolving relative paths + +Environment variables support interpolation with ${VAR_NAME} syntax. +For example: "API_URL": "https://api.${ENVIRONMENT}.example.com" +will substitute the value of the ENVIRONMENT variable at runtime. + + +### `MCPServerConfig` + + +Configuration for a FastMCP server. + +This configuration file allows you to specify all settings needed to run +a FastMCP server in a declarative format. + + +**Methods:** + +#### `validate_source` + +```python +validate_source(cls, v: dict | Source) -> SourceType +``` + +Validate and convert source to proper format. + +Supports: +- Dict format: `{"path": "server.py", "entrypoint": "app"}` +- FileSystemSource instance (passed through) + +No string parsing happens here - that's only at CLI boundaries. +MCPServerConfig works only with properly typed objects. + + +#### `validate_environment` + +```python +validate_environment(cls, v: dict | Any) -> EnvironmentType +``` + +Ensure environment has a type field for discrimination. + +For backward compatibility, if no type is specified, default to "uv". + + +#### `validate_deployment` + +```python +validate_deployment(cls, v: dict | Deployment) -> Deployment +``` + +Validate and convert deployment to Deployment. + +Accepts: +- Deployment instance +- dict that can be converted to Deployment + + +#### `from_file` + +```python +from_file(cls, file_path: Path) -> MCPServerConfig +``` + +Load configuration from a JSON file. + +**Args:** +- `file_path`: Path to the configuration file + +**Returns:** +- MCPServerConfig instance + +**Raises:** +- `FileNotFoundError`: If the file doesn't exist +- `json.JSONDecodeError`: If the file is not valid JSON +- `pydantic.ValidationError`: If the configuration is invalid + + +#### `from_cli_args` + +```python +from_cli_args(cls, source: FileSystemSource, transport: Literal['stdio', 'http', 'sse', 'streamable-http'] | None = None, host: str | None = None, port: int | None = None, path: str | None = None, log_level: Literal['DEBUG', 'INFO', 'WARNING', 'ERROR', 'CRITICAL'] | None = None, python: str | None = None, dependencies: list[str] | None = None, requirements: str | None = None, project: str | None = None, editable: str | None = None, env: dict[str, str] | None = None, cwd: str | None = None, args: list[str] | None = None) -> MCPServerConfig +``` + +Create a config from CLI arguments. + +This allows us to have a single code path where everything +goes through a config object. + +**Args:** +- `source`: Server source (FileSystemSource instance) +- `transport`: Transport protocol +- `host`: Host for HTTP transport +- `port`: Port for HTTP transport +- `path`: URL path for server +- `log_level`: Logging level +- `python`: Python version +- `dependencies`: Python packages to install +- `requirements`: Path to requirements file +- `project`: Path to project directory +- `editable`: Path to install in editable mode +- `env`: Environment variables +- `cwd`: Working directory +- `args`: Server arguments + +**Returns:** +- MCPServerConfig instance + + +#### `find_config` + +```python +find_config(cls, start_path: Path | None = None) -> Path | None +``` + +Find a fastmcp.json file in the specified directory. + +**Args:** +- `start_path`: Directory to look in (defaults to current directory) + +**Returns:** +- Path to the configuration file, or None if not found + + +#### `prepare` + +```python +prepare(self, skip_source: bool = False, output_dir: Path | None = None) -> None +``` + +Prepare environment and source for execution. + +When output_dir is provided, creates a persistent uv project. +When output_dir is None, does ephemeral caching (for backwards compatibility). + +**Args:** +- `skip_source`: Skip source preparation if True +- `output_dir`: Directory to create the persistent uv project in (optional) + + +#### `prepare_environment` + +```python +prepare_environment(self, output_dir: Path | None = None) -> None +``` + +Prepare the Python environment. + +**Args:** +- `output_dir`: If provided, creates a persistent uv project in this directory. + If None, just populates uv's cache for ephemeral use. + +Delegates to the environment's prepare() method + + +#### `prepare_source` + +```python +prepare_source(self) -> None +``` + +Prepare the source for loading. + +Delegates to the source's prepare() method. + + +#### `run_server` + +```python +run_server(self, **kwargs: Any) -> None +``` + +Load and run the server with this configuration. + +**Args:** +- `**kwargs`: Additional arguments to pass to server.run_async() + These override config settings + diff --git a/docs/python-sdk/fastmcp-utilities-mcp_server_config-v1-sources-__init__.mdx b/docs/python-sdk/fastmcp-utilities-mcp_server_config-v1-sources-__init__.mdx new file mode 100644 index 000000000..38d102b15 --- /dev/null +++ b/docs/python-sdk/fastmcp-utilities-mcp_server_config-v1-sources-__init__.mdx @@ -0,0 +1,8 @@ +--- +title: __init__ +sidebarTitle: __init__ +--- + +# `fastmcp.utilities.mcp_server_config.v1.sources` + +*This module is empty or contains only private/internal implementations.* diff --git a/docs/python-sdk/fastmcp-utilities-mcp_server_config-v1-sources-base.mdx b/docs/python-sdk/fastmcp-utilities-mcp_server_config-v1-sources-base.mdx new file mode 100644 index 000000000..764454b6d --- /dev/null +++ b/docs/python-sdk/fastmcp-utilities-mcp_server_config-v1-sources-base.mdx @@ -0,0 +1,42 @@ +--- +title: base +sidebarTitle: base +--- + +# `fastmcp.utilities.mcp_server_config.v1.sources.base` + +## Classes + +### `Source` + + +Abstract base class for all source types. + + +**Methods:** + +#### `prepare` + +```python +prepare(self) -> None +``` + +Prepare the source (download, clone, install, etc). + +For sources that need preparation (e.g., git clone, download), +this method performs that preparation. For sources that don't +need preparation (e.g., local files), this is a no-op. + + +#### `load_server` + +```python +load_server(self) -> Any +``` + +Load and return the FastMCP server instance. + +Must be called after prepare() if the source requires preparation. +All information needed to load the server should be available +as attributes on the source instance. + diff --git a/docs/python-sdk/fastmcp-utilities-mcp_server_config-v1-sources-filesystem.mdx b/docs/python-sdk/fastmcp-utilities-mcp_server_config-v1-sources-filesystem.mdx new file mode 100644 index 000000000..3d791f9cd --- /dev/null +++ b/docs/python-sdk/fastmcp-utilities-mcp_server_config-v1-sources-filesystem.mdx @@ -0,0 +1,37 @@ +--- +title: filesystem +sidebarTitle: filesystem +--- + +# `fastmcp.utilities.mcp_server_config.v1.sources.filesystem` + +## Classes + +### `FileSystemSource` + + +Source for local Python files. + + +**Methods:** + +#### `parse_path_with_object` + +```python +parse_path_with_object(cls, v: str) -> str +``` + +Parse path:object syntax and extract the object name. + +This validator runs before the model is created, allowing us to +handle the "file.py:object" syntax at the model boundary. + + +#### `load_server` + +```python +load_server(self) -> Any +``` + +Load server from filesystem. + diff --git a/docs/python-sdk/fastmcp-utilities-openapi-__init__.mdx b/docs/python-sdk/fastmcp-utilities-openapi-__init__.mdx new file mode 100644 index 000000000..df0331f9e --- /dev/null +++ b/docs/python-sdk/fastmcp-utilities-openapi-__init__.mdx @@ -0,0 +1,9 @@ +--- +title: __init__ +sidebarTitle: __init__ +--- + +# `fastmcp.utilities.openapi` + + +OpenAPI utilities for FastMCP - refactored for better maintainability. diff --git a/docs/python-sdk/fastmcp-utilities-openapi-director.mdx b/docs/python-sdk/fastmcp-utilities-openapi-director.mdx new file mode 100644 index 000000000..0d61900c6 --- /dev/null +++ b/docs/python-sdk/fastmcp-utilities-openapi-director.mdx @@ -0,0 +1,36 @@ +--- +title: director +sidebarTitle: director +--- + +# `fastmcp.utilities.openapi.director` + + +Request director using openapi-core for stateless HTTP request building. + +## Classes + +### `RequestDirector` + + +Builds httpx.Request objects from HTTPRoute and arguments using openapi-core. + + +**Methods:** + +#### `build` + +```python +build(self, route: HTTPRoute, flat_args: dict[str, Any], base_url: str = 'http://localhost') -> httpx.Request +``` + +Constructs a final httpx.Request object, handling all OpenAPI serialization. + +**Args:** +- `route`: HTTPRoute containing OpenAPI operation details +- `flat_args`: Flattened arguments from LLM (may include suffixed parameters) +- `base_url`: Base URL for the request + +**Returns:** +- httpx.Request: Properly formatted HTTP request + diff --git a/docs/python-sdk/fastmcp-utilities-openapi-formatters.mdx b/docs/python-sdk/fastmcp-utilities-openapi-formatters.mdx new file mode 100644 index 000000000..4d5ad3a90 --- /dev/null +++ b/docs/python-sdk/fastmcp-utilities-openapi-formatters.mdx @@ -0,0 +1,96 @@ +--- +title: formatters +sidebarTitle: formatters +--- + +# `fastmcp.utilities.openapi.formatters` + + +Parameter formatting functions for OpenAPI operations. + +## Functions + +### `format_array_parameter` + +```python +format_array_parameter(values: list, parameter_name: str, is_query_parameter: bool = False) -> str | list +``` + + +Format an array parameter according to OpenAPI specifications. + +**Args:** +- `values`: List of values to format +- `parameter_name`: Name of the parameter (for error messages) +- `is_query_parameter`: If True, can return list for explode=True behavior + +**Returns:** +- String (comma-separated) or list (for query params with explode=True) + + +### `format_deep_object_parameter` + +```python +format_deep_object_parameter(param_value: dict, parameter_name: str) -> dict[str, str] +``` + + +Format a dictionary parameter for deep-object style serialization. + +According to OpenAPI 3.0 spec, deepObject style with explode=true serializes +object properties as separate query parameters with bracket notation. + +For example, `{"id": "123", "type": "user"}` becomes +`param[id]=123¶m[type]=user`. + +**Args:** +- `param_value`: Dictionary value to format +- `parameter_name`: Name of the parameter + +**Returns:** +- Dictionary with bracketed parameter names as keys + + +### `generate_example_from_schema` + +```python +generate_example_from_schema(schema: JsonSchema | None) -> Any +``` + + +Generate a simple example value from a JSON schema dictionary. +Very basic implementation focusing on types. + + +### `format_json_for_description` + +```python +format_json_for_description(data: Any, indent: int = 2) -> str +``` + + +Formats Python data as a JSON string block for Markdown. + + +### `format_description_with_responses` + +```python +format_description_with_responses(base_description: str, responses: dict[str, Any], parameters: list[ParameterInfo] | None = None, request_body: RequestBodyInfo | None = None) -> str +``` + + +Formats the base description string with response, parameter, and request body information. + +**Args:** +- `base_description`: The initial description to be formatted. +- `responses`: A dictionary of response information, keyed by status code. +- `parameters`: A list of parameter information, +including path and query parameters. Each parameter includes details such as name, +location, whether it is required, and a description. +- `request_body`: Information about the request body, +including its description, whether it is required, and its content schema. + +**Returns:** +- The formatted description string with additional details about responses, parameters, +- and the request body. + diff --git a/docs/python-sdk/fastmcp-utilities-openapi-json_schema_converter.mdx b/docs/python-sdk/fastmcp-utilities-openapi-json_schema_converter.mdx new file mode 100644 index 000000000..abd1d6869 --- /dev/null +++ b/docs/python-sdk/fastmcp-utilities-openapi-json_schema_converter.mdx @@ -0,0 +1,62 @@ +--- +title: json_schema_converter +sidebarTitle: json_schema_converter +--- + +# `fastmcp.utilities.openapi.json_schema_converter` + + + +Clean OpenAPI 3.0 to JSON Schema converter for the experimental parser. + +This module provides a systematic approach to converting OpenAPI 3.0 schemas +to JSON Schema, inspired by py-openapi-schema-to-json-schema but optimized +for our specific use case. + + +## Functions + +### `convert_openapi_schema_to_json_schema` + +```python +convert_openapi_schema_to_json_schema(schema: dict[str, Any], openapi_version: str | None = None, remove_read_only: bool = False, remove_write_only: bool = False, convert_one_of_to_any_of: bool = True) -> dict[str, Any] +``` + + +Convert an OpenAPI schema to JSON Schema format. + +This is a clean, systematic approach that: +1. Removes OpenAPI-specific fields +2. Converts nullable fields to type arrays (for OpenAPI 3.0 only) +3. Converts oneOf to anyOf for overlapping union handling +4. Recursively processes nested schemas +5. Optionally removes readOnly/writeOnly properties + +**Args:** +- `schema`: OpenAPI schema dictionary +- `openapi_version`: OpenAPI version for optimization +- `remove_read_only`: Whether to remove readOnly properties +- `remove_write_only`: Whether to remove writeOnly properties +- `convert_one_of_to_any_of`: Whether to convert oneOf to anyOf + +**Returns:** +- JSON Schema-compatible dictionary + + +### `convert_schema_definitions` + +```python +convert_schema_definitions(schema_definitions: dict[str, Any] | None, openapi_version: str | None = None, **kwargs) -> dict[str, Any] +``` + + +Convert a dictionary of OpenAPI schema definitions to JSON Schema. + +**Args:** +- `schema_definitions`: Dictionary of schema definitions +- `openapi_version`: OpenAPI version for optimization +- `**kwargs`: Additional arguments passed to convert_openapi_schema_to_json_schema + +**Returns:** +- Dictionary of converted schema definitions + diff --git a/docs/python-sdk/fastmcp-utilities-openapi-models.mdx b/docs/python-sdk/fastmcp-utilities-openapi-models.mdx new file mode 100644 index 000000000..02a3fbe9e --- /dev/null +++ b/docs/python-sdk/fastmcp-utilities-openapi-models.mdx @@ -0,0 +1,35 @@ +--- +title: models +sidebarTitle: models +--- + +# `fastmcp.utilities.openapi.models` + + +Intermediate Representation (IR) models for OpenAPI operations. + +## Classes + +### `ParameterInfo` + + +Represents a single parameter for an HTTP operation in our IR. + + +### `RequestBodyInfo` + + +Represents the request body for an HTTP operation in our IR. + + +### `ResponseInfo` + + +Represents response information in our IR. + + +### `HTTPRoute` + + +Intermediate Representation for a single OpenAPI operation. + diff --git a/docs/python-sdk/fastmcp-utilities-openapi-parser.mdx b/docs/python-sdk/fastmcp-utilities-openapi-parser.mdx new file mode 100644 index 000000000..0a9a2a272 --- /dev/null +++ b/docs/python-sdk/fastmcp-utilities-openapi-parser.mdx @@ -0,0 +1,43 @@ +--- +title: parser +sidebarTitle: parser +--- + +# `fastmcp.utilities.openapi.parser` + + +OpenAPI parsing logic for converting OpenAPI specs to HTTPRoute objects. + +## Functions + +### `parse_openapi_to_http_routes` + +```python +parse_openapi_to_http_routes(openapi_dict: dict[str, Any]) -> list[HTTPRoute] +``` + + +Parses an OpenAPI schema dictionary into a list of HTTPRoute objects +using the openapi-pydantic library. + +Supports both OpenAPI 3.0.x and 3.1.x versions. + + +## Classes + +### `OpenAPIParser` + + +Unified parser for OpenAPI schemas with generic type parameters to handle both 3.0 and 3.1. + + +**Methods:** + +#### `parse` + +```python +parse(self) -> list[HTTPRoute] +``` + +Parse the OpenAPI schema into HTTP routes. + diff --git a/docs/python-sdk/fastmcp-utilities-openapi-schemas.mdx b/docs/python-sdk/fastmcp-utilities-openapi-schemas.mdx new file mode 100644 index 000000000..fad88ee5f --- /dev/null +++ b/docs/python-sdk/fastmcp-utilities-openapi-schemas.mdx @@ -0,0 +1,43 @@ +--- +title: schemas +sidebarTitle: schemas +--- + +# `fastmcp.utilities.openapi.schemas` + + +Schema manipulation utilities for OpenAPI operations. + +## Functions + +### `clean_schema_for_display` + +```python +clean_schema_for_display(schema: JsonSchema | None) -> JsonSchema | None +``` + + +Clean up a schema dictionary for display by removing internal/complex fields. + + +### `extract_output_schema_from_responses` + +```python +extract_output_schema_from_responses(responses: dict[str, ResponseInfo], schema_definitions: dict[str, Any] | None = None, openapi_version: str | None = None) -> dict[str, Any] | None +``` + + +Extract output schema from OpenAPI responses for use as MCP tool output schema. + +This function finds the first successful response (200, 201, 202, 204) with a +JSON-compatible content type and extracts its schema. If the schema is not an +object type, it wraps it to comply with MCP requirements. + +**Args:** +- `responses`: Dictionary of ResponseInfo objects keyed by status code +- `schema_definitions`: Optional schema definitions to include in the output schema +- `openapi_version`: OpenAPI version string, used to optimize nullable field handling + +**Returns:** +- MCP-compliant output schema with potential wrapping, or None if no suitable schema found + diff --git a/docs/python-sdk/fastmcp-utilities-pagination.mdx b/docs/python-sdk/fastmcp-utilities-pagination.mdx new file mode 100644 index 000000000..0381a36aa --- /dev/null +++ b/docs/python-sdk/fastmcp-utilities-pagination.mdx @@ -0,0 +1,66 @@ +--- +title: pagination +sidebarTitle: pagination +--- + +# `fastmcp.utilities.pagination` + + +Pagination utilities for MCP list operations. + +## Functions + +### `paginate_sequence` + +```python +paginate_sequence(items: Sequence[T], cursor: str | None, page_size: int) -> tuple[list[T], str | None] +``` + + +Paginate a sequence of items. + +**Args:** +- `items`: The full sequence to paginate. +- `cursor`: Optional cursor from a previous request. None for first page. +- `page_size`: Maximum number of items per page. + +**Returns:** +- Tuple of (page_items, next_cursor). next_cursor is None if no more pages. + +**Raises:** +- `ValueError`: If the cursor is invalid. + + +## Classes + +### `CursorState` + + +Internal representation of pagination cursor state. + +The cursor encodes the offset into the result set. This is opaque to clients +per the MCP spec - they should not parse or modify cursors. + + +**Methods:** + +#### `encode` + +```python +encode(self) -> str +``` + +Encode cursor state to an opaque string. + + +#### `decode` + +```python +decode(cls, cursor: str) -> CursorState +``` + +Decode cursor from an opaque string. + +**Raises:** +- `ValueError`: If the cursor is invalid or malformed. + diff --git a/docs/python-sdk/fastmcp-utilities-skills.mdx b/docs/python-sdk/fastmcp-utilities-skills.mdx new file mode 100644 index 000000000..ccb0c83b8 --- /dev/null +++ b/docs/python-sdk/fastmcp-utilities-skills.mdx @@ -0,0 +1,114 @@ +--- +title: skills +sidebarTitle: skills +--- + +# `fastmcp.utilities.skills` + + +Client utilities for discovering and downloading skills from MCP servers. + +## Functions + +### `list_skills` + +```python +list_skills(client: Client) -> list[SkillSummary] +``` + + +List all available skills from an MCP server. + +Discovers skills by finding resources with URIs matching the +`skill://{name}/SKILL.md` pattern. + +**Args:** +- `client`: Connected FastMCP client + +**Returns:** +- List of SkillSummary objects with name, description, and URI + + +### `get_skill_manifest` + +```python +get_skill_manifest(client: Client, skill_name: str) -> SkillManifest +``` + + +Get the manifest for a specific skill. + +**Args:** +- `client`: Connected FastMCP client +- `skill_name`: Name of the skill + +**Returns:** +- SkillManifest with file listing + +**Raises:** +- `ValueError`: If manifest cannot be read or parsed + + +### `download_skill` + +```python +download_skill(client: Client, skill_name: str, target_dir: str | Path) -> Path +``` + + +Download a skill and all its files to a local directory. + +Creates a subdirectory named after the skill containing all files. + +**Args:** +- `client`: Connected FastMCP client +- `skill_name`: Name of the skill to download +- `target_dir`: Directory where skill folder will be created +- `overwrite`: If True, overwrite existing skill directory. If False +(default), raise FileExistsError if directory exists. + +**Returns:** +- Path to the downloaded skill directory + +**Raises:** +- `ValueError`: If skill cannot be found or downloaded +- `FileExistsError`: If skill directory exists and overwrite=False + + +### `sync_skills` + +```python +sync_skills(client: Client, target_dir: str | Path) -> list[Path] +``` + + +Download all available skills from a server. + +**Args:** +- `client`: Connected FastMCP client +- `target_dir`: Directory where skill folders will be created +- `overwrite`: If True, overwrite existing files + +**Returns:** +- List of paths to downloaded skill directories + + +## Classes + +### `SkillSummary` + + +Summary information about a skill available on a server. + + +### `SkillFile` + + +Information about a file within a skill. + + +### `SkillManifest` + + +Full manifest of a skill including all files. + diff --git a/docs/python-sdk/fastmcp-utilities-tests.mdx b/docs/python-sdk/fastmcp-utilities-tests.mdx new file mode 100644 index 000000000..5a40ff61f --- /dev/null +++ b/docs/python-sdk/fastmcp-utilities-tests.mdx @@ -0,0 +1,96 @@ +--- +title: tests +sidebarTitle: tests +--- + +# `fastmcp.utilities.tests` + +## Functions + +### `temporary_settings` + +```python +temporary_settings(**kwargs: Any) +``` + + +Temporarily override FastMCP setting values. + +**Args:** +- `**kwargs`: The settings to override, including nested settings. + + +### `run_server_in_process` + +```python +run_server_in_process(server_fn: Callable[..., None], *args: Any, **kwargs: Any) -> Generator[str, None, None] +``` + + +Context manager that runs a FastMCP server in a separate process and +returns the server URL. When the context manager is exited, the server process is killed. + +**Args:** +- `server_fn`: The function that runs a FastMCP server. FastMCP servers are +not pickleable, so we need a function that creates and runs one. +- `*args`: Arguments to pass to the server function. +- `provide_host_and_port`: Whether to provide the host and port to the server function as kwargs. +- `host`: Host to bind the server to (default\: "127.0.0.1"). +- `port`: Port to bind the server to (default\: find available port). +- `**kwargs`: Keyword arguments to pass to the server function. + +**Returns:** +- The server URL. + + +### `run_server_async` + +```python +run_server_async(server: FastMCP, port: int | None = None, transport: Literal['http', 'streamable-http', 'sse'] = 'http', path: str = '/mcp', host: str = '127.0.0.1') -> AsyncGenerator[str, None] +``` + + +Start a FastMCP server as an asyncio task for in-process async testing. + +This is the recommended way to test FastMCP servers. It runs the server +as an async task in the same process, eliminating subprocess coordination, +sleeps, and cleanup issues. + +**Args:** +- `server`: FastMCP server instance +- `port`: Port to bind to (default\: find available port) +- `transport`: Transport type ("http", "streamable-http", or "sse") +- `path`: URL path for the server (default\: "/mcp") +- `host`: Host to bind to (default\: "127.0.0.1") + + +## Classes + +### `HeadlessOAuth` + + +OAuth provider that bypasses browser interaction for testing. + +This simulates the complete OAuth flow programmatically by making HTTP requests +instead of opening a browser and running a callback server. Useful for automated testing. + + +**Methods:** + +#### `redirect_handler` + +```python +redirect_handler(self, authorization_url: str) -> None +``` + +Make HTTP request to authorization URL and store response for callback handler. + + +#### `callback_handler` + +```python +callback_handler(self) -> tuple[str, str | None] +``` + +Parse stored response and return (auth_code, state). + diff --git a/docs/python-sdk/fastmcp-utilities-timeout.mdx b/docs/python-sdk/fastmcp-utilities-timeout.mdx new file mode 100644 index 000000000..3a8cb41b9 --- /dev/null +++ b/docs/python-sdk/fastmcp-utilities-timeout.mdx @@ -0,0 +1,44 @@ +--- +title: timeout +sidebarTitle: timeout +--- + +# `fastmcp.utilities.timeout` + + +Timeout normalization utilities. + +## Functions + +### `normalize_timeout_to_timedelta` + +```python +normalize_timeout_to_timedelta(value: int | float | datetime.timedelta | None) -> datetime.timedelta | None +``` + + +Normalize a timeout value to a timedelta. + +**Args:** +- `value`: Timeout value as int/float (seconds), timedelta, or None + +**Returns:** +- timedelta if value provided, None otherwise + + +### `normalize_timeout_to_seconds` + +```python +normalize_timeout_to_seconds(value: int | float | datetime.timedelta | None) -> float | None +``` + + +Normalize a timeout value to seconds (float). + +**Args:** +- `value`: Timeout value as int/float (seconds), timedelta, or None. +Zero values are treated as "disabled" and return None. + +**Returns:** +- float seconds if value provided and non-zero, None otherwise + diff --git a/docs/python-sdk/fastmcp-utilities-types.mdx b/docs/python-sdk/fastmcp-utilities-types.mdx new file mode 100644 index 000000000..6cae8cdc0 --- /dev/null +++ b/docs/python-sdk/fastmcp-utilities-types.mdx @@ -0,0 +1,169 @@ +--- +title: types +sidebarTitle: types +--- + +# `fastmcp.utilities.types` + + +Common types used across FastMCP. + +## Functions + +### `get_fn_name` + +```python +get_fn_name(fn: Callable[..., Any]) -> str +``` + +### `get_cached_typeadapter` + +```python +get_cached_typeadapter(cls: T) -> TypeAdapter[T] +``` + + +TypeAdapters are heavy objects, and in an application context we'd typically +create them once in a global scope and reuse them as often as possible. +However, this isn't feasible for user-generated functions. Instead, we use a +cache to minimize the cost of creating them as much as possible. + + +### `issubclass_safe` + +```python +issubclass_safe(cls: type, base: type) -> bool +``` + + +Check if cls is a subclass of base, even if cls is a type variable. + + +### `is_class_member_of_type` + +```python +is_class_member_of_type(cls: Any, base: type) -> bool +``` + + +Check if cls is a member of base, even if cls is a type variable. + +Base can be a type, a UnionType, or an Annotated type. Generic types are not +considered members (e.g. T is not a member of list\[T]). + + +### `find_kwarg_by_type` + +```python +find_kwarg_by_type(fn: Callable, kwarg_type: type) -> str | None +``` + + +Find the name of the kwarg that is of type kwarg_type. + +Includes union types that contain the kwarg_type, as well as Annotated types. + + +### `create_function_without_params` + +```python +create_function_without_params(fn: Callable[..., Any], exclude_params: list[str]) -> Callable[..., Any] +``` + + +Create a new function with the same code but without the specified parameters in annotations. + +This is used to exclude parameters from type adapter processing when they can't be serialized. +The excluded parameters are removed from the function's __annotations__ dictionary. + + +### `replace_type` + +```python +replace_type(type_, type_map: dict[type, type]) +``` + + +Given a (possibly generic, nested, or otherwise complex) type, replaces all +instances of old_type with new_type. + +This is useful for transforming types when creating tools. + +**Args:** +- `type_`: The type to replace instances of old_type with new_type. +- `old_type`: The type to replace. +- `new_type`: The type to replace old_type with. + +Examples: +```python +>>> replace_type(list[int | bool], {int: str}) +list[str | bool] + +>>> replace_type(list[list[int]], {int: str}) +list[list[str]] +``` + + +## Classes + +### `FastMCPBaseModel` + + +Base model for FastMCP models. + + +### `Image` + + +Helper class for returning images from tools. + + +**Methods:** + +#### `to_image_content` + +```python +to_image_content(self, mime_type: str | None = None, annotations: Annotations | None = None) -> mcp.types.ImageContent +``` + +Convert to MCP ImageContent. + + +#### `to_data_uri` + +```python +to_data_uri(self, mime_type: str | None = None) -> str +``` + +Get image as a data URI. + + +### `Audio` + + +Helper class for returning audio from tools. + + +**Methods:** + +#### `to_audio_content` + +```python +to_audio_content(self, mime_type: str | None = None, annotations: Annotations | None = None) -> mcp.types.AudioContent +``` + +### `File` + + +Helper class for returning file data from tools. + + +**Methods:** + +#### `to_resource_content` + +```python +to_resource_content(self, mime_type: str | None = None, annotations: Annotations | None = None) -> mcp.types.EmbeddedResource +``` + +### `ContextSamplingFallbackProtocol` diff --git a/docs/python-sdk/fastmcp-utilities-ui.mdx b/docs/python-sdk/fastmcp-utilities-ui.mdx new file mode 100644 index 000000000..eb060d2d3 --- /dev/null +++ b/docs/python-sdk/fastmcp-utilities-ui.mdx @@ -0,0 +1,140 @@ +--- +title: ui +sidebarTitle: ui +--- + +# `fastmcp.utilities.ui` + + + +Shared UI utilities for FastMCP HTML pages. + +This module provides reusable HTML/CSS components for OAuth callbacks, +consent pages, and other user-facing interfaces. + + +## Functions + +### `create_page` + +```python +create_page(content: str, title: str = 'FastMCP', additional_styles: str = '', csp_policy: str = "default-src 'none'; style-src 'unsafe-inline'; img-src https: data:; base-uri 'none'") -> str +``` + + +Create a complete HTML page with FastMCP styling. + +**Args:** +- `content`: HTML content to place inside the page +- `title`: Page title +- `additional_styles`: Extra CSS to include +- `csp_policy`: Content Security Policy header value. +If empty string "", the CSP meta tag is omitted entirely. + +**Returns:** +- Complete HTML page as string + + +### `create_logo` + +```python +create_logo(icon_url: str | None = None, alt_text: str = 'FastMCP') -> str +``` + + +Create logo HTML. + +**Args:** +- `icon_url`: Optional custom icon URL. If not provided, uses the FastMCP logo. +- `alt_text`: Alt text for the logo image. + +**Returns:** +- HTML for logo image tag. + + +### `create_status_message` + +```python +create_status_message(message: str, is_success: bool = True) -> str +``` + + +Create a status message with icon. + +**Args:** +- `message`: Status message text +- `is_success`: True for success (✓), False for error (✕) + +**Returns:** +- HTML for status message + + +### `create_info_box` + +```python +create_info_box(content: str, is_error: bool = False, centered: bool = False, monospace: bool = False) -> str +``` + + +Create an info box. + +**Args:** +- `content`: HTML content for the info box +- `is_error`: True for error styling, False for normal +- `centered`: True to center the text, False for left-aligned +- `monospace`: True to use gray monospace font styling instead of blue + +**Returns:** +- HTML for info box + + +### `create_detail_box` + +```python +create_detail_box(rows: list[tuple[str, str]]) -> str +``` + + +Create a detail box with key-value pairs. + +**Args:** +- `rows`: List of (label, value) tuples + +**Returns:** +- HTML for detail box + + +### `create_button_group` + +```python +create_button_group(buttons: list[tuple[str, str, str]]) -> str +``` + + +Create a group of buttons. + +**Args:** +- `buttons`: List of (text, value, css_class) tuples + +**Returns:** +- HTML for button group + + +### `create_secure_html_response` + +```python +create_secure_html_response(html: str, status_code: int = 200) -> HTMLResponse +``` + + +Create an HTMLResponse with security headers. + +Adds X-Frame-Options: DENY to prevent clickjacking attacks per MCP security best practices. + +**Args:** +- `html`: HTML content to return +- `status_code`: HTTP status code + +**Returns:** +- HTMLResponse with security headers + diff --git a/docs/python-sdk/fastmcp-utilities-version_check.mdx b/docs/python-sdk/fastmcp-utilities-version_check.mdx new file mode 100644 index 000000000..b27951eda --- /dev/null +++ b/docs/python-sdk/fastmcp-utilities-version_check.mdx @@ -0,0 +1,40 @@ +--- +title: version_check +sidebarTitle: version_check +--- + +# `fastmcp.utilities.version_check` + + +Version checking utilities for FastMCP. + +## Functions + +### `get_latest_version` + +```python +get_latest_version(include_prereleases: bool = False) -> str | None +``` + + +Get the latest version of FastMCP from PyPI, using cache when available. + +**Args:** +- `include_prereleases`: If True, include pre-release versions. + +**Returns:** +- The latest version string, or None if unavailable. + + +### `check_for_newer_version` + +```python +check_for_newer_version() -> str | None +``` + + +Check if a newer version of FastMCP is available. + +**Returns:** +- The latest version string if newer than current, None otherwise. + diff --git a/docs/python-sdk/fastmcp-utilities-versions.mdx b/docs/python-sdk/fastmcp-utilities-versions.mdx new file mode 100644 index 000000000..f5e44f296 --- /dev/null +++ b/docs/python-sdk/fastmcp-utilities-versions.mdx @@ -0,0 +1,194 @@ +--- +title: versions +sidebarTitle: versions +--- + +# `fastmcp.utilities.versions` + + +Version comparison utilities for component versioning. + +This module provides utilities for comparing component versions. Versions are +strings that are first attempted to be parsed as PEP 440 versions (using the +`packaging` library), falling back to lexicographic string comparison. + +Examples: + - "1", "2", "10" → parsed as PEP 440, compared semantically (1 < 2 < 10) + - "1.0", "2.0" → parsed as PEP 440 + - "v1.0" → 'v' prefix stripped, parsed as "1.0" + - "2025-01-15" → not valid PEP 440, compared as strings + - None → sorts lowest (unversioned components) + + +## Functions + +### `parse_version_key` + +```python +parse_version_key(version: str | None) -> VersionKey +``` + + +Parse a version string into a sortable key. + +**Args:** +- `version`: The version string, or None for unversioned. + +**Returns:** +- A VersionKey suitable for sorting. + + +### `version_sort_key` + +```python +version_sort_key(component: FastMCPComponent) -> VersionKey +``` + + +Get a sort key for a component based on its version. + +Use with sorted() or max() to order components by version. + +**Args:** +- `component`: The component to get a sort key for. + +**Returns:** +- A sortable VersionKey. + + +### `compare_versions` + +```python +compare_versions(a: str | None, b: str | None) -> int +``` + + +Compare two version strings. + +**Args:** +- `a`: First version string (or None). +- `b`: Second version string (or None). + +**Returns:** +- -1 if a < b, 0 if a == b, 1 if a > b. + + +### `is_version_greater` + +```python +is_version_greater(a: str | None, b: str | None) -> bool +``` + + +Check if version a is greater than version b. + +**Args:** +- `a`: First version string (or None). +- `b`: Second version string (or None). + +**Returns:** +- True if a > b, False otherwise. + + +### `max_version` + +```python +max_version(a: str | None, b: str | None) -> str | None +``` + + +Return the greater of two versions. + +**Args:** +- `a`: First version string (or None). +- `b`: Second version string (or None). + +**Returns:** +- The greater version, or None if both are None. + + +### `min_version` + +```python +min_version(a: str | None, b: str | None) -> str | None +``` + + +Return the lesser of two versions. + +**Args:** +- `a`: First version string (or None). +- `b`: Second version string (or None). + +**Returns:** +- The lesser version, or None if both are None. + + +## Classes + +### `VersionSpec` + + +Specification for filtering components by version. + +Used by transforms and providers to filter components to a specific +version or version range. Unversioned components (version=None) always +match any spec. + +**Args:** +- `gte`: If set, only versions >= this value match. +- `lt`: If set, only versions < this value match. +- `eq`: If set, only this exact version matches (gte/lt ignored). + + +**Methods:** + +#### `matches` + +```python +matches(self, version: str | None) -> bool +``` + +Check if a version matches this spec. + +**Args:** +- `version`: The version to check, or None for unversioned. +- `match_none`: Whether unversioned (None) components match. Defaults to True +for backward compatibility with retrieval operations. Set to False +when filtering (e.g., enable/disable) to exclude unversioned components +from version-specific rules. + +**Returns:** +- True if the version matches the spec. + + +#### `intersect` + +```python +intersect(self, other: VersionSpec | None) -> VersionSpec +``` + +Return a spec that satisfies both this spec and other. + +Used by transforms to combine caller constraints with filter constraints. +For example, if a VersionFilter has lt="3.0" and caller requests eq="1.0", +the intersection validates "1.0" is in range and returns the exact spec. + +**Args:** +- `other`: Another spec to intersect with, or None. + +**Returns:** +- A VersionSpec that matches only versions satisfying both specs. + + +### `VersionKey` + + +A comparable version key that handles None, PEP 440 versions, and strings. + +Comparison order: +1. None (unversioned) sorts lowest +2. PEP 440 versions sort by semantic version order +3. Invalid versions (strings) sort lexicographically +4. When comparing PEP 440 vs string, PEP 440 comes first + diff --git a/docs/servers/auth/authentication.mdx b/docs/servers/auth/authentication.mdx new file mode 100644 index 000000000..9a26df138 --- /dev/null +++ b/docs/servers/auth/authentication.mdx @@ -0,0 +1,252 @@ +--- +title: Authentication +sidebarTitle: Overview +description: Secure your FastMCP server with flexible authentication patterns, from simple API keys to full OAuth 2.1 integration with external identity providers. +icon: user-shield +--- + +import { VersionBadge } from "/snippets/version-badge.mdx" + + + +Authentication in MCP presents unique challenges that differ from traditional web applications. MCP clients need to discover authentication requirements automatically, negotiate OAuth flows without user intervention, and work seamlessly across different identity providers. FastMCP addresses these challenges by providing authentication patterns that integrate with the MCP protocol while remaining simple to implement and deploy. + + +Authentication applies only to FastMCP's HTTP-based transports (`http` and `sse`). The STDIO transport inherits security from its local execution environment. + + + +**Authentication is rapidly evolving in MCP.** The specification and best practices are changing quickly. FastMCP aims to provide stable, secure patterns that adapt to these changes while keeping your code simple and maintainable. + + +## MCP Authentication Challenges + +Traditional web authentication assumes a human user with a browser who can interact with login forms and consent screens. MCP clients are often automated systems that need to authenticate without human intervention. This creates several unique requirements: + +**Automatic Discovery**: MCP clients must discover authentication requirements by examining server metadata rather than encountering login redirects. + +**Programmatic OAuth**: OAuth flows must work without human interaction, relying on pre-configured credentials or Dynamic Client Registration. + +**Token Management**: Clients need to obtain, refresh, and manage tokens automatically across multiple MCP servers. + +**Protocol Integration**: Authentication must integrate cleanly with MCP's transport mechanisms and error handling. + +These challenges mean that not all authentication approaches work well with MCP. The patterns that do work fall into three categories based on the level of authentication responsibility your server assumes. + +## Authentication Responsibility + +Authentication responsibility exists on a spectrum. Your MCP server can validate tokens created elsewhere, coordinate with external identity providers, or handle the complete authentication lifecycle internally. Each approach involves different trade-offs between simplicity, security, and control. + +### Token Validation + +Your server validates tokens but delegates their creation to external systems. This approach treats your MCP server as a pure resource server that trusts tokens signed by known issuers. + +Token validation works well when you already have authentication infrastructure that can issue structured tokens like JWTs. Your existing API gateway, microservices platform, or enterprise SSO system becomes the source of truth for user identity, while your MCP server focuses on its core functionality. + +The key insight is that token validation separates authentication (proving who you are) from authorization (determining what you can do). Your MCP server receives proof of identity in the form of a signed token and makes access decisions based on the claims within that token. + +This pattern excels in microservices architectures where multiple services need to validate the same tokens, or when integrating MCP servers into existing systems that already handle user authentication. + +### External Identity Providers + +Your server coordinates with established identity providers to create seamless authentication experiences for MCP clients. This approach leverages OAuth 2.0 and OpenID Connect protocols to delegate user authentication while maintaining control over authorization decisions. + +External identity providers handle the complex aspects of authentication: user credential verification, multi-factor authentication, account recovery, and security monitoring. Your MCP server receives tokens from these trusted providers and validates them using the provider's public keys. + +The MCP protocol's support for Dynamic Client Registration makes this pattern particularly powerful. MCP clients can automatically discover your authentication requirements and register themselves with your identity provider without manual configuration. + +This approach works best for production applications that need enterprise-grade authentication features without the complexity of building them from scratch. It scales well across multiple applications and provides consistent user experiences. + +### Full OAuth Implementation + +Your server implements a complete OAuth 2.0 authorization server, handling everything from user credential verification to token lifecycle management. This approach provides maximum control at the cost of significant complexity. + +Full OAuth implementation means building user interfaces for login and consent, implementing secure credential storage, managing token lifecycles, and maintaining ongoing security updates. The complexity extends beyond initial implementation to include threat monitoring, compliance requirements, and keeping pace with evolving security best practices. + +This pattern makes sense only when you need complete control over the authentication process, operate in air-gapped environments, or have specialized requirements that external providers cannot meet. + +## FastMCP Authentication Providers + +FastMCP translates these authentication responsibility levels into a variety of concrete classes that handle the complexities of MCP protocol integration. You can build on these classes to handle the complexities of MCP protocol integration. + +### TokenVerifier + +`TokenVerifier` provides pure token validation without OAuth metadata endpoints. This class focuses on the essential task of determining whether a token is valid and extracting authorization information from its claims. + +The implementation handles JWT signature verification, expiration checking, and claim extraction. It validates tokens against known issuers and audiences, ensuring that tokens intended for your server are not accepted by other systems. + +```python +from fastmcp import FastMCP +from fastmcp.server.auth.providers.jwt import JWTVerifier + +auth = JWTVerifier( + jwks_uri="https://your-auth-system.com/.well-known/jwks.json", + issuer="https://your-auth-system.com", + audience="your-mcp-server" +) + +mcp = FastMCP(name="Protected Server", auth=auth) +``` + +This example configures token validation against a JWT issuer. The `JWTVerifier` will fetch public keys from the JWKS endpoint and validate incoming tokens against those keys. Only tokens with the correct issuer and audience claims will be accepted. + +`TokenVerifier` works well when you control both the token issuer and your MCP server, or when integrating with existing JWT-based infrastructure. + +→ **Complete guide**: [Token Verification](/servers/auth/token-verification) + +### RemoteAuthProvider + +`RemoteAuthProvider` enables authentication with identity providers that **support Dynamic Client Registration (DCR)**, such as Descope and WorkOS AuthKit. With DCR, MCP clients can automatically register themselves with the identity provider and obtain credentials without any manual configuration. + +This class combines token validation with OAuth discovery metadata. It extends `TokenVerifier` functionality by adding OAuth 2.0 protected resource endpoints that advertise your authentication requirements. MCP clients examine these endpoints to understand which identity providers you trust and how to obtain valid tokens. + +The key requirement is that your identity provider must support DCR - the ability for clients to dynamically register and obtain credentials. This is what enables the seamless, automated authentication flow that MCP requires. + +For example, the built-in `AuthKitProvider` uses WorkOS AuthKit, which fully supports DCR: + +```python +from fastmcp import FastMCP +from fastmcp.server.auth.providers.workos import AuthKitProvider + +auth = AuthKitProvider( + authkit_domain="https://your-project.authkit.app", + base_url="https://your-fastmcp-server.com" +) + +mcp = FastMCP(name="Enterprise Server", auth=auth) +``` + +This example uses WorkOS AuthKit as the external identity provider. The `AuthKitProvider` automatically configures token validation against WorkOS and provides the OAuth metadata that MCP clients need for automatic authentication. + +`RemoteAuthProvider` is ideal for production applications when your identity provider supports Dynamic Client Registration (DCR). This enables fully automated authentication without manual client configuration. + +→ **Complete guide**: [Remote OAuth](/servers/auth/remote-oauth) + +### OAuthProxy + + + +`OAuthProxy` enables authentication with OAuth providers that **don't support Dynamic Client Registration (DCR)**, such as GitHub, Google, Azure, AWS, and most traditional enterprise identity systems. + +When identity providers require manual app registration and fixed credentials, `OAuthProxy` bridges the gap. It presents a DCR-compliant interface to MCP clients (accepting any registration request) while using your pre-registered credentials with the upstream provider. The proxy handles the complexity of callback forwarding, enabling dynamic client callbacks to work with providers that require fixed redirect URIs. + +This class solves the fundamental incompatibility between MCP's expectation of dynamic registration and traditional OAuth providers' requirement for manual app registration. + +For example, the built-in `GitHubProvider` extends `OAuthProxy` to work with GitHub's OAuth system: + +```python +from fastmcp import FastMCP +from fastmcp.server.auth.providers.github import GitHubProvider + +auth = GitHubProvider( + client_id="Ov23li...", # Your GitHub OAuth App ID + client_secret="abc123...", # Your GitHub OAuth App Secret + base_url="https://your-server.com" +) + +mcp = FastMCP(name="GitHub-Protected Server", auth=auth) +``` + +This example uses the GitHub provider, which extends `OAuthProxy` with GitHub-specific token validation. The proxy handles the complete OAuth flow while making GitHub's non-DCR authentication work seamlessly with MCP clients. + +`OAuthProxy` is essential when integrating with OAuth providers that don't support DCR. This includes most established providers like GitHub, Google, and Azure, which require manual app registration through their developer consoles. + +→ **Complete guide**: [OAuth Proxy](/servers/auth/oauth-proxy) + +### OAuthProvider + +`OAuthProvider` implements a complete OAuth 2.0 authorization server within your MCP server. This class handles the full authentication lifecycle from user credential verification to token management. + +The implementation provides all required OAuth endpoints including authorization, token, and discovery endpoints. It manages client registration, user consent, and token lifecycle while integrating with your user storage and authentication logic. + +```python +from fastmcp import FastMCP +from fastmcp.server.auth.providers.oauth import MyOAuthProvider + +auth = MyOAuthProvider( + user_store=your_user_database, + client_store=your_client_registry, + # Additional configuration... +) + +mcp = FastMCP(name="Auth Server", auth=auth) +``` + +This example shows the basic structure of a custom OAuth provider. The actual implementation requires significant additional configuration for user management, client registration, and security policies. + +`OAuthProvider` should be used only when you have specific requirements that external providers cannot meet and the expertise to implement OAuth securely. + +→ **Complete guide**: [Full OAuth Server](/servers/auth/full-oauth-server) + +### MultiAuth + + + +`MultiAuth` composes multiple authentication sources into a single `auth` provider. When a server needs to accept tokens from different issuers — for example, an OAuth proxy for interactive clients alongside JWT verification for machine-to-machine tokens — `MultiAuth` tries each source in order and accepts the first successful verification. + +```python +from fastmcp import FastMCP +from fastmcp.server.auth import MultiAuth, OAuthProxy +from fastmcp.server.auth.providers.jwt import JWTVerifier + +auth = MultiAuth( + server=OAuthProxy( + issuer_url="https://login.example.com/...", + client_id="my-app", + client_secret="secret", + base_url="https://my-server.com", + ), + verifiers=[ + JWTVerifier( + jwks_uri="https://internal-issuer.example.com/.well-known/jwks.json", + issuer="https://internal-issuer.example.com", + audience="my-mcp-server", + ), + ], +) + +mcp = FastMCP("My Server", auth=auth) +``` + +The server (if provided) owns all OAuth routes and metadata. Verifiers contribute only token verification logic. This keeps the MCP discovery surface clean while supporting multiple token sources. + +→ **Complete guide**: [Multiple Auth Sources](/servers/auth/multi-auth) + +## Configuration + +Authentication providers are configured programmatically by instantiating them directly in your code with their required parameters. This makes dependencies explicit and allows your IDE to provide helpful autocompletion and type checking. + +For production deployments, load sensitive values like client secrets from environment variables: + +```python +import os +from fastmcp import FastMCP +from fastmcp.server.auth.providers.github import GitHubProvider + +# Load secrets from environment variables +auth = GitHubProvider( + client_id=os.environ.get("GITHUB_CLIENT_ID"), + client_secret=os.environ.get("GITHUB_CLIENT_SECRET"), + base_url=os.environ.get("BASE_URL", "http://localhost:8000") +) + +mcp = FastMCP(name="My Server", auth=auth) +``` + +This approach keeps secrets out of your codebase while maintaining explicit configuration. You can use any environment variable names you prefer - there are no special prefixes required. + +## Choosing Your Implementation + +The authentication approach you choose depends on your existing infrastructure, security requirements, and operational constraints. + +**For OAuth providers without DCR support (GitHub, Google, Azure, AWS, most enterprise systems), use OAuth Proxy.** These providers require manual app registration through their developer consoles. OAuth Proxy bridges the gap by presenting a DCR-compliant interface to MCP clients while using your fixed credentials with the provider. The proxy's callback forwarding pattern enables dynamic client ports to work with providers that require fixed redirect URIs. + +**For identity providers with DCR support (Descope, WorkOS AuthKit, modern auth platforms), use RemoteAuthProvider.** These providers allow clients to dynamically register and obtain credentials without manual configuration. This enables the fully automated authentication flow that MCP is designed for, providing the best user experience and simplest implementation. + +**Token validation works well when you already have authentication infrastructure that issues structured tokens.** If your organization already uses JWT-based systems, API gateways, or enterprise SSO that can generate tokens, this approach integrates seamlessly while keeping your MCP server focused on its core functionality. The simplicity comes from leveraging existing investment in authentication infrastructure. + +**When you need tokens from multiple sources, use MultiAuth.** This is common in hybrid architectures where interactive clients authenticate through an OAuth proxy while backend services send JWT tokens directly. `MultiAuth` composes an optional auth server with additional token verifiers, trying each source in order until one succeeds. + +**Full OAuth implementation should be avoided unless you have compelling reasons that external providers cannot address.** Air-gapped environments, specialized compliance requirements, or unique organizational constraints might justify this approach, but it requires significant security expertise and ongoing maintenance commitment. The complexity extends far beyond initial implementation to include threat monitoring, security updates, and keeping pace with evolving attack vectors. + +FastMCP's architecture supports migration between these approaches as your requirements evolve. You can integrate with existing token systems initially and migrate to external identity providers as your application scales, or implement custom solutions when your requirements outgrow standard patterns. \ No newline at end of file diff --git a/docs/servers/auth/full-oauth-server.mdx b/docs/servers/auth/full-oauth-server.mdx new file mode 100644 index 000000000..529a01784 --- /dev/null +++ b/docs/servers/auth/full-oauth-server.mdx @@ -0,0 +1,229 @@ +--- +title: Full OAuth Server +sidebarTitle: Full OAuth Server +description: Build a self-contained authentication system where your FastMCP server manages users, issues tokens, and validates them. +icon: users-between-lines + +--- + +import { VersionBadge } from "/snippets/version-badge.mdx" + + + + +**This is an extremely advanced pattern that most users should avoid.** Building a secure OAuth 2.1 server requires deep expertise in authentication protocols, cryptography, and security best practices. The complexity extends far beyond initial implementation to include ongoing security monitoring, threat response, and compliance maintenance. + +**Use [Remote OAuth](/servers/auth/remote-oauth) instead** unless you have compelling requirements that external identity providers cannot meet, such as air-gapped environments or specialized compliance needs. + + +The Full OAuth Server pattern exists to support the MCP protocol specification's requirements. Your FastMCP server becomes both an Authorization Server and Resource Server, handling the complete authentication lifecycle from user login to token validation. + +This documentation exists for completeness - the vast majority of applications should use external identity providers instead. + +## OAuthProvider + +FastMCP provides the `OAuthProvider` abstract class that implements the OAuth 2.1 specification. To use this pattern, you must subclass `OAuthProvider` and implement all required abstract methods. + + +`OAuthProvider` handles OAuth endpoints, protocol flows, and security requirements, but delegates all storage, user management, and business logic to your implementation of the abstract methods. + + +## Required Implementation + +You must implement these abstract methods to create a functioning OAuth server: + +### Client Management + + + + Retrieve client information by ID from your database. + + + + Client identifier to look up + + + + + + Client information object or `None` if client not found + + + + + + Store new client registration information in your database. + + + + Complete client registration information to store + + + + + + No return value + + + + + +### Authorization Flow + + + + Handle authorization request and return redirect URL. Must implement user authentication and consent collection. + + + + OAuth client making the authorization request + + + Authorization request parameters from the client + + + + + + Redirect URL to send the client to + + + + + + Load authorization code from storage by code string. Return `None` if code is invalid or expired. + + + + OAuth client attempting to use the authorization code + + + Authorization code string to look up + + + + + + Authorization code object or `None` if not found + + + + + +### Token Management + + + + Exchange authorization code for access and refresh tokens. Must validate code and create new tokens. + + + + OAuth client exchanging the authorization code + + + Valid authorization code object to exchange + + + + + + New OAuth token containing access and refresh tokens + + + + + + Load refresh token from storage by token string. Return `None` if token is invalid or expired. + + + + OAuth client attempting to use the refresh token + + + Refresh token string to look up + + + + + + Refresh token object or `None` if not found + + + + + + Exchange refresh token for new access/refresh token pair. Must validate scopes and token. + + + + OAuth client using the refresh token + + + Valid refresh token object to exchange + + + Requested scopes for the new access token + + + + + + New OAuth token with updated access and refresh tokens + + + + + + Load an access token by its token string. + + + + The access token to verify + + + + + + The access token object, or `None` if the token is invalid + + + + + + Revoke access or refresh token, marking it as invalid in storage. + + + + Token object to revoke and mark invalid + + + + + + No return value + + + + + + Verify bearer token for incoming requests. Return `AccessToken` if valid, `None` if invalid. + + + + Bearer token string from incoming request + + + + + + Access token object if valid, `None` if invalid or expired + + + + + +Each method must handle storage, validation, security, and error cases according to the OAuth 2.1 specification. The implementation complexity is substantial and requires expertise in OAuth security considerations. + + +**Security Notice:** OAuth server implementation involves numerous security considerations including PKCE, state parameters, redirect URI validation, token binding, replay attack prevention, and secure storage requirements. Mistakes can lead to serious security vulnerabilities. + \ No newline at end of file diff --git a/docs/servers/auth/multi-auth.mdx b/docs/servers/auth/multi-auth.mdx new file mode 100644 index 000000000..ba54d25ab --- /dev/null +++ b/docs/servers/auth/multi-auth.mdx @@ -0,0 +1,95 @@ +--- +title: Multiple Auth Sources +sidebarTitle: Multiple Auth Sources +description: Accept tokens from multiple authentication sources with a single server. +icon: layer-group +--- + +import { VersionBadge } from "/snippets/version-badge.mdx" + + + +Production servers often need to accept tokens from multiple authentication sources. An interactive application might authenticate through an OAuth proxy, while a backend service sends machine-to-machine JWT tokens directly. `MultiAuth` composes these sources into a single `auth` provider so every valid token is accepted regardless of where it was issued. + +## Understanding MultiAuth + +`MultiAuth` wraps an optional auth server (like `OAuthProxy`) together with one or more token verifiers (like `JWTVerifier`). When a request arrives with a bearer token, `MultiAuth` tries each source in order and accepts the first successful verification. + +The auth server, if provided, is tried first. It owns all OAuth routes and metadata — the verifiers contribute only token verification logic. This keeps the MCP discovery surface clean: one set of routes, one set of metadata, multiple verification paths. + +```python +from fastmcp import FastMCP +from fastmcp.server.auth import MultiAuth, OAuthProxy +from fastmcp.server.auth.providers.jwt import JWTVerifier + +auth = MultiAuth( + server=OAuthProxy( + issuer_url="https://login.example.com/...", + client_id="my-app", + client_secret="secret", + base_url="https://my-server.com", + ), + verifiers=[ + JWTVerifier( + jwks_uri="https://internal-issuer.example.com/.well-known/jwks.json", + issuer="https://internal-issuer.example.com", + audience="my-mcp-server", + ), + ], +) + +mcp = FastMCP("My Server", auth=auth) +``` + +Interactive MCP clients authenticate through the OAuth proxy as usual. Backend services skip OAuth entirely and send a JWT signed by the internal issuer. Both paths are validated, and the first match wins. + +## Verification Order + +`MultiAuth` checks sources in a deterministic order: + +1. **Server** (if provided) — the full auth provider's `verify_token` runs first +2. **Verifiers** — each `TokenVerifier` is tried in list order + +The first source that returns a valid `AccessToken` wins. If every source returns `None`, the request receives a 401 response. + +This ordering means the server acts as the "primary" authentication path, with verifiers as fallbacks for tokens the server doesn't recognize. + +## Verifiers Only + +You don't always need a full OAuth server. If your server only needs to accept tokens from multiple issuers, pass verifiers without a server: + +```python +from fastmcp import FastMCP +from fastmcp.server.auth import MultiAuth +from fastmcp.server.auth.providers.jwt import JWTVerifier, StaticTokenVerifier + +auth = MultiAuth( + verifiers=[ + JWTVerifier( + jwks_uri="https://issuer-a.example.com/.well-known/jwks.json", + issuer="https://issuer-a.example.com", + audience="my-server", + ), + JWTVerifier( + jwks_uri="https://issuer-b.example.com/.well-known/jwks.json", + issuer="https://issuer-b.example.com", + audience="my-server", + ), + ], +) + +mcp = FastMCP("Multi-Issuer Server", auth=auth) +``` + +Without a server, no OAuth routes or metadata are served. This is appropriate for internal systems where clients already know how to obtain tokens. + +## API Reference + +### MultiAuth + +| Parameter | Type | Description | +| --- | --- | --- | +| `server` | `AuthProvider \| None` | Optional auth provider that owns routes and OAuth metadata. Also tried first for token verification. | +| `verifiers` | `list[TokenVerifier] \| TokenVerifier` | One or more token verifiers tried after the server. | +| `base_url` | `str \| None` | Override the base URL. Defaults to the server's `base_url`. | +| `required_scopes` | `list[str] \| None` | Override required scopes. Defaults to the server's scopes. | diff --git a/docs/servers/auth/oauth-proxy.mdx b/docs/servers/auth/oauth-proxy.mdx new file mode 100644 index 000000000..e8e79507c --- /dev/null +++ b/docs/servers/auth/oauth-proxy.mdx @@ -0,0 +1,679 @@ +--- +title: OAuth Proxy +sidebarTitle: OAuth Proxy +description: Bridge traditional OAuth providers to work seamlessly with MCP's authentication flow. +icon: share +tag: NEW +--- + +import { VersionBadge } from "/snippets/version-badge.mdx"; + + + +The OAuth proxy enables FastMCP servers to authenticate with OAuth providers that **don't support Dynamic Client Registration (DCR)**. This includes virtually all traditional OAuth providers: GitHub, Google, Azure, AWS, Discord, Facebook, and most enterprise identity systems. For providers that do support DCR (like Descope and WorkOS AuthKit), use [`RemoteAuthProvider`](/servers/auth/remote-oauth) instead. + +MCP clients expect to register automatically and obtain credentials on the fly, but traditional providers require manual app registration through their developer consoles. The OAuth proxy bridges this gap by presenting a DCR-compliant interface to MCP clients while using your pre-registered credentials with the upstream provider. When a client attempts to register, the proxy returns your fixed credentials. When a client initiates authorization, the proxy handles the complexity of callback forwarding—storing the client's dynamic callback URL, using its own fixed callback with the provider, then forwarding back to the client after token exchange. + +This approach enables any MCP client (whether using random localhost ports or fixed URLs like Claude.ai) to authenticate with any traditional OAuth provider, all while maintaining full OAuth 2.1 and PKCE security. + + + For providers that support OIDC discovery (Auth0, Google with OIDC + configuration, Azure AD), consider using [`OIDC + Proxy`](/servers/auth/oidc-proxy) for automatic configuration. OIDC Proxy + extends the OAuth proxy to automatically discover endpoints from the provider's + `/.well-known/openid-configuration` URL, simplifying setup. + + +## Implementation + +### Provider Setup Requirements + +Before using the OAuth proxy, you need to register your application with your OAuth provider: + +1. **Register your application** in the provider's developer console (GitHub Settings, Google Cloud Console, Azure Portal, etc.) +2. **Configure the redirect URI** as your FastMCP server URL plus your chosen callback path: + - Default: `https://your-server.com/auth/callback` + - Custom: `https://your-server.com/your/custom/path` (if you set `redirect_path`) + - Development: `http://localhost:8000/auth/callback` +3. **Obtain your credentials**: Client ID and Client Secret +4. **Note the OAuth endpoints**: Authorization URL and Token URL (usually found in the provider's OAuth documentation) + + + The redirect URI you configure with your provider must exactly match your + FastMCP server's URL plus the callback path. If you customize `redirect_path` + in the OAuth proxy, update your provider's redirect URI accordingly. + + +### Basic Setup + +Here's how to implement the OAuth proxy with any provider: + +```python +from fastmcp import FastMCP +from fastmcp.server.auth import OAuthProxy +from fastmcp.server.auth.providers.jwt import JWTVerifier + +# Configure token verification for your provider +# See the Token Verification guide for provider-specific setups +token_verifier = JWTVerifier( + jwks_uri="https://your-provider.com/.well-known/jwks.json", + issuer="https://your-provider.com", + audience="your-app-id" +) + +# Create the OAuth proxy +auth = OAuthProxy( + # Provider's OAuth endpoints (from their documentation) + upstream_authorization_endpoint="https://provider.com/oauth/authorize", + upstream_token_endpoint="https://provider.com/oauth/token", + + # Your registered app credentials + upstream_client_id="your-client-id", + upstream_client_secret="your-client-secret", + + # Token validation (see Token Verification guide) + token_verifier=token_verifier, + + # Your FastMCP server's public URL + base_url="https://your-server.com", + + # Optional: customize the callback path (default is "/auth/callback") + # redirect_path="/custom/callback", +) + +mcp = FastMCP(name="My Server", auth=auth) +``` + +### Configuration Parameters + + + + URL of your OAuth provider's authorization endpoint (e.g., `https://github.com/login/oauth/authorize`) + + + + URL of your OAuth provider's token endpoint (e.g., + `https://github.com/login/oauth/access_token`) + + + + Client ID from your registered OAuth application + + + + Client secret from your registered OAuth application + + + + A [`TokenVerifier`](/servers/auth/token-verification) instance to validate the + provider's tokens + + + + Public URL where OAuth endpoints will be accessible, **including any mount path** (e.g., `https://your-server.com/api`). + + This URL is used to construct OAuth callback URLs and operational endpoints. When mounting under a path prefix, include that prefix in `base_url`. Use `issuer_url` separately to specify where auth server metadata is located (typically at root level). + + + + Path for OAuth callbacks. Must match the redirect URI configured in your OAuth + application + + + + Optional URL of provider's token revocation endpoint + + + + Issuer URL for OAuth authorization server metadata (defaults to `base_url`). + + When `issuer_url` has a path component (either explicitly or by defaulting from `base_url`), FastMCP creates path-aware discovery routes per RFC 8414. For example, if `base_url` is `http://localhost:8000/api`, the authorization server metadata will be at `/.well-known/oauth-authorization-server/api`. + + **Default behavior (recommended for most cases):** + ```python + auth = GitHubProvider( + base_url="http://localhost:8000/api", # OAuth endpoints under /api + # issuer_url defaults to base_url - path-aware discovery works automatically + ) + ``` + + **When to set explicitly:** + Set `issuer_url` to root level only if you want multiple MCP servers to share a single discovery endpoint: + ```python + auth = GitHubProvider( + base_url="http://localhost:8000/api", + issuer_url="http://localhost:8000" # Shared root-level discovery + ) + ``` + + See the [HTTP Deployment guide](/deployment/http#mounting-authenticated-servers) for complete mounting examples. + + + + Optional URL to your service documentation + + + + Whether to forward PKCE (Proof Key for Code Exchange) to the upstream OAuth + provider. When enabled and the client uses PKCE, the proxy generates its own + PKCE parameters to send upstream while separately validating the client's + PKCE. This ensures end-to-end PKCE security at both layers (client-to-proxy + and proxy-to-upstream). - `True` (default): Forward PKCE for providers that + support it (Google, Azure, AWS, GitHub, etc.) - `False`: Disable only if upstream + provider doesn't support PKCE + + + + Token endpoint authentication method for the upstream OAuth server. Controls + how the proxy authenticates when exchanging authorization codes and refresh + tokens with the upstream provider. - `"client_secret_basic"`: Send credentials + in Authorization header (most common) - `"client_secret_post"`: Send + credentials in request body (required by some providers) - `"none"`: No + authentication (for public clients) - `None` (default): Uses authlib's default + (typically `"client_secret_basic"`) Set this if your provider requires a + specific authentication method and the default doesn't work. + + + + List of allowed redirect URI patterns for MCP clients. Patterns support + wildcards (e.g., `"http://localhost:*"`, `"https://*.example.com/*"`). - + `None` (default): All redirect URIs allowed (for MCP/DCR compatibility) - + Empty list `[]`: No redirect URIs allowed - Custom list: Only matching + patterns allowed These patterns apply to MCP client loopback redirects, NOT + the upstream OAuth app redirect URI. + + + + List of all possible valid scopes for the OAuth provider. These are advertised + to clients through the `/.well-known` endpoints. Defaults to `required_scopes` + from your TokenVerifier if not specified. + + + + Additional parameters to forward to the upstream authorization endpoint. Useful for provider-specific parameters that aren't part of the standard OAuth2 flow. + + For example, Auth0 requires an `audience` parameter to issue JWT tokens: + ```python + extra_authorize_params={"audience": "https://api.example.com"} + ``` + + These parameters are added to every authorization request sent to the upstream provider. + + + + Additional parameters to forward to the upstream token endpoint during code exchange and token refresh. Useful for provider-specific requirements during token operations. + +For example, some providers require additional context during token exchange: + +```python +extra_token_params={"audience": "https://api.example.com"} +``` + +These parameters are included in all token requests to the upstream provider. + + + + + + + Storage backend for persisting OAuth client registrations and upstream tokens. + + **Default behavior:** + By default, clients are automatically persisted to an encrypted disk store, allowing them to survive server restarts as long as the filesystem remains accessible. This means MCP clients only need to register once and can reconnect seamlessly. The disk store is encrypted using a key derived from the JWT Signing Key (which is derived from the upstream client secret by default). For client registrations to survive upstream client secret rotation, you should provide a JWT Signing Key or your own client_storage. + +For production deployments with multiple servers or cloud deployments, see [Storage Backends](/servers/storage-backends) for available options. + + + **When providing custom storage**, wrap it in `FernetEncryptionWrapper` to encrypt sensitive OAuth tokens at rest: + + ```python + from key_value.aio.stores.redis import RedisStore + from key_value.aio.wrappers.encryption import FernetEncryptionWrapper + from cryptography.fernet import Fernet + import os + + auth = OAuthProxy( + ..., + jwt_signing_key=os.environ["JWT_SIGNING_KEY"], + client_storage=FernetEncryptionWrapper( + key_value=RedisStore(host="redis.example.com", port=6379), + fernet=Fernet(os.environ["STORAGE_ENCRYPTION_KEY"]) + ) + ) + ``` + + Without encryption, upstream OAuth tokens are stored in plaintext. + + +Testing with in-memory storage (unencrypted): + +```python +from key_value.aio.stores.memory import MemoryStore + +# Use in-memory storage for testing (clients lost on restart) +auth = OAuthProxy(..., client_storage=MemoryStore()) +``` + + + + + + + Secret used to sign FastMCP JWT tokens issued to clients. Accepts any string or bytes - will be derived into a proper 32-byte cryptographic key using HKDF. + + **Default behavior (`None`):** + Derives a 32-byte key using PBKDF2 from the upstream client secret. + + **For production:** + Provide an explicit secret (e.g., from environment variable) to use a fixed key instead of the key derived from the upstream client secret. This allows you to manage keys securely in cloud environments, allows keys to work across multiple instances, and allows you to rotate keys without losing client registrations. + + ```python + import os + + auth = OAuthProxy( + ..., + jwt_signing_key=os.environ["JWT_SIGNING_KEY"], # Any sufficiently complex string! + client_storage=RedisStore(...) # Persistent storage + ) + ``` + + See [HTTP Deployment - OAuth Token Security](/deployment/http#oauth-token-security) for complete production setup. + + + + + Whether to require user consent before authorizing MCP clients. When enabled (default), users see a consent screen that displays which client is requesting access, preventing [confused deputy attacks](https://modelcontextprotocol.io/specification/2025-06-18/basic/security_best_practices#confused-deputy-problem) by ensuring users explicitly approve new clients. + + **Default behavior (True):** + Users see a consent screen on first authorization. Consent choices are remembered via signed cookies, so users only need to approve each client once. This protects against malicious clients impersonating the user. + + **Disabling consent (False):** + Authorization proceeds directly to the upstream provider without user confirmation. Only use this for local development or testing environments where the security trade-off is acceptable. + + ```python + # Development/testing only - skip consent screen + auth = OAuthProxy( + ..., + require_authorization_consent=False # ⚠️ Security warning: only for local/testing + ) + ``` + + + Disabling consent removes an important security layer. Only disable for local development or testing environments where you fully control all connecting clients. + + + + + Content Security Policy for the consent page. + + - `None` (default): Uses the built-in CSP policy with appropriate directives for form submission + - Empty string `""`: Disables CSP entirely (no meta tag rendered) + - Custom string: Uses the provided value as the CSP policy + + This is useful for organizations that have their own CSP policies and need to override or disable FastMCP's built-in CSP directives. + + ```python + # Disable CSP entirely (let org CSP policies apply) + auth = OAuthProxy(..., consent_csp_policy="") + + # Use custom CSP policy + auth = OAuthProxy(..., consent_csp_policy="default-src 'self'; style-src 'unsafe-inline'") + ``` + + + +### Using Built-in Providers + +FastMCP includes pre-configured providers for common services: + +```python +from fastmcp.server.auth.providers.github import GitHubProvider + +auth = GitHubProvider( + client_id="your-github-app-id", + client_secret="your-github-app-secret", + base_url="https://your-server.com" +) + +mcp = FastMCP(name="My Server", auth=auth) +``` + +Available providers include `GitHubProvider`, `GoogleProvider`, and others. These handle token verification automatically. + +### Token Verification + +The OAuth proxy requires a compatible `TokenVerifier` to validate tokens from your provider. Different providers use different token formats: + +- **JWT tokens** (Google, Azure): Use `JWTVerifier` with the provider's JWKS endpoint +- **Opaque tokens with RFC 7662 introspection** (Auth0, Okta, WorkOS): Use `IntrospectionTokenVerifier` +- **Opaque tokens (provider-specific)** (GitHub, Discord): Use provider-specific verifiers like `GitHubTokenVerifier` + +See the [Token Verification guide](/servers/auth/token-verification) for detailed setup instructions for your provider. + +### Scope Configuration + +OAuth scopes control what permissions your application requests from users. They're configured through your `TokenVerifier` (required for the OAuth proxy to validate tokens from your provider). Set `required_scopes` to automatically request the permissions your application needs: + +```python +JWTVerifier(..., required_scopes = ["read:user", "write:data"]) +``` + +Dynamic clients created by the proxy will automatically include these scopes in their authorization requests. See the [Token Verification](#token-verification) section below for detailed setup. + +### Custom Parameters + +Some OAuth providers require additional parameters beyond the standard OAuth2 flow. Use `extra_authorize_params` and `extra_token_params` to pass provider-specific requirements. For example, Auth0 requires an `audience` parameter to issue JWT tokens instead of opaque tokens: + +```python +auth = OAuthProxy( + upstream_authorization_endpoint="https://your-domain.auth0.com/authorize", + upstream_token_endpoint="https://your-domain.auth0.com/oauth/token", + upstream_client_id="your-auth0-client-id", + upstream_client_secret="your-auth0-client-secret", + + # Auth0-specific audience parameter + extra_authorize_params={"audience": "https://your-api-identifier.com"}, + extra_token_params={"audience": "https://your-api-identifier.com"}, + + token_verifier=JWTVerifier( + jwks_uri="https://your-domain.auth0.com/.well-known/jwks.json", + issuer="https://your-domain.auth0.com/", + audience="https://your-api-identifier.com" + ), + base_url="https://your-server.com" +) +``` + +The proxy also automatically forwards RFC 8707 `resource` parameters from MCP clients to upstream providers that support them. + +## OAuth Flow + +```mermaid +sequenceDiagram + participant Client as MCP Client
(localhost:random) + participant User as User + participant Proxy as FastMCP OAuth Proxy
(server:8000) + participant Provider as OAuth Provider
(GitHub, etc.) + + Note over Client, Proxy: Dynamic Registration (Local) + Client->>Proxy: 1. POST /register
redirect_uri: localhost:54321/callback + Proxy-->>Client: 2. Returns fixed upstream credentials + + Note over Client, User: Authorization with User Consent + Client->>Proxy: 3. GET /authorize
redirect_uri=localhost:54321/callback
code_challenge=CLIENT_CHALLENGE + Note over Proxy: Store transaction with client PKCE
Generate proxy PKCE pair + Proxy->>User: 4. Show consent page
(client details, redirect URI, scopes) + User->>Proxy: 5. Approve/deny consent + Note over Proxy: Set consent binding cookie
(binds browser to this flow) + Proxy->>Provider: 6. Redirect to provider
redirect_uri=server:8000/auth/callback
code_challenge=PROXY_CHALLENGE + + Note over Provider, Proxy: Provider Callback + Provider->>Proxy: 7. GET /auth/callback
with authorization code + Note over Proxy: Verify consent binding cookie
(reject if missing or mismatched) + Proxy->>Provider: 8. Exchange code for tokens
code_verifier=PROXY_VERIFIER + Provider-->>Proxy: 9. Access & refresh tokens + + Note over Proxy, Client: Client Callback Forwarding + Proxy->>Client: 10. Redirect to localhost:54321/callback
with new authorization code + + Note over Client, Proxy: Token Exchange + Client->>Proxy: 11. POST /token with code
code_verifier=CLIENT_VERIFIER + Proxy-->>Client: 12. Returns FastMCP JWT tokens +``` + +The flow diagram above illustrates the complete OAuth proxy pattern. Let's understand each phase: + +### Registration Phase + +When an MCP client calls `/register` with its dynamic callback URL, the proxy responds with your pre-configured upstream credentials. The client stores these credentials believing it has registered a new app. Meanwhile, the proxy records the client's callback URL for later use. + +### Authorization Phase + +The client initiates OAuth by redirecting to the proxy's `/authorize` endpoint. The proxy: + +1. Stores the client's transaction with its PKCE challenge +2. Generates its own PKCE parameters for upstream security +3. Shows the user a consent page with the client's details, redirect URI, and requested scopes +4. If the user approves (or the client was previously approved), sets a consent binding cookie and redirects to the upstream provider using the fixed callback URL + +This dual-PKCE approach maintains end-to-end security at both the client-to-proxy and proxy-to-provider layers. The consent step protects against confused deputy attacks by ensuring you explicitly approve each client before it can complete authorization, and the consent binding cookie ensures that only the browser that approved consent can complete the callback. + +### Callback Phase + +After user authorization, the provider redirects back to the proxy's fixed callback URL. The proxy: + +1. Verifies the consent binding cookie matches the transaction (rejecting requests from a different browser) +2. Exchanges the authorization code for tokens with the provider +3. Stores these tokens temporarily +4. Generates a new authorization code for the client +5. Redirects to the client's original dynamic callback URL + +### Token Exchange Phase + +Finally, the client exchanges its authorization code with the proxy. The proxy validates the client's PKCE verifier, then issues its own FastMCP JWT tokens (rather than forwarding the upstream provider's tokens). See [Token Architecture](#token-architecture) for details on this design. + +This entire flow is transparent to the MCP client—it experiences a standard OAuth flow with dynamic registration, unaware that a proxy is managing the complexity behind the scenes. + +### Token Architecture + +The OAuth proxy implements a **token factory pattern**: instead of directly forwarding tokens from the upstream OAuth provider, it issues its own JWT tokens to MCP clients. This maintains proper OAuth 2.0 token audience boundaries and enables better security controls. + +**How it works:** + +When an MCP client completes authorization, the proxy: + +1. **Receives upstream tokens** from the OAuth provider (GitHub, Google, etc.) +2. **Encrypts and stores** these tokens using Fernet encryption (AES-128-CBC + HMAC-SHA256) +3. **Issues FastMCP JWT tokens** to the client, signed with HS256 + +The FastMCP JWT contains minimal claims: issuer, audience, client ID, scopes, expiration, and a unique token identifier (JTI). The JTI acts as a reference linking to the encrypted upstream token. + +**Token validation:** + +When a client makes an MCP request with its FastMCP token: + +1. **FastMCP validates the JWT** signature, expiration, issuer, and audience +2. **Looks up the upstream token** using the JTI from the validated JWT +3. **Decrypts and validates** the upstream token with the provider + +This two-tier validation ensures that FastMCP tokens can only be used with this server (via audience validation) while maintaining full upstream token security. + +This architecture also prevents [token passthrough](#token-passthrough) — see the [Security](#security) section for details. + +**Token expiry alignment:** + +FastMCP token lifetimes match the upstream token lifetimes. When the upstream token expires, the FastMCP token also expires, maintaining consistent security boundaries. + +**Refresh tokens:** + +The proxy issues its own refresh tokens that map to upstream refresh tokens. When a client uses a FastMCP refresh token, the proxy refreshes the upstream token and issues a new FastMCP access token. + +### PKCE Forwarding + +The OAuth proxy automatically handles PKCE (Proof Key for Code Exchange) when working with providers that support or require it. The proxy generates its own PKCE parameters to send upstream while separately validating the client's PKCE, ensuring end-to-end security at both layers. + +This is enabled by default via the `forward_pkce` parameter and works seamlessly with providers like Google, Azure AD, and GitHub. Only disable it for legacy providers that don't support PKCE: + +```python +# Disable PKCE forwarding only if upstream doesn't support it +auth = OAuthProxy( + ..., + forward_pkce=False # Default is True +) +``` + +### Redirect URI Validation + +While the OAuth proxy accepts all redirect URIs by default (for DCR compatibility), you can restrict which clients can connect by specifying allowed patterns: + +```python +# Allow only localhost clients (common for development) +auth = OAuthProxy( + # ... other parameters ... + allowed_client_redirect_uris=[ + "http://localhost:*", + "http://127.0.0.1:*" + ] +) + +# Allow specific known clients +auth = OAuthProxy( + # ... other parameters ... + allowed_client_redirect_uris=[ + "http://localhost:*", + "https://claude.ai/api/mcp/auth_callback", + "https://*.mycompany.com/auth/*" # Wildcard patterns supported + ] +) +``` + +Check your server logs for "Client registered with redirect_uri" messages to identify what URLs your clients use. + +## CIMD Support + + + +The OAuth proxy supports **Client ID Metadata Documents (CIMD)**, an alternative to Dynamic Client Registration where clients host a static JSON document at an HTTPS URL. Instead of registering dynamically, clients simply provide their CIMD URL as their `client_id`, and the server fetches and validates the metadata. + +CIMD clients appear in the consent screen with a verified domain badge, giving users confidence about which application is requesting access. This provides stronger identity verification than DCR, where any client can claim any name. + +### How CIMD Works + +When a client presents an HTTPS URL as its `client_id` (for example, `https://myapp.example.com/oauth/client.json`), the OAuth proxy recognizes it as a CIMD client and: + +1. Fetches the JSON document from that URL +2. Validates that the document's `client_id` field matches the URL +3. Extracts client metadata (name, redirect URIs, scopes, etc.) +4. Stores the client persistently alongside DCR clients +5. Shows the verified domain in the consent screen + +This flow happens transparently. MCP clients that support CIMD simply provide their metadata URL instead of registering, and the OAuth proxy handles the rest. + +### CIMD Configuration + +CIMD support is enabled by default for `OAuthProxy`. + + + + Whether to accept CIMD URLs as client identifiers. When enabled, clients can use HTTPS URLs pointing to metadata documents as their `client_id` instead of registering via DCR. + + + +### Private Key JWT Authentication + +CIMD clients can authenticate using `private_key_jwt` instead of the default `none` authentication method. This provides cryptographic proof of client identity by signing JWT assertions with a private key, while the server verifies using the client's public key from their CIMD document. + +To use `private_key_jwt`, the CIMD document must include either a `jwks_uri` (URL to fetch the public key set) or inline `jwks` (the key set directly in the document): + +```json +{ + "client_id": "https://myapp.example.com/oauth/client.json", + "client_name": "My Secure App", + "redirect_uris": ["http://localhost:*/callback"], + "token_endpoint_auth_method": "private_key_jwt", + "jwks_uri": "https://myapp.example.com/.well-known/jwks.json" +} +``` + +The OAuth proxy validates JWT assertions according to RFC 7523, checking the signature, issuer, audience, subject claims, and preventing replay attacks via JTI tracking. + +### Security Considerations + +CIMD provides several security advantages over DCR: + +- **Verified identity**: The domain in the `client_id` URL is verified by HTTPS, so users know which organization is requesting access +- **No registration required**: Clients don't need to store or manage dynamically-issued credentials +- **Redirect URI enforcement**: CIMD documents must declare `redirect_uris`, which are enforced by the proxy (wildcard patterns supported) +- **SSRF protection**: The OAuth proxy blocks fetches to localhost, private IPs, and reserved addresses +- **Replay prevention**: For `private_key_jwt` clients, JTI claims are tracked to prevent assertion replay +- **Cache-aware fetching**: CIMD documents are cached according to HTTP cache headers and revalidated when required + +CIMD is enabled by default. To disable it entirely (for example, to require all clients to register via DCR), set `enable_cimd=False` explicitly: + +```python +auth = OAuthProxy( + ..., + enable_cimd=False, +) +``` + +## Security + +### Key and Storage Management + + +The OAuth proxy requires cryptographic keys for JWT signing and storage encryption, plus persistent storage to maintain valid tokens across server restarts. + +**Default behavior (appropriate for development only):** +- **Mac/Windows**: FastMCP automatically generates keys and stores them in your system keyring. Storage defaults to disk. Tokens survive server restarts. This is **only** suitable for development and local testing. +- **Linux**: Keys are ephemeral (random salt at startup). Storage defaults to memory. Tokens become invalid on server restart. + +**For production:** +Configure the following parameters together: provide a unique `jwt_signing_key` (for signing FastMCP JWTs), and a shared `client_storage` backend (for storing tokens). Both are required for production deployments. Use a network-accessible storage backend like Redis or DynamoDB rather than local disk storage. **Wrap your storage in `FernetEncryptionWrapper` to encrypt sensitive OAuth tokens at rest** (see the `client_storage` parameter documentation above for examples). The keys accept any secret string and derive proper cryptographic keys using HKDF. See [OAuth Token Security](/deployment/http#oauth-token-security) and [Storage Backends](/servers/storage-backends) for complete production setup. + +### Confused Deputy Attacks + + + +A confused deputy attack allows a malicious client to steal your authorization by tricking you into granting it access under your identity. + +The OAuth proxy works by bridging DCR clients to traditional auth providers, which means that multiple MCP clients connect through a single upstream OAuth application. An attacker can exploit this shared application by registering a malicious client with their own redirect URI, then sending you an authorization link. When you click it, your browser goes through the OAuth flow—but since you may have already authorized this OAuth app before, the provider might auto-approve the request. The authorization code then gets sent to the attacker's redirect URI instead of a legitimate client, giving them access under your credentials. + +#### Mitigation + +FastMCP's OAuth proxy defends against confused deputy attacks with two layers of protection: + +**Consent screen.** Before any authorization happens, you see a consent page showing the client's details, redirect URI, and requested scopes. This gives you the opportunity to review and deny suspicious requests. Once you approve a client, it's remembered so you don't see the consent page again for that client. The consent mechanism is implemented with CSRF tokens and cryptographically signed cookies to prevent tampering. + +![](/assets/images/oauth-proxy-consent-screen.png) + +The consent page automatically displays your server's name, icon, and website URL, if available. These visual identifiers help users confirm they're authorizing the correct server. + +**Browser-session binding.** When you approve consent (or when a previously-approved client auto-approves), the proxy sets a cryptographically signed cookie that binds your browser session to the authorization flow. When the identity provider redirects back to the proxy's callback, the proxy verifies that this cookie is present and matches the expected transaction. A different browser — such as a victim who was sent the authorization URL by an attacker — won't have this cookie, and the callback will be rejected with a 403 error. This prevents the attack even when the identity provider skips the consent page for previously-authorized applications. + +**Learn more:** +- [MCP Security Best Practices](https://modelcontextprotocol.io/specification/2025-06-18/basic/security_best_practices#confused-deputy-problem) - Official specification guidance +- [Confused Deputy Attacks Explained](https://den.dev/blog/mcp-confused-deputy-api-management/) - Detailed walkthrough by Den Delimarsky + +### Token Passthrough + +[Token passthrough](https://modelcontextprotocol.io/specification/2025-06-18/basic/security_best_practices#token-passthrough) occurs when an intermediary exposes upstream tokens to downstream clients, allowing those clients to impersonate the intermediary or access services they shouldn't reach. + +#### Client-facing mitigation + +The OAuth proxy's [token factory architecture](#token-architecture) prevents this by design. MCP clients only ever receive FastMCP-issued JWTs — the upstream provider token is never sent to the client. A FastMCP JWT is scoped to your server and cannot be used to access the upstream provider directly, even if intercepted. + +#### Calling downstream services + +When your MCP server needs to call other APIs on behalf of the authenticated user, avoid forwarding the upstream token directly — this reintroduces the token passthrough problem in the other direction. Instead, use a token exchange flow like [OAuth 2.0 Token Exchange (RFC 8693)](https://datatracker.ietf.org/doc/html/rfc8693) or your provider's equivalent (such as Azure's [On-Behalf-Of flow](https://learn.microsoft.com/en-us/entra/identity-platform/v2-oauth2-on-behalf-of-flow)) to obtain a new token scoped to the downstream service. + +The upstream token is available in your tool functions via `get_access_token()` or the `CurrentAccessToken` dependency, which you can use as the assertion for a token exchange. The exchanged token will be scoped to the specific downstream service and identify your MCP server as the authorized intermediary, maintaining proper audience boundaries throughout the chain. + +## Production Configuration + +For production deployments, load sensitive credentials from environment variables: + +```python +import os +from fastmcp import FastMCP +from fastmcp.server.auth.providers.github import GitHubProvider + +# Load secrets from environment variables +auth = GitHubProvider( + client_id=os.environ.get("GITHUB_CLIENT_ID"), + client_secret=os.environ.get("GITHUB_CLIENT_SECRET"), + base_url=os.environ.get("BASE_URL", "https://your-production-server.com") +) + +mcp = FastMCP(name="My Server", auth=auth) + +@mcp.tool +def protected_tool(data: str) -> str: + """This tool is now protected by OAuth.""" + return f"Processed: {data}" + +if __name__ == "__main__": + mcp.run(transport="http", port=8000) +``` + +This keeps secrets out of your codebase while maintaining explicit configuration. diff --git a/docs/servers/auth/oidc-proxy.mdx b/docs/servers/auth/oidc-proxy.mdx new file mode 100644 index 000000000..86661bc16 --- /dev/null +++ b/docs/servers/auth/oidc-proxy.mdx @@ -0,0 +1,280 @@ +--- +title: OIDC Proxy +sidebarTitle: OIDC Proxy +description: Bridge OIDC providers to work seamlessly with MCP's authentication flow. +icon: share +--- + +import { VersionBadge } from "/snippets/version-badge.mdx"; + + + +The OIDC proxy enables FastMCP servers to authenticate with OIDC providers that **don't support Dynamic Client Registration (DCR)** out of the box. This includes OAuth providers like: Auth0, Google, Azure, AWS, etc. For providers that do support DCR (like WorkOS AuthKit), use [`RemoteAuthProvider`](/servers/auth/remote-oauth) instead. + +The OIDC proxy is built upon [`OAuthProxy`](/servers/auth/oauth-proxy) so it has all the same functionality under the covers. + +## Implementation + +### Provider Setup Requirements + +Before using the OIDC proxy, you need to register your application with your OAuth provider: + +1. **Register your application** in the provider's developer console (Auth0 Applications, Google Cloud Console, Azure Portal, etc.) +2. **Configure the redirect URI** as your FastMCP server URL plus your chosen callback path: + - Default: `https://your-server.com/auth/callback` + - Custom: `https://your-server.com/your/custom/path` (if you set `redirect_path`) + - Development: `http://localhost:8000/auth/callback` +3. **Obtain your credentials**: Client ID and Client Secret + + + The redirect URI you configure with your provider must exactly match your + FastMCP server's URL plus the callback path. If you customize `redirect_path` + in the OIDC proxy, update your provider's redirect URI accordingly. + + +### Basic Setup + +Here's how to implement the OIDC proxy with any provider: + +```python +from fastmcp import FastMCP +from fastmcp.server.auth.oidc_proxy import OIDCProxy + +# Create the OIDC proxy +auth = OIDCProxy( + # Provider's configuration URL + config_url="https://provider.com/.well-known/openid-configuration", + + # Your registered app credentials + client_id="your-client-id", + client_secret="your-client-secret", + + # Your FastMCP server's public URL + base_url="https://your-server.com", + + # Optional: customize the callback path (default is "/auth/callback") + # redirect_path="/custom/callback", +) + +mcp = FastMCP(name="My Server", auth=auth) +``` + +### Configuration Parameters + + + + URL of your OAuth provider's OIDC configuration + + + + Client ID from your registered OAuth application + + + + Client secret from your registered OAuth application + + + + Public URL of your FastMCP server (e.g., `https://your-server.com`) + + + + Strict flag for configuration validation. When True, requires all OIDC + mandatory fields. + + + + Audience parameter for OIDC providers that require it (e.g., Auth0). This is + typically your API identifier. + + + + HTTP request timeout in seconds for fetching OIDC configuration + + + + + + Custom token verifier for validating tokens. When provided, FastMCP uses your custom verifier instead of creating a default `JWTVerifier`. + + Cannot be used with `algorithm` or `required_scopes` parameters - configure these on your verifier instead. The verifier's `required_scopes` are automatically loaded and advertised. + + + + JWT algorithm to use for token verification (e.g., "RS256"). If not specified, + uses the provider's default. Only used when `token_verifier` is not provided. + + + + List of OAuth scopes for token validation. These are automatically + included in authorization requests. Only used when `token_verifier` is not provided. + + + + Path for OAuth callbacks. Must match the redirect URI configured in your OAuth + application + + + + List of allowed redirect URI patterns for MCP clients. Patterns support wildcards (e.g., `"http://localhost:*"`, `"https://*.example.com/*"`). + - `None` (default): All redirect URIs allowed (for MCP/DCR compatibility) + - Empty list `[]`: No redirect URIs allowed + - Custom list: Only matching patterns allowed + +These patterns apply to MCP client loopback redirects, NOT the upstream OAuth app redirect URI. + + + + + Token endpoint authentication method for the upstream OAuth server. Controls how the proxy authenticates when exchanging authorization codes and refresh tokens with the upstream provider. + - `"client_secret_basic"`: Send credentials in Authorization header (most common) + - `"client_secret_post"`: Send credentials in request body (required by some providers) + - `"none"`: No authentication (for public clients) + - `None` (default): Uses authlib's default (typically `"client_secret_basic"`) + +Set this if your provider requires a specific authentication method and the default doesn't work. + + + + + + + Secret used to sign FastMCP JWT tokens issued to clients. Accepts any string or bytes - will be derived into a proper 32-byte cryptographic key using HKDF. + + **Default behavior (`None`):** + - **Mac/Windows**: Auto-managed via system keyring. Keys are generated once and persisted, surviving server restarts with zero configuration. Keys are automatically derived from server attributes, so this approach, while convenient, is **only** suitable for development and local testing. For production, you must provide an explicit secret. + - **Linux**: Ephemeral (random salt at startup). Tokens become invalid on server restart, triggering client re-authentication. + + **For production:** + Provide an explicit secret (e.g., from environment variable) to use a fixed key instead of the auto-generated one. + + + + + + Storage backend for persisting OAuth client registrations and upstream tokens. + + **Default behavior:** + - **Mac/Windows**: Encrypted DiskStore in your platform's data directory (derived from `platformdirs`) + - **Linux**: MemoryStore (ephemeral - clients lost on restart) + + By default on Mac/Windows, clients are automatically persisted to encrypted disk storage, allowing them to survive server restarts as long as the filesystem remains accessible. This means MCP clients only need to register once and can reconnect seamlessly. On Linux where keyring isn't available, ephemeral storage is used to match the ephemeral key strategy. + +For production deployments with multiple servers or cloud deployments, use a network-accessible storage backend rather than local disk storage. **Wrap your storage in `FernetEncryptionWrapper` to encrypt sensitive OAuth tokens at rest.** See [Storage Backends](/servers/storage-backends) for available options. + +Testing with in-memory storage (unencrypted): + +```python +from key_value.aio.stores.memory import MemoryStore + +# Use in-memory storage for testing (clients lost on restart) +auth = OIDCProxy(..., client_storage=MemoryStore()) +``` + +Production with encrypted Redis storage: + +```python +from key_value.aio.stores.redis import RedisStore +from key_value.aio.wrappers.encryption import FernetEncryptionWrapper +from cryptography.fernet import Fernet +import os + +auth = OIDCProxy( + ..., + jwt_signing_key=os.environ["JWT_SIGNING_KEY"], + client_storage=FernetEncryptionWrapper( + key_value=RedisStore(host="redis.example.com", port=6379), + fernet=Fernet(os.environ["STORAGE_ENCRYPTION_KEY"]) + ) +) +``` + + + + + Whether to require user consent before authorizing MCP clients. When enabled (default), users see a consent screen that displays which client is requesting access. See [OAuthProxy documentation](/servers/auth/oauth-proxy#confused-deputy-attacks) for details on confused deputy attack protection. + + + + Content Security Policy for the consent page. + + - `None` (default): Uses the built-in CSP policy with appropriate directives for form submission + - Empty string `""`: Disables CSP entirely (no meta tag rendered) + - Custom string: Uses the provided value as the CSP policy + + This is useful for organizations that have their own CSP policies and need to override or disable FastMCP's built-in CSP directives. + + + +### Using Built-in Providers + +FastMCP includes pre-configured OIDC providers for common services: + +```python +from fastmcp.server.auth.providers.auth0 import Auth0Provider + +auth = Auth0Provider( + config_url="https://.../.well-known/openid-configuration", + client_id="your-auth0-client-id", + client_secret="your-auth0-client-secret", + audience="https://...", + base_url="https://localhost:8000" +) + +mcp = FastMCP(name="My Server", auth=auth) +``` + +Available providers include `Auth0Provider` at present. + +### Scope Configuration + +OAuth scopes are configured with `required_scopes` to automatically request the permissions your application needs. + +Dynamic clients created by the proxy will automatically include these scopes in their authorization requests. + +## CIMD Support + + + +The OIDC proxy inherits full CIMD (Client ID Metadata Document) support from `OAuthProxy`. Clients can use HTTPS URLs as their `client_id` instead of registering dynamically, and the proxy will fetch and validate their metadata document. + +See the [OAuth Proxy CIMD documentation](/servers/auth/oauth-proxy#cimd-support) for complete details on how CIMD works, including private key JWT authentication and security considerations. + +The CIMD-related parameters available on `OIDCProxy` are: + + + + Whether to accept CIMD URLs as client identifiers. + + + +## Production Configuration + +For production deployments, load sensitive credentials from environment variables: + +```python +import os +from fastmcp import FastMCP +from fastmcp.server.auth.providers.auth0 import Auth0Provider + +# Load secrets from environment variables +auth = Auth0Provider( + config_url=os.environ.get("AUTH0_CONFIG_URL"), + client_id=os.environ.get("AUTH0_CLIENT_ID"), + client_secret=os.environ.get("AUTH0_CLIENT_SECRET"), + audience=os.environ.get("AUTH0_AUDIENCE"), + base_url=os.environ.get("BASE_URL", "https://localhost:8000") +) + +mcp = FastMCP(name="My Server", auth=auth) + +@mcp.tool +def protected_tool(data: str) -> str: + """This tool is now protected by OAuth.""" + return f"Processed: {data}" + +if __name__ == "__main__": + mcp.run(transport="http", port=8000) +``` + +This keeps secrets out of your codebase while maintaining explicit configuration. diff --git a/docs/servers/auth/remote-oauth.mdx b/docs/servers/auth/remote-oauth.mdx new file mode 100644 index 000000000..7c94a937f --- /dev/null +++ b/docs/servers/auth/remote-oauth.mdx @@ -0,0 +1,240 @@ +--- +title: Remote OAuth +sidebarTitle: Remote OAuth +description: Integrate your FastMCP server with external identity providers like Descope, WorkOS, Auth0, and corporate SSO systems. +icon: camera-cctv +--- + +import { VersionBadge } from "/snippets/version-badge.mdx" + + + +Remote OAuth integration allows your FastMCP server to leverage external identity providers that **support Dynamic Client Registration (DCR)**. With DCR, MCP clients can automatically register themselves with the identity provider and obtain credentials without any manual configuration. This provides enterprise-grade authentication with fully automated flows, making it ideal for production applications with modern identity providers. + + +**When to use RemoteAuthProvider vs OAuth Proxy:** +- **RemoteAuthProvider**: For providers WITH Dynamic Client Registration (Descope, WorkOS AuthKit, modern OIDC providers) +- **OAuth Proxy**: For providers WITHOUT Dynamic Client Registration (GitHub, Google, Azure, AWS, Discord, etc.) + +RemoteAuthProvider requires DCR support for fully automated client registration and authentication. + + +## DCR-Enabled Providers + +RemoteAuthProvider works with identity providers that support **Dynamic Client Registration (DCR)** - a critical capability that enables automated authentication flows: + +| Feature | DCR Providers (RemoteAuth) | Non-DCR Providers (OAuth Proxy) | +|---------|---------------------------|--------------------------------| +| **Client Registration** | Automatic via API | Manual in provider console | +| **Credentials** | Dynamic per client | Fixed app credentials | +| **Configuration** | Zero client config | Pre-shared credentials | +| **Examples** | Descope, WorkOS AuthKit, modern OIDC | GitHub, Google, Azure | +| **FastMCP Class** | `RemoteAuthProvider` | [`OAuthProxy`](/servers/auth/oauth-proxy) | + +If your provider doesn't support DCR (most traditional OAuth providers), you'll need to use [`OAuth Proxy`](/servers/auth/oauth-proxy) instead, which bridges the gap between MCP's DCR expectations and fixed OAuth credentials. + +## The Remote OAuth Challenge + +Traditional OAuth flows assume human users with web browsers who can interact with login forms, consent screens, and redirects. MCP clients operate differently - they're often automated systems that need to authenticate programmatically without human intervention. + +This creates several unique requirements that standard OAuth implementations don't address well: + +**Automatic Discovery**: MCP clients must discover authentication requirements by examining server metadata rather than encountering HTTP redirects. They need to know which identity provider to use and how to reach it before making any authenticated requests. + +**Programmatic Registration**: Clients need to register themselves with identity providers automatically. Manual client registration doesn't work when clients might be dynamically created tools or services. + +**Seamless Token Management**: Clients must obtain, store, and refresh tokens without user interaction. The authentication flow needs to work in headless environments where no human is available to complete OAuth consent flows. + +**Protocol Integration**: The authentication process must integrate cleanly with MCP's JSON-RPC transport layer and error handling mechanisms. + +These requirements mean that your MCP server needs to do more than just validate tokens - it needs to provide discovery metadata that enables MCP clients to understand and navigate your authentication requirements automatically. + +## MCP Authentication Discovery + +MCP authentication discovery relies on well-known endpoints that clients can examine to understand your authentication requirements. Your server becomes a bridge between MCP clients and your chosen identity provider. + +The core discovery endpoint is `/.well-known/oauth-protected-resource`, which tells clients that your server requires OAuth authentication and identifies the authorization servers you trust. This endpoint contains static metadata that points clients to your identity provider without requiring any dynamic lookups. + +```mermaid +sequenceDiagram + participant Client + participant FastMCPServer as FastMCP Server + participant ExternalIdP as Identity Provider + + Client->>FastMCPServer: 1. GET /.well-known/oauth-protected-resource + FastMCPServer-->>Client: 2. "Use https://my-idp.com for auth" + + note over Client, ExternalIdP: Client goes directly to the IdP + Client->>ExternalIdP: 3. Authenticate & get token via DCR + ExternalIdP-->>Client: 4. Access token + + Client->>FastMCPServer: 5. MCP request with Bearer token + FastMCPServer->>FastMCPServer: 6. Verify token signature + FastMCPServer-->>Client: 7. MCP response +``` + +This flow separates concerns cleanly: your MCP server handles resource protection and token validation, while your identity provider handles user authentication and token issuance. The client coordinates between these systems using standardized OAuth discovery mechanisms. + +## FastMCP Remote Authentication + + + +FastMCP provides `RemoteAuthProvider` to handle the complexities of remote OAuth integration. This class combines token validation capabilities with the OAuth discovery metadata that MCP clients require. + +### RemoteAuthProvider + +`RemoteAuthProvider` works by composing a [`TokenVerifier`](/servers/auth/token-verification) with authorization server information. A `TokenVerifier` is another FastMCP authentication class that focuses solely on token validation - signature verification, expiration checking, and claim extraction. The `RemoteAuthProvider` takes that token validation capability and adds the OAuth discovery endpoints that enable MCP clients to automatically find and authenticate with your identity provider. + +This composition pattern means you can use any token validation strategy while maintaining consistent OAuth discovery behavior: +- **JWT tokens**: Use `JWTVerifier` for self-contained tokens +- **Opaque tokens**: Use `IntrospectionTokenVerifier` for RFC 7662 introspection +- **Custom validation**: Implement your own `TokenVerifier` subclass + +The separation allows you to change token validation approaches without affecting the client discovery experience. + +The class automatically generates the required OAuth metadata endpoints using the MCP SDK's standardized route creation functions. This ensures compatibility with MCP clients while reducing the implementation complexity for server developers. + +### Basic Implementation + +Most applications can use `RemoteAuthProvider` directly without subclassing. The implementation requires a `TokenVerifier` instance, a list of trusted authorization servers, and your server's URL for metadata generation. + +```python +from fastmcp import FastMCP +from fastmcp.server.auth import RemoteAuthProvider +from fastmcp.server.auth.providers.jwt import JWTVerifier +from pydantic import AnyHttpUrl + +# Configure token validation for your identity provider +token_verifier = JWTVerifier( + jwks_uri="https://auth.yourcompany.com/.well-known/jwks.json", + issuer="https://auth.yourcompany.com", + audience="mcp-production-api" +) + +# Create the remote auth provider +auth = RemoteAuthProvider( + token_verifier=token_verifier, + authorization_servers=[AnyHttpUrl("https://auth.yourcompany.com")], + base_url="https://api.yourcompany.com", # Your server base URL + # Optional: restrict allowed client redirect URIs (defaults to all for DCR compatibility) + allowed_client_redirect_uris=["http://localhost:*", "http://127.0.0.1:*"] +) + +mcp = FastMCP(name="Company API", auth=auth) +``` + +This configuration creates a server that accepts tokens issued by `auth.yourcompany.com` and provides the OAuth discovery metadata that MCP clients need. The `JWTVerifier` handles token validation using your identity provider's public keys, while the `RemoteAuthProvider` generates the required OAuth endpoints. + +The `authorization_servers` list tells MCP clients which identity providers you trust. The `base_url` identifies your server in OAuth metadata, enabling proper token audience validation. **Important**: The `base_url` should point to your server base URL - for example, if your MCP server is accessible at `https://api.yourcompany.com/mcp`, use `https://api.yourcompany.com` as the base URL. + +### Overriding Advertised Scopes + +Some identity providers use different scope formats for authorization requests versus token claims. For example, Azure AD requires clients to request full URI scopes like `api://client-id/read`, but the token's `scp` claim contains just `read`. The `scopes_supported` parameter lets you advertise the full-form scopes in metadata while validating against the short form: + +```python +auth = RemoteAuthProvider( + token_verifier=token_verifier, + authorization_servers=[AnyHttpUrl("https://auth.example.com")], + base_url="https://api.example.com", + scopes_supported=["api://my-api/read", "api://my-api/write"], +) +``` + +When not set, `scopes_supported` defaults to the token verifier's `required_scopes`. For Azure AD specifically, see the [AzureJWTVerifier](/integrations/azure#token-verification-only-managed-identity) which handles this automatically. + +### Custom Endpoints + +You can extend `RemoteAuthProvider` to add additional endpoints beyond the standard OAuth protected resource metadata. These don't have to be OAuth-specific - you can add any endpoints your authentication integration requires. + +```python +import httpx +from starlette.responses import JSONResponse +from starlette.routing import Route + +class CompanyAuthProvider(RemoteAuthProvider): + def __init__(self): + token_verifier = JWTVerifier( + jwks_uri="https://auth.yourcompany.com/.well-known/jwks.json", + issuer="https://auth.yourcompany.com", + audience="mcp-production-api" + ) + + super().__init__( + token_verifier=token_verifier, + authorization_servers=[AnyHttpUrl("https://auth.yourcompany.com")], + base_url="https://api.yourcompany.com" # Your server base URL + ) + + def get_routes(self) -> list[Route]: + """Add custom endpoints to the standard protected resource routes.""" + + # Get the standard OAuth protected resource routes + routes = super().get_routes() + + # Add authorization server metadata forwarding for client convenience + async def authorization_server_metadata(request): + async with httpx.AsyncClient() as client: + response = await client.get( + "https://auth.yourcompany.com/.well-known/oauth-authorization-server" + ) + response.raise_for_status() + return JSONResponse(response.json()) + + routes.append( + Route("/.well-known/oauth-authorization-server", authorization_server_metadata) + ) + + return routes + +mcp = FastMCP(name="Company API", auth=CompanyAuthProvider()) +``` + +This pattern uses `super().get_routes()` to get the standard protected resource routes, then adds additional endpoints as needed. A common use case is providing authorization server metadata forwarding, which allows MCP clients to discover your identity provider's capabilities through your MCP server rather than contacting the identity provider directly. + +## WorkOS AuthKit Integration + +WorkOS AuthKit provides an excellent example of remote OAuth integration. The `AuthKitProvider` demonstrates how to implement both token validation and OAuth metadata forwarding in a production-ready package. + +```python +from fastmcp import FastMCP +from fastmcp.server.auth.providers.workos import AuthKitProvider + +auth = AuthKitProvider( + authkit_domain="https://your-project.authkit.app", + base_url="https://your-mcp-server.com" +) + +mcp = FastMCP(name="Protected Application", auth=auth) +``` + +The `AuthKitProvider` automatically configures JWT validation against WorkOS's public keys and provides both protected resource metadata and authorization server metadata forwarding. This implementation handles the complete remote OAuth integration with minimal configuration. + +WorkOS's support for Dynamic Client Registration makes it particularly well-suited for MCP applications. Clients can automatically register themselves with your WorkOS project and obtain the credentials needed for authentication without manual intervention. + +→ **Complete WorkOS tutorial**: [AuthKit Integration Guide](/integrations/authkit) + +## Client Redirect URI Security + + +`RemoteAuthProvider` also supports the `allowed_client_redirect_uris` parameter for controlling which redirect URIs are accepted from MCP clients during DCR: + +- `None` (default): All redirect URIs allowed (for DCR compatibility) +- Custom list: Specify allowed patterns with wildcard support +- Empty list `[]`: No redirect URIs allowed + +This provides defense-in-depth even though DCR providers typically validate redirect URIs themselves. + + +## Implementation Considerations + +Remote OAuth integration requires careful attention to several technical details that affect reliability and security. + +**Token Validation Performance**: Your server validates every incoming token by checking signatures against your identity provider's public keys. Consider implementing key caching and rotation handling to minimize latency while maintaining security. + +**Error Handling**: Network issues with your identity provider can affect token validation. Implement appropriate timeouts, retry logic, and graceful degradation to maintain service availability during identity provider outages. + +**Audience Validation**: Ensure that tokens intended for your server are not accepted by other applications. Proper audience validation prevents token misuse across different services in your ecosystem. + +**Scope Management**: Map token scopes to your application's permission model consistently. Consider how scope changes affect existing tokens and plan for smooth permission updates. + +The complexity of these considerations reinforces why external identity providers are recommended over custom OAuth implementations. Established providers handle these technical details with extensive testing and operational experience. \ No newline at end of file diff --git a/docs/servers/auth/token-verification.mdx b/docs/servers/auth/token-verification.mdx new file mode 100644 index 000000000..a9146135f --- /dev/null +++ b/docs/servers/auth/token-verification.mdx @@ -0,0 +1,426 @@ +--- +title: Token Verification +sidebarTitle: Token Verification +description: Protect your server by validating bearer tokens issued by external systems. +icon: key +--- + +import { VersionBadge } from "/snippets/version-badge.mdx" + + + +Token verification enables your FastMCP server to validate bearer tokens issued by external systems without participating in user authentication flows. Your server acts as a pure resource server, focusing on token validation and authorization decisions while delegating identity management to other systems in your infrastructure. + + +Token verification operates somewhat outside the formal MCP authentication flow, which expects OAuth-style discovery. It's best suited for internal systems, microservices architectures, or when you have full control over token generation and distribution. + + +## Understanding Token Verification + +Token verification addresses scenarios where authentication responsibility is distributed across multiple systems. Your MCP server receives structured tokens containing identity and authorization information, validates their authenticity, and makes access control decisions based on their contents. + +This pattern emerges naturally in microservices architectures where a central authentication service issues tokens that multiple downstream services validate independently. It also works well when integrating MCP servers into existing systems that already have established token-based authentication mechanisms. + +### The Token Verification Model + +Token verification treats your MCP server as a resource server in OAuth terminology. The key insight is that token validation and token issuance are separate concerns that can be handled by different systems. + +**Token Issuance**: Another system (API gateway, authentication service, or identity provider) handles user authentication and creates signed tokens containing identity and permission information. + +**Token Validation**: Your MCP server receives these tokens, verifies their authenticity using cryptographic signatures, and extracts authorization information from their claims. + +**Access Control**: Based on token contents, your server determines what resources, tools, and prompts the client can access. + +This separation allows your MCP server to focus on its core functionality while leveraging existing authentication infrastructure. The token acts as a portable proof of identity that travels with each request. + +### Token Security Considerations + +Token-based authentication relies on cryptographic signatures to ensure token integrity. Your MCP server validates tokens using public keys corresponding to the private keys used for token creation. This asymmetric approach means your server never needs access to signing secrets. + +Token validation must address several security requirements: signature verification ensures tokens haven't been tampered with, expiration checking prevents use of stale tokens, and audience validation ensures tokens intended for your server aren't accepted by other systems. + +The challenge in MCP environments is that clients need to obtain valid tokens before making requests, but the MCP protocol doesn't provide built-in discovery mechanisms for token endpoints. Clients must obtain tokens through separate channels or prior configuration. + + +## TokenVerifier Class + +FastMCP provides the `TokenVerifier` class to handle token validation complexity while remaining flexible about token sources and validation strategies. + +`TokenVerifier` focuses exclusively on token validation without providing OAuth discovery metadata. This makes it ideal for internal systems where clients already know how to obtain tokens, or for microservices that trust tokens from known issuers. + +The class validates token signatures, checks expiration timestamps, and extracts authorization information from token claims. It supports various token formats and validation strategies while maintaining a consistent interface for authorization decisions. + +You can subclass `TokenVerifier` to implement custom validation logic for specialized token formats or validation requirements. The base class handles common patterns while allowing extension for unique use cases. + +## JWT Token Verification + +JSON Web Tokens (JWTs) represent the most common token format for modern applications. FastMCP's `JWTVerifier` validates JWTs using industry-standard cryptographic techniques and claim validation. + +### JWKS Endpoint Integration + +JWKS endpoint integration provides the most flexible approach for production systems. The verifier automatically fetches public keys from a JSON Web Key Set endpoint, enabling automatic key rotation without server configuration changes. + +```python +from fastmcp import FastMCP +from fastmcp.server.auth.providers.jwt import JWTVerifier + +# Configure JWT verification against your identity provider +verifier = JWTVerifier( + jwks_uri="https://auth.yourcompany.com/.well-known/jwks.json", + issuer="https://auth.yourcompany.com", + audience="mcp-production-api" +) + +mcp = FastMCP(name="Protected API", auth=verifier) +``` + +This configuration creates a server that validates JWTs issued by `auth.yourcompany.com`. The verifier periodically fetches public keys from the JWKS endpoint and validates incoming tokens against those keys. Only tokens with the correct issuer and audience claims will be accepted. + +The `issuer` parameter ensures tokens come from your trusted authentication system, while `audience` validation prevents tokens intended for other services from being accepted by your MCP server. + +### Symmetric Key Verification (HMAC) + +Symmetric key verification uses a shared secret for both signing and validation, making it ideal for internal microservices and trusted environments where the same secret can be securely distributed to both token issuers and validators. + +This approach is commonly used in microservices architectures where services share a secret key, or when your authentication service and MCP server are both managed by the same organization. The HMAC algorithms (HS256, HS384, HS512) provide strong security when the shared secret is properly managed. + +```python +from fastmcp import FastMCP +from fastmcp.server.auth.providers.jwt import JWTVerifier + +# Use a shared secret for symmetric key verification +verifier = JWTVerifier( + public_key="your-shared-secret-key-minimum-32-chars", # Despite the name, this accepts symmetric secrets + issuer="internal-auth-service", + audience="mcp-internal-api", + algorithm="HS256" # or HS384, HS512 for stronger security +) + +mcp = FastMCP(name="Internal API", auth=verifier) +``` + +The verifier will validate tokens signed with the same secret using the specified HMAC algorithm. This approach offers several advantages for internal systems: + +- **Simplicity**: No key pair management or certificate distribution +- **Performance**: HMAC operations are typically faster than RSA +- **Compatibility**: Works well with existing microservice authentication patterns + + +The parameter is named `public_key` for backwards compatibility, but when using HMAC algorithms (HS256/384/512), it accepts the symmetric secret string. + + + +**Security Considerations for Symmetric Keys:** +- Use a strong, randomly generated secret (minimum 32 characters recommended) +- Never expose the secret in logs, error messages, or version control +- Implement secure key distribution and rotation mechanisms +- Consider using asymmetric keys (RSA/ECDSA) for external-facing APIs + + +### Static Public Key Verification + +Static public key verification works when you have a fixed RSA or ECDSA signing key and don't need automatic key rotation. This approach is primarily useful for development environments or controlled deployments where JWKS endpoints aren't available. + +```python +from fastmcp import FastMCP +from fastmcp.server.auth.providers.jwt import JWTVerifier + +# Use a static public key for token verification +public_key_pem = """-----BEGIN PUBLIC KEY----- +MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEA... +-----END PUBLIC KEY-----""" + +verifier = JWTVerifier( + public_key=public_key_pem, + issuer="https://auth.yourcompany.com", + audience="mcp-production-api" +) + +mcp = FastMCP(name="Protected API", auth=verifier) +``` + +This configuration validates tokens using a specific RSA or ECDSA public key. The key must correspond to the private key used by your token issuer. While less flexible than JWKS endpoints, this approach can be useful in development environments or when testing with fixed keys. +## Opaque Token Verification + +Many authorization servers issue opaque tokens rather than self-contained JWTs. Opaque tokens are random strings that carry no information themselves - the authorization server maintains their state and validation requires querying the server. FastMCP supports opaque token validation through OAuth 2.0 Token Introspection (RFC 7662). + +### Understanding Opaque Tokens + +Opaque tokens differ fundamentally from JWTs in their verification model. Where JWTs carry signed claims that can be validated locally, opaque tokens require network calls to the issuing authorization server for validation. The authorization server maintains token state and can revoke tokens immediately, providing stronger security guarantees for sensitive operations. + +This approach trades performance (network latency on each validation) for security and flexibility. Authorization servers can revoke opaque tokens instantly, implement complex authorization logic, and maintain detailed audit logs of token usage. Many enterprise OAuth providers default to opaque tokens for these security advantages. + +### Token Introspection Protocol + +RFC 7662 standardizes how resource servers validate opaque tokens. The protocol defines an introspection endpoint where resource servers authenticate using client credentials and receive token metadata including active status, scopes, expiration, and subject identity. + +FastMCP implements this protocol through the `IntrospectionTokenVerifier` class, handling authentication, request formatting, and response parsing according to the specification. + +```python +from fastmcp import FastMCP +from fastmcp.server.auth.providers.introspection import IntrospectionTokenVerifier + +# Configure introspection with your OAuth provider +verifier = IntrospectionTokenVerifier( + introspection_url="https://auth.yourcompany.com/oauth/introspect", + client_id="mcp-resource-server", + client_secret="your-client-secret", + required_scopes=["api:read", "api:write"] +) + +mcp = FastMCP(name="Protected API", auth=verifier) +``` + +The verifier authenticates to the introspection endpoint using client credentials and queries it whenever a bearer token arrives. FastMCP checks whether the token is active and has sufficient scopes before allowing access. + +Two standard client authentication methods are supported, both defined in RFC 6749: + +- **`client_secret_basic`** (default): Sends credentials via HTTP Basic Auth header +- **`client_secret_post`**: Sends credentials in the POST request body + +Most OAuth providers support both methods, though some may require one specifically. Configure the authentication method with the `client_auth_method` parameter: + +```python +# Use POST body authentication instead of Basic Auth +verifier = IntrospectionTokenVerifier( + introspection_url="https://auth.yourcompany.com/oauth/introspect", + client_id="mcp-resource-server", + client_secret="your-client-secret", + client_auth_method="client_secret_post", + required_scopes=["api:read", "api:write"] +) +``` + +## Development and Testing + +Development environments often need simpler token management without the complexity of full JWT infrastructure. FastMCP provides tools specifically designed for these scenarios. + +### Static Token Verification + +Static token verification enables rapid development by accepting predefined tokens with associated claims. This approach eliminates the need for token generation infrastructure during development and testing. + +```python +from fastmcp import FastMCP +from fastmcp.server.auth.providers.jwt import StaticTokenVerifier + +# Define development tokens and their associated claims +verifier = StaticTokenVerifier( + tokens={ + "dev-alice-token": { + "client_id": "alice@company.com", + "scopes": ["read:data", "write:data", "admin:users"] + }, + "dev-guest-token": { + "client_id": "guest-user", + "scopes": ["read:data"] + } + }, + required_scopes=["read:data"] +) + +mcp = FastMCP(name="Development Server", auth=verifier) +``` + +Clients can now authenticate using `Authorization: Bearer dev-alice-token` headers. The server will recognize the token and load the associated claims for authorization decisions. This approach enables immediate development without external dependencies. + + +Static token verification stores tokens as plain text and should never be used in production environments. It's designed exclusively for development and testing scenarios. + + + +### Debug/Custom Token Verification + + + +The `DebugTokenVerifier` provides maximum flexibility for testing and special cases where standard token verification isn't applicable. It delegates validation to a user-provided callable, making it useful for prototyping, testing scenarios, or handling opaque tokens without introspection endpoints. + +```python +from fastmcp import FastMCP +from fastmcp.server.auth.providers.debug import DebugTokenVerifier + +# Accept all tokens (useful for rapid development) +verifier = DebugTokenVerifier() + +mcp = FastMCP(name="Development Server", auth=verifier) +``` + +By default, `DebugTokenVerifier` accepts any non-empty token as valid. This eliminates authentication barriers during early development, allowing you to focus on core functionality before adding security. + +For more controlled testing, provide custom validation logic: + +```python +from fastmcp.server.auth.providers.debug import DebugTokenVerifier + +# Synchronous validation - check token prefix +verifier = DebugTokenVerifier( + validate=lambda token: token.startswith("dev-"), + client_id="development-client", + scopes=["read", "write"] +) + +mcp = FastMCP(name="Development Server", auth=verifier) +``` + +The validation callable can also be async, enabling database lookups or external service calls: + +```python +from fastmcp.server.auth.providers.debug import DebugTokenVerifier + +# Asynchronous validation - check against cache +async def validate_token(token: str) -> bool: + # Check if token exists in Redis, database, etc. + return await redis.exists(f"valid_tokens:{token}") + +verifier = DebugTokenVerifier( + validate=validate_token, + client_id="api-client", + scopes=["api:access"] +) + +mcp = FastMCP(name="Custom API", auth=verifier) +``` + +**Use Cases:** + +- **Testing**: Accept any token during integration tests without setting up token infrastructure +- **Prototyping**: Quickly validate concepts without authentication complexity +- **Opaque tokens without introspection**: When you have tokens from an IDP that provides no introspection endpoint, and you're willing to accept tokens without validation (validation happens later at the upstream service) +- **Custom token formats**: Implement validation for non-standard token formats or legacy systems + + +`DebugTokenVerifier` bypasses standard security checks. Only use in controlled environments (development, testing) or when you fully understand the security implications. For production, use proper JWT or introspection-based verification. + + +### Test Token Generation + +Test token generation helps when you need to test JWT verification without setting up complete identity infrastructure. FastMCP includes utilities for generating test key pairs and signed tokens. + +```python +from fastmcp.server.auth.providers.jwt import JWTVerifier, RSAKeyPair + +# Generate a key pair for testing +key_pair = RSAKeyPair.generate() + +# Configure your server with the public key +verifier = JWTVerifier( + public_key=key_pair.public_key, + issuer="https://test.yourcompany.com", + audience="test-mcp-server" +) + +# Generate a test token using the private key +test_token = key_pair.create_token( + subject="test-user-123", + issuer="https://test.yourcompany.com", + audience="test-mcp-server", + scopes=["read", "write", "admin"] +) + +print(f"Test token: {test_token}") +``` + +This pattern enables comprehensive testing of JWT validation logic without depending on external token issuers. The generated tokens are cryptographically valid and will pass all standard JWT validation checks. + +## HTTP Client Customization + + + +All token verifiers that make HTTP calls accept an optional `http_client` parameter. This lets you provide your own `httpx.AsyncClient` for connection pooling, custom TLS configuration, or proxy settings. + +### Connection Pooling + +By default, each token verification call creates a fresh HTTP client. Under high load, this means repeated TCP connections and TLS handshakes. Providing a shared client enables connection pooling across calls: + +```python +import httpx +from fastmcp import FastMCP +from fastmcp.server.auth.providers.introspection import IntrospectionTokenVerifier + +# Create a shared client with connection pooling +http_client = httpx.AsyncClient( + timeout=10, + limits=httpx.Limits(max_connections=20, max_keepalive_connections=10), +) + +verifier = IntrospectionTokenVerifier( + introspection_url="https://auth.yourcompany.com/oauth/introspect", + client_id="mcp-resource-server", + client_secret="your-client-secret", + http_client=http_client, +) + +mcp = FastMCP(name="Protected API", auth=verifier) +``` + +The same pattern works for `JWTVerifier` when using JWKS endpoints: + +```python +from fastmcp.server.auth.providers.jwt import JWTVerifier + +verifier = JWTVerifier( + jwks_uri="https://auth.yourcompany.com/.well-known/jwks.json", + issuer="https://auth.yourcompany.com", + http_client=http_client, +) +``` + + +`JWTVerifier` does not support `http_client` when `ssrf_safe=True`. SSRF-safe mode requires a hardened transport that validates DNS resolution and connection targets, which cannot be guaranteed with a user-provided client. Attempting to use both will raise a `ValueError`. + + + +When you provide an `http_client`, you are responsible for its lifecycle. The verifier will not close it. Use the server's `lifespan` to manage client cleanup: + +```python +from contextlib import asynccontextmanager +from fastmcp import FastMCP +from fastmcp.server.auth.providers.introspection import IntrospectionTokenVerifier + +http_client = httpx.AsyncClient(timeout=10) + +verifier = IntrospectionTokenVerifier( + introspection_url="https://auth.example.com/introspect", + client_id="my-service", + client_secret="secret", + http_client=http_client, +) + +@asynccontextmanager +async def lifespan(app): + yield + await http_client.aclose() + +mcp = FastMCP(name="My API", auth=verifier, lifespan=lifespan) +``` + + +The convenience providers (`GitHubProvider`, `GoogleProvider`, `DiscordProvider`, `WorkOSProvider`, `AzureProvider`) also accept `http_client` and pass it through to their internal token verifier. + +## Production Configuration + +For production deployments, load sensitive configuration from environment variables: + +```python +import os +from fastmcp import FastMCP +from fastmcp.server.auth.providers.jwt import JWTVerifier + +# Load configuration from environment variables +# Parse comma-separated scopes if provided +scopes_env = os.environ.get("JWT_REQUIRED_SCOPES") +required_scopes = scopes_env.split(",") if scopes_env else None + +verifier = JWTVerifier( + jwks_uri=os.environ.get("JWT_JWKS_URI"), + issuer=os.environ.get("JWT_ISSUER"), + audience=os.environ.get("JWT_AUDIENCE"), + required_scopes=required_scopes, +) + +mcp = FastMCP(name="Production API", auth=verifier) +``` + +This keeps configuration out of your codebase while maintaining explicit setup. + +This approach enables the same codebase to run across development, staging, and production environments with different authentication requirements. Development might use static tokens while production uses JWT verification, all controlled through environment configuration. + diff --git a/docs/servers/authorization.mdx b/docs/servers/authorization.mdx new file mode 100644 index 000000000..a48d2a9e8 --- /dev/null +++ b/docs/servers/authorization.mdx @@ -0,0 +1,384 @@ +--- +title: Authorization +sidebarTitle: Authorization +description: Control access to components using callable-based authorization checks that filter visibility and enforce permissions. +icon: shield-halved +tag: NEW +--- + +import { VersionBadge } from "/snippets/version-badge.mdx" + + + +Authorization controls what authenticated users can do with your FastMCP server. While [authentication](/servers/auth/authentication) verifies identity (who you are), authorization determines access (what you can do). FastMCP provides a callable-based authorization system that works at both the component level and globally via middleware. + +The authorization model centers on a simple concept: callable functions that receive context about the current request and return `True` to allow access or `False` to deny it. Multiple checks combine with AND logic, meaning all checks must pass for access to be granted. + + +Authorization relies on OAuth tokens which are only available with HTTP transports (SSE, Streamable HTTP). In STDIO mode, there's no OAuth mechanism, so `get_access_token()` returns `None` and all auth checks are skipped. + + + +When an `AuthProvider` is configured, all requests to the MCP endpoint must carry a valid token—unauthenticated requests are rejected at the transport level before any auth checks run. Authorization checks therefore differentiate between authenticated users based on their scopes and claims, not between authenticated and unauthenticated users. + + +## Auth Checks + +An auth check is any callable that accepts an `AuthContext` and returns a boolean. Auth checks can be synchronous or asynchronous, so checks that need to perform async operations (like reading server state or calling external services) work naturally. + +```python +from fastmcp.server.auth import AuthContext + +def my_custom_check(ctx: AuthContext) -> bool: + # ctx.token is AccessToken | None + # ctx.component is the Tool, Resource, or Prompt being accessed + return ctx.token is not None and "special" in ctx.token.scopes +``` + +FastMCP provides two built-in auth checks that cover common authorization patterns. + +### require_scopes + +Scope-based authorization checks that the token contains all specified OAuth scopes. When multiple scopes are provided, all must be present (AND logic). + +```python +from fastmcp import FastMCP +from fastmcp.server.auth import require_scopes + +mcp = FastMCP("Scoped Server") + +@mcp.tool(auth=require_scopes("admin")) +def admin_operation() -> str: + """Requires the 'admin' scope.""" + return "Admin action completed" + +@mcp.tool(auth=require_scopes("read", "write")) +def read_write_operation() -> str: + """Requires both 'read' AND 'write' scopes.""" + return "Read/write action completed" +``` + +### restrict_tag + +Tag-based restrictions apply scope requirements conditionally. If a component has the specified tag, the token must have the required scopes. Components without the tag are unaffected. + +```python +from fastmcp import FastMCP +from fastmcp.server.auth import restrict_tag +from fastmcp.server.middleware import AuthMiddleware + +mcp = FastMCP( + "Tagged Server", + middleware=[ + AuthMiddleware(auth=restrict_tag("admin", scopes=["admin"])) + ] +) + +@mcp.tool(tags={"admin"}) +def admin_tool() -> str: + """Tagged 'admin', so requires 'admin' scope.""" + return "Admin only" + +@mcp.tool(tags={"public"}) +def public_tool() -> str: + """Not tagged 'admin', so no scope required by the restriction.""" + return "Anyone can access" +``` + +### Combining Checks + +Multiple auth checks can be combined by passing a list. All checks must pass for authorization to succeed (AND logic). + +```python +from fastmcp import FastMCP +from fastmcp.server.auth import require_scopes + +mcp = FastMCP("Combined Auth Server") + +@mcp.tool(auth=[require_scopes("admin"), require_scopes("write")]) +def secure_admin_action() -> str: + """Requires both 'admin' AND 'write' scopes.""" + return "Secure admin action" +``` + +### Custom Auth Checks + +Any callable that accepts `AuthContext` and returns `bool` can serve as an auth check. This enables authorization logic based on token claims, component metadata, or external systems. + +```python +from fastmcp import FastMCP +from fastmcp.server.auth import AuthContext + +mcp = FastMCP("Custom Auth Server") + +def require_premium_user(ctx: AuthContext) -> bool: + """Check for premium user status in token claims.""" + if ctx.token is None: + return False + return ctx.token.claims.get("premium", False) is True + +def require_access_level(minimum_level: int): + """Factory function for level-based authorization.""" + def check(ctx: AuthContext) -> bool: + if ctx.token is None: + return False + user_level = ctx.token.claims.get("level", 0) + return user_level >= minimum_level + return check + +@mcp.tool(auth=require_premium_user) +def premium_feature() -> str: + """Only for premium users.""" + return "Premium content" + +@mcp.tool(auth=require_access_level(5)) +def advanced_feature() -> str: + """Requires access level 5 or higher.""" + return "Advanced feature" +``` + +### Async Auth Checks + +Auth checks can be `async` functions, which is useful when the authorization decision depends on asynchronous operations like reading server state or querying external services. + +```python +from fastmcp import FastMCP +from fastmcp.server.auth import AuthContext + +mcp = FastMCP("Async Auth Server") + +async def check_user_permissions(ctx: AuthContext) -> bool: + """Async auth check that reads server state.""" + if ctx.token is None: + return False + user_id = ctx.token.claims.get("sub") + # Async operations work naturally in auth checks + permissions = await fetch_user_permissions(user_id) + return "admin" in permissions + +@mcp.tool(auth=check_user_permissions) +def admin_tool() -> str: + return "Admin action completed" +``` + +Sync and async checks can be freely combined in a list — each check is handled according to its type. + +### Error Handling + +Auth checks can raise exceptions for explicit denial with custom messages: + +- **`AuthorizationError`**: Propagates with its custom message, useful for explaining why access was denied +- **Other exceptions**: Masked for security (logged internally, treated as denial) + +```python +from fastmcp.server.auth import AuthContext +from fastmcp.exceptions import AuthorizationError + +def require_verified_email(ctx: AuthContext) -> bool: + """Require verified email with explicit denial message.""" + if ctx.token is None: + raise AuthorizationError("Authentication required") + if not ctx.token.claims.get("email_verified"): + raise AuthorizationError("Email verification required") + return True +``` + +## Component-Level Authorization + +The `auth` parameter on decorators controls visibility and access for individual components. When auth checks fail for the current request, the component is hidden from list responses and direct access returns not-found. + +```python +from fastmcp import FastMCP +from fastmcp.server.auth import require_scopes + +mcp = FastMCP("Component Auth Server") + +@mcp.tool(auth=require_scopes("write")) +def write_tool() -> str: + """Only visible to users with 'write' scope.""" + return "Written" + +@mcp.resource("secret://data", auth=require_scopes("read")) +def secret_resource() -> str: + """Only visible to users with 'read' scope.""" + return "Secret data" + +@mcp.prompt(auth=require_scopes("admin")) +def admin_prompt() -> str: + """Only visible to users with 'admin' scope.""" + return "Admin prompt content" +``` + + +Component-level `auth` controls both visibility (list filtering) and access (direct lookups return not-found for unauthorized requests). Additionally use `AuthMiddleware` to apply server-wide authorization rules and get explicit `AuthorizationError` responses on unauthorized execution attempts. + + +## Server-Level Authorization + +For server-wide authorization enforcement, use `AuthMiddleware`. This middleware applies auth checks globally to all components—filtering list responses and blocking unauthorized execution with explicit `AuthorizationError` responses. + +```python +from fastmcp import FastMCP +from fastmcp.server.auth import require_scopes +from fastmcp.server.middleware import AuthMiddleware + +mcp = FastMCP( + "Enforced Auth Server", + middleware=[AuthMiddleware(auth=require_scopes("api"))] +) + +@mcp.tool +def any_tool() -> str: + """Requires 'api' scope to see AND call.""" + return "Protected" +``` + +### Component Auth + Middleware + +Component-level `auth` and `AuthMiddleware` work together as complementary layers. The middleware applies server-wide rules to all components, while component-level auth adds per-component requirements. Both layers are checked—all checks must pass. + +```python +from fastmcp import FastMCP +from fastmcp.server.auth import require_scopes, restrict_tag +from fastmcp.server.middleware import AuthMiddleware + +mcp = FastMCP( + "Layered Auth Server", + middleware=[ + AuthMiddleware(auth=restrict_tag("admin", scopes=["admin"])) + ] +) + +# Requires "write" scope (component-level) +# Also requires "admin" scope if tagged "admin" (middleware-level) +@mcp.tool(auth=require_scopes("write"), tags={"admin"}) +def admin_write() -> str: + """Requires both 'write' AND 'admin' scopes.""" + return "Admin write" + +# Requires "write" scope (component-level only) +@mcp.tool(auth=require_scopes("write")) +def user_write() -> str: + """Requires 'write' scope.""" + return "User write" +``` + +### Tag-Based Global Authorization + +A common pattern uses `restrict_tag` with `AuthMiddleware` to apply scope requirements based on component tags. + +```python +from fastmcp import FastMCP +from fastmcp.server.auth import restrict_tag +from fastmcp.server.middleware import AuthMiddleware + +mcp = FastMCP( + "Tag-Based Auth Server", + middleware=[ + AuthMiddleware(auth=restrict_tag("admin", scopes=["admin"])), + AuthMiddleware(auth=restrict_tag("write", scopes=["write"])), + ] +) + +@mcp.tool(tags={"admin"}) +def delete_all_data() -> str: + """Requires 'admin' scope.""" + return "Deleted" + +@mcp.tool(tags={"write"}) +def update_record(id: str, data: str) -> str: + """Requires 'write' scope.""" + return f"Updated {id}" + +@mcp.tool +def read_record(id: str) -> str: + """No tag restrictions, accessible to all.""" + return f"Record {id}" +``` + +## Accessing Tokens in Tools + +Tools can access the current authentication token using `get_access_token()` from `fastmcp.server.dependencies`. This enables tools to make decisions based on user identity or permissions beyond simple authorization checks. + +```python +from fastmcp import FastMCP +from fastmcp.server.dependencies import get_access_token + +mcp = FastMCP("Token Access Server") + +@mcp.tool +def personalized_greeting() -> str: + """Greet the user based on their token claims.""" + token = get_access_token() + + if token is None: + return "Hello, guest!" + + name = token.claims.get("name", "user") + return f"Hello, {name}!" + +@mcp.tool +def user_dashboard() -> dict: + """Return user-specific data based on token.""" + token = get_access_token() + + if token is None: + return {"error": "Not authenticated"} + + return { + "client_id": token.client_id, + "scopes": token.scopes, + "claims": token.claims, + } +``` + +## Reference + +### AccessToken + +The `AccessToken` object contains information extracted from the OAuth token. + +| Property | Type | Description | +|----------|------|-------------| +| `token` | `str` | The raw token string | +| `client_id` | `str \| None` | OAuth client identifier | +| `scopes` | `list[str]` | Granted OAuth scopes | +| `expires_at` | `datetime \| None` | Token expiration time | +| `claims` | `dict[str, Any]` | All JWT claims or custom token data | + +### AuthContext + +The `AuthContext` dataclass is passed to all auth check functions. + +| Property | Type | Description | +|----------|------|-------------| +| `token` | `AccessToken \| None` | Current access token, or `None` if unauthenticated | +| `component` | `Tool \| Resource \| Prompt` | The component being accessed | + +Access to the component object enables authorization decisions based on metadata like tags, name, or custom properties. + +```python +from fastmcp.server.auth import AuthContext + +def require_matching_tag(ctx: AuthContext) -> bool: + """Require a scope matching each of the component's tags.""" + if ctx.token is None: + return False + user_scopes = set(ctx.token.scopes) + return ctx.component.tags.issubset(user_scopes) +``` + +### Imports + +```python +from fastmcp.server.auth import ( + AccessToken, # Token with .token, .client_id, .scopes, .expires_at, .claims + AuthContext, # Context with .token, .component + AuthCheck, # Type alias: sync or async Callable[[AuthContext], bool] + require_scopes, # Built-in: requires specific scopes + restrict_tag, # Built-in: tag-based scope requirements + run_auth_checks, # Utility: run checks with AND logic +) + +from fastmcp.server.middleware import AuthMiddleware +``` diff --git a/docs/servers/composition.mdx b/docs/servers/composition.mdx new file mode 100644 index 000000000..42523a5cd --- /dev/null +++ b/docs/servers/composition.mdx @@ -0,0 +1,237 @@ +--- +title: Composing Servers +sidebarTitle: Composition +description: Combine multiple servers into one +icon: puzzle-piece +--- + +import { VersionBadge } from '/snippets/version-badge.mdx' + + + +As your application grows, you'll want to split it into focused servers — one for weather, one for calendar, one for admin — and combine them into a single server that clients connect to. That's what `mount()` does. + +When you mount a server, all its tools, resources, and prompts become available through the parent. The connection is live: add a tool to the child after mounting, and it's immediately visible through the parent. + +```python +from fastmcp import FastMCP + +weather = FastMCP("Weather") + +@weather.tool +def get_forecast(city: str) -> str: + """Get weather forecast for a city.""" + return f"Sunny in {city}" + +@weather.resource("data://cities") +def list_cities() -> list[str]: + """List supported cities.""" + return ["London", "Paris", "Tokyo"] + +main = FastMCP("MainApp") +main.mount(weather) + +# main now serves get_forecast and data://cities +``` + +## Mounting External Servers + +Mount remote HTTP servers or subprocess-based MCP servers using `create_proxy()`: + +```python +from fastmcp import FastMCP +from fastmcp.server import create_proxy + +mcp = FastMCP("Orchestrator") + +# Mount a remote HTTP server (URLs work directly) +mcp.mount(create_proxy("http://api.example.com/mcp"), namespace="api") + +# Mount local Python scripts (file paths work directly) +mcp.mount(create_proxy("./my_server.py"), namespace="local") +``` + +### Mounting npm/uvx Packages + +For npm packages or Python tools, use the config dict format: + +```python +from fastmcp import FastMCP +from fastmcp.server import create_proxy + +mcp = FastMCP("Orchestrator") + +# Mount npm package via config +github_config = { + "mcpServers": { + "default": { + "command": "npx", + "args": ["-y", "@modelcontextprotocol/server-github"] + } + } +} +mcp.mount(create_proxy(github_config), namespace="github") + +# Mount Python tool via config +sqlite_config = { + "mcpServers": { + "default": { + "command": "uvx", + "args": ["mcp-server-sqlite", "--db", "data.db"] + } + } +} +mcp.mount(create_proxy(sqlite_config), namespace="db") +``` + +Or use explicit transport classes: + +```python +from fastmcp import FastMCP +from fastmcp.server import create_proxy +from fastmcp.client.transports import NpxStdioTransport, UvxStdioTransport + +mcp = FastMCP("Orchestrator") + +mcp.mount( + create_proxy(NpxStdioTransport(package="@modelcontextprotocol/server-github")), + namespace="github" +) +mcp.mount( + create_proxy(UvxStdioTransport(tool_name="mcp-server-sqlite", tool_args=["--db", "data.db"])), + namespace="db" +) +``` + +For advanced configuration, see [Proxying](/servers/providers/proxy). + +## Namespacing + + + +When mounting multiple servers, use namespaces to avoid naming conflicts: + +```python +weather = FastMCP("Weather") +calendar = FastMCP("Calendar") + +@weather.tool +def get_data() -> str: + return "Weather data" + +@calendar.tool +def get_data() -> str: + return "Calendar data" + +main = FastMCP("Main") +main.mount(weather, namespace="weather") +main.mount(calendar, namespace="calendar") + +# Tools are now: +# - weather_get_data +# - calendar_get_data +``` + +### How Namespacing Works + +| Component Type | Without Namespace | With `namespace="api"` | +|----------------|-------------------|------------------------| +| Tool | `my_tool` | `api_my_tool` | +| Prompt | `my_prompt` | `api_my_prompt` | +| Resource | `data://info` | `data://api/info` | +| Template | `data://{id}` | `data://api/{id}` | + +Namespacing uses [transforms](/servers/transforms/transforms) under the hood. + +## Dynamic Composition + +Because `mount()` creates a live link, you can add components to a child server after mounting and they'll be immediately available through the parent: + +```python +main = FastMCP("Main") +main.mount(dynamic_server, namespace="dynamic") + +# Add a tool AFTER mounting - it's accessible through main +@dynamic_server.tool +def added_later() -> str: + return "Added after mounting!" +``` + +## Tag Filtering + + + +Parent server tag filters apply recursively to mounted servers: + +```python +api_server = FastMCP("API") + +@api_server.tool(tags={"production"}) +def prod_endpoint() -> str: + return "Production data" + +@api_server.tool(tags={"development"}) +def dev_endpoint() -> str: + return "Debug data" + +# Mount with production filter +prod_app = FastMCP("Production") +prod_app.mount(api_server, namespace="api") +prod_app.enable(tags={"production"}, only=True) + +# Only prod_endpoint (namespaced as api_prod_endpoint) is visible +``` + +## Performance Considerations + +Operations like `list_tools()` on the parent are affected by the performance of all mounted servers. This is particularly noticeable with: + +- HTTP-based mounted servers (300-400ms vs 1-2ms for local tools) +- Mounted servers with slow initialization +- Deep mounting hierarchies + +If low latency is critical, consider implementing caching strategies or limiting mounting depth. + +## Custom Routes + + + +Custom HTTP routes defined with `@server.custom_route()` are also forwarded when mounting: + +```python +subserver = FastMCP("Sub") + +@subserver.custom_route("/health", methods=["GET"]) +async def health_check(): + return {"status": "ok"} + +main = FastMCP("Main") +main.mount(subserver, namespace="sub") + +# /health is now accessible through main's HTTP app +``` + +## Conflict Resolution + + + +When mounting multiple servers with the same namespace (or no namespace), the **most recently mounted** server takes precedence for conflicting component names: + +```python +server_a = FastMCP("A") +server_b = FastMCP("B") + +@server_a.tool +def shared_tool() -> str: + return "From A" + +@server_b.tool +def shared_tool() -> str: + return "From B" + +main = FastMCP("Main") +main.mount(server_a) +main.mount(server_b) + +# shared_tool returns "From B" (most recently mounted) +``` diff --git a/docs/servers/context.mdx b/docs/servers/context.mdx new file mode 100644 index 000000000..a10161baf --- /dev/null +++ b/docs/servers/context.mdx @@ -0,0 +1,443 @@ +--- +title: MCP Context +sidebarTitle: Context +description: Access MCP capabilities like logging, progress, and resources within your MCP objects. +icon: rectangle-code +tag: NEW +--- +import { VersionBadge } from '/snippets/version-badge.mdx' + +When defining FastMCP [tools](/servers/tools), [resources](/servers/resources), resource templates, or [prompts](/servers/prompts), your functions might need to interact with the underlying MCP session or access advanced server capabilities. FastMCP provides the `Context` object for this purpose. + + +You access Context through FastMCP's dependency injection system. For other injectable values like HTTP requests, access tokens, and custom dependencies, see [Dependency Injection](/servers/dependency-injection). + + +## What Is Context? + +The `Context` object provides a clean interface to access MCP features within your functions, including: + +- **Logging**: Send debug, info, warning, and error messages back to the client +- **Progress Reporting**: Update the client on the progress of long-running operations +- **Resource Access**: List and read data from resources registered with the server +- **Prompt Access**: List and retrieve prompts registered with the server +- **LLM Sampling**: Request the client's LLM to generate text based on provided messages +- **User Elicitation**: Request structured input from users during tool execution +- **Session State**: Store data that persists across requests within an MCP session +- **Session Visibility**: [Control which components are visible](/servers/visibility#per-session-visibility) to the current session +- **Request Information**: Access metadata about the current request +- **Server Access**: When needed, access the underlying FastMCP server instance + +## Accessing the Context + + + +The preferred way to access context is using the `CurrentContext()` dependency: + +```python {1, 6} +from fastmcp import FastMCP +from fastmcp.dependencies import CurrentContext +from fastmcp.server.context import Context + +mcp = FastMCP(name="Context Demo") + +@mcp.tool +async def process_file(file_uri: str, ctx: Context = CurrentContext()) -> str: + """Processes a file, using context for logging and resource access.""" + await ctx.info(f"Processing {file_uri}") + return "Processed file" +``` + +This works with tools, resources, and prompts: + +```python +from fastmcp import FastMCP +from fastmcp.dependencies import CurrentContext +from fastmcp.server.context import Context + +mcp = FastMCP(name="Context Demo") + +@mcp.resource("resource://user-data") +async def get_user_data(ctx: Context = CurrentContext()) -> dict: + await ctx.debug("Fetching user data") + return {"user_id": "example"} + +@mcp.prompt +async def data_analysis_request(dataset: str, ctx: Context = CurrentContext()) -> str: + return f"Please analyze the following dataset: {dataset}" +``` + +**Key Points:** + +- Dependency parameters are automatically excluded from the MCP schema—clients never see them. +- Context methods are async, so your function usually needs to be async as well. +- **Each MCP request receives a new context object.** Context is scoped to a single request; state or data set in one request will not be available in subsequent requests. +- Context is only available during a request; attempting to use context methods outside a request will raise errors. + +### Legacy Type-Hint Injection + +For backwards compatibility, you can still access context by simply adding a parameter with the `Context` type hint. FastMCP will automatically inject the context instance: + +```python {1, 6} +from fastmcp import FastMCP, Context + +mcp = FastMCP(name="Context Demo") + +@mcp.tool +async def process_file(file_uri: str, ctx: Context) -> str: + """Processes a file, using context for logging and resource access.""" + # Context is injected automatically based on the type hint + return "Processed file" +``` + +This approach still works for tools, resources, and prompts. The parameter name doesn't matter—only the `Context` type hint is important. The type hint can also be a union (`Context | None`) or use `Annotated[]`. + +### Via `get_context()` Function + + + +For code nested deeper within your function calls where passing context through parameters is inconvenient, use `get_context()` to retrieve the active context from anywhere within a request's execution flow: + +```python {2,9} +from fastmcp import FastMCP +from fastmcp.server.dependencies import get_context + +mcp = FastMCP(name="Dependency Demo") + +# Utility function that needs context but doesn't receive it as a parameter +async def process_data(data: list[float]) -> dict: + # Get the active context - only works when called within a request + ctx = get_context() + await ctx.info(f"Processing {len(data)} data points") + +@mcp.tool +async def analyze_dataset(dataset_name: str) -> dict: + # Call utility function that uses context internally + data = load_data(dataset_name) + await process_data(data) +``` + +**Important Notes:** + +- The `get_context()` function should only be used within the context of a server request. Calling it outside of a request will raise a `RuntimeError`. +- The `get_context()` function is server-only and should not be used in client code. + +## Context Capabilities + +FastMCP provides several advanced capabilities through the context object. Each capability has dedicated documentation with comprehensive examples and best practices: + +### Logging + +Send debug, info, warning, and error messages back to the MCP client for visibility into function execution. + +```python +await ctx.debug("Starting analysis") +await ctx.info(f"Processing {len(data)} items") +await ctx.warning("Deprecated parameter used") +await ctx.error("Processing failed") +``` + +See [Server Logging](/servers/logging) for complete documentation and examples. +### Client Elicitation + + + +Request structured input from clients during tool execution, enabling interactive workflows and progressive disclosure. This is a new feature in the 6/18/2025 MCP spec. + +```python +result = await ctx.elicit("Enter your name:", response_type=str) +if result.action == "accept": + name = result.data +``` + +See [User Elicitation](/servers/elicitation) for detailed examples and supported response types. + +### LLM Sampling + + + +Request the client's LLM to generate text based on provided messages, useful for leveraging AI capabilities within your tools. + +```python +response = await ctx.sample("Analyze this data", temperature=0.7) +``` + +See [LLM Sampling](/servers/sampling) for comprehensive usage and advanced techniques. + + +### Progress Reporting + +Update clients on the progress of long-running operations, enabling progress indicators and better user experience. + +```python +await ctx.report_progress(progress=50, total=100) # 50% complete +``` + +See [Progress Reporting](/servers/progress) for detailed patterns and examples. + +### Resource Access + +List and read data from resources registered with your FastMCP server, allowing access to files, configuration, or dynamic content. + +```python +# List available resources +resources = await ctx.list_resources() + +# Read a specific resource +content_list = await ctx.read_resource("resource://config") +content = content_list[0].content +``` + +**Method signatures:** +- **`ctx.list_resources() -> list[MCPResource]`**: Returns list of all available resources +- **`ctx.read_resource(uri: str | AnyUrl) -> list[ReadResourceContents]`**: Returns a list of resource content parts + +### Prompt Access + + + +List and retrieve prompts registered with your FastMCP server, allowing tools and middleware to discover and use available prompts programmatically. + +```python +# List available prompts +prompts = await ctx.list_prompts() + +# Get a specific prompt with arguments +result = await ctx.get_prompt("analyze_data", {"dataset": "users"}) +messages = result.messages +``` + +**Method signatures:** +- **`ctx.list_prompts() -> list[MCPPrompt]`**: Returns list of all available prompts +- **`ctx.get_prompt(name: str, arguments: dict[str, Any] | None = None) -> GetPromptResult`**: Get a specific prompt with optional arguments + +### Session State + + + +Store data that persists across multiple requests within the same MCP session. Session state is automatically keyed by the client's session, ensuring isolation between different clients. + +```python +from fastmcp import FastMCP, Context + +mcp = FastMCP("stateful-app") + +@mcp.tool +async def increment_counter(ctx: Context) -> int: + """Increment a counter that persists across tool calls.""" + count = await ctx.get_state("counter") or 0 + await ctx.set_state("counter", count + 1) + return count + 1 + +@mcp.tool +async def get_counter(ctx: Context) -> int: + """Get the current counter value.""" + return await ctx.get_state("counter") or 0 +``` + +Each client session has its own isolated state—two different clients calling `increment_counter` will each have their own counter. + +**Method signatures:** +- **`await ctx.set_state(key, value, *, serializable=True)`**: Store a value in session state +- **`await ctx.get_state(key)`**: Retrieve a value (returns None if not found) +- **`await ctx.delete_state(key)`**: Remove a value from session state + + +State methods are async and require `await`. State expires after 1 day to prevent unbounded memory growth. + + +#### Non-Serializable Values + +By default, state values must be JSON-serializable (dicts, lists, strings, numbers, etc.) so they can be persisted across requests. For non-serializable values like HTTP clients or database connections, pass `serializable=False`: + +```python +@mcp.tool +async def my_tool(ctx: Context) -> str: + # This object can't be JSON-serialized + client = SomeHTTPClient(base_url="https://api.example.com") + await ctx.set_state("client", client, serializable=False) + + # Retrieve it later in the same request + client = await ctx.get_state("client") + return await client.fetch("/data") +``` + +Values stored with `serializable=False` only live for the current MCP request (a single tool call, resource read, or prompt render). They will not be available in subsequent requests within the session. + +#### Custom Storage Backends + +By default, session state uses an in-memory store suitable for single-server deployments. For distributed or serverless deployments, provide a custom storage backend: + +```python +from key_value.aio.stores.redis import RedisStore + +# Use Redis for distributed state +mcp = FastMCP("distributed-app", session_state_store=RedisStore(...)) +``` + +Any backend compatible with the [py-key-value-aio](https://github.com/strawgate/py-key-value) `AsyncKeyValue` protocol works. See [Storage Backends](/servers/storage-backends) for more options including Redis, DynamoDB, and MongoDB. + +#### State During Initialization + +State set during `on_initialize` middleware persists to subsequent tool calls when using the same session object (STDIO, SSE, single-server HTTP). For distributed/serverless HTTP deployments where different machines handle init and tool calls, state is isolated by the `mcp-session-id` header. + +### Session Visibility + + + +Tools can customize which components are visible to their current session using `ctx.enable_components()`, `ctx.disable_components()`, and `ctx.reset_visibility()`. These methods apply visibility rules that affect only the calling session, leaving other sessions unchanged. See [Per-Session Visibility](/servers/visibility#per-session-visibility) for complete documentation, filter criteria, and patterns like namespace activation. + +### Change Notifications + + + +FastMCP automatically sends list change notifications when components (such as tools, resources, or prompts) are added, removed, enabled, or disabled. In rare cases where you need to manually trigger these notifications, you can use the context's notification methods: + +```python +import mcp.types + +@mcp.tool +async def custom_tool_management(ctx: Context) -> str: + """Example of manual notification after custom tool changes.""" + await ctx.send_notification(mcp.types.ToolListChangedNotification()) + await ctx.send_notification(mcp.types.ResourceListChangedNotification()) + await ctx.send_notification(mcp.types.PromptListChangedNotification()) + return "Notifications sent" +``` + +These methods are primarily used internally by FastMCP's automatic notification system and most users will not need to invoke them directly. + +### FastMCP Server + +To access the underlying FastMCP server instance, you can use the `ctx.fastmcp` property: + +```python +@mcp.tool +async def my_tool(ctx: Context) -> None: + # Access the FastMCP server instance + server_name = ctx.fastmcp.name + ... +``` + +### Transport + + + +The `ctx.transport` property indicates which transport is being used to run the server. This is useful when your tool needs to behave differently depending on whether the server is running over STDIO, SSE, or Streamable HTTP. For example, you might want to return shorter responses over STDIO or adjust timeout behavior based on transport characteristics. + +The transport type is set once when the server starts and remains constant for the server's lifetime. It returns `None` when called outside of a server context (for example, in unit tests or when running code outside of an MCP request). + +```python +from fastmcp import FastMCP, Context + +mcp = FastMCP("example") + +@mcp.tool +def connection_info(ctx: Context) -> str: + if ctx.transport == "stdio": + return "Connected via STDIO" + elif ctx.transport == "sse": + return "Connected via SSE" + elif ctx.transport == "streamable-http": + return "Connected via Streamable HTTP" + else: + return "Transport unknown" +``` + +**Property signature:** `ctx.transport -> Literal["stdio", "sse", "streamable-http"] | None` + +### MCP Request + +Access metadata about the current request and client. + +```python +@mcp.tool +async def request_info(ctx: Context) -> dict: + """Return information about the current request.""" + return { + "request_id": ctx.request_id, + "client_id": ctx.client_id or "Unknown client" + } +``` + +**Available Properties:** + +- **`ctx.request_id -> str`**: Get the unique ID for the current MCP request +- **`ctx.client_id -> str | None`**: Get the ID of the client making the request, if provided during initialization +- **`ctx.session_id -> str`**: Get the MCP session ID for session-based data sharing. Raises `RuntimeError` if the MCP session is not yet established. + +#### Request Context Availability + + + +The `ctx.request_context` property provides access to the underlying MCP request context, but returns `None` when the MCP session has not been established yet. This typically occurs: + +- During middleware execution in the `on_request` hook before the MCP handshake completes +- During the initialization phase of client connections + +The MCP request context is distinct from the HTTP request. For HTTP transports, HTTP request data may be available even when the MCP session is not yet established. + +To safely access the request context in situations where it may not be available: + +```python +from fastmcp import FastMCP, Context +from fastmcp.server.dependencies import get_http_request + +mcp = FastMCP(name="Session Aware Demo") + +@mcp.tool +async def session_info(ctx: Context) -> dict: + """Return session information when available.""" + + # Check if MCP session is available + if ctx.request_context: + # MCP session available - can access MCP-specific attributes + return { + "session_id": ctx.session_id, + "request_id": ctx.request_id, + "has_meta": ctx.request_context.meta is not None + } + else: + # MCP session not available - use HTTP helpers for request data (if using HTTP transport) + request = get_http_request() + return { + "message": "MCP session not available", + "user_agent": request.headers.get("user-agent", "Unknown") + } +``` + +For HTTP request access that works regardless of MCP session availability (when using HTTP transports), use the [HTTP request helpers](/servers/dependency-injection#http-request) like `get_http_request()` and `get_http_headers()`. + +#### Client Metadata + + + +Clients can send contextual information with their requests using the `meta` parameter. This metadata is accessible through `ctx.request_context.meta` and is available for all MCP operations (tools, resources, prompts). + +The `meta` field is `None` when clients don't provide metadata. When provided, metadata is accessible via attribute access (e.g., `meta.user_id`) rather than dictionary access. The structure of metadata is determined by the client making the request. + +```python +@mcp.tool +def send_email(to: str, subject: str, body: str, ctx: Context) -> str: + """Send an email, logging metadata about the request.""" + + # Access client-provided metadata + meta = ctx.request_context.meta + + if meta: + # Meta is accessed as an object with attribute access + user_id = meta.user_id if hasattr(meta, 'user_id') else None + trace_id = meta.trace_id if hasattr(meta, 'trace_id') else None + + # Use metadata for logging, observability, etc. + if trace_id: + log_with_trace(f"Sending email for user {user_id}", trace_id) + + # Send the email... + return f"Email sent to {to}" +``` + + +The MCP request is part of the low-level MCP SDK and intended for advanced use cases. Most users will not need to use it directly. + + diff --git a/docs/servers/dependency-injection.mdx b/docs/servers/dependency-injection.mdx new file mode 100644 index 000000000..d13f43952 --- /dev/null +++ b/docs/servers/dependency-injection.mdx @@ -0,0 +1,427 @@ +--- +title: Dependency Injection +sidebarTitle: Dependencies +description: Inject runtime values like HTTP requests, access tokens, and custom dependencies into your MCP components. +icon: syringe +tag: NEW +--- + +import { VersionBadge } from "/snippets/version-badge.mdx"; + +FastMCP uses dependency injection to provide runtime values to your tools, resources, and prompts. Instead of passing context through every layer of your code, you declare what you need as parameter defaults—FastMCP resolves them automatically when your function runs. + +The dependency injection system is powered by [Docket](https://github.com/chrisguidry/docket) and its dependency system [uncalled-for](https://github.com/chrisguidry/uncalled-for). Core DI features like `Depends()` and `CurrentContext()` work without installing Docket. For background tasks and advanced task-related dependencies, install `fastmcp[tasks]`. For comprehensive coverage of dependency patterns, see the [Docket dependency documentation](https://docket.lol/en/latest/dependency-injection/). + + +Dependency parameters are automatically excluded from the MCP schema—clients never see them as callable parameters. This separation keeps your function signatures clean while giving you access to the runtime context you need. + + +## How Dependency Injection Works + +Dependency injection in FastMCP follows a simple pattern: declare a parameter with a recognized type annotation or a dependency default value, and FastMCP injects the resolved value at runtime. + +```python +from fastmcp import FastMCP +from fastmcp.server.context import Context + +mcp = FastMCP("Demo") + + +@mcp.tool +async def my_tool(query: str, ctx: Context) -> str: + await ctx.info(f"Processing: {query}") + return f"Results for: {query}" +``` + +When a client calls `my_tool`, they only see `query` as a parameter. The `ctx` parameter is injected automatically because it has a `Context` type annotation—FastMCP recognizes this and provides the active context for the request. + +This works identically for tools, resources, resource templates, and prompts. + +### Explicit Dependencies with CurrentContext + +For more explicit code, you can use `CurrentContext()` as a default value instead of relying on the type annotation: + +```python +from fastmcp import FastMCP +from fastmcp.dependencies import CurrentContext +from fastmcp.server.context import Context + +mcp = FastMCP("Demo") + + +@mcp.tool +async def my_tool(query: str, ctx: Context = CurrentContext()) -> str: + await ctx.info(f"Processing: {query}") + return f"Results for: {query}" +``` + +Both approaches work identically. The type-annotation approach is more concise; the explicit `CurrentContext()` approach makes the dependency injection visible in the signature. + +## Built-in Dependencies + +### MCP Context + +The MCP Context provides logging, progress reporting, resource access, and other request-scoped operations. See [MCP Context](/servers/context) for the full API. + +**Dependency injection:** Use a `Context` type annotation (FastMCP injects automatically) or `CurrentContext()`: + +```python +from fastmcp import FastMCP +from fastmcp.server.context import Context + +mcp = FastMCP("Demo") + + +@mcp.tool +async def process_data(data: str, ctx: Context) -> str: + await ctx.info(f"Processing: {data}") + return "Done" + + +# Or explicitly with CurrentContext() +from fastmcp.dependencies import CurrentContext + +@mcp.tool +async def process_data(data: str, ctx: Context = CurrentContext()) -> str: + ... +``` + +**Function:** Use `get_context()` in helper functions or middleware: + +```python +from fastmcp.server.dependencies import get_context + +async def log_something(message: str): + ctx = get_context() + await ctx.info(message) +``` + +### Server Instance + + + +Access the FastMCP server instance for introspection or server-level configuration. + +**Dependency injection:** Use `CurrentFastMCP()`: + +```python +from fastmcp import FastMCP +from fastmcp.dependencies import CurrentFastMCP + +mcp = FastMCP("Demo") + + +@mcp.tool +async def server_info(server: FastMCP = CurrentFastMCP()) -> str: + return f"Server: {server.name}" +``` + +**Function:** Use `get_server()`: + +```python +from fastmcp.server.dependencies import get_server + +def get_server_name() -> str: + return get_server().name +``` + +### HTTP Request + + + +Access the Starlette Request when running over HTTP transports (SSE or Streamable HTTP). + +**Dependency injection:** Use `CurrentRequest()`: + +```python +from fastmcp import FastMCP +from fastmcp.dependencies import CurrentRequest +from starlette.requests import Request + +mcp = FastMCP("Demo") + + +@mcp.tool +async def client_info(request: Request = CurrentRequest()) -> dict: + return { + "user_agent": request.headers.get("user-agent", "Unknown"), + "client_ip": request.client.host if request.client else "Unknown", + } +``` + +**Function:** Use `get_http_request()`: + +```python +from fastmcp.server.dependencies import get_http_request + +def get_client_ip() -> str: + request = get_http_request() + return request.client.host if request.client else "Unknown" +``` + + +Both raise `RuntimeError` when called outside an HTTP context (e.g., STDIO transport). Use HTTP Headers if you need graceful fallback. + + +### HTTP Headers + + + +Access HTTP headers with graceful fallback—returns an empty dictionary when no HTTP request is available, making it safe for code that might run over any transport. + +**Dependency injection:** Use `CurrentHeaders()`: + +```python +from fastmcp import FastMCP +from fastmcp.dependencies import CurrentHeaders + +mcp = FastMCP("Demo") + + +@mcp.tool +async def get_auth_type(headers: dict = CurrentHeaders()) -> str: + auth = headers.get("authorization", "") + return "Bearer" if auth.startswith("Bearer ") else "None" +``` + +**Function:** Use `get_http_headers()`: + +```python +from fastmcp.server.dependencies import get_http_headers + +def get_user_agent() -> str: + headers = get_http_headers() + return headers.get("user-agent", "Unknown") +``` + +By default, problematic headers like `host` and `content-length` are excluded. Use `get_http_headers(include_all=True)` to include all headers. + +### Access Token + + + +Access the authenticated user's token when your server uses authentication. + +**Dependency injection:** Use `CurrentAccessToken()` (raises if not authenticated): + +```python +from fastmcp import FastMCP +from fastmcp.dependencies import CurrentAccessToken +from fastmcp.server.auth import AccessToken + +mcp = FastMCP("Demo") + + +@mcp.tool +async def get_user_id(token: AccessToken = CurrentAccessToken()) -> str: + return token.claims.get("sub", "unknown") +``` + +**Function:** Use `get_access_token()` (returns `None` if not authenticated): + +```python +from fastmcp.server.dependencies import get_access_token + +@mcp.tool +async def get_user_info() -> dict: + token = get_access_token() + if token is None: + return {"authenticated": False} + return {"authenticated": True, "user": token.claims.get("sub")} +``` + +The `AccessToken` object provides: + +- **`client_id`**: The OAuth client identifier +- **`scopes`**: List of granted permission scopes +- **`expires_at`**: Token expiration timestamp (if available) +- **`claims`**: Dictionary of all token claims (JWT claims or provider-specific data) + +### Token Claims + +When you need just one specific value from the token—like a user ID or tenant identifier—`TokenClaim()` extracts it directly without needing the full token object. + +```python +from fastmcp import FastMCP +from fastmcp.server.dependencies import TokenClaim + +mcp = FastMCP("Demo") + + +@mcp.tool +async def add_expense( + amount: float, + user_id: str = TokenClaim("oid"), # Azure object ID +) -> dict: + await db.insert({"user_id": user_id, "amount": amount}) + return {"status": "created", "user_id": user_id} +``` + +`TokenClaim()` raises a `RuntimeError` if the claim doesn't exist, listing available claims to help with debugging. + +Common claims vary by identity provider: + +| Provider | User ID Claim | Email Claim | Name Claim | +|----------|--------------|-------------|------------| +| Azure/Entra | `oid` | `email` | `name` | +| GitHub | `sub` | `email` | `name` | +| Google | `sub` | `email` | `name` | +| Auth0 | `sub` | `email` | `name` | + +### Background Task Dependencies + + + +For background task execution, FastMCP provides dependencies that integrate with [Docket](https://github.com/chrisguidry/docket). These require installing `fastmcp[tasks]`. + +```python +from fastmcp import FastMCP +from fastmcp.dependencies import CurrentDocket, CurrentWorker, Progress + +mcp = FastMCP("Task Demo") + + +@mcp.tool(task=True) +async def long_running_task( + data: str, + docket=CurrentDocket(), + worker=CurrentWorker(), + progress=Progress(), +) -> str: + await progress.set_total(100) + + for i in range(100): + # Process chunk... + await progress.increment() + await progress.set_message(f"Processing chunk {i + 1}") + + return "Complete" +``` + +- **`CurrentDocket()`**: Access the Docket instance for scheduling additional background work +- **`CurrentWorker()`**: Access the worker processing tasks (name, concurrency settings) +- **`Progress()`**: Track task progress with atomic updates + + +Task dependencies require `pip install 'fastmcp[tasks]'`. They're only available within task-enabled components (`task=True`). For comprehensive task patterns, see the [Docket documentation](https://chrisguidry.github.io/docket/dependencies/). + + +## Custom Dependencies + +Beyond the built-in dependencies, you can create your own to inject configuration, database connections, API clients, or any other values your functions need. + +### Using Depends() + +The `Depends()` function wraps any callable and injects its return value. This works with synchronous functions, async functions, and async context managers. + +```python +from fastmcp import FastMCP +from fastmcp.dependencies import Depends + +mcp = FastMCP("Custom Deps Demo") + + +def get_config() -> dict: + return {"api_url": "https://api.example.com", "timeout": 30} + + +async def get_user_id() -> int: + # Could fetch from database, external service, etc. + return 42 + + +@mcp.tool +async def fetch_data( + query: str, + config: dict = Depends(get_config), + user_id: int = Depends(get_user_id), +) -> str: + return f"User {user_id} fetching '{query}' from {config['api_url']}" +``` + +### Caching + +Dependencies are cached per-request. If multiple parameters use the same dependency, or if nested dependencies share a common dependency, it's resolved once and the same instance is reused. + +```python +from fastmcp import FastMCP +from fastmcp.dependencies import Depends + +mcp = FastMCP("Caching Demo") + + +def get_db_connection(): + print("Connecting to database...") # Only printed once per request + return {"connection": "active"} + + +def get_user_repo(db=Depends(get_db_connection)): + return {"db": db, "type": "user"} + + +def get_order_repo(db=Depends(get_db_connection)): + return {"db": db, "type": "order"} + + +@mcp.tool +async def process_order( + order_id: str, + users=Depends(get_user_repo), + orders=Depends(get_order_repo), +) -> str: + # Both repos share the same db connection + return f"Processed order {order_id}" +``` + +### Resource Management + +For dependencies that need cleanup—database connections, file handles, HTTP clients—use an async context manager. The cleanup code runs after your function completes, even if an error occurs. + +```python +from contextlib import asynccontextmanager + +from fastmcp import FastMCP +from fastmcp.dependencies import Depends + +mcp = FastMCP("Resource Demo") + + +@asynccontextmanager +async def get_database(): + db = await connect_to_database() + try: + yield db + finally: + await db.close() + + +@mcp.tool +async def query_users(sql: str, db=Depends(get_database)) -> list: + return await db.execute(sql) +``` + +### Nested Dependencies + +Dependencies can depend on other dependencies. FastMCP resolves them in the correct order and applies caching across the dependency tree. + +```python +from fastmcp import FastMCP +from fastmcp.dependencies import Depends + +mcp = FastMCP("Nested Demo") + + +def get_base_url() -> str: + return "https://api.example.com" + + +def get_api_client(base_url: str = Depends(get_base_url)) -> dict: + return {"base_url": base_url, "version": "v1"} + + +@mcp.tool +async def call_api(endpoint: str, client: dict = Depends(get_api_client)) -> str: + return f"Calling {client['base_url']}/{client['version']}/{endpoint}" +``` + +For advanced dependency patterns—like `TaskArgument()` for accessing task parameters, or custom `Dependency` subclasses—see the [Docket dependency documentation](https://chrisguidry.github.io/docket/dependencies/). diff --git a/docs/servers/elicitation.mdx b/docs/servers/elicitation.mdx new file mode 100644 index 000000000..600a3d2fe --- /dev/null +++ b/docs/servers/elicitation.mdx @@ -0,0 +1,357 @@ +--- +title: User Elicitation +sidebarTitle: Elicitation +description: Request structured input from users during tool execution through the MCP context. +icon: message-question +--- + +import { VersionBadge } from '/snippets/version-badge.mdx' + + + +User elicitation allows MCP servers to request structured input from users during tool execution. Instead of requiring all inputs upfront, tools can interactively ask for missing parameters, clarification, or additional context as needed. + +Elicitation enables tools to pause execution and request specific information from users: + +- **Missing parameters**: Ask for required information not provided initially +- **Clarification requests**: Get user confirmation or choices for ambiguous scenarios +- **Progressive disclosure**: Collect complex information step-by-step +- **Dynamic workflows**: Adapt tool behavior based on user responses + +For example, a file management tool might ask "Which directory should I create?" or a data analysis tool might request "What date range should I analyze?" + +## Overview + +Use the `ctx.elicit()` method within any tool function to request user input. Specify the message to display and the type of response you expect. + +```python +from fastmcp import FastMCP, Context +from dataclasses import dataclass + +mcp = FastMCP("Elicitation Server") + +@dataclass +class UserInfo: + name: str + age: int + +@mcp.tool +async def collect_user_info(ctx: Context) -> str: + """Collect user information through interactive prompts.""" + result = await ctx.elicit( + message="Please provide your information", + response_type=UserInfo + ) + + if result.action == "accept": + user = result.data + return f"Hello {user.name}, you are {user.age} years old" + elif result.action == "decline": + return "Information not provided" + else: # cancel + return "Operation cancelled" +``` + +The elicitation result contains an `action` field indicating how the user responded: + +| Action | Description | +|--------|-------------| +| `accept` | User provided valid input—data is available in the `data` field | +| `decline` | User chose not to provide the requested information | +| `cancel` | User cancelled the entire operation | + +FastMCP also provides typed result classes for pattern matching: + +```python +from fastmcp.server.elicitation import ( + AcceptedElicitation, + DeclinedElicitation, + CancelledElicitation, +) + +@mcp.tool +async def pattern_example(ctx: Context) -> str: + result = await ctx.elicit("Enter your name:", response_type=str) + + match result: + case AcceptedElicitation(data=name): + return f"Hello {name}!" + case DeclinedElicitation(): + return "No name provided" + case CancelledElicitation(): + return "Operation cancelled" +``` + +### Multi-Turn Elicitation + +Tools can make multiple elicitation calls to gather information progressively: + +```python +@mcp.tool +async def plan_meeting(ctx: Context) -> str: + """Plan a meeting by gathering details step by step.""" + + title_result = await ctx.elicit("What's the meeting title?", response_type=str) + if title_result.action != "accept": + return "Meeting planning cancelled" + + duration_result = await ctx.elicit("Duration in minutes?", response_type=int) + if duration_result.action != "accept": + return "Meeting planning cancelled" + + priority_result = await ctx.elicit( + "Is this urgent?", + response_type=["yes", "no"] + ) + if priority_result.action != "accept": + return "Meeting planning cancelled" + + urgent = priority_result.data == "yes" + return f"Meeting '{title_result.data}' for {duration_result.data} minutes (Urgent: {urgent})" +``` + +### Client Requirements + +Elicitation requires the client to implement an elicitation handler. If a client doesn't support elicitation, calls to `ctx.elicit()` will raise an error indicating that elicitation is not supported. + +See [Client Elicitation](/clients/elicitation) for details on how clients handle these requests. + +## Schema and Response Types + +The server must send a schema to the client indicating the type of data it expects in response to the elicitation request. The MCP spec only supports a limited subset of JSON Schema types for elicitation responses—specifically JSON **objects** with **primitive** properties including `string`, `number` (or `integer`), `boolean`, and `enum` fields. + +FastMCP makes it easy to request a broader range of types, including scalars (e.g. `str`) or no response at all, by automatically wrapping them in MCP-compatible object schemas. + +### Scalar Types + +You can request simple scalar data types for basic input, such as a string, integer, or boolean. When you request a scalar type, FastMCP automatically wraps it in an object schema for MCP spec compatibility. Clients will see a schema requesting a single "value" field of the requested type. Once clients respond, the provided object is "unwrapped" and the scalar value is returned directly in the `data` field. + + +```python title="String" +@mcp.tool +async def get_user_name(ctx: Context) -> str: + result = await ctx.elicit("What's your name?", response_type=str) + + if result.action == "accept": + return f"Hello, {result.data}!" + return "No name provided" +``` +```python title="Integer" +@mcp.tool +async def pick_a_number(ctx: Context) -> str: + result = await ctx.elicit("Pick a number!", response_type=int) + + if result.action == "accept": + return f"You picked {result.data}" + return "No number provided" +``` +```python title="Boolean" +@mcp.tool +async def pick_a_boolean(ctx: Context) -> str: + result = await ctx.elicit("True or false?", response_type=bool) + + if result.action == "accept": + return f"You picked {result.data}" + return "No boolean provided" +``` + + +### No Response + +Sometimes, the goal of an elicitation is to simply get a user to approve or reject an action. Pass `None` as the response type to indicate that no data is expected. The `data` field will be `None` when the user accepts. + +```python +@mcp.tool +async def approve_action(ctx: Context) -> str: + result = await ctx.elicit("Approve this action?", response_type=None) + + if result.action == "accept": + return do_action() + else: + raise ValueError("Action rejected") +``` + +### Constrained Options + +Constrain the user's response to a specific set of values using a `Literal` type, Python enum, or a list of strings as a convenient shortcut. + + +```python title="List of strings" +@mcp.tool +async def set_priority(ctx: Context) -> str: + result = await ctx.elicit( + "What priority level?", + response_type=["low", "medium", "high"], + ) + + if result.action == "accept": + return f"Priority set to: {result.data}" +``` +```python title="Literal type" +from typing import Literal + +@mcp.tool +async def set_priority(ctx: Context) -> str: + result = await ctx.elicit( + "What priority level?", + response_type=Literal["low", "medium", "high"] + ) + + if result.action == "accept": + return f"Priority set to: {result.data}" + return "No priority set" +``` +```python title="Python enum" +from enum import Enum + +class Priority(Enum): + LOW = "low" + MEDIUM = "medium" + HIGH = "high" + +@mcp.tool +async def set_priority(ctx: Context) -> str: + result = await ctx.elicit("What priority level?", response_type=Priority) + + if result.action == "accept": + return f"Priority set to: {result.data.value}" + return "No priority set" +``` + + +### Multi-Select + + + +Enable multi-select by wrapping your choices in an additional list level. This allows users to select multiple values from the available options. + + +```python title="List of strings" +@mcp.tool +async def select_tags(ctx: Context) -> str: + result = await ctx.elicit( + "Choose tags", + response_type=[["bug", "feature", "documentation"]] # Note: list of a list + ) + + if result.action == "accept": + tags = result.data + return f"Selected tags: {', '.join(tags)}" +``` +```python title="list[Enum] type" +from enum import Enum + +class Tag(Enum): + BUG = "bug" + FEATURE = "feature" + DOCS = "documentation" + +@mcp.tool +async def select_tags(ctx: Context) -> str: + result = await ctx.elicit( + "Choose tags", + response_type=list[Tag] + ) + if result.action == "accept": + tags = [tag.value for tag in result.data] + return f"Selected: {', '.join(tags)}" +``` + + +### Titled Options + + + +For better UI display, provide human-readable titles for enum options. FastMCP generates SEP-1330 compliant schemas using the `oneOf` pattern with `const` and `title` fields. + +```python +@mcp.tool +async def set_priority(ctx: Context) -> str: + result = await ctx.elicit( + "What priority level?", + response_type={ + "low": {"title": "Low Priority"}, + "medium": {"title": "Medium Priority"}, + "high": {"title": "High Priority"} + } + ) + + if result.action == "accept": + return f"Priority set to: {result.data}" +``` + +For multi-select with titles, wrap the dict in a list: + +```python +@mcp.tool +async def select_priorities(ctx: Context) -> str: + result = await ctx.elicit( + "Choose priorities", + response_type=[{ + "low": {"title": "Low Priority"}, + "medium": {"title": "Medium Priority"}, + "high": {"title": "High Priority"} + }] + ) + + if result.action == "accept": + return f"Selected: {', '.join(result.data)}" +``` + +### Structured Responses + +Request structured data with multiple fields by using a dataclass, typed dict, or Pydantic model as the response type. Note that the MCP spec only supports shallow objects with scalar (string, number, boolean) or enum properties. + +```python +from dataclasses import dataclass +from typing import Literal + +@dataclass +class TaskDetails: + title: str + description: str + priority: Literal["low", "medium", "high"] + due_date: str + +@mcp.tool +async def create_task(ctx: Context) -> str: + result = await ctx.elicit( + "Please provide task details", + response_type=TaskDetails + ) + + if result.action == "accept": + task = result.data + return f"Created task: {task.title} (Priority: {task.priority})" + return "Task creation cancelled" +``` + +### Default Values + + + +Provide default values for elicitation fields using Pydantic's `Field(default=...)`. Clients will pre-populate form fields with these defaults. Fields with default values are automatically marked as optional. + +```python +from pydantic import BaseModel, Field +from enum import Enum + +class Priority(Enum): + LOW = "low" + MEDIUM = "medium" + HIGH = "high" + +class TaskDetails(BaseModel): + title: str = Field(description="Task title") + description: str = Field(default="", description="Task description") + priority: Priority = Field(default=Priority.MEDIUM, description="Task priority") + +@mcp.tool +async def create_task(ctx: Context) -> str: + result = await ctx.elicit("Please provide task details", response_type=TaskDetails) + if result.action == "accept": + return f"Created: {result.data.title}" + return "Task creation cancelled" +``` + +Default values are supported for strings, integers, numbers, booleans, and enums. diff --git a/docs/servers/icons.mdx b/docs/servers/icons.mdx new file mode 100644 index 000000000..c9b558094 --- /dev/null +++ b/docs/servers/icons.mdx @@ -0,0 +1,151 @@ +--- +title: Icons +description: Add visual icons to your servers, tools, resources, and prompts +icon: image +--- + +import { VersionBadge } from '/snippets/version-badge.mdx' + + + +Icons provide visual representations for your MCP servers and components, helping client applications present better user interfaces. When displayed in MCP clients, icons help users quickly identify and navigate your server's capabilities. + +## Icon Format + +Icons use the standard MCP Icon type from the MCP protocol specification. Each icon specifies a source URL or data URI, and optionally includes MIME type and size information. + +```python +from mcp.types import Icon + +icon = Icon( + src="https://example.com/icon.png", + mimeType="image/png", + sizes=["48x48"] +) +``` + +The fields serve different purposes: + +- **src**: URL or data URI pointing to the icon image +- **mimeType** (optional): MIME type of the image (e.g., "image/png", "image/svg+xml") +- **sizes** (optional): Array of size descriptors (e.g., ["48x48"], ["any"]) + +## Server Icons + +Add icons and a website URL to your server for display in client applications. Multiple icons at different sizes help clients choose the best resolution for their display context. + +```python +from fastmcp import FastMCP +from mcp.types import Icon + +mcp = FastMCP( + name="WeatherService", + website_url="https://weather.example.com", + icons=[ + Icon( + src="https://weather.example.com/icon-48.png", + mimeType="image/png", + sizes=["48x48"] + ), + Icon( + src="https://weather.example.com/icon-96.png", + mimeType="image/png", + sizes=["96x96"] + ), + ] +) +``` + +Server icons appear in MCP client interfaces to help users identify your server among others they may have installed. + +## Component Icons + +Icons can be added to individual tools, resources, resource templates, and prompts. This helps users visually distinguish between different component types and purposes. + +### Tool Icons + +```python +from mcp.types import Icon + +@mcp.tool( + icons=[Icon(src="https://example.com/calculator-icon.png")] +) +def calculate_sum(a: int, b: int) -> int: + """Add two numbers together.""" + return a + b +``` + +### Resource Icons + +```python +@mcp.resource( + "config://settings", + icons=[Icon(src="https://example.com/config-icon.png")] +) +def get_settings() -> dict: + """Retrieve application settings.""" + return {"theme": "dark", "language": "en"} +``` + +### Resource Template Icons + +```python +@mcp.resource( + "user://{user_id}/profile", + icons=[Icon(src="https://example.com/user-icon.png")] +) +def get_user_profile(user_id: str) -> dict: + """Get a user's profile.""" + return {"id": user_id, "name": f"User {user_id}"} +``` + +### Prompt Icons + +```python +@mcp.prompt( + icons=[Icon(src="https://example.com/prompt-icon.png")] +) +def analyze_code(code: str): + """Create a prompt for code analysis.""" + return f"Please analyze this code:\n\n{code}" +``` + +## Using Data URIs + +For small icons or when you want to embed the icon directly without external dependencies, use data URIs. This approach eliminates the need for hosting and ensures the icon is always available. + +```python +from mcp.types import Icon +from fastmcp.utilities.types import Image + +# SVG icon as data URI +svg_icon = Icon( + src="data:image/svg+xml;base64,PHN2ZyB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciIHdpZHRoPSIyNCIgaGVpZ2h0PSIyNCI+PHBhdGggZD0iTTEyIDJDNi40OCAyIDIgNi40OCAyIDEyczQuNDggMTAgMTAgMTAgMTAtNC40OCAxMC0xMFMxNy41MiAyIDEyIDJ6Ii8+PC9zdmc+", + mimeType="image/svg+xml" +) + +@mcp.tool(icons=[svg_icon]) +def my_tool() -> str: + """A tool with an embedded SVG icon.""" + return "result" +``` + +### Generating Data URIs from Files + +FastMCP provides the `Image` utility class to convert local image files into data URIs. + +```python +from mcp.types import Icon +from fastmcp.utilities.types import Image + +# Generate a data URI from a local image file +img = Image(path="./assets/brand/favicon.png") +icon = Icon(src=img.to_data_uri()) + +@mcp.tool(icons=[icon]) +def file_icon_tool() -> str: + """A tool with an icon generated from a local file.""" + return "result" +``` + +This approach is useful when you have local image assets and want to embed them directly in your server definition. diff --git a/docs/servers/lifespan.mdx b/docs/servers/lifespan.mdx new file mode 100644 index 000000000..822e4f8a1 --- /dev/null +++ b/docs/servers/lifespan.mdx @@ -0,0 +1,148 @@ +--- +title: Lifespans +sidebarTitle: Lifespan +description: Server-level setup and teardown with composable lifespans +icon: heart-pulse +tag: NEW +--- + +import { VersionBadge } from '/snippets/version-badge.mdx' + + + +Lifespans let you run code once when the server starts and clean up when it stops. Unlike per-session handlers, lifespans run exactly once regardless of how many clients connect. + +## Basic Usage + +Use the `@lifespan` decorator to define a lifespan: + +```python +from fastmcp import FastMCP +from fastmcp.server.lifespan import lifespan + +@lifespan +async def app_lifespan(server): + # Setup: runs once when server starts + print("Starting up...") + try: + yield {"started_at": "2024-01-01"} + finally: + # Teardown: runs when server stops + print("Shutting down...") + +mcp = FastMCP("MyServer", lifespan=app_lifespan) +``` + +The dict you yield becomes the **lifespan context**, accessible from tools. + + +Always use `try/finally` for cleanup code to ensure it runs even if the server is cancelled. + + +## Accessing Lifespan Context + +Access the lifespan context in tools via `ctx.lifespan_context`: + +```python +from fastmcp import FastMCP, Context +from fastmcp.server.lifespan import lifespan + +@lifespan +async def app_lifespan(server): + # Initialize shared state + data = {"users": ["alice", "bob"]} + yield {"data": data} + +mcp = FastMCP("MyServer", lifespan=app_lifespan) + +@mcp.tool +def list_users(ctx: Context) -> list[str]: + data = ctx.lifespan_context["data"] + return data["users"] +``` + +## Composing Lifespans + +Compose multiple lifespans with the `|` operator: + +```python +from fastmcp import FastMCP +from fastmcp.server.lifespan import lifespan + +@lifespan +async def config_lifespan(server): + config = {"debug": True, "version": "1.0"} + yield {"config": config} + +@lifespan +async def data_lifespan(server): + data = {"items": []} + yield {"data": data} + +# Compose with | +mcp = FastMCP("MyServer", lifespan=config_lifespan | data_lifespan) +``` + +Composed lifespans: +- Enter in order (left to right) +- Exit in reverse order (right to left) +- Merge their context dicts (later values overwrite earlier on conflict) + +## Backwards Compatibility + +Existing `@asynccontextmanager` lifespans still work when passed directly to FastMCP: + +```python +from contextlib import asynccontextmanager +from fastmcp import FastMCP + +@asynccontextmanager +async def legacy_lifespan(server): + yield {"key": "value"} + +mcp = FastMCP("MyServer", lifespan=legacy_lifespan) +``` + +To compose an `@asynccontextmanager` function with `@lifespan` functions, wrap it with `ContextManagerLifespan`: + +```python +from contextlib import asynccontextmanager +from fastmcp.server.lifespan import lifespan, ContextManagerLifespan + +@asynccontextmanager +async def legacy_lifespan(server): + yield {"legacy": True} + +@lifespan +async def new_lifespan(server): + yield {"new": True} + +# Wrap the legacy lifespan explicitly for composition +combined = ContextManagerLifespan(legacy_lifespan) | new_lifespan +``` + +## With FastAPI + +When mounting FastMCP into FastAPI, use `combine_lifespans` to run both your app's lifespan and the MCP server's lifespan: + +```python +from contextlib import asynccontextmanager + +from fastapi import FastAPI +from fastmcp import FastMCP +from fastmcp.utilities.lifespan import combine_lifespans + +@asynccontextmanager +async def app_lifespan(app): + print("FastAPI starting...") + yield + print("FastAPI shutting down...") + +mcp = FastMCP("Tools") +mcp_app = mcp.http_app() + +app = FastAPI(lifespan=combine_lifespans(app_lifespan, mcp_app.lifespan)) +app.mount("/mcp", mcp_app) +``` + +See the [FastAPI integration guide](/integrations/fastapi#combining-lifespans) for full details. diff --git a/docs/servers/logging.mdx b/docs/servers/logging.mdx new file mode 100644 index 000000000..e01fdd875 --- /dev/null +++ b/docs/servers/logging.mdx @@ -0,0 +1,87 @@ +--- +title: Client Logging +sidebarTitle: Logging +description: Send log messages back to MCP clients through the context. +icon: receipt +--- + +import { VersionBadge } from '/snippets/version-badge.mdx' + + +This documentation covers **MCP client logging**—sending messages from your server to MCP clients. For standard server-side logging (e.g., writing to files, console), use `fastmcp.utilities.logging.get_logger()` or Python's built-in `logging` module. + + +Server logging allows MCP tools to send debug, info, warning, and error messages back to the client. Unlike standard Python logging, MCP server logging sends messages directly to the client, making them visible in the client's interface or logs. + +## Basic Usage + +Use the context logging methods within any tool function: + +```python +from fastmcp import FastMCP, Context + +mcp = FastMCP("LoggingDemo") + +@mcp.tool +async def analyze_data(data: list[float], ctx: Context) -> dict: + """Analyze numerical data with comprehensive logging.""" + await ctx.debug("Starting analysis of numerical data") + await ctx.info(f"Analyzing {len(data)} data points") + + try: + if not data: + await ctx.warning("Empty data list provided") + return {"error": "Empty data list"} + + result = sum(data) / len(data) + await ctx.info(f"Analysis complete, average: {result}") + return {"average": result, "count": len(data)} + + except Exception as e: + await ctx.error(f"Analysis failed: {str(e)}") + raise +``` + +## Log Levels + +| Level | Use Case | +|-------|----------| +| `ctx.debug()` | Detailed execution information for diagnosing problems | +| `ctx.info()` | General information about normal program execution | +| `ctx.warning()` | Potentially harmful situations that don't prevent execution | +| `ctx.error()` | Error events that might still allow the application to continue | + +## Structured Logging + +All logging methods accept an `extra` parameter for sending structured data to the client. This is useful for creating rich, queryable logs. + +```python +@mcp.tool +async def process_transaction(transaction_id: str, amount: float, ctx: Context): + await ctx.info( + f"Processing transaction {transaction_id}", + extra={ + "transaction_id": transaction_id, + "amount": amount, + "currency": "USD" + } + ) +``` + +## Server-Side Logs + +Messages sent to clients via `ctx.log()` and its convenience methods are also logged to the server's log at `DEBUG` level. Enable debug logging on the `fastmcp.server.context.to_client` logger to see these messages: + +```python +import logging +from fastmcp.utilities.logging import get_logger + +to_client_logger = get_logger(name="fastmcp.server.context.to_client") +to_client_logger.setLevel(level=logging.DEBUG) +``` + +## Client Handling + +Log messages are sent to the client through the MCP protocol. How clients handle these messages depends on their implementation—development clients may display logs in real-time, production clients may store them for analysis, and integration clients may forward them to external logging systems. + +See [Client Logging](/clients/logging) for details on how clients handle server log messages. diff --git a/docs/servers/middleware.mdx b/docs/servers/middleware.mdx new file mode 100644 index 000000000..424f5afa7 --- /dev/null +++ b/docs/servers/middleware.mdx @@ -0,0 +1,871 @@ +--- +title: Middleware +sidebarTitle: Middleware +description: Add cross-cutting functionality to your MCP server with middleware that intercepts and modifies requests and responses. +icon: layer-group +--- + +import { VersionBadge } from "/snippets/version-badge.mdx" + + + +Middleware adds behavior that applies across multiple operations—authentication, logging, rate limiting, or request transformation—without modifying individual tools or resources. + + +MCP middleware is a FastMCP-specific concept and is not part of the official MCP protocol specification. + + +## Overview + +MCP middleware forms a pipeline around your server's operations. When a request arrives, it flows through each middleware in order—each can inspect, modify, or reject the request before passing it along. After the operation completes, the response flows back through the same middleware in reverse order. + +``` +Request → Middleware A → Middleware B → Handler → Middleware B → Middleware A → Response +``` + +This bidirectional flow means middleware can: +- **Pre-process**: Validate authentication, log incoming requests, check rate limits +- **Post-process**: Transform responses, record timing metrics, handle errors consistently + +The key decision point is `call_next(context)`. Calling it continues the chain; not calling it stops processing entirely. + +```python +from fastmcp import FastMCP +from fastmcp.server.middleware import Middleware, MiddlewareContext + +class LoggingMiddleware(Middleware): + async def on_message(self, context: MiddlewareContext, call_next): + print(f"→ {context.method}") + result = await call_next(context) + print(f"← {context.method}") + return result + +mcp = FastMCP("MyServer") +mcp.add_middleware(LoggingMiddleware()) +``` + +### Execution Order + +Middleware executes in the order added to the server. The first middleware runs first on the way in and last on the way out: + +```python +from fastmcp import FastMCP +from fastmcp.server.middleware.error_handling import ErrorHandlingMiddleware +from fastmcp.server.middleware.rate_limiting import RateLimitingMiddleware +from fastmcp.server.middleware.logging import LoggingMiddleware + +mcp = FastMCP("MyServer") +mcp.add_middleware(ErrorHandlingMiddleware()) # 1st in, last out +mcp.add_middleware(RateLimitingMiddleware()) # 2nd in, 2nd out +mcp.add_middleware(LoggingMiddleware()) # 3rd in, first out +``` + +This ordering matters. Place error handling early so it catches exceptions from all subsequent middleware. Place logging late so it records the actual execution after other middleware has processed the request. + +### Server Composition + +When using [mounted servers](/servers/composition), middleware behavior follows a clear hierarchy: + +- **Parent middleware** runs for all requests, including those routed to mounted servers +- **Mounted server middleware** only runs for requests handled by that specific server + +```python +from fastmcp import FastMCP +from fastmcp.server.middleware.logging import LoggingMiddleware + +parent = FastMCP("Parent") +parent.add_middleware(AuthMiddleware()) # Runs for ALL requests + +child = FastMCP("Child") +child.add_middleware(LoggingMiddleware()) # Only runs for child's tools + +parent.mount(child, namespace="child") +``` + +Requests to `child_tool` flow through the parent's `AuthMiddleware` first, then through the child's `LoggingMiddleware`. + +## Hooks + +Rather than processing every message identically, FastMCP provides specialized hooks at different levels of specificity. Multiple hooks fire for a single request, going from general to specific: + +| Level | Hooks | Purpose | +|-------|-------|---------| +| Message | `on_message` | All MCP traffic (requests and notifications) | +| Type | `on_request`, `on_notification` | Requests expecting responses vs fire-and-forget | +| Operation | `on_call_tool`, `on_read_resource`, `on_get_prompt`, etc. | Specific MCP operations | + +When a client calls a tool, the middleware chain processes `on_message` first, then `on_request`, then `on_call_tool`. This hierarchy lets you target exactly the right scope—use `on_message` for logging everything, `on_request` for authentication, and `on_call_tool` for tool-specific behavior. + +### Hook Signature + +Every hook follows the same pattern: + +```python +async def hook_name(self, context: MiddlewareContext, call_next) -> result_type: + # Pre-processing + result = await call_next(context) + # Post-processing + return result +``` + +**Parameters:** +- `context` — `MiddlewareContext` containing request information +- `call_next` — Async function to continue the middleware chain + +**Returns:** The appropriate result type for the hook (varies by operation). + +### MiddlewareContext + +The `context` parameter provides access to request details: + +| Attribute | Type | Description | +|-----------|------|-------------| +| `method` | `str` | MCP method name (e.g., `"tools/call"`) | +| `source` | `str` | Origin: `"client"` or `"server"` | +| `type` | `str` | Message type: `"request"` or `"notification"` | +| `message` | `object` | The MCP message data | +| `timestamp` | `datetime` | When the request was received | +| `fastmcp_context` | `Context` | FastMCP context object (if available) | + +### Message Hooks + +#### on_message + +Called for every MCP message—both requests and notifications. + +```python +async def on_message(self, context: MiddlewareContext, call_next): + result = await call_next(context) + return result +``` + +Use for: Logging, metrics, or any cross-cutting concern that applies to all traffic. + +#### on_request + +Called for MCP requests that expect a response. + +```python +async def on_request(self, context: MiddlewareContext, call_next): + result = await call_next(context) + return result +``` + +Use for: Authentication, authorization, request validation. + +#### on_notification + +Called for fire-and-forget MCP notifications. + +```python +async def on_notification(self, context: MiddlewareContext, call_next): + await call_next(context) + # Notifications don't return values +``` + +Use for: Event logging, async side effects. + +### Operation Hooks + +#### on_call_tool + +Called when a tool is executed. The `context.message` contains `name` (tool name) and `arguments` (dict). + +```python +async def on_call_tool(self, context: MiddlewareContext, call_next): + tool_name = context.message.name + args = context.message.arguments + result = await call_next(context) + return result +``` + +**Returns:** Tool execution result or raises `ToolError`. + +#### on_read_resource + +Called when a resource is read. The `context.message` contains `uri` (resource URI). + +```python +async def on_read_resource(self, context: MiddlewareContext, call_next): + uri = context.message.uri + result = await call_next(context) + return result +``` + +**Returns:** Resource content. + +#### on_get_prompt + +Called when a prompt is retrieved. The `context.message` contains `name` (prompt name) and `arguments` (dict). + +```python +async def on_get_prompt(self, context: MiddlewareContext, call_next): + prompt_name = context.message.name + result = await call_next(context) + return result +``` + +**Returns:** Prompt messages. + +#### on_list_tools + +Called when listing available tools. Returns a list of FastMCP `Tool` objects before MCP conversion. + +```python +async def on_list_tools(self, context: MiddlewareContext, call_next): + tools = await call_next(context) + # Filter or modify the tool list + return tools +``` + +**Returns:** `list[Tool]` — Can be filtered before returning to client. + +#### on_list_resources + +Called when listing available resources. Returns FastMCP `Resource` objects. + +```python +async def on_list_resources(self, context: MiddlewareContext, call_next): + resources = await call_next(context) + return resources +``` + +**Returns:** `list[Resource]` + +#### on_list_resource_templates + +Called when listing resource templates. + +```python +async def on_list_resource_templates(self, context: MiddlewareContext, call_next): + templates = await call_next(context) + return templates +``` + +**Returns:** `list[ResourceTemplate]` + +#### on_list_prompts + +Called when listing available prompts. + +```python +async def on_list_prompts(self, context: MiddlewareContext, call_next): + prompts = await call_next(context) + return prompts +``` + +**Returns:** `list[Prompt]` + +#### on_initialize + + + +Called when a client connects and initializes the session. This hook cannot modify the initialization response. + +```python +from mcp import McpError +from mcp.types import ErrorData + +async def on_initialize(self, context: MiddlewareContext, call_next): + client_info = context.message.params.get("clientInfo", {}) + client_name = client_info.get("name", "unknown") + + # Reject before call_next to send error to client + if client_name == "blocked-client": + raise McpError(ErrorData(code=-32000, message="Client not supported")) + + await call_next(context) + print(f"Client {client_name} initialized") +``` + +**Returns:** `None` — The initialization response is handled internally by the MCP protocol. + + +Raising `McpError` after `call_next()` will only log the error, not send it to the client. The response has already been sent. Always reject **before** `call_next()`. + + +### Raw Handler + +For complete control over all messages, override `__call__` instead of individual hooks: + +```python +from fastmcp.server.middleware import Middleware, MiddlewareContext + +class RawMiddleware(Middleware): + async def __call__(self, context: MiddlewareContext, call_next): + print(f"Processing: {context.method}") + result = await call_next(context) + print(f"Completed: {context.method}") + return result +``` + +This bypasses the hook dispatch system entirely. Use when you need uniform handling regardless of message type. + +### Session Availability + + + +The MCP session may not be available during certain phases like initialization. Check before accessing session-specific attributes: + +```python +async def on_request(self, context: MiddlewareContext, call_next): + ctx = context.fastmcp_context + + if ctx.request_context: + # MCP session available + session_id = ctx.session_id + request_id = ctx.request_id + else: + # Session not yet established (e.g., during initialization) + # Use HTTP helpers if needed + from fastmcp.server.dependencies import get_http_headers + headers = get_http_headers() + + return await call_next(context) +``` + +For HTTP-specific data (headers, client IP) when using HTTP transports, see [HTTP Requests](/servers/context#http-requests). + +## Built-in Middleware + +FastMCP includes production-ready middleware for common server concerns. + +### Logging + +```python +from fastmcp.server.middleware.logging import LoggingMiddleware, StructuredLoggingMiddleware +``` + +`LoggingMiddleware` provides human-readable request and response logging. `StructuredLoggingMiddleware` outputs JSON-formatted logs for aggregation tools like Datadog or Splunk. + +```python +from fastmcp import FastMCP +from fastmcp.server.middleware.logging import LoggingMiddleware + +mcp = FastMCP("MyServer") +mcp.add_middleware(LoggingMiddleware( + include_payloads=True, + max_payload_length=1000 +)) +``` + +| Parameter | Type | Default | Description | +|-----------|------|---------|-------------| +| `include_payloads` | `bool` | `False` | Log request/response content | +| `max_payload_length` | `int` | `500` | Truncate payloads beyond this length | +| `logger` | `Logger` | module logger | Custom logger instance | + +### Timing + +```python +from fastmcp.server.middleware.timing import TimingMiddleware, DetailedTimingMiddleware +``` + +`TimingMiddleware` logs execution duration for all requests. `DetailedTimingMiddleware` provides per-operation timing with separate tracking for tools, resources, and prompts. + +```python +from fastmcp import FastMCP +from fastmcp.server.middleware.timing import TimingMiddleware + +mcp = FastMCP("MyServer") +mcp.add_middleware(TimingMiddleware()) +``` + +### Caching + +```python +from fastmcp.server.middleware.caching import ResponseCachingMiddleware +``` + +Caches tool calls, resource reads, and list operations with TTL-based expiration. + +```python +from fastmcp import FastMCP +from fastmcp.server.middleware.caching import ResponseCachingMiddleware + +mcp = FastMCP("MyServer") +mcp.add_middleware(ResponseCachingMiddleware()) +``` + +Each operation type can be configured independently using settings classes: + +```python +from fastmcp.server.middleware.caching import ( + ResponseCachingMiddleware, + CallToolSettings, + ListToolsSettings, + ReadResourceSettings +) + +mcp.add_middleware(ResponseCachingMiddleware( + list_tools_settings=ListToolsSettings(ttl=30), + call_tool_settings=CallToolSettings(included_tools=["expensive_tool"]), + read_resource_settings=ReadResourceSettings(enabled=False) +)) +``` + +| Settings Class | Configures | +|----------------|------------| +| `ListToolsSettings` | `on_list_tools` caching | +| `CallToolSettings` | `on_call_tool` caching | +| `ListResourcesSettings` | `on_list_resources` caching | +| `ReadResourceSettings` | `on_read_resource` caching | +| `ListPromptsSettings` | `on_list_prompts` caching | +| `GetPromptSettings` | `on_get_prompt` caching | + +Each settings class accepts: +- `enabled` — Enable/disable caching for this operation +- `ttl` — Time-to-live in seconds +- `included_*` / `excluded_*` — Whitelist or blacklist specific items + +For persistence or distributed deployments, configure a different storage backend: + +```python +from fastmcp.server.middleware.caching import ResponseCachingMiddleware +from key_value.aio.stores.disk import DiskStore + +mcp.add_middleware(ResponseCachingMiddleware( + cache_storage=DiskStore(directory="cache") +)) +``` + +See [Storage Backends](/servers/storage-backends) for complete options. + + +Cache keys are based on the operation name and arguments only — they do not include user or session identity. If your tools return user-specific data derived from auth context (e.g., headers or session state) rather than from the request arguments, you should either disable caching for those tools or ensure user identity is part of the tool arguments. + + +### Rate Limiting + +```python +from fastmcp.server.middleware.rate_limiting import ( + RateLimitingMiddleware, + SlidingWindowRateLimitingMiddleware +) +``` + +`RateLimitingMiddleware` uses a token bucket algorithm allowing controlled bursts. `SlidingWindowRateLimitingMiddleware` provides precise time-window rate limiting without burst allowance. + +```python +from fastmcp import FastMCP +from fastmcp.server.middleware.rate_limiting import RateLimitingMiddleware + +mcp = FastMCP("MyServer") +mcp.add_middleware(RateLimitingMiddleware( + max_requests_per_second=10.0, + burst_capacity=20 +)) +``` + +| Parameter | Type | Default | Description | +|-----------|------|---------|-------------| +| `max_requests_per_second` | `float` | `10.0` | Sustained request rate | +| `burst_capacity` | `int` | `20` | Maximum burst size | +| `client_id_func` | `Callable` | `None` | Custom client identification | + +For sliding window rate limiting: + +```python +from fastmcp.server.middleware.rate_limiting import SlidingWindowRateLimitingMiddleware + +mcp.add_middleware(SlidingWindowRateLimitingMiddleware( + max_requests=100, + window_minutes=1 +)) +``` + +### Error Handling + +```python +from fastmcp.server.middleware.error_handling import ErrorHandlingMiddleware, RetryMiddleware +``` + +`ErrorHandlingMiddleware` provides centralized error logging and transformation. `RetryMiddleware` automatically retries with exponential backoff for transient failures. + +```python +from fastmcp import FastMCP +from fastmcp.server.middleware.error_handling import ErrorHandlingMiddleware + +mcp = FastMCP("MyServer") +mcp.add_middleware(ErrorHandlingMiddleware( + include_traceback=True, + transform_errors=True, + error_callback=my_error_callback +)) +``` + +| Parameter | Type | Default | Description | +|-----------|------|---------|-------------| +| `include_traceback` | `bool` | `False` | Include stack traces in logs | +| `transform_errors` | `bool` | `False` | Convert exceptions to MCP errors | +| `error_callback` | `Callable` | `None` | Custom callback on errors | + +For automatic retries: + +```python +from fastmcp.server.middleware.error_handling import RetryMiddleware + +mcp.add_middleware(RetryMiddleware( + max_retries=3, + retry_exceptions=(ConnectionError, TimeoutError) +)) +``` + +### Ping + + + +```python +from fastmcp.server.middleware import PingMiddleware +``` + +Keeps long-lived connections alive by sending periodic pings. + +```python +from fastmcp import FastMCP +from fastmcp.server.middleware import PingMiddleware + +mcp = FastMCP("MyServer") +mcp.add_middleware(PingMiddleware(interval_ms=5000)) +``` + +| Parameter | Type | Default | Description | +|-----------|------|---------|-------------| +| `interval_ms` | `int` | `30000` | Ping interval in milliseconds | + +The ping task starts on the first message and stops automatically when the session ends. Most useful for stateful HTTP connections; has no effect on stateless connections. + +### Response Limiting + + + +```python +from fastmcp.server.middleware.response_limiting import ResponseLimitingMiddleware +``` + +Large tool responses can overwhelm LLM context windows or cause memory issues. You can add response-limiting middleware to enforce size constraints on tool outputs. + +```python +from fastmcp import FastMCP +from fastmcp.server.middleware.response_limiting import ResponseLimitingMiddleware + +mcp = FastMCP("MyServer") + +# Limit all tool responses to 500KB +mcp.add_middleware(ResponseLimitingMiddleware(max_size=500_000)) + +@mcp.tool +def search(query: str) -> str: + # This could return a very large result + return "x" * 1_000_000 # 1MB response + +# When called, the response will be truncated to ~500KB with: +# "...\n\n[Response truncated due to size limit]" +``` + +When a response exceeds the limit, the middleware extracts all text content, joins it together, truncates to fit within the limit, and returns a single `TextContent` block. For non-text responses, the serialized JSON is used as the text source. + + +If a tool defines an `output_schema`, truncated responses will no longer conform to that schema — the client will receive a plain `TextContent` block instead of the expected structured output. Keep this in mind when setting size limits for tools with structured responses. + + +```python +# Limit only specific tools +mcp.add_middleware(ResponseLimitingMiddleware( + max_size=100_000, + tools=["search", "fetch_data"], +)) +``` + +| Parameter | Type | Default | Description | +|-----------|------|---------|-------------| +| `max_size` | `int` | `1_000_000` | Maximum response size in bytes (1MB default) | +| `truncation_suffix` | `str` | `"\n\n[Response truncated due to size limit]"` | Suffix appended to truncated responses | +| `tools` | `list[str] \| None` | `None` | Limit only these tools (None = all tools) | + +### Combining Middleware + +Order matters. Place middleware that should run first (on the way in) earliest: + +```python +from fastmcp import FastMCP +from fastmcp.server.middleware.error_handling import ErrorHandlingMiddleware +from fastmcp.server.middleware.rate_limiting import RateLimitingMiddleware +from fastmcp.server.middleware.timing import TimingMiddleware +from fastmcp.server.middleware.logging import LoggingMiddleware + +mcp = FastMCP("Production Server") + +mcp.add_middleware(ErrorHandlingMiddleware()) # Catch all errors +mcp.add_middleware(RateLimitingMiddleware(max_requests_per_second=50)) +mcp.add_middleware(TimingMiddleware()) +mcp.add_middleware(LoggingMiddleware()) + +@mcp.tool +def my_tool(data: str) -> str: + return f"Processed: {data}" +``` + +## Custom Middleware + +When the built-in middleware doesn't fit your needs—custom authentication schemes, domain-specific logging, or request transformation—subclass `Middleware` and override the hooks you need. + +```python +from fastmcp import FastMCP +from fastmcp.server.middleware import Middleware, MiddlewareContext + +class CustomMiddleware(Middleware): + async def on_request(self, context: MiddlewareContext, call_next): + # Pre-processing + print(f"→ {context.method}") + + result = await call_next(context) + + # Post-processing + print(f"← {context.method}") + return result + +mcp = FastMCP("MyServer") +mcp.add_middleware(CustomMiddleware()) +``` + +Override only the hooks relevant to your use case. Unoverridden hooks pass through automatically. + +### Denying Requests + +Raise the appropriate error type to stop processing and return an error to the client. + +```python +from fastmcp.server.middleware import Middleware, MiddlewareContext +from fastmcp.exceptions import ToolError + +class AuthMiddleware(Middleware): + async def on_call_tool(self, context: MiddlewareContext, call_next): + tool_name = context.message.name + + if tool_name in ["delete_all", "admin_config"]: + raise ToolError("Access denied: requires admin privileges") + + return await call_next(context) +``` + +| Operation | Error Type | +|-----------|------------| +| Tool calls | `ToolError` | +| Resource reads | `ResourceError` | +| Prompt retrieval | `PromptError` | +| General requests | `McpError` | + +Do not return error values or skip `call_next()` to indicate errors—raise exceptions for proper error propagation. + +### Modifying Requests + +Change the message before passing it down the chain. + +```python +from fastmcp.server.middleware import Middleware, MiddlewareContext + +class InputSanitizer(Middleware): + async def on_call_tool(self, context: MiddlewareContext, call_next): + if context.message.name == "search": + # Normalize search query + query = context.message.arguments.get("query", "") + context.message.arguments["query"] = query.strip().lower() + + return await call_next(context) +``` + +### Modifying Responses + +Transform results after the handler executes. + +```python +from fastmcp.server.middleware import Middleware, MiddlewareContext + +class ResponseEnricher(Middleware): + async def on_call_tool(self, context: MiddlewareContext, call_next): + result = await call_next(context) + + if context.message.name == "get_data" and result.structured_content: + result.structured_content["processed_by"] = "enricher" + + return result +``` + +For more complex tool transformations, consider [Transforms](/servers/transforms/transforms) instead. + +### Filtering Lists + +List operations return FastMCP objects that you can filter before they reach the client. When filtering list results, also block execution in the corresponding operation hook to maintain consistency: + +```python +from fastmcp.server.middleware import Middleware, MiddlewareContext +from fastmcp.exceptions import ToolError + +class PrivateToolFilter(Middleware): + async def on_list_tools(self, context: MiddlewareContext, call_next): + tools = await call_next(context) + return [tool for tool in tools if "private" not in tool.tags] + + async def on_call_tool(self, context: MiddlewareContext, call_next): + if context.fastmcp_context: + tool = await context.fastmcp_context.fastmcp.get_tool(context.message.name) + if "private" in tool.tags: + raise ToolError("Tool not found") + + return await call_next(context) +``` + +### Accessing Component Metadata + +During execution hooks, component metadata (like tags) isn't directly available. Look up the component through the server: + +```python +from fastmcp.server.middleware import Middleware, MiddlewareContext +from fastmcp.exceptions import ToolError + +class TagBasedAuth(Middleware): + async def on_call_tool(self, context: MiddlewareContext, call_next): + if context.fastmcp_context: + try: + tool = await context.fastmcp_context.fastmcp.get_tool(context.message.name) + + if "requires-auth" in tool.tags: + # Check authentication here + pass + + except Exception: + pass # Let execution handle missing tools + + return await call_next(context) +``` + +The same pattern works for resources and prompts: + +```python +resource = await context.fastmcp_context.fastmcp.get_resource(context.message.uri) +prompt = await context.fastmcp_context.fastmcp.get_prompt(context.message.name) +``` + +### Storing State + + + +Middleware can store state that tools access later through the FastMCP context. + +```python +from fastmcp.server.middleware import Middleware, MiddlewareContext + +class UserMiddleware(Middleware): + async def on_request(self, context: MiddlewareContext, call_next): + # Extract user from headers (HTTP transport) + from fastmcp.server.dependencies import get_http_headers + headers = get_http_headers() or {} + user_id = headers.get("x-user-id", "anonymous") + + # Store for tools to access + if context.fastmcp_context: + context.fastmcp_context.set_state("user_id", user_id) + + return await call_next(context) +``` + +Tools retrieve the state: + +```python +from fastmcp import FastMCP, Context + +mcp = FastMCP("MyServer") + +@mcp.tool +def get_user_data(ctx: Context) -> str: + user_id = ctx.get_state("user_id") + return f"Data for user: {user_id}" +``` + +See [Context State Management](/servers/context#state-management) for details. + +### Constructor Parameters + +Initialize middleware with configuration: + +```python +from fastmcp.server.middleware import Middleware, MiddlewareContext + +class ConfigurableMiddleware(Middleware): + def __init__(self, api_key: str, rate_limit: int = 100): + self.api_key = api_key + self.rate_limit = rate_limit + self.request_counts = {} + + async def on_request(self, context: MiddlewareContext, call_next): + # Use self.api_key, self.rate_limit, etc. + return await call_next(context) + +mcp.add_middleware(ConfigurableMiddleware( + api_key="secret", + rate_limit=50 +)) +``` + +### Error Handling in Custom Middleware + +Wrap `call_next()` to handle errors from downstream middleware and handlers. + +```python +from fastmcp.server.middleware import Middleware, MiddlewareContext + +class ErrorLogger(Middleware): + async def on_request(self, context: MiddlewareContext, call_next): + try: + return await call_next(context) + except Exception as e: + print(f"Error in {context.method}: {type(e).__name__}: {e}") + raise # Re-raise to let error propagate +``` + +Catching and not re-raising suppresses the error entirely. Usually you want to log and re-raise. + +### Complete Example + +Authentication middleware checking API keys for specific tools: + +```python +from fastmcp import FastMCP +from fastmcp.server.middleware import Middleware, MiddlewareContext +from fastmcp.server.dependencies import get_http_headers +from fastmcp.exceptions import ToolError + +class ApiKeyAuth(Middleware): + def __init__(self, valid_keys: set[str], protected_tools: set[str]): + self.valid_keys = valid_keys + self.protected_tools = protected_tools + + async def on_call_tool(self, context: MiddlewareContext, call_next): + tool_name = context.message.name + + if tool_name not in self.protected_tools: + return await call_next(context) + + headers = get_http_headers() or {} + api_key = headers.get("x-api-key") + + if api_key not in self.valid_keys: + raise ToolError(f"Invalid API key for protected tool: {tool_name}") + + return await call_next(context) + +mcp = FastMCP("Secure Server") +mcp.add_middleware(ApiKeyAuth( + valid_keys={"key-1", "key-2"}, + protected_tools={"delete_user", "admin_panel"} +)) + +@mcp.tool +def delete_user(user_id: str) -> str: + return f"Deleted user {user_id}" + +@mcp.tool +def get_user(user_id: str) -> str: + return f"User {user_id}" # Not protected +``` diff --git a/docs/servers/pagination.mdx b/docs/servers/pagination.mdx new file mode 100644 index 000000000..97ad2c7a2 --- /dev/null +++ b/docs/servers/pagination.mdx @@ -0,0 +1,93 @@ +--- +title: Pagination +sidebarTitle: Pagination +description: Control how servers return large lists of components to clients. +icon: page +tag: NEW +--- + +import { VersionBadge } from '/snippets/version-badge.mdx' + + + +When a server exposes many tools, resources, or prompts, returning them all in a single response can be impractical. MCP supports pagination for list operations, allowing servers to return results in manageable chunks that clients can fetch incrementally. + +## Server Configuration + +By default, FastMCP servers return all components in a single response for backward compatibility. To enable pagination, set the `list_page_size` parameter when creating your server. This value determines the maximum number of items returned per page across all list operations. + +```python +from fastmcp import FastMCP + +# Enable pagination with 50 items per page +server = FastMCP("ComponentRegistry", list_page_size=50) + +# Register tools (in practice, these might come from a database or config) +@server.tool +def search(query: str) -> str: + return f"Results for: {query}" + +@server.tool +def analyze(data: str) -> dict: + return {"status": "analyzed", "data": data} + +# ... many more tools, resources, prompts +``` + +When `list_page_size` is configured, the `tools/list`, `resources/list`, `resources/templates/list`, and `prompts/list` endpoints all paginate their responses. Each response includes a `nextCursor` field when more results exist, which clients use to fetch subsequent pages. + +### Cursor Format + +Cursors are opaque base64-encoded strings per the MCP specification. Clients should treat them as black boxes, passing them unchanged between requests. The cursor encodes the offset into the result set, but this is an implementation detail that may change. + +## Client Behavior + +The FastMCP Client handles pagination transparently. Convenience methods like `list_tools()`, `list_resources()`, `list_resource_templates()`, and `list_prompts()` automatically fetch all pages and return the complete list. Existing code continues to work without modification. + +```python +from fastmcp import Client + +async with Client(server) as client: + # Returns all 200 tools, fetching pages automatically + tools = await client.list_tools() + print(f"Total tools: {len(tools)}") # 200 +``` + +### Manual Pagination + +For scenarios where you want to process results incrementally (memory-constrained environments, progress reporting, or early termination), use the `_mcp` variants with explicit cursor handling. + +```python +from fastmcp import Client + +async with Client(server) as client: + # Fetch first page + result = await client.list_tools_mcp() + print(f"Page 1: {len(result.tools)} tools") + + # Continue fetching while more pages exist + while result.nextCursor: + result = await client.list_tools_mcp(cursor=result.nextCursor) + print(f"Next page: {len(result.tools)} tools") +``` + +The `_mcp` methods return the raw MCP protocol objects, which include both the items and the `nextCursor` for the next page. When `nextCursor` is `None`, you've reached the end of the result set. + +All four list operations support manual pagination: + +| Operation | Convenience Method | Manual Method | +|-----------|-------------------|---------------| +| Tools | `list_tools()` | `list_tools_mcp(cursor=...)` | +| Resources | `list_resources()` | `list_resources_mcp(cursor=...)` | +| Resource Templates | `list_resource_templates()` | `list_resource_templates_mcp(cursor=...)` | +| Prompts | `list_prompts()` | `list_prompts_mcp(cursor=...)` | + +## When to Use Pagination + +Pagination becomes valuable when your server exposes a large number of components. Consider enabling it when: + +- Your server dynamically generates many components (e.g., from a database or file system) +- Memory usage is a concern for clients +- You want to reduce initial response latency + +For servers with a fixed, modest number of components (fewer than 100), pagination adds complexity without meaningful benefit. The default behavior of returning everything in one response is simpler and efficient for typical use cases. diff --git a/docs/servers/progress.mdx b/docs/servers/progress.mdx new file mode 100644 index 000000000..9600a05ce --- /dev/null +++ b/docs/servers/progress.mdx @@ -0,0 +1,51 @@ +--- +title: Progress Reporting +sidebarTitle: Progress +description: Update clients on the progress of long-running operations through the MCP context. +icon: chart-line +--- + +import { VersionBadge } from '/snippets/version-badge.mdx' + +Progress reporting allows MCP tools to notify clients about the progress of long-running operations. Clients can display progress indicators and provide better user experience during time-consuming tasks. + +## Basic Usage + +Use `ctx.report_progress()` to send progress updates to the client. The method accepts a `progress` value representing how much work is complete, and an optional `total` representing the full scope of work. + +```python +from fastmcp import FastMCP, Context +import asyncio + +mcp = FastMCP("ProgressDemo") + +@mcp.tool +async def process_items(items: list[str], ctx: Context) -> dict: + """Process a list of items with progress updates.""" + total = len(items) + results = [] + + for i, item in enumerate(items): + await ctx.report_progress(progress=i, total=total) + await asyncio.sleep(0.1) + results.append(item.upper()) + + await ctx.report_progress(progress=total, total=total) + return {"processed": len(results), "results": results} +``` + +## Progress Patterns + +| Pattern | Description | Example | +|---------|-------------|---------| +| Percentage | Progress as 0-100 percentage | `progress=75, total=100` | +| Absolute | Completed items of a known count | `progress=3, total=10` | +| Indeterminate | Progress without known endpoint | `progress=files_found` (no total) | + +For multi-stage operations, map each stage to a portion of the total progress range. A four-stage operation might allocate 0-25% to validation, 25-60% to export, 60-80% to transform, and 80-100% to import. + +## Client Requirements + +Progress reporting requires clients to support progress handling. Clients must send a `progressToken` in the initial request to receive progress updates. If no progress token is provided, progress calls have no effect (they don't error). + +See [Client Progress](/clients/progress) for details on implementing client-side progress handling. diff --git a/docs/servers/prompts.mdx b/docs/servers/prompts.mdx new file mode 100644 index 000000000..bdfefc24e --- /dev/null +++ b/docs/servers/prompts.mdx @@ -0,0 +1,459 @@ +--- +title: Prompts +sidebarTitle: Prompts +description: Create reusable, parameterized prompt templates for MCP clients. +icon: message-lines +--- + +import { VersionBadge } from "/snippets/version-badge.mdx" + +Prompts are reusable message templates that help LLMs generate structured, purposeful responses. FastMCP simplifies defining these templates, primarily using the `@mcp.prompt` decorator. + +## What Are Prompts? + +Prompts provide parameterized message templates for LLMs. When a client requests a prompt: + +1. FastMCP finds the corresponding prompt definition. +2. If it has parameters, they are validated against your function signature. +3. Your function executes with the validated inputs. +4. The generated message(s) are returned to the LLM to guide its response. + +This allows you to define consistent, reusable templates that LLMs can use across different clients and contexts. + +## Prompts + +### The `@prompt` Decorator + +The most common way to define a prompt is by decorating a Python function. The decorator uses the function name as the prompt's identifier. + +```python +from fastmcp import FastMCP +from fastmcp.prompts import Message + +mcp = FastMCP(name="PromptServer") + +# Basic prompt returning a string (converted to user message automatically) +@mcp.prompt +def ask_about_topic(topic: str) -> str: + """Generates a user message asking for an explanation of a topic.""" + return f"Can you please explain the concept of '{topic}'?" + +# Prompt returning multiple messages +@mcp.prompt +def generate_code_request(language: str, task_description: str) -> list[Message]: + """Generates a conversation for code generation.""" + return [ + Message(f"Write a {language} function that performs the following task: {task_description}"), + Message("I'll help you write that function.", role="assistant"), + ] +``` + +**Key Concepts:** + +* **Name:** By default, the prompt name is taken from the function name. +* **Parameters:** The function parameters define the inputs needed to generate the prompt. +* **Inferred Metadata:** By default: + * Prompt Name: Taken from the function name (`ask_about_topic`). + * Prompt Description: Taken from the function's docstring. + +Functions with `*args` or `**kwargs` are not supported as prompts. This restriction exists because FastMCP needs to generate a complete parameter schema for the MCP protocol, which isn't possible with variable argument lists. + + +#### Decorator Arguments + +While FastMCP infers the name and description from your function, you can override these and add additional metadata using arguments to the `@mcp.prompt` decorator: + +```python +@mcp.prompt( + name="analyze_data_request", # Custom prompt name + description="Creates a request to analyze data with specific parameters", # Custom description + tags={"analysis", "data"}, # Optional categorization tags + meta={"version": "1.1", "author": "data-team"} # Custom metadata +) +def data_analysis_prompt( + data_uri: str = Field(description="The URI of the resource containing the data."), + analysis_type: str = Field(default="summary", description="Type of analysis.") +) -> str: + """This docstring is ignored when description is provided.""" + return f"Please perform a '{analysis_type}' analysis on the data found at {data_uri}." +``` + + + + Sets the explicit prompt name exposed via MCP. If not provided, uses the function name + + + + A human-readable title for the prompt + + + + Provides the description exposed via MCP. If set, the function's docstring is ignored for this purpose + + + + A set of strings used to categorize the prompt. These can be used by the server and, in some cases, by clients to filter or group available prompts. + + + + Deprecated in v3.0.0. Use `mcp.enable()` / `mcp.disable()` at the server level instead. + A boolean to enable or disable the prompt. See [Component Visibility](#component-visibility) for the recommended approach. + + + + + + Optional list of icon representations for this prompt. See [Icons](/servers/icons) for detailed examples + + + + + + Optional meta information about the prompt. This data is passed through to the MCP client as the `meta` field of the client-side prompt object and can be used for custom metadata, versioning, or other application-specific purposes. + + + + + + Optional version identifier for this prompt. See [Versioning](/servers/versioning) for details. + + + +#### Using with Methods + +For decorating instance or class methods, use the standalone `@prompt` decorator and register the bound method. See [Tools: Using with Methods](/servers/tools#using-with-methods) for the pattern. + +### Argument Types + + + +The MCP specification requires that all prompt arguments be passed as strings, but FastMCP allows you to use typed annotations for better developer experience. When you use complex types like `list[int]` or `dict[str, str]`, FastMCP: + +1. **Automatically converts** string arguments from MCP clients to the expected types +2. **Generates helpful descriptions** showing the exact JSON string format needed +3. **Preserves direct usage** - you can still call prompts with properly typed arguments + +Since the MCP specification only allows string arguments, clients need to know what string format to use for complex types. FastMCP solves this by automatically enhancing the argument descriptions with JSON schema information, making it clear to both humans and LLMs how to format their arguments. + + + +```python Python Code +@mcp.prompt +def analyze_data( + numbers: list[int], + metadata: dict[str, str], + threshold: float +) -> str: + """Analyze numerical data.""" + avg = sum(numbers) / len(numbers) + return f"Average: {avg}, above threshold: {avg > threshold}" +``` + +```json Resulting MCP Prompt +{ + "name": "analyze_data", + "description": "Analyze numerical data.", + "arguments": [ + { + "name": "numbers", + "description": "Provide as a JSON string matching the following schema: {\"items\":{\"type\":\"integer\"},\"type\":\"array\"}", + "required": true + }, + { + "name": "metadata", + "description": "Provide as a JSON string matching the following schema: {\"additionalProperties\":{\"type\":\"string\"},\"type\":\"object\"}", + "required": true + }, + { + "name": "threshold", + "description": "Provide as a JSON string matching the following schema: {\"type\":\"number\"}", + "required": true + } + ] +} +``` + + + +**MCP clients will call this prompt with string arguments:** +```json +{ + "numbers": "[1, 2, 3, 4, 5]", + "metadata": "{\"source\": \"api\", \"version\": \"1.0\"}", + "threshold": "2.5" +} +``` + +**But you can still call it directly with proper types:** +```python +# This also works for direct calls +result = await prompt.render({ + "numbers": [1, 2, 3, 4, 5], + "metadata": {"source": "api", "version": "1.0"}, + "threshold": 2.5 +}) +``` + + +Keep your type annotations simple when using this feature. Complex nested types or custom classes may not convert reliably from JSON strings. The automatically generated schema descriptions are the only guidance users receive about the expected format. + +Good choices: `list[int]`, `dict[str, str]`, `float`, `bool` +Avoid: Complex Pydantic models, deeply nested structures, custom classes + + +### Return Values + +Prompt functions must return one of these types: + +- **`str`**: Sent as a single user message. +- **`list[Message | str]`**: A sequence of messages (a conversation). Strings are auto-converted to user Messages. +- **`PromptResult`**: Full control over messages, description, and metadata. See [PromptResult](#promptresult) below. + +```python +from fastmcp.prompts import Message + +@mcp.prompt +def roleplay_scenario(character: str, situation: str) -> list[Message]: + """Sets up a roleplaying scenario with initial messages.""" + return [ + Message(f"Let's roleplay. You are {character}. The situation is: {situation}"), + Message("Okay, I understand. I am ready. What happens next?", role="assistant") + ] +``` + +#### Message + + + +`Message` provides a user-friendly wrapper for prompt messages with automatic serialization. + +```python +from fastmcp.prompts import Message + +# String content (user role by default) +Message("Hello, world!") + +# Explicit role +Message("I can help with that.", role="assistant") + +# Auto-serialized to JSON text +Message({"key": "value"}) +Message(["item1", "item2"]) +``` + +`Message` accepts two fields: + +**`content`** - The message content. Strings pass through directly. Other types (dict, list, BaseModel) are automatically JSON-serialized to text. + +**`role`** - The message role, either `"user"` (default) or `"assistant"`. + + + + The content data. Strings pass through directly. Other types (dict, list, BaseModel) are automatically JSON-serialized. + + + The message role. + + + +#### PromptResult + + + +`PromptResult` gives you explicit control over prompt responses: multiple messages, roles, and metadata at both the message and result level. + +```python +from fastmcp import FastMCP +from fastmcp.prompts import PromptResult, Message + +mcp = FastMCP(name="PromptServer") + +@mcp.prompt +def code_review(code: str) -> PromptResult: + """Returns a code review prompt with metadata.""" + return PromptResult( + messages=[ + Message(f"Please review this code:\n\n```\n{code}\n```"), + Message("I'll analyze this code for issues.", role="assistant"), + ], + description="Code review prompt", + meta={"review_type": "security", "priority": "high"} + ) +``` + +For simple cases, you can pass a string directly to `PromptResult`: + +```python +return PromptResult("Please help me with this task") # auto-converts to single Message +``` + + + + Messages to return. Strings are wrapped as a single user Message. + + + Optional description of the prompt result. If not provided, defaults to the prompt's docstring. + + + Result-level metadata, included in the MCP response's `_meta` field. Use this for runtime metadata like categorization, priority, or other client-specific data. + + + + +The `meta` field in `PromptResult` is for runtime metadata specific to this render response. This is separate from the `meta` parameter in `@mcp.prompt(meta={...})`, which provides static metadata about the prompt definition itself (returned when listing prompts). + + +You can still return plain `str` or `list[Message | str]` from your prompt functions—`PromptResult` is opt-in for when you need to include metadata. + +### Required vs. Optional Parameters + +Parameters in your function signature are considered **required** unless they have a default value. + +```python +@mcp.prompt +def data_analysis_prompt( + data_uri: str, # Required - no default value + analysis_type: str = "summary", # Optional - has default value + include_charts: bool = False # Optional - has default value +) -> str: + """Creates a request to analyze data with specific parameters.""" + prompt = f"Please perform a '{analysis_type}' analysis on the data found at {data_uri}." + if include_charts: + prompt += " Include relevant charts and visualizations." + return prompt +``` + +In this example, the client *must* provide `data_uri`. If `analysis_type` or `include_charts` are omitted, their default values will be used. + +### Component Visibility + + + +You can control which prompts are enabled for clients using server-level enabled control. Disabled prompts don't appear in `list_prompts` and can't be called. + +```python +from fastmcp import FastMCP + +mcp = FastMCP("MyServer") + +@mcp.prompt(tags={"public"}) +def public_prompt(topic: str) -> str: + return f"Discuss: {topic}" + +@mcp.prompt(tags={"internal"}) +def internal_prompt() -> str: + return "Internal system prompt" + +# Disable specific prompts by key +mcp.disable(keys={"prompt:internal_prompt"}) + +# Disable prompts by tag +mcp.disable(tags={"internal"}) + +# Or use allowlist mode - only enable prompts with specific tags +mcp.enable(tags={"public"}, only=True) +``` + +See [Visibility](/servers/visibility) for the complete visibility control API including key formats, tag-based filtering, and provider-level control. + +### Async Prompts + +FastMCP supports both standard (`def`) and asynchronous (`async def`) functions as prompts. Synchronous functions automatically run in a threadpool to avoid blocking the event loop. + +```python +# Synchronous prompt (runs in threadpool) +@mcp.prompt +def simple_question(question: str) -> str: + """Generates a simple question to ask the LLM.""" + return f"Question: {question}" + +# Asynchronous prompt +@mcp.prompt +async def data_based_prompt(data_id: str) -> str: + """Generates a prompt based on data that needs to be fetched.""" + # In a real scenario, you might fetch data from a database or API + async with aiohttp.ClientSession() as session: + async with session.get(f"https://api.example.com/data/{data_id}") as response: + data = await response.json() + return f"Analyze this data: {data['content']}" +``` + +Use `async def` when your prompt function performs I/O operations like network requests or database queries, since async is more efficient than threadpool dispatch. + +### Accessing MCP Context + + + +Prompts can access additional MCP information and features through the `Context` object. To access it, add a parameter to your prompt function with a type annotation of `Context`: + +```python {6} +from fastmcp import FastMCP, Context + +mcp = FastMCP(name="PromptServer") + +@mcp.prompt +async def generate_report_request(report_type: str, ctx: Context) -> str: + """Generates a request for a report.""" + return f"Please create a {report_type} report. Request ID: {ctx.request_id}" +``` + +For full documentation on the Context object and all its capabilities, see the [Context documentation](/servers/context). + +### Notifications + + + +FastMCP automatically sends `notifications/prompts/list_changed` notifications to connected clients when prompts are added, enabled, or disabled. This allows clients to stay up-to-date with the current prompt set without manually polling for changes. + +```python +@mcp.prompt +def example_prompt() -> str: + return "Hello!" + +# These operations trigger notifications: +mcp.add_prompt(example_prompt) # Sends prompts/list_changed notification +mcp.disable(keys={"prompt:example_prompt"}) # Sends prompts/list_changed notification +mcp.enable(keys={"prompt:example_prompt"}) # Sends prompts/list_changed notification +``` + +Notifications are only sent when these operations occur within an active MCP request context (e.g., when called from within a tool or other MCP operation). Operations performed during server initialization do not trigger notifications. + +Clients can handle these notifications using a [message handler](/clients/notifications) to automatically refresh their prompt lists or update their interfaces. + +## Server Behavior + +### Duplicate Prompts + + + +You can configure how the FastMCP server handles attempts to register multiple prompts with the same name. Use the `on_duplicate_prompts` setting during `FastMCP` initialization. + +```python +from fastmcp import FastMCP + +mcp = FastMCP( + name="PromptServer", + on_duplicate_prompts="error" # Raise an error if a prompt name is duplicated +) + +@mcp.prompt +def greeting(): return "Hello, how can I help you today?" + +# This registration attempt will raise a ValueError because +# "greeting" is already registered and the behavior is "error". +# @mcp.prompt +# def greeting(): return "Hi there! What can I do for you?" +``` + +The duplicate behavior options are: + +- `"warn"` (default): Logs a warning, and the new prompt replaces the old one. +- `"error"`: Raises a `ValueError`, preventing the duplicate registration. +- `"replace"`: Silently replaces the existing prompt with the new one. +- `"ignore"`: Keeps the original prompt and ignores the new registration attempt. + +## Versioning + + + +Prompts support versioning, allowing you to maintain multiple implementations under the same name while clients automatically receive the highest version. See [Versioning](/servers/versioning) for complete documentation on version comparison, retrieval, and migration patterns. diff --git a/docs/servers/providers/custom.mdx b/docs/servers/providers/custom.mdx new file mode 100644 index 000000000..f5673c683 --- /dev/null +++ b/docs/servers/providers/custom.mdx @@ -0,0 +1,245 @@ +--- +title: Custom Providers +sidebarTitle: Custom +description: Build providers that source components from any data source +icon: code +tag: NEW +--- + +import { VersionBadge } from '/snippets/version-badge.mdx' + + + +Custom providers let you source components from anywhere - databases, APIs, configuration systems, or dynamic runtime logic. If you can write Python code to fetch or generate a component, you can wrap it in a provider. + +## When to Build Custom + +The built-in providers handle common cases: decorators (`LocalProvider`), composition (`FastMCPProvider`), and proxying (`ProxyProvider`). Build a custom provider when your components come from somewhere else: + +- **Database-backed tools**: Admin users define tools in a database, and your server exposes them dynamically +- **API-backed resources**: Resources that fetch content from external services on demand +- **Configuration-driven components**: Components loaded from YAML/JSON config files at startup +- **Multi-tenant systems**: Different users see different tools based on their permissions +- **Plugin systems**: Third-party code registers components at runtime + +## Providers vs Middleware + +Both providers and [middleware](/servers/middleware) can influence what components a client sees, but they work at different levels. + +**Providers** are objects that source components. They make it easy to reason about where tools, resources, and prompts come from - a database, another server, an API. + +**Middleware** intercepts individual requests. It's well-suited for request-specific decisions like logging, rate limiting, or authentication. + +You *could* use middleware to dynamically add tools based on request context. But it's often cleaner to have a provider source all possible tools, then use middleware or [visibility controls](/servers/visibility) to filter what each request can see. This separation makes it easier to reason about how components are sourced and how they interact with other server machinery. + +## The Provider Interface + +A provider implements protected `_list_*` methods that return available components. The public `list_*` methods handle transforms automatically - you override the underscore-prefixed versions: + +```python +from collections.abc import Sequence +from fastmcp.server.providers import Provider +from fastmcp.tools import Tool +from fastmcp.resources import Resource +from fastmcp.prompts import Prompt + +class MyProvider(Provider): + async def _list_tools(self) -> Sequence[Tool]: + """Return all tools this provider offers.""" + return [] + + async def _list_resources(self) -> Sequence[Resource]: + """Return all resources this provider offers.""" + return [] + + async def _list_prompts(self) -> Sequence[Prompt]: + """Return all prompts this provider offers.""" + return [] +``` + +You only need to implement the methods for component types you provide. The base class returns empty sequences by default. + +The `_get_*` methods (`_get_tool`, `_get_resource`, `_get_prompt`) have default implementations that search through the list results. Override them only if you can fetch individual components more efficiently than iterating the full list. + +## What Providers Return + +Providers return component objects that are ready to use. When a client calls a tool, FastMCP invokes the tool's function - your provider isn't involved in execution. This means the `Tool`, `Resource`, or `Prompt` you return must actually work. + +The easiest way to create components is from functions: + +```python +from fastmcp.tools import Tool + +def add(a: int, b: int) -> int: + """Add two numbers.""" + return a + b + +tool = Tool.from_function(add) +``` + +The function's type hints become the input schema, and the docstring becomes the description. You can override these: + +```python +tool = Tool.from_function( + add, + name="calculator_add", + description="Add two integers together" +) +``` + +Similar `from_function` methods exist for `Resource` and `Prompt`. + +## Registering Providers + +Add providers when creating the server: + +```python +mcp = FastMCP( + "MyServer", + providers=[ + DatabaseProvider(db_url), + ConfigProvider(config_path), + ] +) +``` + +Or add them after creation: + +```python +mcp = FastMCP("MyServer") +mcp.add_provider(DatabaseProvider(db_url)) +``` + +## A Simple Provider + +Here's a minimal provider that serves tools from a dictionary: + +```python +from collections.abc import Callable, Sequence +from fastmcp import FastMCP +from fastmcp.server.providers import Provider +from fastmcp.tools import Tool + +class DictProvider(Provider): + def __init__(self, tools: dict[str, Callable]): + super().__init__() + self._tools = [ + Tool.from_function(fn, name=name) + for name, fn in tools.items() + ] + + async def _list_tools(self) -> Sequence[Tool]: + return self._tools +``` + +Use it like this: + +```python +def add(a: int, b: int) -> int: + """Add two numbers.""" + return a + b + +def multiply(a: int, b: int) -> int: + """Multiply two numbers.""" + return a * b + +mcp = FastMCP("Calculator", providers=[ + DictProvider({"add": add, "multiply": multiply}) +]) +``` + +## Lifecycle Management + +Providers often need to set up connections when the server starts and clean them up when it stops. Override the `lifespan` method: + +```python +from contextlib import asynccontextmanager +from collections.abc import AsyncIterator, Sequence + +class DatabaseProvider(Provider): + def __init__(self, db_url: str): + super().__init__() + self.db_url = db_url + self.db = None + + @asynccontextmanager + async def lifespan(self) -> AsyncIterator[None]: + self.db = await connect_database(self.db_url) + try: + yield + finally: + await self.db.close() + + async def _list_tools(self) -> Sequence[Tool]: + rows = await self.db.fetch("SELECT * FROM tools") + return [self._make_tool(row) for row in rows] +``` + +FastMCP calls your provider's `lifespan` during server startup and shutdown. The connection is available to your methods while the server runs. + +## Full Example: API-Backed Resources + +Here's a complete provider that fetches resources from an external REST API: + +```python +from contextlib import asynccontextmanager +from collections.abc import AsyncIterator, Sequence +from fastmcp.server.providers import Provider +from fastmcp.resources import Resource +import httpx + +class ApiResourceProvider(Provider): + """Provides resources backed by an external API.""" + + def __init__(self, base_url: str, api_key: str): + super().__init__() + self.base_url = base_url + self.api_key = api_key + self.client = None + + @asynccontextmanager + async def lifespan(self) -> AsyncIterator[None]: + self.client = httpx.AsyncClient( + base_url=self.base_url, + headers={"Authorization": f"Bearer {self.api_key}"} + ) + try: + yield + finally: + await self.client.aclose() + + async def _list_resources(self) -> Sequence[Resource]: + response = await self.client.get("/resources") + response.raise_for_status() + return [ + self._make_resource(item) + for item in response.json()["items"] + ] + + def _make_resource(self, data: dict) -> Resource: + resource_id = data["id"] + + async def read_content() -> str: + response = await self.client.get( + f"/resources/{resource_id}/content" + ) + return response.text + + return Resource.from_function( + read_content, + uri=f"api://resources/{resource_id}", + name=data["name"], + description=data.get("description", ""), + mime_type=data.get("mime_type", "text/plain") + ) +``` + +Register it like any other provider: + +```python +from fastmcp import FastMCP + +mcp = FastMCP("API Resources", providers=[ + ApiResourceProvider("https://api.example.com", "my-api-key") +]) +``` diff --git a/docs/servers/providers/filesystem.mdx b/docs/servers/providers/filesystem.mdx new file mode 100644 index 000000000..a5b798faa --- /dev/null +++ b/docs/servers/providers/filesystem.mdx @@ -0,0 +1,256 @@ +--- +title: Filesystem Provider +sidebarTitle: Filesystem +description: Automatic component discovery from Python files +icon: folder-tree +tag: NEW +--- + +import { VersionBadge } from '/snippets/version-badge.mdx' + + + +`FileSystemProvider` scans a directory for Python files and automatically registers functions decorated with `@tool`, `@resource`, or `@prompt`. This enables a file-based organization pattern similar to Next.js routing, where your project structure becomes your component registry. + +## Why Filesystem Discovery + +Traditional FastMCP servers require coordination between files. Either your tool files import the server to call `@server.tool()`, or your server file imports all the tool modules. Both approaches create coupling that some developers prefer to avoid. + +`FileSystemProvider` eliminates this coordination. Each file is self-contained—it uses standalone decorators (`@tool`, `@resource`, `@prompt`) that don't require access to a server instance. The provider discovers these files at startup, so you can add new tools without modifying your server file. + +This is a convention some teams prefer, not necessarily better for all projects. The tradeoffs: + +- **No coordination**: Files don't import the server; server doesn't import files +- **Predictable naming**: Function names become component names (unless overridden) +- **Development mode**: Optionally re-scan files on every request for rapid iteration + +## Quick Start + +Create a provider pointing to your components directory, then pass it to your server. Use `Path(__file__).parent` to make the path relative to your server file. + +```python +from pathlib import Path + +from fastmcp import FastMCP +from fastmcp.server.providers import FileSystemProvider + +mcp = FastMCP("MyServer", providers=[FileSystemProvider(Path(__file__).parent / "mcp")]) +``` + +In your `mcp/` directory, create Python files with decorated functions. + +```python +# mcp/tools/greet.py +from fastmcp.tools import tool + +@tool +def greet(name: str) -> str: + """Greet someone by name.""" + return f"Hello, {name}!" +``` + +When the server starts, `FileSystemProvider` scans the directory, imports all Python files, and registers any decorated functions it finds. + +## Decorators + +FastMCP provides standalone decorators that mark functions for discovery: `@tool` from `fastmcp.tools`, `@resource` from `fastmcp.resources`, and `@prompt` from `fastmcp.prompts`. These support the full syntax of server-bound decorators—all the same parameters work identically. + +### @tool + +Mark a function as a tool. The function name becomes the tool name by default. + +```python +from fastmcp.tools import tool + +@tool +def calculate_sum(a: float, b: float) -> float: + """Add two numbers together.""" + return a + b +``` + +Customize the tool with optional parameters. + +```python +from fastmcp.tools import tool + +@tool( + name="add-numbers", + description="Add two numbers together.", + tags={"math", "arithmetic"}, +) +def add(a: float, b: float) -> float: + return a + b +``` + +The decorator supports all standard tool options: `name`, `title`, `description`, `icons`, `tags`, `output_schema`, `annotations`, and `meta`. + +### @resource + +Mark a function as a resource. Unlike `@tool`, the `@resource` decorator requires a URI argument. + +```python +from fastmcp.resources import resource + +@resource("config://app") +def get_app_config() -> str: + """Get application configuration.""" + return '{"version": "1.0"}' +``` + +URIs with template parameters create resource templates. The provider automatically detects whether to register a static resource or a template based on whether the URI contains `{parameters}` or the function has arguments. + +```python +from fastmcp.resources import resource + +@resource("users://{user_id}/profile") +def get_user_profile(user_id: str) -> str: + """Get a user's profile by ID.""" + return f'{{"id": "{user_id}", "name": "User"}}' +``` + +The decorator supports: `uri` (required), `name`, `title`, `description`, `icons`, `mime_type`, `tags`, `annotations`, and `meta`. + +### @prompt + +Mark a function as a prompt template. + +```python +from fastmcp.prompts import prompt + +@prompt +def code_review(code: str, language: str = "python") -> str: + """Generate a code review prompt.""" + return f"Please review this {language} code:\n\n```{language}\n{code}\n```" +``` + +```python +from fastmcp.prompts import prompt + +@prompt(name="explain-concept", tags={"education"}) +def explain(topic: str) -> str: + """Generate an explanation prompt.""" + return f"Explain {topic} using clear examples and analogies." +``` + +The decorator supports: `name`, `title`, `description`, `icons`, `tags`, and `meta`. + +## Directory Structure + +The directory structure is purely organizational. The provider recursively scans all `.py` files regardless of which subdirectory they're in. Subdirectories like `tools/`, `resources/`, and `prompts/` are optional conventions that help you organize code. + +``` +mcp/ +├── tools/ +│ ├── greeting.py # @tool functions +│ └── calculator.py # @tool functions +├── resources/ +│ └── config.py # @resource functions +└── prompts/ + └── assistant.py # @prompt functions +``` + +You can also put all components in a single file or organize by feature rather than type. + +``` +mcp/ +├── user_management.py # @tool, @resource, @prompt for users +├── billing.py # @tool, @resource for billing +└── analytics.py # @tool for analytics +``` + +## Discovery Rules + +The provider follows these rules when scanning: + +| Rule | Behavior | +|------|----------| +| File extensions | Only `.py` files are scanned | +| `__init__.py` | Skipped (used for package structure, not components) | +| `__pycache__` | Skipped | +| Private functions | Functions starting with `_` are ignored, even if decorated | +| No decorators | Files without `@tool`, `@resource`, or `@prompt` are silently skipped | +| Multiple components | A single file can contain any number of decorated functions | + +### Package Imports + +If your directory contains an `__init__.py` file, the provider imports files as proper Python package members. This means relative imports work correctly within your components directory. + +```python +# mcp/__init__.py exists + +# mcp/tools/greeting.py +from ..helpers import format_name # Relative imports work + +@tool +def greet(name: str) -> str: + return f"Hello, {format_name(name)}!" +``` + +Without `__init__.py`, files are imported directly using `importlib.util.spec_from_file_location`. + +## Reload Mode + +During development, you may want changes to component files to take effect without restarting the server. Enable reload mode to re-scan the directory on every request. + +```python +from pathlib import Path + +from fastmcp.server.providers import FileSystemProvider + +provider = FileSystemProvider(Path(__file__).parent / "mcp", reload=True) +``` + +With `reload=True`, the provider: + +1. Re-discovers all Python files on each request +2. Re-imports modules that have changed +3. Updates the component registry with any new, modified, or removed components + + +Reload mode adds overhead to every request. Use it only during development, not in production. + + +## Error Handling + +When a file fails to import (syntax error, missing dependency, etc.), the provider logs a warning and continues scanning other files. Failed imports don't prevent the server from starting. + +``` +WARNING - Failed to import /path/to/broken.py: No module named 'missing_dep' +``` + +The provider tracks which files have failed and only re-logs warnings when the file's modification time changes. This prevents log spam when a broken file is repeatedly scanned in reload mode. + +## Example Project + +A complete example is available in the repository at `examples/filesystem-provider/`. The structure demonstrates the recommended organization. + +``` +examples/filesystem-provider/ +├── server.py # Server entry point +└── mcp/ + ├── tools/ + │ ├── greeting.py # greet, farewell tools + │ └── calculator.py # add, multiply tools + ├── resources/ + │ └── config.py # Static and templated resources + └── prompts/ + └── assistant.py # code_review, explain prompts +``` + +The server entry point is minimal. + +```python +from pathlib import Path + +from fastmcp import FastMCP +from fastmcp.server.providers import FileSystemProvider + +provider = FileSystemProvider( + root=Path(__file__).parent / "mcp", + reload=True, +) + +mcp = FastMCP("FilesystemDemo", providers=[provider]) +``` + +Run with `fastmcp run examples/filesystem-provider/server.py` or inspect with `fastmcp inspect examples/filesystem-provider/server.py`. diff --git a/docs/servers/providers/local.mdx b/docs/servers/providers/local.mdx new file mode 100644 index 000000000..86726655a --- /dev/null +++ b/docs/servers/providers/local.mdx @@ -0,0 +1,161 @@ +--- +title: Local Provider +sidebarTitle: Local +description: The default provider for decorator-registered components +icon: house +tag: NEW +--- + +import { VersionBadge } from '/snippets/version-badge.mdx' + + + +`LocalProvider` stores components that you define directly on your server. When you use `@mcp.tool`, `@mcp.resource`, or `@mcp.prompt`, you're adding components to your server's `LocalProvider`. + +## How It Works + +Every FastMCP server has a `LocalProvider` as its first provider. Components registered via decorators or direct methods are stored here: + +```python +from fastmcp import FastMCP + +mcp = FastMCP("MyServer") + +# These are stored in the server's `LocalProvider` +@mcp.tool +def greet(name: str) -> str: + """Greet someone by name.""" + return f"Hello, {name}!" + +@mcp.resource("data://config") +def get_config() -> str: + """Return configuration data.""" + return '{"version": "1.0"}' + +@mcp.prompt +def analyze(topic: str) -> str: + """Create an analysis prompt.""" + return f"Please analyze: {topic}" +``` + +The `LocalProvider` is always queried first when clients request components, ensuring that your directly-defined components take precedence over those from mounted or proxied servers. + +## Component Registration + +### Using Decorators + +The most common way to register components: + +```python +@mcp.tool +def my_tool(x: int) -> str: + return str(x) + +@mcp.resource("data://info") +def my_resource() -> str: + return "info" + +@mcp.prompt +def my_prompt(topic: str) -> str: + return f"Discuss: {topic}" +``` + +### Using Direct Methods + +You can also add pre-built component objects: + +```python +from fastmcp.tools import Tool + +# Create a tool object +my_tool = Tool.from_function(some_function, name="custom_tool") + +# Add it to the server +mcp.add_tool(my_tool) +mcp.add_resource(my_resource) +mcp.add_prompt(my_prompt) +``` + +### Removing Components + +Remove components by name or URI: + +```python +mcp.local_provider.remove_tool("my_tool") +mcp.local_provider.remove_resource("data://info") +mcp.local_provider.remove_prompt("my_prompt") +``` + +## Duplicate Handling + +When you try to add a component that already exists, the behavior depends on the `on_duplicate` setting: + +| Mode | Behavior | +|------|----------| +| `"error"` (default) | Raise `ValueError` | +| `"warn"` | Log warning and replace | +| `"replace"` | Silently replace | +| `"ignore"` | Keep existing component | + +Configure this when creating the server: + +```python +mcp = FastMCP("MyServer", on_duplicate="warn") +``` + +## Component Visibility + + + +Components can be dynamically enabled or disabled at runtime. Disabled components don't appear in listings and can't be called. + +```python +@mcp.tool(tags={"admin"}) +def delete_all() -> str: + """Delete everything.""" + return "Deleted" + +@mcp.tool +def get_status() -> str: + """Get system status.""" + return "OK" + +# Disable admin tools +mcp.disable(tags={"admin"}) + +# Or only enable specific tools +mcp.enable(keys={"tool:get_status"}, only=True) +``` + +See [Visibility](/servers/visibility) for the full documentation on keys, tags, allowlist mode, and provider-level control. + +## Standalone LocalProvider + +You can create a LocalProvider independently and attach it to multiple servers: + +```python +from fastmcp import FastMCP +from fastmcp.server.providers import LocalProvider + +# Create a reusable provider +shared_tools = LocalProvider() + +@shared_tools.tool +def greet(name: str) -> str: + return f"Hello, {name}!" + +@shared_tools.resource("data://version") +def get_version() -> str: + return "1.0.0" + +# Attach to multiple servers +server1 = FastMCP("Server1", providers=[shared_tools]) +server2 = FastMCP("Server2", providers=[shared_tools]) +``` + +This is useful for: +- Sharing components across servers +- Testing components in isolation +- Building reusable component libraries + +Standalone providers also support visibility control with `enable()` and `disable()`. See [Visibility](/servers/visibility) for details. diff --git a/docs/servers/providers/overview.mdx b/docs/servers/providers/overview.mdx new file mode 100644 index 000000000..d3e3e4e5f --- /dev/null +++ b/docs/servers/providers/overview.mdx @@ -0,0 +1,81 @@ +--- +title: Providers +sidebarTitle: Overview +description: How FastMCP sources tools, resources, and prompts +icon: layer-group +tag: NEW +--- + +import { VersionBadge } from '/snippets/version-badge.mdx' + + + +Every FastMCP server has one or more component providers. A provider is a source of tools, resources, and prompts - it's what makes components available to clients. + +## What Is a Provider? + +When a client connects to your server and asks "what tools do you have?", FastMCP asks each provider that question and combines the results. When a client calls a specific tool, FastMCP finds which provider has it and delegates the call. + +You're already using providers. When you write `@mcp.tool`, you're adding a tool to your server's `LocalProvider` - the default provider that stores components you define directly in code. You just don't have to think about it for simple servers. + +Providers become important when your components come from multiple sources: another FastMCP server to include, a remote MCP server to proxy, or a database where tools are defined dynamically. Each source gets its own provider, and FastMCP queries them all seamlessly. + +## Why Providers? + +The provider abstraction solves a common problem: as servers grow, you need to organize components across multiple sources without tangling everything together. + +**Composition**: Break a large server into focused modules. A "weather" server and a "calendar" server can each be developed independently, then mounted into a main server. Each mounted server becomes a `FastMCPProvider`. + +**Proxying**: Expose a remote MCP server through your local server. Maybe you're bridging transports (remote HTTP to local stdio) or aggregating multiple backends. Remote connections become `ProxyProvider` instances. + +**Dynamic sources**: Load tools from a database, generate them from an OpenAPI spec, or create them based on user permissions. Custom providers let components come from anywhere. + +## Built-in Providers + +FastMCP includes providers for common patterns: + +| Provider | What it does | How you use it | +|----------|--------------|----------------| +| `LocalProvider` | Stores components you define in code | `@mcp.tool`, `mcp.add_tool()` | +| `FastMCPProvider` | Wraps another FastMCP server | `mcp.mount(server)` | +| `ProxyProvider` | Connects to remote MCP servers | `create_proxy(client)` | + +Most users only interact with `LocalProvider` (through decorators) and occasionally mount or proxy other servers. The provider abstraction stays invisible until you need it. + +## Transforms + +[Transforms](/servers/transforms/transforms) modify components as they flow from providers to clients. Each transform sits in a chain, intercepting queries and modifying results before passing them along. + +| Transform | Purpose | +|-----------|---------| +| `Namespace` | Prefixes names to avoid conflicts | +| `ToolTransform` | Modifies tool schemas (rename, description, arguments) | + +The most common use is namespacing mounted servers to prevent name collisions. When you call `mount(server, namespace="api")`, FastMCP creates a `Namespace` transform automatically. + +Transforms can be added to individual providers (affecting just that source) or to the server itself (affecting all components). See [Transforms](/servers/transforms/transforms) for the full picture. + +## Provider Order + +When a client requests a tool, FastMCP queries providers in registration order. The first provider that has the tool handles the request. + +`LocalProvider` is always first, so your decorator-defined tools take precedence. Additional providers are queried in the order you added them. This means if two providers have a tool with the same name, the first one wins. + +## When to Care About Providers + +**You can ignore providers entirely** if you're building a simple server with decorators. Just use `@mcp.tool`, `@mcp.resource`, and `@mcp.prompt` - FastMCP handles the rest. + +**Learn about providers when** you want to: +- [Mount another server](/servers/composition) into yours +- [Proxy a remote server](/servers/providers/proxy) through yours +- [Control visibility state](/servers/visibility) of components +- [Build dynamic sources](/servers/providers/custom) like database-backed tools + +## Next Steps + +- [Local](/servers/providers/local) - How decorators work +- [Mounting](/servers/composition) - Compose servers together +- [Proxying](/servers/providers/proxy) - Connect to remote servers +- [Transforms](/servers/transforms/transforms) - Namespace, rename, and modify components +- [Visibility](/servers/visibility) - Control which components clients can access +- [Custom](/servers/providers/custom) - Build your own providers diff --git a/docs/servers/providers/proxy.mdx b/docs/servers/providers/proxy.mdx new file mode 100644 index 000000000..a2def6892 --- /dev/null +++ b/docs/servers/providers/proxy.mdx @@ -0,0 +1,301 @@ +--- +title: MCP Proxy Provider +sidebarTitle: MCP Proxy +description: Source components from other MCP servers +icon: arrows-retweet +--- + +import { VersionBadge } from '/snippets/version-badge.mdx' + + + +The Proxy Provider sources components from another MCP server through a client connection. This lets you expose any MCP server's tools, resources, and prompts through your own server, whether the source is local or accessed over the network. + +## Why Use Proxy Provider + +The Proxy Provider enables: + +- **Bridge transports**: Make an HTTP server available via stdio, or vice versa +- **Aggregate servers**: Combine multiple source servers into one unified server +- **Add security**: Act as a controlled gateway with authentication and authorization +- **Simplify access**: Provide a stable endpoint even if backend servers change + +```mermaid +sequenceDiagram + participant Client as Your Client + participant Proxy as FastMCP Proxy + participant Backend as Source Server + + Client->>Proxy: MCP Request (stdio) + Proxy->>Backend: MCP Request (HTTP/stdio/SSE) + Backend-->>Proxy: MCP Response + Proxy-->>Client: MCP Response +``` + +## Quick Start + + + +Create a proxy using `create_proxy()`: + +```python +from fastmcp.server import create_proxy + +# create_proxy() accepts URLs, file paths, and transports directly +proxy = create_proxy("http://example.com/mcp", name="MyProxy") + +if __name__ == "__main__": + proxy.run() +``` + +This gives you: +- Safe concurrent request handling +- Automatic forwarding of MCP features (sampling, elicitation, etc.) +- Session isolation to prevent context mixing + + +To mount a proxy inside another FastMCP server, see [Mounting External Servers](/servers/composition#mounting-external-servers). + + +## Transport Bridging + +A common use case is bridging transports between servers: + +```python +from fastmcp.server import create_proxy + +# Bridge HTTP server to local stdio +http_proxy = create_proxy("http://example.com/mcp/sse", name="HTTP-to-stdio") + +# Run locally via stdio for Claude Desktop +if __name__ == "__main__": + http_proxy.run() # Defaults to stdio +``` + +Or expose a local server via HTTP: + +```python +from fastmcp.server import create_proxy + +# Bridge local server to HTTP +local_proxy = create_proxy("local_server.py", name="stdio-to-HTTP") + +if __name__ == "__main__": + local_proxy.run(transport="http", host="0.0.0.0", port=8080) +``` + +## Session Isolation + + + +`create_proxy()` provides session isolation - each request gets its own isolated backend session: + +```python +from fastmcp.server import create_proxy + +# Each request creates a fresh backend session (recommended) +proxy = create_proxy("backend_server.py") + +# Multiple clients can use this proxy simultaneously: +# - Client A calls a tool → gets isolated session +# - Client B calls a tool → gets different session +# - No context mixing +``` + +### Shared Sessions + +If you pass an already-connected client, the proxy reuses that session: + +```python +from fastmcp import Client +from fastmcp.server import create_proxy + +async with Client("backend_server.py") as connected_client: + # This proxy reuses the connected session + proxy = create_proxy(connected_client) + + # ⚠️ Warning: All requests share the same session +``` + + +Shared sessions may cause context mixing in concurrent scenarios. Use only in single-threaded situations or with explicit synchronization. + + +## MCP Feature Forwarding + + + +Proxies automatically forward MCP protocol features: + +| Feature | Description | +|---------|-------------| +| Roots | Filesystem root access requests | +| Sampling | LLM completion requests | +| Elicitation | User input requests | +| Logging | Log messages from backend | +| Progress | Progress notifications | + +```python +from fastmcp.server import create_proxy + +# All features forwarded automatically +proxy = create_proxy("advanced_backend.py") + +# When the backend: +# - Requests LLM sampling → forwarded to your client +# - Logs messages → appear in your client +# - Reports progress → shown in your client +``` + +### Disabling Features + +Selectively disable forwarding: + +```python +from fastmcp.server.providers.proxy import ProxyClient + +backend = ProxyClient( + "backend_server.py", + sampling_handler=None, # Disable LLM sampling + log_handler=None # Disable log forwarding +) +``` + +## Configuration-Based Proxies + + + +Create proxies from configuration dictionaries: + +```python +from fastmcp.server import create_proxy + +config = { + "mcpServers": { + "default": { + "url": "https://example.com/mcp", + "transport": "http" + } + } +} + +proxy = create_proxy(config, name="Config-Based Proxy") +``` + +### Multi-Server Proxies + +Combine multiple servers with automatic namespacing: + +```python +from fastmcp.server import create_proxy + +config = { + "mcpServers": { + "weather": { + "url": "https://weather-api.example.com/mcp", + "transport": "http" + }, + "calendar": { + "url": "https://calendar-api.example.com/mcp", + "transport": "http" + } + } +} + +# Creates unified proxy with prefixed components: +# - weather_get_forecast +# - calendar_add_event +composite = create_proxy(config, name="Composite") +``` + +## Component Prefixing + +Proxied components follow standard prefixing rules: + +| Component Type | Pattern | +|----------------|---------| +| Tools | `{prefix}_{tool_name}` | +| Prompts | `{prefix}_{prompt_name}` | +| Resources | `protocol://{prefix}/path` | +| Templates | `protocol://{prefix}/...` | + +## Mirrored Components + + + +Components from a proxy server are "mirrored" - they reflect the remote server's state and cannot be modified directly. + +To modify a proxied component (like disabling it), create a local copy: + +```python +from fastmcp import FastMCP +from fastmcp.server import create_proxy + +proxy = create_proxy("backend_server.py") + +# Get mirrored tool +mirrored_tool = await proxy.get_tool("useful_tool") + +# Create modifiable local copy +local_tool = mirrored_tool.copy() + +# Add to your own server +my_server = FastMCP("MyServer") +my_server.add_tool(local_tool) + +# Now you can control enabled state +my_server.disable(keys={local_tool.key}) +``` + +## Performance Considerations + +Proxying introduces network latency: + +| Operation | Local | Proxied (HTTP) | +|-----------|-------|----------------| +| `list_tools()` | 1-2ms | 300-400ms | +| `call_tool()` | 1-2ms | 200-500ms | + +When mounting proxy servers, this latency affects all operations on the parent server. + +For low-latency requirements, consider caching strategies or limiting mounting depth. + +## Advanced Usage + +### FastMCPProxy Class + +For explicit session control, use `FastMCPProxy` directly: + +```python +from fastmcp.server.providers.proxy import FastMCPProxy, ProxyClient + +# Custom session factory +def create_client(): + return ProxyClient("backend_server.py") + +proxy = FastMCPProxy(client_factory=create_client) +``` + +This gives you full control over session creation and reuse strategies. + +### Adding Proxied Components to Existing Server + +Mount a proxy to add components from another server: + +```python +from fastmcp import FastMCP +from fastmcp.server import create_proxy + +server = FastMCP("My Server") + +# Add local tools +@server.tool +def local_tool() -> str: + return "Local result" + +# Mount proxied tools from another server +external = create_proxy("http://external-server/mcp") +server.mount(external) + +# Now server has both local and proxied tools +``` diff --git a/docs/servers/providers/skills.mdx b/docs/servers/providers/skills.mdx new file mode 100644 index 000000000..3c810b3f2 --- /dev/null +++ b/docs/servers/providers/skills.mdx @@ -0,0 +1,301 @@ +--- +title: Skills Provider +sidebarTitle: Skills +description: Expose agent skills as MCP resources +icon: wand-magic-sparkles +tag: NEW +--- + +import { VersionBadge } from '/snippets/version-badge.mdx' + + + +Agent skills are directories containing instructions and supporting files that teach an AI assistant how to perform specific tasks. Tools like Claude Code, Cursor, and VS Code Copilot each have their own skills directories where users can add custom capabilities. The Skills Provider exposes these skill directories as MCP resources, making skills discoverable and shareable across different AI tools and clients. + +## Why Skills as Resources + +Skills live in platform-specific directories (`~/.claude/skills/`, `~/.cursor/skills/`, etc.) and typically contain a main instruction file plus supporting reference materials. When you want to share skills between tools or access them from a custom client, you need a way to discover and retrieve these files programmatically. + +The Skills Provider solves this by exposing each skill as a set of MCP resources. A client can list available skills, read the main instruction file, check the manifest to see what supporting files exist, and fetch any file it needs. This transforms local skill directories into a standardized API that works with any MCP client. + +## Quick Start + +Create a provider pointing to your skills directory, then add it to your server. + +```python +from pathlib import Path + +from fastmcp import FastMCP +from fastmcp.server.providers.skills import SkillsDirectoryProvider + +mcp = FastMCP("Skills Server") +mcp.add_provider(SkillsDirectoryProvider(roots=Path.home() / ".claude" / "skills")) +``` + +Each subdirectory containing a `SKILL.md` file becomes a discoverable skill. Clients can then list resources to see available skills and read them as needed. + +```python +from fastmcp import Client + +async with Client(mcp) as client: + # List all skill resources + resources = await client.list_resources() + for r in resources: + print(r.uri) # skill://my-skill/SKILL.md, skill://my-skill/_manifest, ... + + # Read a skill's main instruction file + result = await client.read_resource("skill://my-skill/SKILL.md") + print(result[0].text) +``` + +## Skill Structure + +A skill is a directory containing a main instruction file (default: `SKILL.md`) and optionally supporting files. The directory name becomes the skill's identifier. + +``` +~/.claude/skills/ +├── pdf-processing/ +│ ├── SKILL.md # Main instructions +│ ├── reference.md # Supporting documentation +│ └── examples/ +│ └── sample.pdf +└── code-review/ + └── SKILL.md +``` + +The main file can include YAML frontmatter to provide metadata. If no frontmatter exists, the provider extracts a description from the first meaningful line of content. + +```markdown +--- +description: Process and extract information from PDF documents +--- + +# PDF Processing + +Instructions for handling PDFs... +``` + +## Resource URIs + +Each skill exposes three types of resources, all using the `skill://` URI scheme. + +The main instruction file contains the primary skill content. This is the resource clients read to understand what a skill does and how to use it. + +``` +skill://pdf-processing/SKILL.md +``` + +The manifest is a synthetic JSON resource listing all files in the skill directory with their sizes and SHA256 hashes. Clients use this to discover supporting files and verify content integrity. + +``` +skill://pdf-processing/_manifest +``` + +Reading the manifest returns structured file information. + +```json +{ + "skill": "pdf-processing", + "files": [ + {"path": "SKILL.md", "size": 1234, "hash": "sha256:abc123..."}, + {"path": "reference.md", "size": 567, "hash": "sha256:def456..."}, + {"path": "examples/sample.pdf", "size": 89012, "hash": "sha256:ghi789..."} + ] +} +``` + +Supporting files are any additional files in the skill directory. These might be reference documentation, code examples, or binary assets. + +``` +skill://pdf-processing/reference.md +skill://pdf-processing/examples/sample.pdf +``` + +## Provider Architecture + +The Skills Provider uses a two-layer architecture to handle both single skills and skill directories. + +### SkillProvider + +`SkillProvider` handles a single skill directory. It loads the main file, parses any frontmatter, scans for supporting files, and creates the appropriate resources. + +```python +from pathlib import Path + +from fastmcp import FastMCP +from fastmcp.server.providers.skills import SkillProvider + +mcp = FastMCP("Single Skill") +mcp.add_provider(SkillProvider(Path.home() / ".claude" / "skills" / "pdf-processing")) +``` + +Use `SkillProvider` when you want to expose exactly one skill, or when you need fine-grained control over individual skill configuration. + +### SkillsDirectoryProvider + +`SkillsDirectoryProvider` scans one or more root directories and creates a `SkillProvider` for each valid skill folder it finds. A folder is considered a valid skill if it contains the main file (default: `SKILL.md`). + +```python +from pathlib import Path + +from fastmcp import FastMCP +from fastmcp.server.providers.skills import SkillsDirectoryProvider + +mcp = FastMCP("Skills") +mcp.add_provider(SkillsDirectoryProvider(roots=Path.home() / ".claude" / "skills")) +``` + +When scanning multiple root directories, provide them as a list. The first directory takes precedence if the same skill name appears in multiple roots. + +```python +from pathlib import Path + +from fastmcp import FastMCP +from fastmcp.server.providers.skills import SkillsDirectoryProvider + +mcp = FastMCP("Skills") +mcp.add_provider(SkillsDirectoryProvider(roots=[ + Path.cwd() / ".claude" / "skills", # Project-level skills first + Path.home() / ".claude" / "skills", # User-level fallback +])) +``` + +## Vendor Providers + +FastMCP includes pre-configured providers for popular AI coding tools. Each vendor provider extends `SkillsDirectoryProvider` with the appropriate default directory for that platform. + +| Provider | Default Directory | +|----------|-------------------| +| `ClaudeSkillsProvider` | `~/.claude/skills/` | +| `CursorSkillsProvider` | `~/.cursor/skills/` | +| `VSCodeSkillsProvider` | `~/.copilot/skills/` | +| `CodexSkillsProvider` | `/etc/codex/skills/` and `~/.codex/skills/` | +| `GeminiSkillsProvider` | `~/.gemini/skills/` | +| `GooseSkillsProvider` | `~/.config/agents/skills/` | +| `CopilotSkillsProvider` | `~/.copilot/skills/` | +| `OpenCodeSkillsProvider` | `~/.config/opencode/skills/` | + +Vendor providers accept the same configuration options as `SkillsDirectoryProvider` (except for `roots`, which is locked to the platform default). + +```python +from fastmcp import FastMCP +from fastmcp.server.providers.skills import ClaudeSkillsProvider + +mcp = FastMCP("Claude Skills") +mcp.add_provider(ClaudeSkillsProvider()) # Uses ~/.claude/skills/ +``` + +`CodexSkillsProvider` scans both system-level (`/etc/codex/skills/`) and user-level (`~/.codex/skills/`) directories, with system skills taking precedence. + +## Supporting Files Disclosure + +The `supporting_files` parameter controls how supporting files (everything except the main file and manifest) appear to clients. + +### Template Mode (Default) + +With `supporting_files="template"`, supporting files are accessed through a `ResourceTemplate` rather than being listed as individual resources. Clients see only the main file and manifest in `list_resources()`, then discover supporting files by reading the manifest. + +```python +from pathlib import Path + +from fastmcp.server.providers.skills import SkillsDirectoryProvider + +# Default behavior - supporting files hidden from list_resources() +provider = SkillsDirectoryProvider( + roots=Path.home() / ".claude" / "skills", + supporting_files="template", # This is the default +) +``` + +This keeps the resource list compact when skills contain many files. Clients that need supporting files read the manifest first, then request specific files by URI. + +### Resources Mode + +With `supporting_files="resources"`, every file in every skill appears as an individual resource in `list_resources()`. Clients get full enumeration upfront without needing to read manifests. + +```python +from pathlib import Path + +from fastmcp.server.providers.skills import SkillsDirectoryProvider + +# All files visible as individual resources +provider = SkillsDirectoryProvider( + roots=Path.home() / ".claude" / "skills", + supporting_files="resources", +) +``` + +Use this mode when clients need to discover all available files without additional round trips, or when integrating with tools that expect flat resource lists. + +## Reload Mode + +Enable reload mode to re-scan the skills directory on every request. Changes to skills take effect immediately without restarting the server. + +```python +from pathlib import Path + +from fastmcp.server.providers.skills import SkillsDirectoryProvider + +provider = SkillsDirectoryProvider( + roots=Path.home() / ".claude" / "skills", + reload=True, +) +``` + +With `reload=True`, the provider re-discovers skills on each `list_resources()` or `read_resource()` call. New skills appear, removed skills disappear, and modified content reflects current file state. + + +Reload mode adds overhead to every request. Use it during development when you're actively editing skills, but disable it in production. + + +## Client Utilities + +FastMCP provides utilities for downloading skills from any MCP server that exposes them. These are standalone functions in `fastmcp.utilities.skills`. + +### Discovering Skills + +Use `list_skills()` to see what skills are available on a server. + +```python +from fastmcp import Client +from fastmcp.utilities.skills import list_skills + +async with Client("http://skills-server/mcp") as client: + skills = await list_skills(client) + for skill in skills: + print(f"{skill.name}: {skill.description}") +``` + +### Downloading Skills + +Use `download_skill()` to download a single skill, or `sync_skills()` to download all available skills. + +```python +from pathlib import Path + +from fastmcp import Client +from fastmcp.utilities.skills import download_skill, sync_skills + +async with Client("http://skills-server/mcp") as client: + # Download one skill + path = await download_skill(client, "pdf-processing", Path.home() / ".claude" / "skills") + + # Or download all skills + paths = await sync_skills(client, Path.home() / ".claude" / "skills") +``` + +Both functions accept an `overwrite` parameter. When `False` (default), existing skills are skipped. When `True`, existing files are replaced. + +### Inspecting Manifests + +Use `get_skill_manifest()` to see what files a skill contains before downloading. + +```python +from fastmcp import Client +from fastmcp.utilities.skills import get_skill_manifest + +async with Client("http://skills-server/mcp") as client: + manifest = await get_skill_manifest(client, "pdf-processing") + for file in manifest.files: + print(f"{file.path} ({file.size} bytes, {file.hash})") +``` diff --git a/docs/servers/resources.mdx b/docs/servers/resources.mdx new file mode 100644 index 000000000..0a8a772aa --- /dev/null +++ b/docs/servers/resources.mdx @@ -0,0 +1,719 @@ +--- +title: Resources & Templates +sidebarTitle: Resources +description: Expose data sources and dynamic content generators to your MCP client. +icon: folder-open +--- + +import { VersionBadge } from "/snippets/version-badge.mdx" + +Resources represent data or files that an MCP client can read, and resource templates extend this concept by allowing clients to request dynamically generated resources based on parameters passed in the URI. + +FastMCP simplifies defining both static and dynamic resources, primarily using the `@mcp.resource` decorator. + +## What Are Resources? + +Resources provide read-only access to data for the LLM or client application. When a client requests a resource URI: + +1. FastMCP finds the corresponding resource definition. +2. If it's dynamic (defined by a function), the function is executed. +3. The content (text, JSON, binary data) is returned to the client. + +This allows LLMs to access files, database content, configuration, or dynamically generated information relevant to the conversation. + +## Resources + +### The `@resource` Decorator + +The most common way to define a resource is by decorating a Python function. The decorator requires the resource's unique URI. + +```python +import json +from fastmcp import FastMCP + +mcp = FastMCP(name="DataServer") + +# Basic dynamic resource returning a string +@mcp.resource("resource://greeting") +def get_greeting() -> str: + """Provides a simple greeting message.""" + return "Hello from FastMCP Resources!" + +# Resource returning JSON data +@mcp.resource("data://config") +def get_config() -> str: + """Provides application configuration as JSON.""" + return json.dumps({ + "theme": "dark", + "version": "1.2.0", + "features": ["tools", "resources"], + }) +``` + +**Key Concepts:** + +* **URI:** The first argument to `@resource` is the unique URI (e.g., `"resource://greeting"`) clients use to request this data. +* **Lazy Loading:** The decorated function (`get_greeting`, `get_config`) is only executed when a client specifically requests that resource URI via `resources/read`. +* **Inferred Metadata:** By default: + * Resource Name: Taken from the function name (`get_greeting`). + * Resource Description: Taken from the function's docstring. + +#### Decorator Arguments + +You can customize the resource's properties using arguments in the `@mcp.resource` decorator: + +```python +from fastmcp import FastMCP + +mcp = FastMCP(name="DataServer") + +# Example specifying metadata +@mcp.resource( + uri="data://app-status", # Explicit URI (required) + name="ApplicationStatus", # Custom name + description="Provides the current status of the application.", # Custom description + mime_type="application/json", # Explicit MIME type + tags={"monitoring", "status"}, # Categorization tags + meta={"version": "2.1", "team": "infrastructure"} # Custom metadata +) +def get_application_status() -> str: + """Internal function description (ignored if description is provided above).""" + return json.dumps({"status": "ok", "uptime": 12345, "version": mcp.settings.version}) +``` + + + + The unique identifier for the resource + + + + A human-readable name. If not provided, defaults to function name + + + + Explanation of the resource. If not provided, defaults to docstring + + + + Specifies the content type. FastMCP often infers a default like `text/plain` or `application/json`, but explicit is better for non-text types + + + + A set of strings used to categorize the resource. These can be used by the server and, in some cases, by clients to filter or group available resources. + + + + Deprecated in v3.0.0. Use `mcp.enable()` / `mcp.disable()` at the server level instead. + A boolean to enable or disable the resource. See [Component Visibility](#component-visibility) for the recommended approach. + + + + + + Optional list of icon representations for this resource or template. See [Icons](/servers/icons) for detailed examples + + + + An optional `Annotations` object or dictionary to add additional metadata about the resource. + + + If true, the resource is read-only and does not modify its environment. + + + If true, reading the resource repeatedly will have no additional effect on its environment. + + + + + + + + Optional meta information about the resource. This data is passed through to the MCP client as the `meta` field of the client-side resource object and can be used for custom metadata, versioning, or other application-specific purposes. + + + + + + Optional version identifier for this resource. See [Versioning](/servers/versioning) for details. + + + +#### Using with Methods + +For decorating instance or class methods, use the standalone `@resource` decorator and register the bound method. See [Tools: Using with Methods](/servers/tools#using-with-methods) for the pattern. + +### Return Values + +Resource functions must return one of three types: + +- **`str`**: Sent as `TextResourceContents` (with `mime_type="text/plain"` by default). +- **`bytes`**: Base64 encoded and sent as `BlobResourceContents`. You should specify an appropriate `mime_type` (e.g., `"image/png"`, `"application/octet-stream"`). +- **`ResourceResult`**: Full control over contents, MIME types, and metadata. See [ResourceResult](#resourceresult) below. + + +To return structured data like dicts or lists, serialize them to JSON strings using `json.dumps()`. This explicit approach ensures your type checker catches errors during development rather than at runtime when a client reads the resource. + + +#### ResourceResult + + + +`ResourceResult` gives you explicit control over resource responses: multiple content items, per-item MIME types, and metadata at both the item and result level. + +```python +from fastmcp import FastMCP +from fastmcp.resources import ResourceResult, ResourceContent + +mcp = FastMCP() + +@mcp.resource("data://users") +def get_users() -> ResourceResult: + return ResourceResult( + contents=[ + ResourceContent(content='[{"id": 1}]', mime_type="application/json"), + ResourceContent(content="# Users\n...", mime_type="text/markdown"), + ], + meta={"total": 1} + ) +``` + +`ResourceContent` accepts three fields: + +**`content`** - The actual resource content. Can be `str` (text content) or `bytes` (binary content). This is the data that will be returned to the client. + +**`mime_type`** - Optional MIME type for the content. Defaults to `"text/plain"` for string content and `"application/octet-stream"` for binary content. + +**`meta`** - Optional metadata dictionary that will be included in the MCP response's `meta` field. Use this for runtime metadata like Content Security Policy headers, caching hints, or other client-specific data. + +For simple cases, you can pass `str` or `bytes` directly to `ResourceResult`: + +```python +return ResourceResult("plain text") # auto-converts to ResourceContent +return ResourceResult(b"\x00\x01\x02") # binary content +``` + + + + Content to return. Strings and bytes are wrapped in a single `ResourceContent`. Use a list of `ResourceContent` for multiple items or custom MIME types. + + + Result-level metadata, included in the MCP response's `_meta` field. + + + + + + The content data. Strings and bytes pass through directly. Other types (dict, list, BaseModel) are automatically JSON-serialized. + + + MIME type. Defaults to `text/plain` for strings, `application/octet-stream` for bytes, `application/json` for serialized objects. + + + Item-level metadata for this specific content. + + + +### Component Visibility + + + +You can control which resources are enabled for clients using server-level enabled control. Disabled resources don't appear in `list_resources` and can't be read. + +```python +from fastmcp import FastMCP + +mcp = FastMCP("MyServer") + +@mcp.resource("data://public", tags={"public"}) +def get_public(): return "public" + +@mcp.resource("data://secret", tags={"internal"}) +def get_secret(): return "secret" + +# Disable specific resources by key +mcp.disable(keys={"resource:data://secret"}) + +# Disable resources by tag +mcp.disable(tags={"internal"}) + +# Or use allowlist mode - only enable resources with specific tags +mcp.enable(tags={"public"}, only=True) +``` + +See [Visibility](/servers/visibility) for the complete visibility control API including key formats, tag-based filtering, and provider-level control. + + +### Accessing MCP Context + + + +Resources and resource templates can access additional MCP information and features through the `Context` object. To access it, add a parameter to your resource function with a type annotation of `Context`: + +```python {6, 14} +from fastmcp import FastMCP, Context + +mcp = FastMCP(name="DataServer") + +@mcp.resource("resource://system-status") +async def get_system_status(ctx: Context) -> str: + """Provides system status information.""" + return json.dumps({ + "status": "operational", + "request_id": ctx.request_id + }) + +@mcp.resource("resource://{name}/details") +async def get_details(name: str, ctx: Context) -> str: + """Get details for a specific name.""" + return json.dumps({ + "name": name, + "accessed_at": ctx.request_id + }) +``` + +For full documentation on the Context object and all its capabilities, see the [Context documentation](/servers/context). + + +### Async Resources + +FastMCP supports both `async def` and regular `def` resource functions. Synchronous functions automatically run in a threadpool to avoid blocking the event loop. + +For I/O-bound operations, async functions are more efficient: + +```python +import aiofiles +from fastmcp import FastMCP + +mcp = FastMCP(name="DataServer") + +@mcp.resource("file:///app/data/important_log.txt", mime_type="text/plain") +async def read_important_log() -> str: + """Reads content from a specific log file asynchronously.""" + try: + async with aiofiles.open("/app/data/important_log.txt", mode="r") as f: + content = await f.read() + return content + except FileNotFoundError: + return "Log file not found." +``` + + +### Resource Classes + +While `@mcp.resource` is ideal for dynamic content, you can directly register pre-defined resources (like static files or simple text) using `mcp.add_resource()` and concrete `Resource` subclasses. + +```python +from pathlib import Path +from fastmcp import FastMCP +from fastmcp.resources import FileResource, TextResource, DirectoryResource + +mcp = FastMCP(name="DataServer") + +# 1. Exposing a static file directly +readme_path = Path("./README.md").resolve() +if readme_path.exists(): + # Use a file:// URI scheme + readme_resource = FileResource( + uri=f"file://{readme_path.as_posix()}", + path=readme_path, # Path to the actual file + name="README File", + description="The project's README.", + mime_type="text/markdown", + tags={"documentation"} + ) + mcp.add_resource(readme_resource) + +# 2. Exposing simple, predefined text +notice_resource = TextResource( + uri="resource://notice", + name="Important Notice", + text="System maintenance scheduled for Sunday.", + tags={"notification"} +) +mcp.add_resource(notice_resource) + +# 3. Exposing a directory listing +data_dir_path = Path("./app_data").resolve() +if data_dir_path.is_dir(): + data_listing_resource = DirectoryResource( + uri="resource://data-files", + path=data_dir_path, # Path to the directory + name="Data Directory Listing", + description="Lists files available in the data directory.", + recursive=False # Set to True to list subdirectories + ) + mcp.add_resource(data_listing_resource) # Returns JSON list of files +``` + +**Common Resource Classes:** + +- `TextResource`: For simple string content. +- `BinaryResource`: For raw `bytes` content. +- `FileResource`: Reads content from a local file path. Handles text/binary modes and lazy reading. +- `HttpResource`: Fetches content from an HTTP(S) URL (requires `httpx`). +- `DirectoryResource`: Lists files in a local directory (returns JSON). +- (`FunctionResource`: Internal class used by `@mcp.resource`). + +Use these when the content is static or sourced directly from a file/URL, bypassing the need for a dedicated Python function. + +### Notifications + + + +FastMCP automatically sends `notifications/resources/list_changed` notifications to connected clients when resources or templates are added, enabled, or disabled. This allows clients to stay up-to-date with the current resource set without manually polling for changes. + +```python +@mcp.resource("data://example") +def example_resource() -> str: + return "Hello!" + +# These operations trigger notifications: +mcp.add_resource(example_resource) # Sends resources/list_changed notification +mcp.disable(keys={"resource:data://example"}) # Sends resources/list_changed notification +mcp.enable(keys={"resource:data://example"}) # Sends resources/list_changed notification +``` + +Notifications are only sent when these operations occur within an active MCP request context (e.g., when called from within a tool or other MCP operation). Operations performed during server initialization do not trigger notifications. + +Clients can handle these notifications using a [message handler](/clients/notifications) to automatically refresh their resource lists or update their interfaces. + +### Annotations + + + +FastMCP allows you to add specialized metadata to your resources through annotations. These annotations communicate how resources behave to client applications without consuming token context in LLM prompts. + +Annotations serve several purposes in client applications: +- Indicating whether resources are read-only or may have side effects +- Describing the safety profile of resources (idempotent vs. non-idempotent) +- Helping clients optimize caching and access patterns + +You can add annotations to a resource using the `annotations` parameter in the `@mcp.resource` decorator: + +```python +@mcp.resource( + "data://config", + annotations={ + "readOnlyHint": True, + "idempotentHint": True + } +) +def get_config() -> str: + """Get application configuration.""" + return json.dumps({"version": "1.0", "debug": False}) +``` + +FastMCP supports these standard annotations: + +| Annotation | Type | Default | Purpose | +| :--------- | :--- | :------ | :------ | +| `readOnlyHint` | boolean | true | Indicates if the resource only provides data without side effects | +| `idempotentHint` | boolean | true | Indicates if repeated reads have the same effect as a single read | + +Remember that annotations help make better user experiences but should be treated as advisory hints. They help client applications present appropriate UI elements and optimize access patterns, but won't enforce behavior on their own. Always focus on making your annotations accurately represent what your resource actually does. + +## Resource Templates + +Resource Templates allow clients to request resources whose content depends on parameters embedded in the URI. Define a template using the **same `@mcp.resource` decorator**, but include `{parameter_name}` placeholders in the URI string and add corresponding arguments to your function signature. + +Resource templates share most configuration options with regular resources (name, description, mime_type, tags, annotations), but add the ability to define URI parameters that map to function parameters. + +Resource templates generate a new resource for each unique set of parameters, which means that resources can be dynamically created on-demand. For example, if the resource template `"user://profile/{name}"` is registered, MCP clients could request `"user://profile/ford"` or `"user://profile/marvin"` to retrieve either of those two user profiles as resources, without having to register each resource individually. + + +Functions with `*args` are not supported as resource templates. However, unlike tools and prompts, resource templates do support `**kwargs` because the URI template defines specific parameter names that will be collected and passed as keyword arguments. + + +Here is a complete example that shows how to define two resource templates: + +```python +import json +from fastmcp import FastMCP + +mcp = FastMCP(name="DataServer") + +# Template URI includes {city} placeholder +@mcp.resource("weather://{city}/current") +def get_weather(city: str) -> str: + """Provides weather information for a specific city.""" + return json.dumps({ + "city": city.capitalize(), + "temperature": 22, + "condition": "Sunny", + "unit": "celsius" + }) + +# Template with multiple parameters and annotations +@mcp.resource( + "repos://{owner}/{repo}/info", + annotations={ + "readOnlyHint": True, + "idempotentHint": True + } +) +def get_repo_info(owner: str, repo: str) -> str: + """Retrieves information about a GitHub repository.""" + return json.dumps({ + "owner": owner, + "name": repo, + "full_name": f"{owner}/{repo}", + "stars": 120, + "forks": 48 + }) +``` + +With these two templates defined, clients can request a variety of resources: +- `weather://london/current` → Returns weather for London +- `weather://paris/current` → Returns weather for Paris +- `repos://PrefectHQ/fastmcp/info` → Returns info about the PrefectHQ/fastmcp repository +- `repos://prefecthq/prefect/info` → Returns info about the prefecthq/prefect repository + +### RFC 6570 URI Templates + + +FastMCP implements [RFC 6570 URI Templates](https://datatracker.ietf.org/doc/html/rfc6570) for resource templates, providing a standardized way to define parameterized URIs. This includes support for simple expansion, wildcard path parameters, and form-style query parameters. + +#### Wildcard Parameters + + + +Resource templates support wildcard parameters that can match multiple path segments. While standard parameters (`{param}`) only match a single path segment and don't cross "/" boundaries, wildcard parameters (`{param*}`) can capture multiple segments including slashes. Wildcards capture all subsequent path segments *up until* the defined part of the URI template (whether literal or another parameter). This allows you to have multiple wildcard parameters in a single URI template. + +```python {15, 23} +from fastmcp import FastMCP + +mcp = FastMCP(name="DataServer") + + +# Standard parameter only matches one segment +@mcp.resource("files://{filename}") +def get_file(filename: str) -> str: + """Retrieves a file by name.""" + # Will only match files:// + return f"File content for: {filename}" + + +# Wildcard parameter can match multiple segments +@mcp.resource("path://{filepath*}") +def get_path_content(filepath: str) -> str: + """Retrieves content at a specific path.""" + # Can match path://docs/server/resources.mdx + return f"Content at path: {filepath}" + + +# Mixing standard and wildcard parameters +@mcp.resource("repo://{owner}/{path*}/template.py") +def get_template_file(owner: str, path: str) -> dict: + """Retrieves a file from a specific repository and path, but + only if the resource ends with `template.py`""" + # Can match repo://PrefectHQ/fastmcp/src/resources/template.py + return { + "owner": owner, + "path": path + "/template.py", + "content": f"File at {path}/template.py in {owner}'s repository" + } +``` + +Wildcard parameters are useful when: + +- Working with file paths or hierarchical data +- Creating APIs that need to capture variable-length path segments +- Building URL-like patterns similar to REST APIs + +Note that like regular parameters, each wildcard parameter must still be a named parameter in your function signature, and all required function parameters must appear in the URI template. + +#### Query Parameters + + + +FastMCP supports RFC 6570 form-style query parameters using the `{?param1,param2}` syntax. Query parameters provide a clean way to pass optional configuration to resources without cluttering the path. + +Query parameters must be optional function parameters (have default values), while path parameters map to required function parameters. This enforces a clear separation: required data goes in the path, optional configuration in query params. + +```python +from fastmcp import FastMCP + +mcp = FastMCP(name="DataServer") + +# Basic query parameters +@mcp.resource("data://{id}{?format}") +def get_data(id: str, format: str = "json") -> str: + """Retrieve data in specified format.""" + if format == "xml": + return f"" + return f'{{"id": "{id}"}}' + +# Multiple query parameters with type coercion +@mcp.resource("api://{endpoint}{?version,limit,offset}") +def call_api(endpoint: str, version: int = 1, limit: int = 10, offset: int = 0) -> dict: + """Call API endpoint with pagination.""" + return { + "endpoint": endpoint, + "version": version, + "limit": limit, + "offset": offset, + "results": fetch_results(endpoint, version, limit, offset) + } + +# Query parameters with wildcards +@mcp.resource("files://{path*}{?encoding,lines}") +def read_file(path: str, encoding: str = "utf-8", lines: int = 100) -> str: + """Read file with optional encoding and line limit.""" + return read_file_content(path, encoding, lines) +``` + +**Example requests:** +- `data://123` → Uses default format `"json"` +- `data://123?format=xml` → Uses format `"xml"` +- `api://users?version=2&limit=50` → `version=2, limit=50, offset=0` +- `files://src/main.py?encoding=ascii&lines=50` → Custom encoding and line limit + +FastMCP automatically coerces query parameter string values to the correct types based on your function's type hints (`int`, `float`, `bool`, `str`). + +**Query parameters vs. hidden defaults:** + +Query parameters expose optional configuration to clients. To hide optional parameters from clients entirely (always use defaults), simply omit them from the URI template: + +```python +# Clients CAN override max_results via query string +@mcp.resource("search://{query}{?max_results}") +def search_configurable(query: str, max_results: int = 10) -> dict: + return {"query": query, "limit": max_results} + +# Clients CANNOT override max_results (not in URI template) +@mcp.resource("search://{query}") +def search_fixed(query: str, max_results: int = 10) -> dict: + return {"query": query, "limit": max_results} +``` + +### Template Parameter Rules + + + +FastMCP enforces these validation rules when creating resource templates: + +1. **Required function parameters** (no default values) must appear in the URI path template +2. **Query parameters** (specified with `{?param}` syntax) must be optional function parameters with default values +3. **All URI template parameters** (path and query) must exist as function parameters + +Optional function parameters (those with default values) can be: +- Included as query parameters (`{?param}`) - clients can override via query string +- Omitted from URI template - always uses default value, not exposed to clients +- Used in alternative path templates - enables multiple ways to access the same resource + +**Multiple templates for one function:** + +Create multiple resource templates that expose the same function through different URI patterns by manually applying decorators: + +```python +from fastmcp import FastMCP + +mcp = FastMCP(name="DataServer") + +# Define a user lookup function that can be accessed by different identifiers +def lookup_user(name: str | None = None, email: str | None = None) -> dict: + """Look up a user by either name or email.""" + if email: + return find_user_by_email(email) # pseudocode + elif name: + return find_user_by_name(name) # pseudocode + else: + return {"error": "No lookup parameters provided"} + +# Manually apply multiple decorators to the same function +mcp.resource("users://email/{email}")(lookup_user) +mcp.resource("users://name/{name}")(lookup_user) +``` + +Now an LLM or client can retrieve user information in two different ways: +- `users://email/alice@example.com` → Looks up user by email (with name=None) +- `users://name/Bob` → Looks up user by name (with email=None) + +This approach allows a single function to be registered with multiple URI patterns while keeping the implementation clean and straightforward. + +Templates provide a powerful way to expose parameterized data access points following REST-like principles. + +## Error Handling + + + +If your resource function encounters an error, you can raise a standard Python exception (`ValueError`, `TypeError`, `FileNotFoundError`, custom exceptions, etc.) or a FastMCP `ResourceError`. + +By default, all exceptions (including their details) are logged and converted into an MCP error response to be sent back to the client LLM. This helps the LLM understand failures and react appropriately. + +If you want to mask internal error details for security reasons, you can: + +1. Use the `mask_error_details=True` parameter when creating your `FastMCP` instance: +```python +mcp = FastMCP(name="SecureServer", mask_error_details=True) +``` + +2. Or use `ResourceError` to explicitly control what error information is sent to clients: +```python +from fastmcp import FastMCP +from fastmcp.exceptions import ResourceError + +mcp = FastMCP(name="DataServer") + +@mcp.resource("resource://safe-error") +def fail_with_details() -> str: + """This resource provides detailed error information.""" + # ResourceError contents are always sent back to clients, + # regardless of mask_error_details setting + raise ResourceError("Unable to retrieve data: file not found") + +@mcp.resource("resource://masked-error") +def fail_with_masked_details() -> str: + """This resource masks internal error details when mask_error_details=True.""" + # This message would be masked if mask_error_details=True + raise ValueError("Sensitive internal file path: /etc/secrets.conf") + +@mcp.resource("data://{id}") +def get_data_by_id(id: str) -> dict: + """Template resources also support the same error handling pattern.""" + if id == "secure": + raise ValueError("Cannot access secure data") + elif id == "missing": + raise ResourceError("Data ID 'missing' not found in database") + return {"id": id, "value": "data"} +``` + +When `mask_error_details=True`, only error messages from `ResourceError` will include details, other exceptions will be converted to a generic message. + +## Server Behavior + +### Duplicate Resources + + + +You can configure how the FastMCP server handles attempts to register multiple resources or templates with the same URI. Use the `on_duplicate_resources` setting during `FastMCP` initialization. + +```python +from fastmcp import FastMCP + +mcp = FastMCP( + name="ResourceServer", + on_duplicate_resources="error" # Raise error on duplicates +) + +@mcp.resource("data://config") +def get_config_v1(): return {"version": 1} + +# This registration attempt will raise a ValueError because +# "data://config" is already registered and the behavior is "error". +# @mcp.resource("data://config") +# def get_config_v2(): return {"version": 2} +``` + +The duplicate behavior options are: + +- `"warn"` (default): Logs a warning, and the new resource/template replaces the old one. +- `"error"`: Raises a `ValueError`, preventing the duplicate registration. +- `"replace"`: Silently replaces the existing resource/template with the new one. +- `"ignore"`: Keeps the original resource/template and ignores the new registration attempt. + +## Versioning + + + +Resources and resource templates support versioning, allowing you to maintain multiple implementations under the same URI while clients automatically receive the highest version. See [Versioning](/servers/versioning) for complete documentation on version comparison, retrieval, and migration patterns. \ No newline at end of file diff --git a/docs/servers/sampling.mdx b/docs/servers/sampling.mdx new file mode 100644 index 000000000..8ea479eb0 --- /dev/null +++ b/docs/servers/sampling.mdx @@ -0,0 +1,573 @@ +--- +title: Sampling +sidebarTitle: Sampling +description: Request LLM text generation from the client or a configured provider through the MCP context. +icon: robot +--- + +import { VersionBadge } from "/snippets/version-badge.mdx" + + + +LLM sampling allows your MCP tools to request text generation from an LLM during execution. This enables tools to leverage AI capabilities for analysis, generation, reasoning, and more—without the client needing to orchestrate multiple calls. + +By default, sampling requests are routed to the client's LLM. You can also configure a fallback handler to use a specific provider (like OpenAI) when the client doesn't support sampling, or to always use your own LLM regardless of client capabilities. + +## Overview + +The simplest use of sampling is passing a prompt string to `ctx.sample()`. The method sends the prompt to the LLM, waits for the complete response, and returns a `SamplingResult`. You can access the generated text through the `.text` attribute. + +```python +from fastmcp import FastMCP, Context + +mcp = FastMCP() + +@mcp.tool +async def summarize(content: str, ctx: Context) -> str: + """Generate a summary of the provided content.""" + result = await ctx.sample(f"Please summarize this:\n\n{content}") + return result.text or "" +``` + +The `SamplingResult` also provides `.result` (identical to `.text` for plain text responses) and `.history` containing the full message exchange—useful if you need to continue the conversation or debug the interaction. + +### System Prompts + +System prompts let you establish the LLM's role and behavioral guidelines before it processes your request. This is useful for controlling tone, enforcing constraints, or providing context that shouldn't clutter the user-facing prompt. + +````python +from fastmcp import FastMCP, Context + +mcp = FastMCP() + +@mcp.tool +async def generate_code(concept: str, ctx: Context) -> str: + """Generate a Python code example for a concept.""" + result = await ctx.sample( + messages=f"Write a Python example demonstrating '{concept}'.", + system_prompt=( + "You are an expert Python programmer. " + "Provide concise, working code without explanations." + ), + temperature=0.7, + max_tokens=300 + ) + return f"```python\n{result.text}\n```" +```` + +The `temperature` parameter controls randomness—higher values (up to 1.0) produce more varied outputs, while lower values make responses more deterministic. The `max_tokens` parameter limits response length. + +### Model Preferences + +Model preferences let you hint at which LLM the client should use for a request. You can pass a single model name or a list of preferences in priority order. These are hints rather than requirements—the actual model used depends on what the client has available. + +```python +from fastmcp import FastMCP, Context + +mcp = FastMCP() + +@mcp.tool +async def technical_analysis(data: str, ctx: Context) -> str: + """Analyze data using a reasoning-focused model.""" + result = await ctx.sample( + messages=f"Analyze this data:\n\n{data}", + model_preferences=["claude-opus-4-5", "gpt-5-2"], + temperature=0.2, + ) + return result.text or "" +``` + +Use model preferences when different tasks benefit from different model characteristics. Creative writing might prefer faster models with higher temperature, while complex analysis might benefit from larger reasoning-focused models. + +### Multi-Turn Conversations + +For requests that need conversational context, construct a list of `SamplingMessage` objects representing the conversation history. Each message has a `role` ("user" or "assistant") and `content` (a `TextContent` object). + +```python +from mcp.types import SamplingMessage, TextContent +from fastmcp import FastMCP, Context + +mcp = FastMCP() + +@mcp.tool +async def contextual_analysis(query: str, data: str, ctx: Context) -> str: + """Analyze data with conversational context.""" + messages = [ + SamplingMessage( + role="user", + content=TextContent(type="text", text=f"Here's my data: {data}"), + ), + SamplingMessage( + role="assistant", + content=TextContent(type="text", text="I see the data. What would you like to know?"), + ), + SamplingMessage( + role="user", + content=TextContent(type="text", text=query), + ), + ] + result = await ctx.sample(messages=messages) + return result.text or "" +``` + +The LLM receives the full conversation thread and responds with awareness of the preceding context. + +### Fallback Handlers + +Client support for sampling is optional—some clients may not implement it. To ensure your tools work regardless of client capabilities, configure a `sampling_handler` that sends requests directly to an LLM provider. + +FastMCP provides built-in handlers for [OpenAI and Anthropic APIs](/clients/sampling#built-in-handlers). These handlers support the full sampling API including tools, automatically converting your Python functions to each provider's format. + + +Install handlers with `pip install fastmcp[openai]` or `pip install fastmcp[anthropic]`. + + +```python +from fastmcp import FastMCP +from fastmcp.client.sampling.handlers.openai import OpenAISamplingHandler + +server = FastMCP( + name="My Server", + sampling_handler=OpenAISamplingHandler(default_model="gpt-4o-mini"), + sampling_handler_behavior="fallback", +) +``` + +The `sampling_handler_behavior` parameter controls when the handler is used: + +- **`"fallback"`** (default): Use the handler only when the client doesn't support sampling. This lets capable clients use their own LLM while ensuring your tools still work with clients that lack sampling support. +- **`"always"`**: Always use the handler, bypassing the client entirely. Use this when you need guaranteed control over which LLM processes requests—for cost control, compliance requirements, or when specific model characteristics are essential. + +## Structured Output + + + +When you need validated, typed data instead of free-form text, use the `result_type` parameter. FastMCP ensures the LLM returns data matching your type, handling validation and retries automatically. + +The `result_type` parameter accepts Pydantic models, dataclasses, and basic types like `int`, `list[str]`, or `dict[str, int]`. When you specify a result type, FastMCP automatically creates a `final_response` tool that the LLM calls to provide its response. If validation fails, the error is sent back to the LLM for retry. + +```python +from pydantic import BaseModel +from fastmcp import FastMCP, Context + +mcp = FastMCP() + +class SentimentResult(BaseModel): + sentiment: str + confidence: float + reasoning: str + +@mcp.tool +async def analyze_sentiment(text: str, ctx: Context) -> SentimentResult: + """Analyze text sentiment with structured output.""" + result = await ctx.sample( + messages=f"Analyze the sentiment of: {text}", + result_type=SentimentResult, + ) + return result.result # A validated SentimentResult object +``` + +When you call this tool, the LLM returns a structured response that FastMCP validates against your Pydantic model. You access the validated object through `result.result`, while `result.text` contains the JSON representation. + +### Structured Output with Tools + +Combine structured output with tools for agentic workflows that return validated data. The LLM uses your tools to gather information, then returns a response matching your type. + +```python +from pydantic import BaseModel +from fastmcp import FastMCP, Context + +mcp = FastMCP() + +def search(query: str) -> str: + """Search the web for information.""" + return f"Results for: {query}" + +def fetch_url(url: str) -> str: + """Fetch content from a URL.""" + return f"Content from: {url}" + +class ResearchResult(BaseModel): + summary: str + sources: list[str] + confidence: float + +@mcp.tool +async def research(topic: str, ctx: Context) -> ResearchResult: + """Research a topic and return structured findings.""" + result = await ctx.sample( + messages=f"Research: {topic}", + tools=[search, fetch_url], + result_type=ResearchResult, + ) + return result.result +``` + + +Structured output with automatic validation only applies to `sample()`. With `sample_step()`, you must manage structured output yourself. + + +## Tool Use + + + +Sampling with tools enables agentic workflows where the LLM can call functions to gather information before responding. This implements [SEP-1577](https://github.com/modelcontextprotocol/modelcontextprotocol/issues/1577), allowing the LLM to autonomously orchestrate multi-step operations. + +Pass Python functions to the `tools` parameter, and FastMCP handles the execution loop automatically—calling tools, returning results to the LLM, and continuing until the LLM provides a final response. + +### Defining Tools + +Define regular Python functions with type hints and docstrings. FastMCP extracts the function's name, docstring, and parameter types to create tool schemas that the LLM can understand. + +```python +from fastmcp import FastMCP, Context + +def search(query: str) -> str: + """Search the web for information.""" + return f"Results for: {query}" + +def get_time() -> str: + """Get the current time.""" + from datetime import datetime + return datetime.now().strftime("%H:%M:%S") + +mcp = FastMCP() + +@mcp.tool +async def research(question: str, ctx: Context) -> str: + """Answer questions using available tools.""" + result = await ctx.sample( + messages=question, + tools=[search, get_time], + ) + return result.text or "" +``` + +The LLM sees each function's signature and docstring, using this information to decide when and how to call them. Tool errors are caught and sent back to the LLM, allowing it to recover gracefully. An internal safety limit prevents infinite loops. + +### Custom Tool Definitions + +For custom names or descriptions, use `SamplingTool.from_function()`: + +```python +from fastmcp.server.sampling import SamplingTool + +tool = SamplingTool.from_function( + my_func, + name="custom_name", + description="Custom description" +) + +result = await ctx.sample(messages="...", tools=[tool]) +``` + +### Error Handling + +By default, when a sampling tool raises an exception, the error message (including details) is sent back to the LLM so it can attempt recovery. To prevent sensitive information from leaking to the LLM, use the `mask_error_details` parameter: + +```python +result = await ctx.sample( + messages=question, + tools=[search], + mask_error_details=True, # Generic error messages only +) +``` + +When `mask_error_details=True`, tool errors become generic messages like `"Error executing tool 'search'"` instead of exposing stack traces or internal details. + +To intentionally provide specific error messages to the LLM regardless of masking, raise `ToolError`: + +```python +from fastmcp.exceptions import ToolError + +def search(query: str) -> str: + """Search for information.""" + if not query.strip(): + raise ToolError("Search query cannot be empty") + return f"Results for: {query}" +``` + +`ToolError` messages always pass through to the LLM, making it the escape hatch for errors you want the LLM to see and handle. + +### Concurrent Tool Execution + +By default, tools execute sequentially — one at a time, in order. When your tools are independent (no shared state between them), you can execute them in parallel with `tool_concurrency`: + +```python +result = await ctx.sample( + messages="Research these three topics", + tools=[search, fetch_url], + tool_concurrency=0, # Unlimited parallel execution +) +``` + +The `tool_concurrency` parameter controls how many tools run at once: + +- **`None`** (default): Sequential execution +- **`0`**: Unlimited parallel execution +- **`N > 0`**: Execute at most N tools concurrently + +For tools that must not run concurrently (file writes, shared state mutations, etc.), mark them as `sequential` when creating the `SamplingTool`: + +```python +from fastmcp.server.sampling import SamplingTool + +db_writer = SamplingTool.from_function( + write_to_db, + sequential=True, # Forces all tools in the batch to run sequentially +) + +result = await ctx.sample( + messages="Process this data", + tools=[search, db_writer], + tool_concurrency=0, # Would be parallel, but db_writer forces sequential +) +``` + + +When any tool in a batch has `sequential=True`, the entire batch executes sequentially regardless of `tool_concurrency`. This is a conservative guarantee — if one tool needs ordering, all tools in that batch respect it. + + +### Client Requirements + + +Sampling with tools requires the client to advertise the `sampling.tools` capability. FastMCP clients do this automatically. For external clients that don't support tool-enabled sampling, configure a fallback handler with `sampling_handler_behavior="always"`. + + +## Advanced Control + + + +While `sample()` handles the tool execution loop automatically, some scenarios require fine-grained control over each step. The `sample_step()` method makes a single LLM call and returns a `SampleStep` containing the response and updated history. + +Unlike `sample()`, `sample_step()` is stateless—it doesn't remember previous calls. You control the conversation by passing the full message history each time. The returned `step.history` includes all messages up through the current response, making it easy to continue the loop. + +Use `sample_step()` when you need to: + +- Inspect tool calls before they execute +- Implement custom termination conditions +- Add logging, metrics, or checkpointing between steps +- Build custom agentic loops with domain-specific logic + +### Basic Loop + +By default, `sample_step()` executes any tool calls and includes the results in the history. Call it in a loop, passing the updated history each time, until a stop condition is met. + +```python +from mcp.types import SamplingMessage +from fastmcp import FastMCP, Context + +mcp = FastMCP() + +def search(query: str) -> str: + return f"Results for: {query}" + +def get_time() -> str: + return "12:00 PM" + +@mcp.tool +async def controlled_agent(question: str, ctx: Context) -> str: + """Agent with manual loop control.""" + messages: list[str | SamplingMessage] = [question] + + while True: + step = await ctx.sample_step( + messages=messages, + tools=[search, get_time], + ) + + if step.is_tool_use: + # Tools already executed (execute_tools=True by default) + for call in step.tool_calls: + print(f"Called tool: {call.name}") + + if not step.is_tool_use: + return step.text or "" + + messages = step.history +``` + +### SampleStep Properties + +Each `SampleStep` provides information about what the LLM returned: + +| Property | Description | +|----------|-------------| +| `step.is_tool_use` | True if the LLM requested tool calls | +| `step.tool_calls` | List of tool calls requested (if any) | +| `step.text` | The text content (if any) | +| `step.history` | All messages exchanged so far | + +The contents of `step.history` depend on `execute_tools`: +- **`execute_tools=True`** (default): Includes tool results, ready for the next iteration +- **`execute_tools=False`**: Includes the assistant's tool request, but you add results yourself + +### Manual Tool Execution + +Set `execute_tools=False` to handle tool execution yourself. When disabled, `step.history` contains the user message and the assistant's response with tool calls—but no tool results. You execute the tools and append the results as a user message. + +```python +from mcp.types import SamplingMessage, ToolResultContent, TextContent +from fastmcp import FastMCP, Context + +mcp = FastMCP() + +@mcp.tool +async def research(question: str, ctx: Context) -> str: + """Research with manual tool handling.""" + + def search(query: str) -> str: + return f"Results for: {query}" + + def get_time() -> str: + return "12:00 PM" + + tools = {"search": search, "get_time": get_time} + messages: list[SamplingMessage] = [question] + + while True: + step = await ctx.sample_step( + messages=messages, + tools=list(tools.values()), + execute_tools=False, + ) + + if not step.is_tool_use: + return step.text or "" + + # Execute tools and collect results + tool_results = [] + for call in step.tool_calls: + fn = tools[call.name] + result = fn(**call.input) + tool_results.append( + ToolResultContent( + type="tool_result", + toolUseId=call.id, + content=[TextContent(type="text", text=result)], + ) + ) + + messages = list(step.history) + messages.append(SamplingMessage(role="user", content=tool_results)) +``` + +To report an error to the LLM, set `isError=True` on the tool result: + +```python +tool_result = ToolResultContent( + type="tool_result", + toolUseId=call.id, + content=[TextContent(type="text", text="Permission denied")], + isError=True, +) +``` + +## Method Reference + + + + Request text generation from the LLM, running to completion automatically. + + + + The prompt to send. Can be a simple string or a list of messages for multi-turn conversations. + + + + Instructions that establish the LLM's role and behavior. + + + + Controls randomness (0.0 = deterministic, 1.0 = creative). + + + + Maximum tokens to generate. + + + + Hints for which model the client should use. + + + + Functions the LLM can call during sampling. + + + + A type for validated structured output. Supports Pydantic models, dataclasses, and basic types like `int`, `list[str]`, or `dict[str, int]`. + + + + If True, mask detailed error messages from tool execution. When None (default), uses the global `settings.mask_error_details` value. Tools can raise `ToolError` to bypass masking and provide specific error messages to the LLM. + + + + Controls parallel execution of tools. `None` (default) for sequential, `0` for unlimited parallel, or a positive integer for bounded concurrency. If any tool has `sequential=True`, all tools execute sequentially regardless. + + + + + + + - `.text`: The raw text response (or JSON for structured output) + - `.result`: The typed result—same as `.text` for plain text, or a validated Pydantic object for structured output + - `.history`: All messages exchanged during sampling + + + + + + + + Make a single LLM sampling call. Use this for fine-grained control over the sampling loop. + + + + The prompt or conversation history. + + + + Instructions that establish the LLM's role and behavior. + + + + Controls randomness (0.0 = deterministic, 1.0 = creative). + + + + Maximum tokens to generate. + + + + Functions the LLM can call during sampling. + + + + Controls tool usage: `"auto"`, `"required"`, or `"none"`. + + + + If True, execute tool calls and append results to history. If False, return immediately with tool calls available for manual execution. + + + + If True, mask detailed error messages from tool execution. + + + + Controls parallel execution of tools. `None` (default) for sequential, `0` for unlimited parallel, or a positive integer for bounded concurrency. + + + + + + - `.response`: The raw LLM response + - `.history`: Messages including input, assistant response, and tool results + - `.is_tool_use`: True if the LLM requested tool execution + - `.tool_calls`: List of tool calls (if any) + - `.text`: The text content (if any) + + + + diff --git a/docs/servers/server.mdx b/docs/servers/server.mdx new file mode 100644 index 000000000..ed84b5e48 --- /dev/null +++ b/docs/servers/server.mdx @@ -0,0 +1,248 @@ +--- +title: The FastMCP Server +sidebarTitle: Overview +description: The core FastMCP server class for building MCP applications +icon: server +--- + +import { VersionBadge } from "/snippets/version-badge.mdx" + +The `FastMCP` class is the central piece of every FastMCP application. It acts as the container for your tools, resources, and prompts, managing communication with MCP clients and orchestrating the entire server lifecycle. + +## Creating a Server + +Instantiate a server by providing a name that identifies it in client applications and logs. You can also provide instructions that help clients understand the server's purpose. + +```python +from fastmcp import FastMCP + +mcp = FastMCP(name="MyAssistantServer") + +# Instructions help clients understand how to interact with the server +mcp_with_instructions = FastMCP( + name="HelpfulAssistant", + instructions=""" + This server provides data analysis tools. + Call get_average() to analyze numerical data. + """, +) +``` + +The `FastMCP` constructor accepts several configuration options. The most commonly used parameters control server identity, authentication, and component behavior. + + + + A human-readable name for your server + + + + Description of how to interact with this server. These instructions help clients understand the server's purpose and available functionality + + + + Version string for your server. If not provided, defaults to the FastMCP library version + + + + + + URL to a website with more information about your server. Displayed in client applications + + + + + + List of icon representations for your server. Icons help users visually identify your server in client applications. See [Icons](/servers/icons) for detailed examples + + + + Authentication provider for securing HTTP-based transports. See [Authentication](/servers/auth/authentication) for configuration options + + + + Server-level setup and teardown logic. See [Lifespans](/servers/lifespan) for composable lifespans + + + + A list of tools (or functions to convert to tools) to add to the server. In some cases, providing tools programmatically may be more convenient than using the `@mcp.tool` decorator + + + + + + Server-level [transforms](/servers/transforms/transforms) to apply to all components. Transforms modify how tools, resources, and prompts are presented to clients — for example, [search transforms](/servers/transforms/tool-search) replace large catalogs with on-demand discovery, and [CodeMode](/servers/transforms/code-mode) lets LLMs write scripts that chain tool calls in a sandbox + + + + How to handle duplicate component registrations + + + + + + Controls how tool input parameters are validated. When `False` (default), FastMCP uses Pydantic's flexible validation that coerces compatible inputs (e.g., `"10"` to `10` for int parameters). When `True`, uses the MCP SDK's JSON Schema validation to validate inputs against the exact schema before passing them to your function, rejecting any type mismatches. The default mode improves compatibility with LLM clients while maintaining type safety. See [Input Validation Modes](/servers/tools#input-validation-modes) for details + + + + + Maximum number of items per page for list operations (`tools/list`, `resources/list`, etc.). When `None` (default), all results are returned in a single response. When set, responses are paginated and include a `nextCursor` for fetching additional pages. See [Pagination](/servers/pagination) for details + + + + +## Components + +FastMCP servers expose three types of components to clients. Each type serves a distinct purpose in the MCP protocol. + +### Tools + +Tools are functions that clients can invoke to perform actions or access external systems. They're the primary way clients interact with your server's capabilities. + +```python +@mcp.tool +def multiply(a: float, b: float) -> float: + """Multiplies two numbers together.""" + return a * b +``` + +See [Tools](/servers/tools) for detailed documentation. + +### Resources + +Resources expose data that clients can read. Unlike tools, resources are passive data sources that clients pull from rather than invoke. + +```python +@mcp.resource("data://config") +def get_config() -> dict: + """Provides the application configuration.""" + return {"theme": "dark", "version": "1.0"} +``` + +See [Resources](/servers/resources) for detailed documentation. + +### Resource Templates + +Resource templates are parameterized resources. The client provides values for template parameters in the URI, and the server returns data specific to those parameters. + +```python +@mcp.resource("users://{user_id}/profile") +def get_user_profile(user_id: int) -> dict: + """Retrieves a user's profile by ID.""" + return {"id": user_id, "name": f"User {user_id}", "status": "active"} +``` + +See [Resource Templates](/servers/resources#resource-templates) for detailed documentation. + +### Prompts + +Prompts are reusable message templates that guide LLM interactions. They help establish consistent patterns for how clients should frame requests. + +```python +@mcp.prompt +def analyze_data(data_points: list[float]) -> str: + """Creates a prompt asking for analysis of numerical data.""" + formatted_data = ", ".join(str(point) for point in data_points) + return f"Please analyze these data points: {formatted_data}" +``` + +See [Prompts](/servers/prompts) for detailed documentation. + +## Tag-Based Filtering + + + +Tags let you categorize components and selectively expose them based on configurable include/exclude sets. This is useful for creating different views of your server for different environments or user types. + +Components can be tagged when defined using the `tags` parameter. A component can have multiple tags, and filtering operates on tag membership. + +```python +@mcp.tool(tags={"public", "utility"}) +def public_tool() -> str: + return "This tool is public" + +@mcp.tool(tags={"internal", "admin"}) +def admin_tool() -> str: + return "This tool is for admins only" +``` + +The filtering logic works as follows: +- **Enable with `only=True`**: Switches to allowlist mode — only components with at least one matching tag are exposed +- **Disable**: Components with any matching tag are hidden +- **Precedence**: Later calls override earlier ones, so call `disable` after `enable` to exclude from an allowlist + + +To ensure a component is never exposed, you can set `enabled=False` on the component itself. See the component-specific documentation for details. + + +Configure tag-based filtering after creating your server. + +```python +# Only expose components tagged with "public" +mcp = FastMCP() +mcp.enable(tags={"public"}, only=True) + +# Hide components tagged as "internal" or "deprecated" +mcp = FastMCP() +mcp.disable(tags={"internal", "deprecated"}) + +# Combine both: show admin tools but hide deprecated ones +mcp = FastMCP() +mcp.enable(tags={"admin"}, only=True).disable(tags={"deprecated"}) +``` + +This filtering applies to all component types (tools, resources, resource templates, and prompts) and affects both listing and access. + +## Running the Server + +FastMCP servers communicate with clients through transport mechanisms. Start your server by calling `mcp.run()`, typically within an `if __name__ == "__main__":` block. This pattern ensures compatibility with various MCP clients. + +```python +from fastmcp import FastMCP + +mcp = FastMCP(name="MyServer") + +@mcp.tool +def greet(name: str) -> str: + """Greet a user by name.""" + return f"Hello, {name}!" + +if __name__ == "__main__": + # Defaults to STDIO transport + mcp.run() + + # Or use HTTP transport + # mcp.run(transport="http", host="127.0.0.1", port=9000) +``` + +FastMCP supports several transports: +- **STDIO** (default): For local integrations and CLI tools +- **HTTP**: For web services using the Streamable HTTP protocol +- **SSE**: Legacy web transport (deprecated) + +The server can also be run using the FastMCP CLI. For detailed information on transports and configuration, see the [Running Your Server](/deployment/running-server) guide. + +## Custom Routes + +When running with HTTP transport, you can add custom web routes alongside your MCP endpoint using the `@custom_route` decorator. This is useful for auxiliary endpoints like health checks. + +```python +from fastmcp import FastMCP +from starlette.requests import Request +from starlette.responses import PlainTextResponse + +mcp = FastMCP("MyServer") + +@mcp.custom_route("/health", methods=["GET"]) +async def health_check(request: Request) -> PlainTextResponse: + return PlainTextResponse("OK") + +if __name__ == "__main__": + mcp.run(transport="http") # Health check at http://localhost:8000/health +``` + +Custom routes are served alongside your MCP endpoint and are useful for: +- Health check endpoints for monitoring +- Simple status or info endpoints +- Basic webhooks or callbacks + +For more complex web applications, consider [mounting your MCP server into a FastAPI or Starlette app](/deployment/http#integration-with-web-frameworks). diff --git a/docs/servers/storage-backends.mdx b/docs/servers/storage-backends.mdx new file mode 100644 index 000000000..1bdb19b20 --- /dev/null +++ b/docs/servers/storage-backends.mdx @@ -0,0 +1,294 @@ +--- +title: Storage Backends +sidebarTitle: Storage Backends +description: Configure persistent and distributed storage for caching and OAuth state management +icon: database +tag: NEW +--- + +import { VersionBadge } from "/snippets/version-badge.mdx" + + + +FastMCP uses pluggable storage backends for caching responses and managing OAuth state. By default, all storage is in-memory, which is perfect for development but doesn't persist across restarts. FastMCP includes support for multiple storage backends, and you can easily extend it with custom implementations. + + +The storage layer is powered by **[py-key-value-aio](https://github.com/strawgate/py-key-value)**, an async key-value library maintained by a core FastMCP maintainer. This library provides a unified interface for multiple backends, making it easy to swap implementations based on your deployment needs. + + +## Available Backends + +### In-Memory Storage + +**Best for:** Development, testing, single-process deployments + +In-memory storage is the default for all FastMCP storage needs. It's fast, requires no setup, and is perfect for getting started. + +```python +from key_value.aio.stores.memory import MemoryStore + +# Used by default - no configuration needed +# But you can also be explicit: +cache_store = MemoryStore() +``` + +**Characteristics:** +- ✅ No setup required +- ✅ Very fast +- ❌ Data lost on restart +- ❌ Not suitable for multi-process deployments + +### File Storage + +**Best for:** Single-server production deployments, persistent caching + +File storage persists data to the filesystem as one JSON file per key, allowing it to survive server restarts. This is the default backend for OAuth storage on Mac and Windows. + +```python +from pathlib import Path +from key_value.aio.stores.filetree import ( + FileTreeStore, + FileTreeV1KeySanitizationStrategy, + FileTreeV1CollectionSanitizationStrategy, +) +from fastmcp.server.middleware.caching import ResponseCachingMiddleware + +storage_dir = Path("/var/cache/fastmcp") +store = FileTreeStore( + data_directory=storage_dir, + key_sanitization_strategy=FileTreeV1KeySanitizationStrategy(storage_dir), + collection_sanitization_strategy=FileTreeV1CollectionSanitizationStrategy(storage_dir), +) + +# Persistent response cache +middleware = ResponseCachingMiddleware(cache_storage=store) +``` + +The sanitization strategies ensure keys and collection names are safe for the filesystem — alphanumeric names pass through as-is for readability, while special characters are hashed to prevent path traversal. + +**Characteristics:** +- ✅ Data persists across restarts +- ✅ No external dependencies +- ✅ Human-readable files on disk +- ❌ Not suitable for distributed deployments +- ❌ Filesystem access required + +### Redis + +**Best for:** Distributed production deployments, shared caching across multiple servers + + +Redis support requires an optional dependency: `pip install 'py-key-value-aio[redis]'` + + +Redis provides distributed caching and state management, ideal for production deployments with multiple server instances. + +```python +from key_value.aio.stores.redis import RedisStore +from fastmcp.server.middleware.caching import ResponseCachingMiddleware + +# Distributed response cache +middleware = ResponseCachingMiddleware( + cache_storage=RedisStore(host="redis.example.com", port=6379) +) +``` + +With authentication: + +```python +from key_value.aio.stores.redis import RedisStore + +cache_store = RedisStore( + host="redis.example.com", + port=6379, + password="your-redis-password" +) +``` + +For OAuth token storage: + +```python +import os +from fastmcp.server.auth.providers.github import GitHubProvider +from key_value.aio.stores.redis import RedisStore + +auth = GitHubProvider( + client_id=os.environ["GITHUB_CLIENT_ID"], + client_secret=os.environ["GITHUB_CLIENT_SECRET"], + base_url="https://your-server.com", + jwt_signing_key=os.environ["JWT_SIGNING_KEY"], + client_storage=RedisStore(host="redis.example.com", port=6379) +) +``` + +**Characteristics:** +- ✅ Distributed and highly available +- ✅ Fast in-memory performance +- ✅ Works across multiple server instances +- ✅ Built-in TTL support +- ❌ Requires Redis infrastructure +- ❌ Network latency vs local storage + +### Other Backends from py-key-value-aio + +The py-key-value-aio library includes additional implementations for various storage systems: + +- **DynamoDB** - AWS distributed database +- **MongoDB** - NoSQL document store +- **Elasticsearch** - Distributed search and analytics +- **Memcached** - Distributed memory caching +- **RocksDB** - Embedded high-performance key-value store +- **Valkey** - Redis-compatible server + +For configuration details on these backends, consult the [py-key-value-aio documentation](https://github.com/strawgate/py-key-value). + + +Before using these backends in production, review the [py-key-value documentation](https://github.com/strawgate/py-key-value) to understand the maturity level and limitations of your chosen backend. Some backends may be in preview or have specific constraints that make them unsuitable for production use. + + +## Use Cases in FastMCP + +### Server-Side OAuth Token Storage + +The [OAuth Proxy](/servers/auth/oauth-proxy) and OAuth auth providers use storage for persisting OAuth client registrations and upstream tokens. **By default, storage is automatically encrypted using `FernetEncryptionWrapper`.** When providing custom storage, wrap it in `FernetEncryptionWrapper` to encrypt sensitive OAuth tokens at rest. + +**Development (default behavior):** + +By default, FastMCP automatically manages keys and storage based on your platform: +- **Mac/Windows**: Keys are auto-managed via system keyring, storage defaults to disk. Suitable **only** for development and local testing. +- **Linux**: Keys are ephemeral, storage defaults to memory. + +No configuration needed: + +```python +from fastmcp.server.auth.providers.github import GitHubProvider + +auth = GitHubProvider( + client_id="your-id", + client_secret="your-secret", + base_url="https://your-server.com" +) +``` + +**Production:** + +For production deployments, configure explicit keys and persistent network-accessible storage with encryption: + +```python +import os +from fastmcp.server.auth.providers.github import GitHubProvider +from key_value.aio.stores.redis import RedisStore +from key_value.aio.wrappers.encryption import FernetEncryptionWrapper +from cryptography.fernet import Fernet + +auth = GitHubProvider( + client_id=os.environ["GITHUB_CLIENT_ID"], + client_secret=os.environ["GITHUB_CLIENT_SECRET"], + base_url="https://your-server.com", + # Explicit JWT signing key (required for production) + jwt_signing_key=os.environ["JWT_SIGNING_KEY"], + # Encrypted persistent storage (required for production) + client_storage=FernetEncryptionWrapper( + key_value=RedisStore(host="redis.example.com", port=6379), + fernet=Fernet(os.environ["STORAGE_ENCRYPTION_KEY"]) + ) +) +``` + +Both parameters are required for production. **Wrap your storage in `FernetEncryptionWrapper` to encrypt sensitive OAuth tokens at rest** - without it, tokens are stored in plaintext. See [OAuth Token Security](/deployment/http#oauth-token-security) and [Key and Storage Management](/servers/auth/oauth-proxy#key-and-storage-management) for complete setup details. + +### Response Caching Middleware + +The [Response Caching Middleware](/servers/middleware#caching-middleware) caches tool calls, resource reads, and prompt requests. Storage configuration is passed via the `cache_storage` parameter: + +```python +from pathlib import Path +from fastmcp import FastMCP +from fastmcp.server.middleware.caching import ResponseCachingMiddleware +from key_value.aio.stores.filetree import ( + FileTreeStore, + FileTreeV1KeySanitizationStrategy, + FileTreeV1CollectionSanitizationStrategy, +) + +mcp = FastMCP("My Server") + +cache_dir = Path("cache") +cache_store = FileTreeStore( + data_directory=cache_dir, + key_sanitization_strategy=FileTreeV1KeySanitizationStrategy(cache_dir), + collection_sanitization_strategy=FileTreeV1CollectionSanitizationStrategy(cache_dir), +) + +# Cache to disk instead of memory +mcp.add_middleware(ResponseCachingMiddleware(cache_storage=cache_store)) +``` + +For multi-server deployments sharing a Redis instance: + +```python +from fastmcp.server.middleware.caching import ResponseCachingMiddleware +from key_value.aio.stores.redis import RedisStore +from key_value.aio.wrappers.prefix_collections import PrefixCollectionsWrapper + +base_store = RedisStore(host="redis.example.com") +namespaced_store = PrefixCollectionsWrapper( + key_value=base_store, + prefix="my-server" +) + +middleware = ResponseCachingMiddleware(cache_storage=namespaced_store) +``` + +### Client-Side OAuth Token Storage + +The [FastMCP Client](/clients/client) uses storage for persisting OAuth tokens locally. By default, tokens are stored in memory: + +```python +from pathlib import Path +from fastmcp.client.auth import OAuthClientProvider +from key_value.aio.stores.filetree import ( + FileTreeStore, + FileTreeV1KeySanitizationStrategy, + FileTreeV1CollectionSanitizationStrategy, +) + +# Store tokens on disk for persistence across restarts +token_dir = Path("~/.local/share/fastmcp/tokens").expanduser() +token_storage = FileTreeStore( + data_directory=token_dir, + key_sanitization_strategy=FileTreeV1KeySanitizationStrategy(token_dir), + collection_sanitization_strategy=FileTreeV1CollectionSanitizationStrategy(token_dir), +) + +oauth_provider = OAuthClientProvider( + mcp_url="https://your-mcp-server.com/mcp/sse", + token_storage=token_storage +) +``` + +This allows clients to reconnect without re-authenticating after restarts. + +## Choosing a Backend + +| Backend | Development | Single Server | Multi-Server | Cloud Native | +|---------|-------------|---------------|--------------|--------------| +| Memory | ✅ Best | ⚠️ Limited | ❌ | ❌ | +| File | ✅ Good | ✅ Recommended | ❌ | ⚠️ | +| Redis | ⚠️ Overkill | ✅ Good | ✅ Best | ✅ Best | +| DynamoDB | ❌ | ⚠️ | ✅ | ✅ Best (AWS) | +| MongoDB | ❌ | ⚠️ | ✅ | ✅ Good | + +**Decision tree:** + +1. **Just starting?** Use **Memory** (default) - no configuration needed +2. **Single server, needs persistence?** Use **File** +3. **Multiple servers or cloud deployment?** Use **Redis** or **DynamoDB** +4. **Existing infrastructure?** Look for a matching py-key-value-aio backend + +## More Resources + +- [py-key-value-aio GitHub](https://github.com/strawgate/py-key-value) - Full library documentation +- [Response Caching Middleware](/servers/middleware#caching-middleware) - Using storage for caching +- [OAuth Token Security](/deployment/http#oauth-token-security) - Production OAuth configuration +- [HTTP Deployment](/deployment/http) - Complete deployment guide diff --git a/docs/servers/tasks.mdx b/docs/servers/tasks.mdx new file mode 100644 index 000000000..d4aae9f54 --- /dev/null +++ b/docs/servers/tasks.mdx @@ -0,0 +1,263 @@ +--- +title: Background Tasks +sidebarTitle: Background Tasks +description: Run long-running operations asynchronously with progress tracking +icon: clock +tag: "NEW" +--- + +import { VersionBadge } from "/snippets/version-badge.mdx" + + + + +Background tasks require the `tasks` optional extra. See [installation instructions](#enabling-background-tasks) below. + + +FastMCP implements the MCP background task protocol ([SEP-1686](https://modelcontextprotocol.io/specification/2025-11-25/basic/utilities/tasks)), giving your servers a production-ready distributed task scheduler with a single decorator change. + + +**What is Docket?** FastMCP's task system is powered by [Docket](https://github.com/chrisguidry/docket), originally built by [Prefect](https://prefect.io) to power [Prefect Cloud](https://www.prefect.io/prefect/cloud)'s managed task scheduling and execution service, where it processes millions of concurrent tasks every day. Docket is now open-sourced for the community. + + + +## What Are MCP Background Tasks? + +In MCP, all component interactions are blocking by default. When a client calls a tool, reads a resource, or fetches a prompt, it sends a request and waits for the response. For operations that take seconds or minutes, this creates a poor user experience. + +The MCP background task protocol solves this by letting clients: +1. **Start** an operation and receive a task ID immediately +2. **Track** progress as the operation runs +3. **Retrieve** the result when ready + +FastMCP handles all of this for you. Add `task=True` to your decorator, and your function gains full background execution with progress reporting, distributed processing, and horizontal scaling. + +### MCP Background Tasks vs Python Concurrency + +You can always use Python's concurrency primitives (asyncio, threads, multiprocessing) or external task queues in your FastMCP servers. FastMCP is just Python—run code however you like. + +MCP background tasks are different: they're **protocol-native**. This means MCP clients that support the task protocol can start operations, receive progress updates, and retrieve results through the standard MCP interface. The coordination happens at the protocol level, not inside your application code. + +## Enabling Background Tasks + + Background tasks require the `tasks` extra: + +```bash +pip install "fastmcp[tasks]" +``` + +Add `task=True` to any tool, resource, resource template, or prompt decorator. This marks the component as capable of background execution. + +```python {6} +import asyncio +from fastmcp import FastMCP + +mcp = FastMCP("MyServer") + +@mcp.tool(task=True) +async def slow_computation(duration: int) -> str: + """A long-running operation.""" + for i in range(duration): + await asyncio.sleep(1) + return f"Completed in {duration} seconds" +``` + +When a client requests background execution, the call returns immediately with a task ID. The work executes in a background worker, and the client can poll for status or wait for the result. + + +Background tasks require async functions. Attempting to use `task=True` with a sync function raises a `ValueError` at registration time. + + +## Execution Modes + +For fine-grained control over task execution behavior, use `TaskConfig` instead of the boolean shorthand. The MCP task protocol defines three execution modes: + +| Mode | Client calls without task | Client calls with task | +|------|--------------------------|------------------------| +| `"forbidden"` | Executes synchronously | Error: task not supported | +| `"optional"` | Executes synchronously | Executes as background task | +| `"required"` | Error: task required | Executes as background task | + +```python +from fastmcp import FastMCP +from fastmcp.server.tasks import TaskConfig + +mcp = FastMCP("MyServer") + +# Supports both sync and background execution (default when task=True) +@mcp.tool(task=TaskConfig(mode="optional")) +async def flexible_task() -> str: + return "Works either way" + +# Requires background execution - errors if client doesn't request task +@mcp.tool(task=TaskConfig(mode="required")) +async def must_be_background() -> str: + return "Only runs as a background task" + +# No task support (default when task=False or omitted) +@mcp.tool(task=TaskConfig(mode="forbidden")) +async def sync_only() -> str: + return "Never runs as background task" +``` + +The boolean shortcuts map to these modes: +- `task=True` → `TaskConfig(mode="optional")` +- `task=False` → `TaskConfig(mode="forbidden")` + +### Poll Interval + + + +When clients poll for task status, the server tells them how frequently to check back. By default, FastMCP suggests a 5-second interval, but you can customize this per component: + +```python +from datetime import timedelta +from fastmcp import FastMCP +from fastmcp.server.tasks import TaskConfig + +mcp = FastMCP("MyServer") + +# Poll every 2 seconds for a fast-completing task +@mcp.tool(task=TaskConfig(mode="optional", poll_interval=timedelta(seconds=2))) +async def quick_task() -> str: + return "Done quickly" + +# Poll every 30 seconds for a long-running task +@mcp.tool(task=TaskConfig(mode="optional", poll_interval=timedelta(seconds=30))) +async def slow_task() -> str: + return "Eventually done" +``` + +Shorter intervals give clients faster feedback but increase server load. Longer intervals reduce load but delay status updates. + +### Server-Wide Default + +To enable background task support for all components by default, pass `tasks=True` to the constructor. Individual decorators can still override this with `task=False`. + +```python +mcp = FastMCP("MyServer", tasks=True) +``` + + +If your server defines any synchronous tools, resources, or prompts, you will need to explicitly set `task=False` on their decorators to avoid an error. + + +### Graceful Degradation + +When a client requests background execution but the component has `mode="forbidden"`, FastMCP executes synchronously and returns the result inline. This follows the SEP-1686 specification for graceful degradation—clients can always request background execution without worrying about server capabilities. + +Conversely, when a component has `mode="required"` but the client doesn't request background execution, FastMCP returns an error indicating that task execution is required. + +### Configuration + +| Environment Variable | Default | Description | +|---------------------|---------|-------------| +| `FASTMCP_DOCKET_URL` | `memory://` | Backend URL (`memory://` or `redis://host:port/db`) | + +## Backends + +FastMCP supports two backends for task execution, each with different tradeoffs. + +### In-Memory Backend (Default) + +The in-memory backend (`memory://`) requires zero configuration and works out of the box. + +**Advantages:** +- No external dependencies +- Simple single-process deployment + +**Disadvantages:** +- **Ephemeral**: If the server restarts, all pending tasks are lost +- **Higher latency**: ~250ms task pickup time vs single-digit milliseconds with Redis +- **No horizontal scaling**: Single process only—you cannot add additional workers + +### Redis Backend + +For production deployments, use Redis (or Valkey) as your backend by setting `FASTMCP_DOCKET_URL=redis://localhost:6379`. + +**Advantages:** +- **Persistent**: Tasks survive server restarts +- **Fast**: Single-digit millisecond task pickup latency +- **Scalable**: Add workers to distribute load across processes or machines + +## Workers + +Every FastMCP server with task-enabled components automatically starts an **embedded worker**. You do not need to start a separate worker process for tasks to execute. + +To scale horizontally, add more workers using the CLI: + +```bash +fastmcp tasks worker server.py +``` + +Each additional worker pulls tasks from the same queue, distributing load across processes. Configure worker concurrency via environment: + +```bash +export FASTMCP_DOCKET_CONCURRENCY=20 +fastmcp tasks worker server.py +``` + + +Additional workers only work with Redis/Valkey backends. The in-memory backend is single-process only. + + + +Task-enabled components must be defined at server startup to be registered with all workers. Components added dynamically after the server starts will not be available for background execution. + + +## Progress Reporting + +The `Progress` dependency lets you report progress back to clients. Inject it as a parameter with a default value, and FastMCP will provide the active progress reporter. + +```python +from fastmcp import FastMCP +from fastmcp.dependencies import Progress + +mcp = FastMCP("MyServer") + +@mcp.tool(task=True) +async def process_files(files: list[str], progress: Progress = Progress()) -> str: + await progress.set_total(len(files)) + + for file in files: + await progress.set_message(f"Processing {file}") + # ... do work ... + await progress.increment() + + return f"Processed {len(files)} files" +``` + +The progress API: +- `await progress.set_total(n)` — Set the total number of steps +- `await progress.increment(amount=1)` — Increment progress +- `await progress.set_message(text)` — Update the status message + +Progress works in both immediate and background execution modes—you can use the same code regardless of how the client invokes your function. + +## Docket Dependencies + +FastMCP exposes Docket's full dependency injection system within your task-enabled functions. Beyond `Progress`, you can access the Docket instance, worker information, and use advanced features like retries and timeouts. + +```python +from docket import Docket, Worker +from fastmcp import FastMCP +from fastmcp.dependencies import Progress, CurrentDocket, CurrentWorker + +mcp = FastMCP("MyServer") + +@mcp.tool(task=True) +async def my_task( + progress: Progress = Progress(), + docket: Docket = CurrentDocket(), + worker: Worker = CurrentWorker(), +) -> str: + # Schedule additional background work + await docket.add(another_task, arg1, arg2) + + # Access worker metadata + worker_name = worker.name + + return "Done" +``` + +With `CurrentDocket()`, you can schedule additional background tasks, chain work together, and coordinate complex workflows. See the [Docket documentation](https://chrisguidry.github.io/docket/) for the complete API, including retry policies, timeouts, and custom dependencies. diff --git a/docs/servers/telemetry.mdx b/docs/servers/telemetry.mdx new file mode 100644 index 000000000..1055dc0c0 --- /dev/null +++ b/docs/servers/telemetry.mdx @@ -0,0 +1,280 @@ +--- +title: OpenTelemetry +sidebarTitle: Telemetry +description: Native OpenTelemetry instrumentation for distributed tracing. +icon: chart-line +tag: NEW +--- + +FastMCP includes native OpenTelemetry instrumentation for observability. Traces are automatically generated for tool, prompt, resource, and resource template operations, providing visibility into server behavior, request handling, and provider delegation chains. + +## How It Works + +FastMCP uses the OpenTelemetry API for instrumentation. This means: + +- **Zero configuration required** - Instrumentation is always active +- **No overhead when unused** - Without an SDK, all operations are no-ops +- **Bring your own SDK** - You control collection, export, and sampling +- **Works with any OTEL backend** - Jaeger, Zipkin, Datadog, New Relic, etc. + +## Enabling Telemetry + +The easiest way to export traces is using `opentelemetry-instrument`, which configures the SDK automatically: + +```bash +pip install opentelemetry-distro opentelemetry-exporter-otlp +opentelemetry-bootstrap -a install +``` + +Then run your server with tracing enabled: + +```bash +opentelemetry-instrument \ + --service_name my-fastmcp-server \ + --exporter_otlp_endpoint http://localhost:4317 \ + fastmcp run server.py +``` + +Or configure via environment variables: + +```bash +export OTEL_SERVICE_NAME=my-fastmcp-server +export OTEL_EXPORTER_OTLP_ENDPOINT=http://localhost:4317 + +opentelemetry-instrument fastmcp run server.py +``` + +This works with any OTLP-compatible backend (Jaeger, Zipkin, Grafana Tempo, Datadog, etc.) and requires no changes to your FastMCP code. + + + Learn more about the OpenTelemetry Python SDK, auto-instrumentation, and available exporters. + + +## Tracing + +FastMCP creates spans for all MCP operations, providing end-to-end visibility into request handling. + +### Server Spans + +The server creates spans for each operation using [MCP semantic conventions](https://opentelemetry.io/docs/specs/semconv/gen-ai/mcp/): + +| Span Name | Description | +|-----------|-------------| +| `tools/call {name}` | Tool execution (e.g., `tools/call get_weather`) | +| `resources/read {uri}` | Resource read (e.g., `resources/read config://database`) | +| `prompts/get {name}` | Prompt render (e.g., `prompts/get greeting`) | + +For mounted servers, an additional `delegate {name}` span shows the delegation to the child server. + +### Client Spans + +The FastMCP client creates spans for outgoing requests with the same naming pattern (`tools/call {name}`, `resources/read {uri}`, `prompts/get {name}`). + +### Span Hierarchy + +Spans form a hierarchy showing the request flow. For mounted servers: + +``` +tools/call weather_forecast (CLIENT) + └── tools/call weather_forecast (SERVER, provider=FastMCPProvider) + └── delegate get_weather (INTERNAL) + └── tools/call get_weather (SERVER, provider=LocalProvider) +``` + +For proxy providers connecting to remote servers: + +``` +tools/call remote_search (CLIENT) + └── tools/call remote_search (SERVER, provider=ProxyProvider) + └── [remote server spans via trace context propagation] +``` + +## Programmatic Configuration + +For more control, configure the SDK in your Python code before importing FastMCP: + +```python +from opentelemetry import trace +from opentelemetry.sdk.trace import TracerProvider +from opentelemetry.sdk.trace.export import BatchSpanProcessor +from opentelemetry.exporter.otlp.proto.grpc.trace_exporter import OTLPSpanExporter + +# Configure the SDK with OTLP exporter +provider = TracerProvider() +processor = BatchSpanProcessor(OTLPSpanExporter(endpoint="http://localhost:4317")) +provider.add_span_processor(processor) +trace.set_tracer_provider(provider) + +# Now import and use FastMCP - traces will be exported automatically +from fastmcp import FastMCP + +mcp = FastMCP("my-server") + +@mcp.tool() +def greet(name: str) -> str: + return f"Hello, {name}!" +``` + + +The SDK must be configured **before** importing FastMCP to ensure the tracer provider is set when FastMCP initializes. + + +### Local Development + +For quick local trace visualization, [otel-desktop-viewer](https://github.com/CtrlSpice/otel-desktop-viewer) is a lightweight single-binary tool: + +```bash +# macOS +brew install nico-barbas/brew/otel-desktop-viewer + +# Or download from GitHub releases +``` + +Run it alongside your server: + +```bash +# Terminal 1: Start the viewer (UI at http://localhost:8000, OTLP on :4317) +otel-desktop-viewer + +# Terminal 2: Run your server with tracing +opentelemetry-instrument fastmcp run server.py +``` + +For more features, use [Jaeger](https://www.jaegertracing.io/): + +```bash +docker run -d --name jaeger \ + -p 16686:16686 \ + -p 4317:4317 \ + jaegertracing/all-in-one:latest +``` + +Then view traces at http://localhost:16686 + +## Custom Spans + +You can add your own spans using the FastMCP tracer: + +```python +from fastmcp import FastMCP +from fastmcp.telemetry import get_tracer + +mcp = FastMCP("custom-spans") + +@mcp.tool() +async def complex_operation(input: str) -> str: + tracer = get_tracer() + + with tracer.start_as_current_span("parse_input") as span: + span.set_attribute("input.length", len(input)) + parsed = parse(input) + + with tracer.start_as_current_span("process_data") as span: + span.set_attribute("data.count", len(parsed)) + result = process(parsed) + + return result +``` + +## Error Handling + +When errors occur, spans are automatically marked with error status and the exception is recorded: + +```python +@mcp.tool() +def risky_operation() -> str: + raise ValueError("Something went wrong") + +# The span will have: +# - status = ERROR +# - exception event with stack trace +``` + +## Attributes Reference + +### RPC Semantic Conventions + +Standard [RPC semantic conventions](https://opentelemetry.io/docs/specs/semconv/rpc/rpc-spans/): + +| Attribute | Value | +|-----------|-------| +| `rpc.system` | `"mcp"` | +| `rpc.service` | Server name | +| `rpc.method` | MCP protocol method | + +### MCP Semantic Conventions + +FastMCP implements the [OpenTelemetry MCP semantic conventions](https://opentelemetry.io/docs/specs/semconv/gen-ai/mcp/): + +| Attribute | Description | +|-----------|-------------| +| `mcp.method.name` | The MCP method being called (`tools/call`, `resources/read`, `prompts/get`) | +| `mcp.session.id` | Session identifier for the MCP connection | +| `mcp.resource.uri` | The resource URI (for resource operations) | + +### Auth Attributes + +Standard [identity attributes](https://opentelemetry.io/docs/specs/semconv/attributes-registry/enduser/): + +| Attribute | Description | +|-----------|-------------| +| `enduser.id` | Client ID from access token (when authenticated) | +| `enduser.scope` | Space-separated OAuth scopes (when authenticated) | + +### FastMCP Custom Attributes + +All custom attributes use the `fastmcp.` prefix for features unique to FastMCP: + +| Attribute | Description | +|-----------|-------------| +| `fastmcp.server.name` | Server name | +| `fastmcp.component.type` | `tool`, `resource`, `prompt`, or `resource_template` | +| `fastmcp.component.key` | Full component identifier (e.g., `tool:greet`) | +| `fastmcp.provider.type` | Provider class (`LocalProvider`, `FastMCPProvider`, `ProxyProvider`) | + +Provider-specific attributes for delegation context: + +| Attribute | Description | +|-----------|-------------| +| `fastmcp.delegate.original_name` | Original tool/prompt name before namespacing | +| `fastmcp.delegate.original_uri` | Original resource URI before namespacing | +| `fastmcp.proxy.backend_name` | Remote server tool/prompt name | +| `fastmcp.proxy.backend_uri` | Remote server resource URI | + +## Testing with Telemetry + +For testing, use the in-memory exporter: + +```python +import pytest +from collections.abc import Generator +from opentelemetry import trace +from opentelemetry.sdk.trace import TracerProvider +from opentelemetry.sdk.trace.export import SimpleSpanProcessor +from opentelemetry.sdk.trace.export.in_memory_span_exporter import InMemorySpanExporter + +from fastmcp import FastMCP + +@pytest.fixture +def trace_exporter() -> Generator[InMemorySpanExporter, None, None]: + exporter = InMemorySpanExporter() + provider = TracerProvider() + provider.add_span_processor(SimpleSpanProcessor(exporter)) + original_provider = trace.get_tracer_provider() + trace.set_tracer_provider(provider) + yield exporter + exporter.clear() + trace.set_tracer_provider(original_provider) + +async def test_tool_creates_span(trace_exporter: InMemorySpanExporter) -> None: + mcp = FastMCP("test") + + @mcp.tool() + def hello() -> str: + return "world" + + await mcp.call_tool("hello", {}) + + spans = trace_exporter.get_finished_spans() + assert any(s.name == "tools/call hello" for s in spans) +``` diff --git a/docs/servers/testing.mdx b/docs/servers/testing.mdx new file mode 100644 index 000000000..7bd8600c5 --- /dev/null +++ b/docs/servers/testing.mdx @@ -0,0 +1,104 @@ +--- +title: Testing your FastMCP Server +sidebarTitle: Testing +description: How to test your FastMCP server. +icon: vial +--- + +The best way to ensure a reliable and maintainable FastMCP Server is to test it! The FastMCP Client combined with Pytest provides a simple and powerful way to test your FastMCP servers. + +## Prerequisites + +Testing FastMCP servers requires `pytest-asyncio` to handle async test functions and fixtures. Install it as a development dependency: + +```bash +pip install pytest-asyncio +``` + +We recommend configuring pytest to automatically handle async tests by setting the asyncio mode to `auto` in your `pyproject.toml`: + +```toml +[tool.pytest.ini_options] +asyncio_mode = "auto" +``` + +This eliminates the need to decorate every async test with `@pytest.mark.asyncio`. + +## Testing with Pytest Fixtures + +Using Pytest Fixtures, you can wrap your FastMCP Server in a Client instance that makes interacting with your server fast and easy. This is especially useful when building your own MCP Servers and enables a tight development loop by allowing you to avoid using a separate tool like MCP Inspector during development: + +```python +import pytest +from fastmcp.client import Client +from fastmcp.client.transports import FastMCPTransport + +from my_project.main import mcp + +@pytest.fixture +async def main_mcp_client(): + async with Client(transport=mcp) as mcp_client: + yield mcp_client + +async def test_list_tools(main_mcp_client: Client[FastMCPTransport]): + list_tools = await main_mcp_client.list_tools() + + assert len(list_tools) == 5 +``` + +We recommend the [inline-snapshot library](https://github.com/15r10nk/inline-snapshot) for asserting complex data structures coming from your MCP Server. This library allows you to write tests that are easy to read and understand, and are also easy to update when the data structure changes. + +```python +from inline_snapshot import snapshot + +async def test_list_tools(main_mcp_client: Client[FastMCPTransport]): + list_tools = await main_mcp_client.list_tools() + + assert list_tools == snapshot() +``` + +Simply run `pytest --inline-snapshot=fix,create` to fill in the `snapshot()` with actual data. + + +For values that change you can leverage the [dirty-equals](https://github.com/samuelcolvin/dirty-equals) library to perform flexible equality assertions on dynamic or non-deterministic values. + + +Using the pytest `parametrize` decorator, you can easily test your tools with a wide variety of inputs. + +```python +import pytest +from my_project.main import mcp + +from fastmcp.client import Client +from fastmcp.client.transports import FastMCPTransport +@pytest.fixture +async def main_mcp_client(): + async with Client(mcp) as client: + yield client + + +@pytest.mark.parametrize( + "first_number, second_number, expected", + [ + (1, 2, 3), + (2, 3, 5), + (3, 4, 7), + ], +) +async def test_add( + first_number: int, + second_number: int, + expected: int, + main_mcp_client: Client[FastMCPTransport], +): + result = await main_mcp_client.call_tool( + name="add", arguments={"x": first_number, "y": second_number} + ) + assert result.data is not None + assert isinstance(result.data, int) + assert result.data == expected +``` + + +The [FastMCP Repository contains thousands of tests](https://github.com/PrefectHQ/fastmcp/tree/main/tests) for the FastMCP Client and Server. Everything from connecting to remote MCP servers, to testing tools, resources, and prompts is covered, take a look for inspiration! + \ No newline at end of file diff --git a/docs/servers/tools.mdx b/docs/servers/tools.mdx new file mode 100644 index 000000000..91d96d1be --- /dev/null +++ b/docs/servers/tools.mdx @@ -0,0 +1,1088 @@ +--- +title: Tools +sidebarTitle: Tools +description: Expose functions as executable capabilities for your MCP client. +icon: wrench +--- + +import { VersionBadge } from '/snippets/version-badge.mdx' + +Tools are the core building blocks that allow your LLM to interact with external systems, execute code, and access data that isn't in its training data. In FastMCP, tools are Python functions exposed to LLMs through the MCP protocol. + +Tools in FastMCP transform regular Python functions into capabilities that LLMs can invoke during conversations. When an LLM decides to use a tool: + +1. It sends a request with parameters based on the tool's schema. +2. FastMCP validates these parameters against your function's signature. +3. Your function executes with the validated inputs. +4. The result is returned to the LLM, which can use it in its response. + +This allows LLMs to perform tasks like querying databases, calling APIs, making calculations, or accessing files—extending their capabilities beyond what's in their training data. + + +## The `@tool` Decorator + +Creating a tool is as simple as decorating a Python function with `@mcp.tool`: + +```python +from fastmcp import FastMCP + +mcp = FastMCP(name="CalculatorServer") + +@mcp.tool +def add(a: int, b: int) -> int: + """Adds two integer numbers together.""" + return a + b +``` + +When this tool is registered, FastMCP automatically: +- Uses the function name (`add`) as the tool name. +- Uses the function's docstring (`Adds two integer numbers...`) as the tool description. +- Generates an input schema based on the function's parameters and type annotations. +- Handles parameter validation and error reporting. + +The way you define your Python function dictates how the tool appears and behaves for the LLM client. + + +Functions with `*args` or `**kwargs` are not supported as tools. This restriction exists because FastMCP needs to generate a complete parameter schema for the MCP protocol, which isn't possible with variable argument lists. + + +### Decorator Arguments + +While FastMCP infers the name and description from your function, you can override these and add additional metadata using arguments to the `@mcp.tool` decorator: + +```python +@mcp.tool( + name="find_products", # Custom tool name for the LLM + description="Search the product catalog with optional category filtering.", # Custom description + tags={"catalog", "search"}, # Optional tags for organization/filtering + meta={"version": "1.2", "author": "product-team"} # Custom metadata +) +def search_products_implementation(query: str, category: str | None = None) -> list[dict]: + """Internal function description (ignored if description is provided above).""" + # Implementation... + print(f"Searching for '{query}' in category '{category}'") + return [{"id": 2, "name": "Another Product"}] +``` + + + + Sets the explicit tool name exposed via MCP. If not provided, uses the function name + + + + Provides the description exposed via MCP. If set, the function's docstring is ignored for this purpose + + + + A set of strings used to categorize the tool. These can be used by the server and, in some cases, by clients to filter or group available tools. + + + + Deprecated in v3.0.0. Use `mcp.enable()` / `mcp.disable()` at the server level instead. + A boolean to enable or disable the tool. See [Component Visibility](#component-visibility) for the recommended approach. + + + + + + Optional list of icon representations for this tool. See [Icons](/servers/icons) for detailed examples + + + + An optional `ToolAnnotations` object or dictionary to add additional metadata about the tool. + + + A human-readable title for the tool. + + + If true, the tool does not modify its environment. + + + If true, the tool may perform destructive updates to its environment. + + + If true, calling the tool repeatedly with the same arguments will have no additional effect on the its environment. + + + If true, this tool may interact with an "open world" of external entities. If false, the tool's domain of interaction is closed. + + + + + + + + Optional meta information about the tool. This data is passed through to the MCP client as the `meta` field of the client-side tool object and can be used for custom metadata, versioning, or other application-specific purposes. + + + + + + Execution timeout in seconds. If the tool takes longer than this to complete, an MCP error is returned to the client. See [Timeouts](#timeouts) for details. + + + + + + Optional version identifier for this tool. See [Versioning](/servers/versioning) for details. + + + + + + Optional JSON schema for the tool's output. When provided, the tool must return structured output matching this schema. If not provided, FastMCP automatically generates a schema from the function's return type annotation. See [Output Schemas](#output-schemas) for details. + + + +### Using with Methods + +The `@mcp.tool` decorator registers tools immediately, which doesn't work with instance or class methods (you'd see `self` or `cls` as required parameters). For methods, use the standalone `@tool` decorator to attach metadata, then register the bound method: + +```python +from fastmcp import FastMCP +from fastmcp.tools import tool + +class Calculator: + def __init__(self, multiplier: int): + self.multiplier = multiplier + + @tool() + def multiply(self, x: int) -> int: + """Multiply x by the instance multiplier.""" + return x * self.multiplier + +calc = Calculator(multiplier=3) +mcp = FastMCP() +mcp.add_tool(calc.multiply) # Registers with correct schema (only 'x', not 'self') +``` + +### Async Support + +FastMCP supports both asynchronous (`async def`) and synchronous (`def`) functions as tools. Synchronous tools automatically run in a threadpool to avoid blocking the event loop, so multiple tool calls can execute concurrently even if individual tools perform blocking operations. + +```python +from fastmcp import FastMCP +import time + +mcp = FastMCP() + +@mcp.tool +def slow_tool(x: int) -> int: + """This sync function won't block other concurrent requests.""" + time.sleep(2) # Runs in threadpool, not on the event loop + return x * 2 +``` + +For I/O-bound operations like network requests or database queries, async tools are still preferred since they're more efficient than threadpool dispatch. Use sync tools when working with synchronous libraries or for simple operations where the threading overhead doesn't matter. + +## Arguments + +By default, FastMCP converts Python functions into MCP tools by inspecting the function's signature and type annotations. This allows you to use standard Python type annotations for your tools. In general, the framework strives to "just work": idiomatic Python behaviors like parameter defaults and type annotations are automatically translated into MCP schemas. However, there are a number of ways to customize the behavior of your tools. + + +FastMCP automatically dereferences `$ref` entries in tool schemas to ensure compatibility with MCP clients that don't fully support JSON Schema references (e.g., VS Code Copilot, Claude Desktop). This means complex Pydantic models with shared types are inlined in the schema rather than using `$defs` references. + +Dereferencing happens at serve-time via middleware, so your schemas are stored with `$ref` intact and only inlined when sent to clients. If you know your clients handle `$ref` correctly and prefer smaller schemas, you can opt out: + +```python +mcp = FastMCP("my-server", dereference_schemas=False) +``` + + +### Type Annotations + +MCP tools have typed arguments, and FastMCP uses type annotations to determine those types. Therefore, you should use standard Python type annotations for tool arguments: + +```python +@mcp.tool +def analyze_text( + text: str, + max_tokens: int = 100, + language: str | None = None +) -> dict: + """Analyze the provided text.""" + # Implementation... +``` + +FastMCP supports a wide range of type annotations, including all Pydantic types: + +| Type Annotation | Example | Description | +| :---------------------- | :---------------------------- | :---------------------------------- | +| Basic types | `int`, `float`, `str`, `bool` | Simple scalar values | +| Binary data | `bytes` | Binary content (raw strings, not auto-decoded base64) | +| Date and Time | `datetime`, `date`, `timedelta` | Date and time objects (ISO format strings) | +| Collection types | `list[str]`, `dict[str, int]`, `set[int]` | Collections of items | +| Optional types | `float \| None`, `Optional[float]`| Parameters that may be null/omitted | +| Union types | `str \| int`, `Union[str, int]`| Parameters accepting multiple types | +| Constrained types | `Literal["A", "B"]`, `Enum` | Parameters with specific allowed values | +| Paths | `Path` | File system paths (auto-converted from strings) | +| UUIDs | `UUID` | Universally unique identifiers (auto-converted from strings) | +| Pydantic models | `UserData` | Complex structured data with validation | + +FastMCP supports all types that Pydantic supports as fields, including all Pydantic custom types. A few FastMCP-specific behaviors to note: + +**Binary Data**: `bytes` parameters accept raw strings without automatic base64 decoding. For base64 data, use `str` and decode manually with `base64.b64decode()`. + +**Enums**: Clients send enum values (`"red"`), not names (`"RED"`). Your function receives the Enum member (`Color.RED`). + +**Paths and UUIDs**: String inputs are automatically converted to `Path` and `UUID` objects. + +**Pydantic Models**: Must be provided as JSON objects (dicts), not stringified JSON. Even with flexible validation, `{"user": {"name": "Alice"}}` works, but `{"user": '{"name": "Alice"}'}` does not. + +### Optional Arguments + +FastMCP follows Python's standard function parameter conventions. Parameters without default values are required, while those with default values are optional. + +```python +@mcp.tool +def search_products( + query: str, # Required - no default value + max_results: int = 10, # Optional - has default value + sort_by: str = "relevance", # Optional - has default value + category: str | None = None # Optional - can be None +) -> list[dict]: + """Search the product catalog.""" + # Implementation... +``` + +In this example, the LLM must provide a `query` parameter, while `max_results`, `sort_by`, and `category` will use their default values if not explicitly provided. + +### Validation Modes + + + +By default, FastMCP uses Pydantic's flexible validation that coerces compatible inputs to match your type annotations. This improves compatibility with LLM clients that may send string representations of values (like `"10"` for an integer parameter). + +If you need stricter validation that rejects any type mismatches, you can enable strict input validation. Strict mode uses the MCP SDK's built-in JSON Schema validation to validate inputs against the exact schema before passing them to your function: + +```python +# Enable strict validation for this server +mcp = FastMCP("StrictServer", strict_input_validation=True) + +@mcp.tool +def add_numbers(a: int, b: int) -> int: + """Add two numbers.""" + return a + b + +# With strict_input_validation=True, sending {"a": "10", "b": "20"} will fail +# With strict_input_validation=False (default), it will be coerced to integers +``` + +**Validation Behavior Comparison:** + +| Input Type | strict_input_validation=False (default) | strict_input_validation=True | +| :--------- | :-------------------------------------- | :--------------------------- | +| String integers (`"10"` for `int`) | ✅ Coerced to integer | ❌ Validation error | +| String floats (`"3.14"` for `float`) | ✅ Coerced to float | ❌ Validation error | +| String booleans (`"true"` for `bool`) | ✅ Coerced to boolean | ❌ Validation error | +| Lists with string elements (`["1", "2"]` for `list[int]`) | ✅ Elements coerced | ❌ Validation error | +| Pydantic model fields with type mismatches | ✅ Fields coerced | ❌ Validation error | +| Invalid values (`"abc"` for `int`) | ❌ Validation error | ❌ Validation error | + + +**Note on Pydantic Models:** Even with `strict_input_validation=False`, Pydantic model parameters must be provided as JSON objects (dicts), not as stringified JSON. For example, `{"user": {"name": "Alice"}}` works, but `{"user": '{"name": "Alice"}'}` does not. + + +The default flexible validation mode is recommended for most use cases as it handles common LLM client behaviors gracefully while still providing strong type safety through Pydantic's validation. + +### Parameter Metadata + +You can provide additional metadata about parameters in several ways: + +#### Simple String Descriptions + + + +For basic parameter descriptions, you can use a convenient shorthand with `Annotated`: + +```python +from typing import Annotated + +@mcp.tool +def process_image( + image_url: Annotated[str, "URL of the image to process"], + resize: Annotated[bool, "Whether to resize the image"] = False, + width: Annotated[int, "Target width in pixels"] = 800, + format: Annotated[str, "Output image format"] = "jpeg" +) -> dict: + """Process an image with optional resizing.""" + # Implementation... +``` + +This shorthand syntax is equivalent to using `Field(description=...)` but more concise for simple descriptions. + + +This shorthand syntax is only applied to `Annotated` types with a single string description. + + +#### Advanced Metadata with Field + +For validation constraints and advanced metadata, use Pydantic's `Field` class with `Annotated`: + +```python +from typing import Annotated +from pydantic import Field + +@mcp.tool +def process_image( + image_url: Annotated[str, Field(description="URL of the image to process")], + resize: Annotated[bool, Field(description="Whether to resize the image")] = False, + width: Annotated[int, Field(description="Target width in pixels", ge=1, le=2000)] = 800, + format: Annotated[ + Literal["jpeg", "png", "webp"], + Field(description="Output image format") + ] = "jpeg" +) -> dict: + """Process an image with optional resizing.""" + # Implementation... +``` + + +You can also use the Field as a default value, though the Annotated approach is preferred: + +```python +@mcp.tool +def search_database( + query: str = Field(description="Search query string"), + limit: int = Field(10, description="Maximum number of results", ge=1, le=100) +) -> list: + """Search the database with the provided query.""" + # Implementation... +``` + +Field provides several validation and documentation features: +- `description`: Human-readable explanation of the parameter (shown to LLMs) +- `ge`/`gt`/`le`/`lt`: Greater/less than (or equal) constraints +- `min_length`/`max_length`: String or collection length constraints +- `pattern`: Regex pattern for string validation +- `default`: Default value if parameter is omitted + +### Hiding Parameters from the LLM + + + +To inject values at runtime without exposing them to the LLM (such as `user_id`, credentials, or database connections), use dependency injection with `Depends()`. Parameters using `Depends()` are automatically excluded from the tool schema: + +```python +from fastmcp import FastMCP +from fastmcp.dependencies import Depends + +mcp = FastMCP() + +def get_user_id() -> str: + return "user_123" # Injected at runtime + +@mcp.tool +def get_user_details(user_id: str = Depends(get_user_id)) -> str: + # user_id is injected by the server, not provided by the LLM + return f"Details for {user_id}" +``` + +See [Custom Dependencies](/servers/context#custom-dependencies) for more details on dependency injection. + +## Return Values + + +FastMCP tools can return data in two complementary formats: **traditional content blocks** (like text and images) and **structured outputs** (machine-readable JSON). When you add return type annotations, FastMCP automatically generates **output schemas** to validate the structured data and enables clients to deserialize results back to Python objects. + +Understanding how these three concepts work together: + +- **Return Values**: What your Python function returns (determines both content blocks and structured data) +- **Structured Outputs**: JSON data sent alongside traditional content for machine processing +- **Output Schemas**: JSON Schema declarations that describe and validate the structured output format + +The following sections explain each concept in detail. + +### Content Blocks + +FastMCP automatically converts tool return values into appropriate MCP content blocks: + +- **`str`**: Sent as `TextContent` +- **`bytes`**: Base64 encoded and sent as `BlobResourceContents` (within an `EmbeddedResource`) +- **`fastmcp.utilities.types.Image`**: Sent as `ImageContent` +- **`fastmcp.utilities.types.Audio`**: Sent as `AudioContent` +- **`fastmcp.utilities.types.File`**: Sent as base64-encoded `EmbeddedResource` +- **MCP SDK content blocks**: Sent as-is +- **A list of any of the above**: Converts each item according to the above rules +- **`None`**: Results in an empty response + +#### Media Helper Classes + +FastMCP provides helper classes for returning images, audio, and files. When you return one of these classes, either directly or as part of a list, FastMCP automatically converts it to the appropriate MCP content block. For example, if you return a `fastmcp.utilities.types.Image` object, FastMCP will convert it to an MCP `ImageContent` block with the correct MIME type and base64 encoding. + +```python +from fastmcp.utilities.types import Image, Audio, File + +@mcp.tool +def get_chart() -> Image: + """Generate a chart image.""" + return Image(path="chart.png") + +@mcp.tool +def get_multiple_charts() -> list[Image]: + """Return multiple charts.""" + return [Image(path="chart1.png"), Image(path="chart2.png")] +``` + + +Helper classes are only automatically converted to MCP content blocks when returned **directly** or as part of a **list**. For more complex containers like dicts, you can manually convert them to MCP types: + +```python +# ✅ Automatic conversion +return Image(path="chart.png") +return [Image(path="chart1.png"), "text content"] + +# ❌ Will not be automatically converted +return {"image": Image(path="chart.png")} + +# ✅ Manual conversion for nested use +return {"image": Image(path="chart.png").to_image_content()} +``` + + +Each helper class accepts either `path=` or `data=` (mutually exclusive): +- **`path`**: File path (string or Path object) - MIME type detected from extension +- **`data`**: Raw bytes - requires `format=` parameter for MIME type +- **`format`**: Optional format override (e.g., "png", "wav", "pdf") +- **`name`**: Optional name for `File` when using `data=` +- **`annotations`**: Optional MCP annotations for the content + +### Structured Output + + + +The 6/18/2025 MCP spec update [introduced](https://modelcontextprotocol.io/specification/2025-06-18/server/tools#structured-content) structured content, which is a new way to return data from tools. Structured content is a JSON object that is sent alongside traditional content. FastMCP automatically creates structured outputs alongside traditional content when your tool returns data that has a JSON object representation. This provides machine-readable JSON data that clients can deserialize back to Python objects. + +**Automatic Structured Content Rules:** +- **Object-like results** (`dict`, Pydantic models, dataclasses) → Always become structured content (even without output schema) +- **Non-object results** (`int`, `str`, `list`) → Only become structured content if there's an output schema to validate/serialize them +- **All results** → Always become traditional content blocks for backward compatibility + + +This automatic behavior enables clients to receive machine-readable data alongside human-readable content without requiring explicit output schemas for object-like returns. + + +#### Dictionaries and Objects + +When your tool returns a dictionary, dataclass, or Pydantic model, FastMCP automatically creates structured content from it. The structured content contains the actual object data, making it easy for clients to deserialize back to native objects. + + +```python Tool Definition +@mcp.tool +def get_user_data(user_id: str) -> dict: + """Get user data.""" + return {"name": "Alice", "age": 30, "active": True} +``` + +```json MCP Result +{ + "content": [ + { + "type": "text", + "text": "{\n \"name\": \"Alice\",\n \"age\": 30,\n \"active\": true\n}" + } + ], + "structuredContent": { + "name": "Alice", + "age": 30, + "active": true + } +} +``` + + +#### Primitives and Collections + +When your tool returns a primitive type (int, str, bool) or a collection (list, set), FastMCP needs a return type annotation to generate structured content. The annotation tells FastMCP how to validate and serialize the result. + +Without a type annotation, the tool only produces `content`: + + +```python Tool Definition +@mcp.tool +def calculate_sum(a: int, b: int): + """Calculate sum without return annotation.""" + return a + b # Returns 8 +``` + +```json MCP Result +{ + "content": [ + { + "type": "text", + "text": "8" + } + ] +} +``` + + +When you add a return annotation, such as `-> int`, FastMCP generates `structuredContent` by wrapping the primitive value in a `{"result": ...}` object, since JSON schemas require object-type roots for structured output: + + +```python Tool Definition +@mcp.tool +def calculate_sum(a: int, b: int) -> int: + """Calculate sum with return annotation.""" + return a + b # Returns 8 +``` + +```json MCP Result +{ + "content": [ + { + "type": "text", + "text": "8" + } + ], + "structuredContent": { + "result": 8 + } +} +``` + + +#### Typed Models + +Return type annotations work with any type that can be converted to a JSON schema. Dataclasses and Pydantic models are particularly useful because FastMCP extracts their field definitions to create detailed schemas. + + +```python Tool Definition +from dataclasses import dataclass +from fastmcp import FastMCP + +mcp = FastMCP() + +@dataclass +class Person: + name: str + age: int + email: str + +@mcp.tool +def get_user_profile(user_id: str) -> Person: + """Get a user's profile information.""" + return Person( + name="Alice", + age=30, + email="alice@example.com", + ) +``` + +```json Generated Output Schema +{ + "properties": { + "name": {"title": "Name", "type": "string"}, + "age": {"title": "Age", "type": "integer"}, + "email": {"title": "Email", "type": "string"} + }, + "required": ["name", "age", "email"], + "title": "Person", + "type": "object" +} +``` + +```json MCP Result +{ + "content": [ + { + "type": "text", + "text": "{\"name\": \"Alice\", \"age\": 30, \"email\": \"alice@example.com\"}" + } + ], + "structuredContent": { + "name": "Alice", + "age": 30, + "email": "alice@example.com" + } +} +``` + + +The `Person` dataclass becomes an output schema (second tab) that describes the expected format. When executed, clients receive the result (third tab) with both `content` and `structuredContent` fields. + +### Output Schemas + + + +The 6/18/2025 MCP spec update [introduced](https://modelcontextprotocol.io/specification/2025-06-18/server/tools#output-schema) output schemas, which are a new way to describe the expected output format of a tool. When an output schema is provided, the tool *must* return structured output that matches the schema. + +When you add return type annotations to your functions, FastMCP automatically generates JSON schemas that describe the expected output format. These schemas help MCP clients understand and validate the structured data they receive. + +#### Primitive Type Wrapping + +For primitive return types (like `int`, `str`, `bool`), FastMCP automatically wraps the result under a `"result"` key to create valid structured output: + + +```python Primitive Return Type +@mcp.tool +def calculate_sum(a: int, b: int) -> int: + """Add two numbers together.""" + return a + b +``` + +```json Generated Schema (Wrapped) +{ + "type": "object", + "properties": { + "result": {"type": "integer"} + }, + "x-fastmcp-wrap-result": true +} +``` + +```json Structured Output +{ + "result": 8 +} +``` + + +#### Manual Schema Control + +You can override the automatically generated schema by providing a custom `output_schema`: + +```python +@mcp.tool(output_schema={ + "type": "object", + "properties": { + "data": {"type": "string"}, + "metadata": {"type": "object"} + } +}) +def custom_schema_tool() -> dict: + """Tool with custom output schema.""" + return {"data": "Hello", "metadata": {"version": "1.0"}} +``` + +Schema generation works for most common types including basic types, collections, union types, Pydantic models, TypedDict structures, and dataclasses. + + +**Important Constraints**: +- Output schemas must be object types (`"type": "object"`) +- If you provide an output schema, your tool **must** return structured output that matches it +- However, you can provide structured output without an output schema (using `ToolResult`) + + +### ToolResult and Metadata + +For complete control over tool responses, return a `ToolResult` object. This gives you explicit control over all aspects of the tool's output: traditional content, structured data, and metadata. + +```python +from fastmcp.tools.tool import ToolResult +from mcp.types import TextContent + +@mcp.tool +def advanced_tool() -> ToolResult: + """Tool with full control over output.""" + return ToolResult( + content=[TextContent(type="text", text="Human-readable summary")], + structured_content={"data": "value", "count": 42}, + meta={"execution_time_ms": 145} + ) +``` + +`ToolResult` accepts three fields: + +**`content`** - The traditional MCP content blocks that clients display to users. Can be a string (automatically converted to `TextContent`), a list of MCP content blocks, or any serializable value (converted to JSON string). At least one of `content` or `structured_content` must be provided. + +```python +# Simple string +ToolResult(content="Hello, world!") + +# List of content blocks +ToolResult(content=[ + TextContent(type="text", text="Result: 42"), + ImageContent(type="image", data="base64...", mimeType="image/png") +]) +``` + +**`structured_content`** - A dictionary containing structured data that matches your tool's output schema. This enables clients to programmatically process the results. If you provide `structured_content`, it must be a dictionary or `None`. If only `structured_content` is provided, it will also be used as `content` (converted to JSON string). + +```python +ToolResult( + content="Found 3 users", + structured_content={"users": [{"name": "Alice"}, {"name": "Bob"}]} +) +``` + +**`meta`** + +Runtime metadata about the tool execution. Use this for performance metrics, debugging information, or any client-specific data that doesn't belong in the content or structured output. + +```python +ToolResult( + content="Analysis complete", + structured_content={"result": "positive"}, + meta={ + "execution_time_ms": 145, + "model_version": "2.1", + "confidence": 0.95 + } +) +``` + + +The `meta` field in `ToolResult` is for runtime metadata about tool execution (e.g., execution time, performance metrics). This is separate from the `meta` parameter in `@mcp.tool(meta={...})`, which provides static metadata about the tool definition itself. + + +When returning `ToolResult`, you have full control - FastMCP won't automatically wrap or transform your data. `ToolResult` can be returned with or without an output schema. + +### Custom Serialization + +When you need custom serialization (like YAML, Markdown tables, or specialized formats), return `ToolResult` with your serialized content. This makes the serialization explicit and visible in your tool's code: + +```python +import yaml +from fastmcp import FastMCP +from fastmcp.tools.tool import ToolResult + +mcp = FastMCP("MyServer") + +@mcp.tool +def get_config() -> ToolResult: + """Returns configuration as YAML.""" + data = {"api_key": "abc123", "debug": True, "rate_limit": 100} + return ToolResult( + content=yaml.dump(data, sort_keys=False), + structured_content=data + ) +``` + + +For reusable serialization across multiple tools, create a wrapper decorator that returns `ToolResult`. This lets you compose serializers with other behaviors (logging, validation, caching) and keeps the serialization visible at the tool definition. See [examples/custom_tool_serializer_decorator.py](https://github.com/PrefectHQ/fastmcp/blob/main/examples/custom_tool_serializer_decorator.py) for a complete implementation. + + +## Error Handling + + + +If your tool encounters an error, you can raise a standard Python exception (`ValueError`, `TypeError`, `FileNotFoundError`, custom exceptions, etc.) or a FastMCP `ToolError`. + +By default, all exceptions (including their details) are logged and converted into an MCP error response to be sent back to the client LLM. This helps the LLM understand failures and react appropriately. + +If you want to mask internal error details for security reasons, you can: + +1. Use the `mask_error_details=True` parameter when creating your `FastMCP` instance: +```python +mcp = FastMCP(name="SecureServer", mask_error_details=True) +``` + +2. Or use `ToolError` to explicitly control what error information is sent to clients: +```python +from fastmcp import FastMCP +from fastmcp.exceptions import ToolError + +@mcp.tool +def divide(a: float, b: float) -> float: + """Divide a by b.""" + + if b == 0: + # Error messages from ToolError are always sent to clients, + # regardless of mask_error_details setting + raise ToolError("Division by zero is not allowed.") + + # If mask_error_details=True, this message would be masked + if not isinstance(a, (int, float)) or not isinstance(b, (int, float)): + raise TypeError("Both arguments must be numbers.") + + return a / b +``` + +When `mask_error_details=True`, only error messages from `ToolError` will include details, other exceptions will be converted to a generic message. + +## Timeouts + + + +Tools can specify a `timeout` parameter to limit how long execution can take. When the timeout is exceeded, the client receives an MCP error and the tool stops processing. This protects your server from unexpectedly slow operations that could block resources or leave clients waiting indefinitely. + +```python +from fastmcp import FastMCP + +mcp = FastMCP() + +@mcp.tool(timeout=30.0) +async def fetch_data(url: str) -> dict: + """Fetch data with a 30-second timeout.""" + # If this takes longer than 30 seconds, + # the client receives an MCP error + ... +``` + +Timeouts are specified in seconds as a float. When a tool exceeds its timeout, FastMCP returns an MCP error with code `-32000` and a message indicating which tool timed out and how long it ran. Both sync and async tools support timeouts—sync functions run in thread pools, so the timeout applies to the entire operation regardless of execution model. + + +Tools must explicitly opt-in to timeouts. There is no server-level default timeout setting. + + +### Timeouts vs Background Tasks + +Timeouts apply to **foreground execution**—when a tool runs directly in response to a client request. They protect your server from tools that unexpectedly hang due to network issues, resource contention, or other transient problems. + + +The `timeout` parameter does **not** apply to background tasks. When a tool runs as a background task (`task=True`), execution happens in a Docket worker where the FastMCP timeout is not enforced. + +For task timeouts, use Docket's `Timeout` dependency directly in your function signature: + +```python +from datetime import timedelta +from docket import Timeout + +@mcp.tool(task=True) +async def long_running_task( + data: str, + timeout: Timeout = Timeout(timedelta(minutes=10)) +) -> str: + """Task with a 10-minute timeout enforced by Docket.""" + ... +``` + +See the [Docket documentation](https://chrisguidry.github.io/docket/dependencies/#task-timeouts) for more on task timeouts and retries. + + +When a tool times out, FastMCP logs a warning suggesting task mode. For operations you know will be long-running, use `task=True` instead—background tasks offload work to distributed workers and let clients poll for progress. + +## Component Visibility + + + +You can control which tools are enabled for clients using server-level enabled control. Disabled tools don't appear in `list_tools` and can't be called. + +```python +from fastmcp import FastMCP + +mcp = FastMCP("MyServer") + +@mcp.tool(tags={"admin"}) +def admin_action() -> str: + """Admin-only action.""" + return "Done" + +@mcp.tool(tags={"public"}) +def public_action() -> str: + """Public action.""" + return "Done" + +# Disable specific tools by key +mcp.disable(keys={"tool:admin_action"}) + +# Disable tools by tag +mcp.disable(tags={"admin"}) + +# Or use allowlist mode - only enable tools with specific tags +mcp.enable(tags={"public"}, only=True) +``` + +See [Visibility](/servers/visibility) for the complete visibility control API including key formats, tag-based filtering, and provider-level control. + +## MCP Annotations + + + +FastMCP allows you to add specialized metadata to your tools through annotations. These annotations communicate how tools behave to client applications without consuming token context in LLM prompts. + +Annotations serve several purposes in client applications: +- Adding user-friendly titles for display purposes +- Indicating whether tools modify data or systems +- Describing the safety profile of tools (destructive vs. non-destructive) +- Signaling if tools interact with external systems + +You can add annotations to a tool using the `annotations` parameter in the `@mcp.tool` decorator: + +```python +@mcp.tool( + annotations={ + "title": "Calculate Sum", + "readOnlyHint": True, + "openWorldHint": False + } +) +def calculate_sum(a: float, b: float) -> float: + """Add two numbers together.""" + return a + b +``` + +FastMCP supports these standard annotations: + +| Annotation | Type | Default | Purpose | +| :--------- | :--- | :------ | :------ | +| `title` | string | - | Display name for user interfaces | +| `readOnlyHint` | boolean | false | Indicates if the tool only reads without making changes | +| `destructiveHint` | boolean | true | For non-readonly tools, signals if changes are destructive | +| `idempotentHint` | boolean | false | Indicates if repeated identical calls have the same effect as a single call | +| `openWorldHint` | boolean | true | Specifies if the tool interacts with external systems | + +Remember that annotations help make better user experiences but should be treated as advisory hints. They help client applications present appropriate UI elements and safety controls, but won't enforce security boundaries on their own. Always focus on making your annotations accurately represent what your tool actually does. + +### Using Annotation Hints + +MCP clients like Claude and ChatGPT use annotation hints to determine when to skip confirmation prompts and how to present tools to users. The most commonly used hint is `readOnlyHint`, which signals that a tool only reads data without making changes. + +**Read-only tools** improve user experience by: +- Skipping confirmation prompts for safe operations +- Allowing broader access without security concerns +- Enabling more aggressive batching and caching + +Mark a tool as read-only when it retrieves data, performs calculations, or checks status without modifying state: + +```python +from fastmcp import FastMCP +from mcp.types import ToolAnnotations + +mcp = FastMCP("Data Server") + +@mcp.tool(annotations={"readOnlyHint": True}) +def get_user(user_id: str) -> dict: + """Retrieve user information by ID.""" + return {"id": user_id, "name": "Alice"} + +@mcp.tool( + annotations=ToolAnnotations( + readOnlyHint=True, + idempotentHint=True, # Same result for repeated calls + openWorldHint=False # Only internal data + ) +) +def search_products(query: str) -> list[dict]: + """Search the product catalog.""" + return [{"id": 1, "name": "Widget", "price": 29.99}] + +# Write operations - no readOnlyHint +@mcp.tool() +def update_user(user_id: str, name: str) -> dict: + """Update user information.""" + return {"id": user_id, "name": name, "updated": True} + +@mcp.tool(annotations={"destructiveHint": True}) +def delete_user(user_id: str) -> dict: + """Permanently delete a user account.""" + return {"deleted": user_id} +``` + +For tools that write to databases, send notifications, create/update/delete resources, or trigger workflows, omit `readOnlyHint` or set it to `False`. Use `destructiveHint=True` for operations that cannot be undone. + +Client-specific behavior: +- **ChatGPT**: Skips confirmation prompts for read-only tools in Chat mode (see [ChatGPT integration](/integrations/chatgpt)) +- **Claude**: Uses hints to understand tool safety profiles and make better execution decisions + +## Notifications + + + +FastMCP automatically sends `notifications/tools/list_changed` notifications to connected clients when tools are added, removed, enabled, or disabled. This allows clients to stay up-to-date with the current tool set without manually polling for changes. + +```python +@mcp.tool +def example_tool() -> str: + return "Hello!" + +# These operations trigger notifications: +mcp.add_tool(example_tool) # Sends tools/list_changed notification +mcp.disable(keys={"tool:example_tool"}) # Sends tools/list_changed notification +mcp.enable(keys={"tool:example_tool"}) # Sends tools/list_changed notification +mcp.local_provider.remove_tool("example_tool") # Sends tools/list_changed notification +``` + +Notifications are only sent when these operations occur within an active MCP request context (e.g., when called from within a tool or other MCP operation). Operations performed during server initialization do not trigger notifications. + +Clients can handle these notifications using a [message handler](/clients/notifications) to automatically refresh their tool lists or update their interfaces. + +## Accessing the MCP Context + +Tools can access MCP features like logging, reading resources, or reporting progress through the `Context` object. To use it, add a parameter to your tool function with the type hint `Context`. + +```python +from fastmcp import FastMCP, Context + +mcp = FastMCP(name="ContextDemo") + +@mcp.tool +async def process_data(data_uri: str, ctx: Context) -> dict: + """Process data from a resource with progress reporting.""" + await ctx.info(f"Processing data from {data_uri}") + + # Read a resource + resource = await ctx.read_resource(data_uri) + data = resource[0].content if resource else "" + + # Report progress + await ctx.report_progress(progress=50, total=100) + + # Example request to the client's LLM for help + summary = await ctx.sample(f"Summarize this in 10 words: {data[:200]}") + + await ctx.report_progress(progress=100, total=100) + return { + "length": len(data), + "summary": summary.text + } +``` + +The Context object provides access to: + +- **Logging**: `ctx.debug()`, `ctx.info()`, `ctx.warning()`, `ctx.error()` +- **Progress Reporting**: `ctx.report_progress(progress, total)` +- **Resource Access**: `ctx.read_resource(uri)` +- **LLM Sampling**: `ctx.sample(...)` +- **Request Information**: `ctx.request_id`, `ctx.client_id` + +For full documentation on the Context object and all its capabilities, see the [Context documentation](/servers/context). + +## Server Behavior + +### Duplicate Tools + + + +You can control how the FastMCP server behaves if you try to register multiple tools with the same name. This is configured using the `on_duplicate_tools` argument when creating the `FastMCP` instance. + +```python +from fastmcp import FastMCP + +mcp = FastMCP( + name="StrictServer", + # Configure behavior for duplicate tool names + on_duplicate_tools="error" +) + +@mcp.tool +def my_tool(): return "Version 1" + +# This will now raise a ValueError because 'my_tool' already exists +# and on_duplicate_tools is set to "error". +# @mcp.tool +# def my_tool(): return "Version 2" +``` + +The duplicate behavior options are: + +- `"warn"` (default): Logs a warning and the new tool replaces the old one. +- `"error"`: Raises a `ValueError`, preventing the duplicate registration. +- `"replace"`: Silently replaces the existing tool with the new one. +- `"ignore"`: Keeps the original tool and ignores the new registration attempt. + +### Removing Tools + + + +You can dynamically remove tools from a server through its [local provider](/servers/providers/local): + +```python +from fastmcp import FastMCP + +mcp = FastMCP(name="DynamicToolServer") + +@mcp.tool +def calculate_sum(a: int, b: int) -> int: + """Add two numbers together.""" + return a + b + +mcp.local_provider.remove_tool("calculate_sum") +``` + +## Versioning + + + +Tools support versioning, allowing you to maintain multiple implementations under the same name while clients automatically receive the highest version. See [Versioning](/servers/versioning) for complete documentation on version comparison, retrieval, and migration patterns. diff --git a/docs/servers/transforms/code-mode.mdx b/docs/servers/transforms/code-mode.mdx new file mode 100644 index 000000000..f09c22b6f --- /dev/null +++ b/docs/servers/transforms/code-mode.mdx @@ -0,0 +1,339 @@ +--- +title: Code Mode +sidebarTitle: Code Mode +description: Let LLMs write Python to orchestrate tools in a sandbox +icon: flask +tag: NEW +--- + +import { VersionBadge } from '/snippets/version-badge.mdx' + + + + +CodeMode is experimental. The core interface is stable, but the specific discovery tools and their parameters may evolve as we learn more about what works best in practice. + + +Standard MCP tool usage has two scaling problems. First, every tool in the catalog is loaded into the LLM's context upfront — with hundreds of tools, that's tens of thousands of tokens spent before the LLM even reads the user's request. Second, every tool call is a round-trip: the LLM calls a tool, the result passes back through the context window, the LLM reasons about it, calls another tool, and so on. Intermediate results that only exist to feed the next step still burn tokens flowing through the model. + +CodeMode solves both problems. Instead of seeing your entire tool catalog, the LLM gets meta-tools for discovering what's available and for writing and executing code that calls the tools it needs. It discovers on demand, writes a script that chains tool calls in a sandbox, and gets back only the final answer. + +The approach was introduced by Cloudflare in [Code Mode](https://blog.cloudflare.com/code-mode/) and explored further by Anthropic in [Code Execution with MCP](https://www.anthropic.com/engineering/code-execution-with-mcp). + +## Getting Started + + +CodeMode requires the `code-mode` extra for sandbox support. Install it with `pip install "fastmcp[code-mode]"`. + + +You take a normal server with normally registered tools and add a `CodeMode` transform. The transform wraps your existing tools in the code mode machinery — your tool functions don't change at all: + +```python +from fastmcp import FastMCP +from fastmcp.experimental.transforms.code_mode import CodeMode + +mcp = FastMCP("Server", transforms=[CodeMode()]) + +@mcp.tool +def add(x: int, y: int) -> int: + """Add two numbers.""" + return x + y + +@mcp.tool +def multiply(x: int, y: int) -> int: + """Multiply two numbers.""" + return x * y +``` + +Clients connecting to this server no longer see `add` and `multiply` directly. Instead, they see the meta-tools that CodeMode provides — tools for discovering what's available and executing code against it. The original tools are still there, but they're accessed through the CodeMode layer. + +## Discovery + +Before the LLM can write code that calls your tools, it needs to know what tools exist and how to call them. This is the **discovery** process — the LLM uses meta-tools to learn about your tool catalog, then writes code against what it finds. + +The fundamental tradeoff is **tokens vs. round-trips**. Each discovery step is an LLM round-trip: the model calls a tool, waits for the response, reasons about it, then decides what to do next. More steps mean less wasted context (each step is targeted) but more latency and API calls. Fewer steps mean the LLM gets information upfront but pays for detail it might not need. + +By default, CodeMode gives the LLM three tools — `search`, `get_schema`, and `execute` — creating a three-stage discovery flow: + + + +First, the LLM uses the `search` meta-tool to find tools by keyword. + +For example, it might do `search(query="math numbers")` and receive the following response: + +``` +- add: Add two numbers. +- multiply: Multiply two numbers. +``` + +This lets the LLM know which tools are available and what they do, significantly reducing the surface area it needs to consider. + + + +Next, the LLM calls `get_schema` to get parameter details for the tools it found in the previous step. + +For example, it might do `get_schema(tools=["add", "multiply"])` and receive the following response: + +``` +### add + +Add two numbers. + +**Parameters** +- `x` (integer, required) +- `y` (integer, required) + +### multiply + +Multiply two numbers. + +**Parameters** +- `x` (integer, required) +- `y` (integer, required) +``` + +Now the LLM knows the parameters for the tools it found, and can write code that chains the tool calls. If it needed more detail, it could have called `get_schema` with `detail="full"` to get the complete JSON schema. + + + +Finally, the LLM writes and executes code that chains the tool calls in a Python sandbox. Inside the sandbox, `call_tool(name, params)` is the only function available. The LLM uses this to compose tools into a workflow and return a final result. + +For example, it might write the following code and call the `execute` tool with it: + +```python +a = await call_tool("add", {"x": 3, "y": 4}) +b = await call_tool("multiply", {"x": a, "y": 2}) +return b +``` + +The result is returned to the LLM. + + + +This three-stage flow works well for most servers — each step pulls in only the information needed for the next one, keeping context usage minimal. But CodeMode's discovery surface is fully configurable. The sections below explain each built-in discovery tool and how to combine them into different patterns. + +## Discovery Tools + +CodeMode ships with four built-in discovery tools: `Search`, `GetSchemas`, `GetTags`, and `ListTools`. By default, only `Search` and `GetSchemas` are enabled. Each tool supports a `default_detail` parameter that sets the default verbosity level, and the LLM can override the detail level on any individual call. + +### Detail Levels + +`Search` and `GetSchemas` share the same three detail levels, so the same `detail` value produces the same output format regardless of which tool the LLM calls: + +| Level | Output | Token cost | +|---|---|---| +| `"brief"` | Tool names and one-line descriptions | Cheapest — good for scanning | +| `"detailed"` | Compact markdown with parameter names, types, and required markers | Medium — often enough to write code | +| `"full"` | Complete JSON schema | Most expensive — everything | + +`Search` defaults to `"brief"` and `GetSchemas` defaults to `"detailed"`. + +### Search + +`Search` finds tools by natural-language query using BM25 ranking. At its default `"brief"` detail, results include just tool names and descriptions — enough to decide which tools are worth inspecting further. The LLM can request `"detailed"` to get parameter schemas inline, or `"full"` for the complete JSON. + +Search results include an annotation like `"2 of 10 tools:"` when the result set is smaller than the full catalog, so the LLM knows there are more tools to discover with different queries. + +You can cap result count with `default_limit`. The LLM can also override the limit per call. This is useful for large catalogs where you want to keep search results focused: + +```python +Search(default_limit=5) # return at most 5 results per search +``` + +If your tools use [tags](/servers/tools#tags), Search also accepts a `tags` parameter so the LLM can narrow results to specific categories before searching. + +### GetSchemas + +`GetSchemas` returns parameter details for specific tools by name. At its default `"detailed"` level, it renders compact markdown with parameter names, types, and required markers. At `"full"`, it returns the complete JSON schema — useful when tools have deeply nested parameters that the compact format doesn't capture. + +### GetTags + +`GetTags` lets the LLM browse tools by category using [tag](/servers/tools#tags) metadata. At brief detail, the LLM sees tag names with counts. At full detail, it sees tools listed under each tag: + +``` +- math (3 tools) +- text (2 tools) +- untagged (1 tool) +``` + +`GetTags` isn't included in the defaults — add it when browsing by category would help the LLM orient itself in a large catalog. The LLM can browse tags first, then pass specific tags into Search to narrow results. + +### ListTools + +`ListTools` dumps the entire catalog at whatever detail level the LLM requests. It supports the same three detail levels as `Search` and `GetSchemas`, defaulting to `"brief"`. + +`ListTools` isn't included in the defaults — for large catalogs, search-based discovery is more token-efficient. But for smaller catalogs (under ~20 tools), letting the LLM see everything upfront can be faster than multiple search round-trips: + +```python +from fastmcp.experimental.transforms.code_mode import CodeMode, ListTools, GetSchemas + +code_mode = CodeMode( + discovery_tools=[ListTools(), GetSchemas()], +) +``` + +## Discovery Patterns + +The right discovery configuration depends on your server — how many tools you have and how complex their parameters are. It may be tempting to minimize round-trips by collapsing everything into fewer steps, but for the complex servers that benefit most from CodeMode, our experience is that staged discovery leads to better results. Flooding the LLM with detailed schemas for tools it doesn't end up using can hurt more than the extra round-trip costs. Each pattern below is a complete, copyable configuration. + +### Three-Stage + +The default. The LLM searches for candidates, inspects schemas for the ones it wants, then writes code. Best for **large or complex tool sets** where you want to minimize context usage — the LLM only pays for schemas it actually needs. + +```python +from fastmcp import FastMCP +from fastmcp.experimental.transforms.code_mode import CodeMode + +mcp = FastMCP("Server", transforms=[CodeMode()]) +``` + +If your tools use [tags](/servers/tools#tags), add `GetTags` so the LLM can browse by category before searching — giving it four stages of progressive disclosure: + +```python +from fastmcp import FastMCP +from fastmcp.experimental.transforms.code_mode import CodeMode +from fastmcp.experimental.transforms.code_mode import GetTags, Search, GetSchemas + +code_mode = CodeMode( + discovery_tools=[GetTags(), Search(), GetSchemas()], +) + +mcp = FastMCP("Server", transforms=[code_mode]) +``` + +### Two-Stage + +Search returns parameter schemas inline, so the LLM can go straight from search to execute. Best for **smaller catalogs** where the extra tokens per search result are a reasonable price for one fewer round-trip. + +```python +from fastmcp import FastMCP +from fastmcp.experimental.transforms.code_mode import CodeMode +from fastmcp.experimental.transforms.code_mode import Search, GetSchemas + +code_mode = CodeMode( + discovery_tools=[Search(default_detail="detailed"), GetSchemas()], +) + +mcp = FastMCP("Server", transforms=[code_mode]) +``` + +`GetSchemas` is still available as a fallback — the LLM can call it with `detail="full"` if it encounters a tool with complex nested parameters where the compact markdown isn't enough. + +### Single-Stage + +Skip discovery entirely and bake tool instructions into the execute tool's description. Best for **very simple servers** where the LLM already knows what tools are available — maybe there are only a few, or they're described in the system prompt. + +```python +from fastmcp import FastMCP +from fastmcp.experimental.transforms.code_mode import CodeMode + +code_mode = CodeMode( + discovery_tools=[], + execute_description=( + "Available tools:\n" + "- add(x: int, y: int) -> int: Add two numbers\n" + "- multiply(x: int, y: int) -> int: Multiply two numbers\n\n" + "Write Python using `await call_tool(name, params)` and `return` the result." + ), +) + +mcp = FastMCP("Server", transforms=[code_mode]) +``` + +## Custom Discovery Tools + +Discovery tools are composable — you can mix the built-ins with your own. Each discovery tool is a callable that receives catalog access and returns a `Tool`. The catalog accessor is a function (not the catalog itself) because the catalog is request-scoped — different users may see different tools based on auth. + +Here's a minimal example: + +```python +from fastmcp.experimental.transforms.code_mode import CodeMode +from fastmcp.experimental.transforms.code_mode import GetToolCatalog, GetSchemas +from fastmcp.server.context import Context +from fastmcp.tools.tool import Tool + +def list_all_tools(get_catalog: GetToolCatalog) -> Tool: + async def list_tools(ctx: Context) -> str: + """List all available tool names.""" + tools = await get_catalog(ctx) + return ", ".join(t.name for t in tools) + + return Tool.from_function(fn=list_tools, name="list_tools") + +code_mode = CodeMode(discovery_tools=[list_all_tools, GetSchemas()]) +``` + +The LLM sees the docstring of each discovery tool's inner function as its description — that's how it learns what each tool does and when to use it. Write docstrings that explain what the tool returns and when the LLM should call it. + +Discovery tools and the execute tool can also have custom names: + +```python +from fastmcp.experimental.transforms.code_mode import Search, GetSchemas + +code_mode = CodeMode( + discovery_tools=[ + Search(name="find_tools"), + GetSchemas(name="describe"), + ], + execute_tool_name="run_workflow", +) + +mcp = FastMCP("Server", transforms=[code_mode]) +``` + +## Sandbox Configuration + +### Resource Limits + +The default `MontySandboxProvider` can enforce execution limits — timeouts, memory caps, recursion depth, and more. Without limits, LLM-generated scripts can run indefinitely. + +```python +from fastmcp.experimental.transforms.code_mode import CodeMode +from fastmcp.experimental.transforms.code_mode import MontySandboxProvider + +sandbox = MontySandboxProvider( + limits={"max_duration_secs": 10, "max_memory": 50_000_000}, +) + +mcp = FastMCP("Server", transforms=[CodeMode(sandbox_provider=sandbox)]) +``` + +All keys are optional — omit any to leave that dimension uncapped: + +| Key | Type | Description | +|---|---|---| +| `max_duration_secs` | `float` | Maximum wall-clock execution time | +| `max_memory` | `int` | Memory ceiling in bytes | +| `max_allocations` | `int` | Cap on total object allocations | +| `max_recursion_depth` | `int` | Maximum recursion depth | +| `gc_interval` | `int` | Garbage collection frequency | + +### Custom Sandbox Providers + +You can replace the default sandbox with any object implementing the `SandboxProvider` protocol: + +```python +from collections.abc import Callable +from typing import Any + +from fastmcp.experimental.transforms.code_mode import CodeMode +from fastmcp.experimental.transforms.code_mode import SandboxProvider + +class RemoteSandboxProvider: + async def run( + self, + code: str, + *, + inputs: dict[str, Any] | None = None, + external_functions: dict[str, Callable[..., Any]] | None = None, + ) -> Any: + # Send code to your remote sandbox runtime + ... + +mcp = FastMCP( + "Server", + transforms=[CodeMode(sandbox_provider=RemoteSandboxProvider())], +) +``` + +The `external_functions` dict contains async callables injected into the sandbox scope — `execute` uses this to provide `call_tool`. diff --git a/docs/servers/transforms/namespace.mdx b/docs/servers/transforms/namespace.mdx new file mode 100644 index 000000000..715bebd39 --- /dev/null +++ b/docs/servers/transforms/namespace.mdx @@ -0,0 +1,64 @@ +--- +title: Namespace Transform +sidebarTitle: Namespace +description: Prefix component names to prevent conflicts +icon: tag +tag: NEW +--- + +import { VersionBadge } from '/snippets/version-badge.mdx' + + + +The `Namespace` transform prefixes all component names, preventing conflicts when composing multiple servers. + +Tools and prompts receive an underscore-separated prefix. Resources and templates receive a path-segment prefix in their URIs. + +| Component | Original | With `Namespace("api")` | +|-----------|----------|-------------------------| +| Tool | `my_tool` | `api_my_tool` | +| Prompt | `my_prompt` | `api_my_prompt` | +| Resource | `data://info` | `data://api/info` | +| Template | `data://{id}` | `data://api/{id}` | + +The most common use is through the `mount()` method's `namespace` parameter. + +```python +from fastmcp import FastMCP + +weather = FastMCP("Weather") +calendar = FastMCP("Calendar") + +@weather.tool +def get_data() -> str: + return "Weather data" + +@calendar.tool +def get_data() -> str: + return "Calendar data" + +# Without namespacing, these would conflict +main = FastMCP("Main") +main.mount(weather, namespace="weather") +main.mount(calendar, namespace="calendar") + +# Clients see: weather_get_data, calendar_get_data +``` + +You can also apply namespacing directly using the `Namespace` transform. + +```python +from fastmcp import FastMCP +from fastmcp.server.transforms import Namespace + +mcp = FastMCP("Server") + +@mcp.tool +def greet(name: str) -> str: + return f"Hello, {name}!" + +# Namespace all components +mcp.add_transform(Namespace("api")) + +# Tool is now: api_greet +``` diff --git a/docs/servers/transforms/namespacing.mdx b/docs/servers/transforms/namespacing.mdx new file mode 100644 index 000000000..009a1ee39 --- /dev/null +++ b/docs/servers/transforms/namespacing.mdx @@ -0,0 +1,9 @@ +--- +title: Namespacing +sidebarTitle: Namespacing +description: Namespace and transform components with transforms +icon: wand-magic-sparkles +redirect: /servers/transforms/transforms +--- + +This page has moved to [Transforms](/servers/transforms/transforms). diff --git a/docs/servers/transforms/prompts-as-tools.mdx b/docs/servers/transforms/prompts-as-tools.mdx new file mode 100644 index 000000000..b68c0891d --- /dev/null +++ b/docs/servers/transforms/prompts-as-tools.mdx @@ -0,0 +1,126 @@ +--- +title: Prompts as Tools +sidebarTitle: Prompts as Tools +description: Expose prompts to tool-only clients +icon: message-lines +tag: NEW +--- + +import { VersionBadge } from '/snippets/version-badge.mdx' + + + +Some MCP clients only support tools. They cannot list or get prompts directly because they lack prompt protocol support. The `PromptsAsTools` transform bridges this gap by generating tools that provide access to your server's prompts. + +When you add `PromptsAsTools` to a server, it creates two tools that clients can call instead of using the prompt protocol: + +- **`list_prompts`** returns JSON describing all available prompts and their arguments +- **`get_prompt`** renders a specific prompt with provided arguments + +This means any client that can call tools can now access prompts, even if the client has no native prompt support. + +## Basic Usage + +Pass your server to `PromptsAsTools` when adding the transform. The transform queries that server for prompts whenever the generated tools are called. + +```python +from fastmcp import FastMCP +from fastmcp.server.transforms import PromptsAsTools + +mcp = FastMCP("My Server") + +@mcp.prompt +def analyze_code(code: str, language: str = "python") -> str: + """Analyze code for potential issues.""" + return f"Analyze this {language} code:\n{code}" + +@mcp.prompt +def explain_concept(concept: str) -> str: + """Explain a programming concept.""" + return f"Explain: {concept}" + +# Add the transform - creates list_prompts and get_prompt tools +mcp.add_transform(PromptsAsTools(mcp)) +``` + +Clients now see three items: whatever tools you defined directly, plus `list_prompts` and `get_prompt`. + +## Listing Prompts + +The `list_prompts` tool returns JSON with metadata for each prompt, including its arguments. + +```python +result = await client.call_tool("list_prompts", {}) +prompts = json.loads(result.data) +# [ +# { +# "name": "analyze_code", +# "description": "Analyze code for potential issues.", +# "arguments": [ +# {"name": "code", "description": null, "required": true}, +# {"name": "language", "description": null, "required": false} +# ] +# }, +# { +# "name": "explain_concept", +# "description": "Explain a programming concept.", +# "arguments": [ +# {"name": "concept", "description": null, "required": true} +# ] +# } +#] +``` + +Each argument includes: +- `name`: The argument name +- `description`: Optional description from type hints or docstrings +- `required`: Whether the argument must be provided + +## Getting Prompts + +The `get_prompt` tool accepts a prompt name and optional arguments dict. It returns the rendered prompt as JSON with a messages array. + +```python +# Prompt with required and optional arguments +result = await client.call_tool( + "get_prompt", + { + "name": "analyze_code", + "arguments": { + "code": "x = 1\nprint(x)", + "language": "python" + } + } +) + +response = json.loads(result.data) +# { +# "messages": [ +# { +# "role": "user", +# "content": "Analyze this python code:\nx = 1\nprint(x)" +# } +# ] +# } +``` + +If a prompt has no arguments, you can omit the `arguments` field or pass an empty dict: + +```python +result = await client.call_tool( + "get_prompt", + {"name": "simple_prompt"} +) +``` + +## Message Format + +Rendered prompts return a messages array following the standard MCP format. Each message includes: +- `role`: The message role ("user" or "assistant") +- `content`: The message text content + +Multi-message prompts are supported - the array will contain all messages in order. + +## Binary Content + +Unlike resources, prompts always return text content. There is no binary encoding needed. diff --git a/docs/servers/transforms/resources-as-tools.mdx b/docs/servers/transforms/resources-as-tools.mdx new file mode 100644 index 000000000..8c7e8bbed --- /dev/null +++ b/docs/servers/transforms/resources-as-tools.mdx @@ -0,0 +1,105 @@ +--- +title: Resources as Tools +sidebarTitle: Resources as Tools +description: Expose resources to tool-only clients +icon: toolbox +tag: NEW +--- + +import { VersionBadge } from '/snippets/version-badge.mdx' + + + +Some MCP clients only support tools. They cannot list or read resources directly because they lack resource protocol support. The `ResourcesAsTools` transform bridges this gap by generating tools that provide access to your server's resources. + +When you add `ResourcesAsTools` to a server, it creates two tools that clients can call instead of using the resource protocol: + +- **`list_resources`** returns JSON describing all available resources and templates +- **`read_resource`** reads a specific resource by URI + +This means any client that can call tools can now access resources, even if the client has no native resource support. + +## Basic Usage + +Pass your server to `ResourcesAsTools` when adding the transform. The transform queries that server for resources whenever the generated tools are called. + +```python +from fastmcp import FastMCP +from fastmcp.server.transforms import ResourcesAsTools + +mcp = FastMCP("My Server") + +@mcp.resource("config://app") +def app_config() -> str: + """Application configuration.""" + return '{"app_name": "My App", "version": "1.0.0"}' + +@mcp.resource("user://{user_id}/profile") +def user_profile(user_id: str) -> str: + """Get a user's profile by ID.""" + return f'{{"user_id": "{user_id}", "name": "User {user_id}"}}' + +# Add the transform - creates list_resources and read_resource tools +mcp.add_transform(ResourcesAsTools(mcp)) +``` + +Clients now see three tools: whatever tools you defined directly, plus `list_resources` and `read_resource`. + +## Static Resources vs Templates + +Resources come in two forms, and the `list_resources` tool distinguishes between them in its JSON output. + +Static resources have fixed URIs. They represent concrete data that exists at a known location. In the listing output, static resources include a `uri` field containing the exact URI to request. + +Resource templates have parameterized URIs with placeholders like `{user_id}`. They represent patterns for accessing dynamic data. In the listing output, templates include a `uri_template` field showing the pattern with its placeholders. + +When a client calls `list_resources`, it receives JSON like this: + +```json +[ + { + "uri": "config://app", + "name": "app_config", + "description": "Application configuration.", + "mime_type": "text/plain" + }, + { + "uri_template": "user://{user_id}/profile", + "name": "user_profile", + "description": "Get a user's profile by ID." + } +] +``` + +The client can distinguish resource types by checking which field is present: `uri` for static resources, `uri_template` for templates. + +## Reading Resources + +The `read_resource` tool accepts a single `uri` argument. For static resources, pass the exact URI. For templates, fill in the placeholders with actual values. + +```python +# Reading a static resource +result = await client.call_tool("read_resource", {"uri": "config://app"}) +print(result.data) # '{"app_name": "My App", "version": "1.0.0"}' + +# Reading a templated resource - fill in {user_id} with an actual ID +result = await client.call_tool("read_resource", {"uri": "user://42/profile"}) +print(result.data) # '{"user_id": "42", "name": "User 42"}' +``` + +The transform handles template matching automatically. When you request `user://42/profile`, it matches against the `user://{user_id}/profile` template, extracts `user_id=42`, and calls your resource function with that parameter. + +## Binary Content + +Resources that return binary data (like images or files) are automatically base64-encoded when read through the `read_resource` tool. This ensures binary content can be transmitted as a string in the tool response. + +```python +@mcp.resource("data://binary", mime_type="application/octet-stream") +def binary_data() -> bytes: + return b"\x00\x01\x02\x03" + +# Client receives base64-encoded string +result = await client.call_tool("read_resource", {"uri": "data://binary"}) +decoded = base64.b64decode(result.data) # b'\x00\x01\x02\x03' +``` + diff --git a/docs/servers/transforms/tool-search.mdx b/docs/servers/transforms/tool-search.mdx new file mode 100644 index 000000000..204004f5c --- /dev/null +++ b/docs/servers/transforms/tool-search.mdx @@ -0,0 +1,173 @@ +--- +title: Tool Search +sidebarTitle: Tool Search +description: Replace large tool catalogs with on-demand search +icon: magnifying-glass +tag: NEW +--- + +import { VersionBadge } from '/snippets/version-badge.mdx' + + + +When a server exposes hundreds or thousands of tools, sending the full catalog to an LLM wastes tokens and degrades tool selection accuracy. Search transforms solve this by replacing the tool listing with a search interface — the LLM discovers tools on demand instead of receiving everything upfront. + +## How It Works + +When you add a search transform, `list_tools()` returns just two synthetic tools instead of the full catalog: + +- **`search_tools`** finds tools matching a query and returns their full definitions +- **`call_tool`** executes a discovered tool by name + +The original tools are still callable. They're hidden from the listing but remain fully functional — the search transform controls *discovery*, not *access*. + +Both synthetic tools search across tool names, descriptions, parameter names, and parameter descriptions. A search for `"email"` would match a tool named `send_email`, a tool with "email" in its description, or a tool with an `email_address` parameter. + +Search results are returned in the same JSON format as `list_tools`, including the full input schema, so the LLM can construct valid calls immediately without a second round-trip. + +## Search Strategies + +FastMCP provides two search transforms. They share the same interface — two synthetic tools, same configuration options — but differ in how they match queries to tools. + +### Regex Search + +`RegexSearchTransform` matches tools against a regex pattern using case-insensitive `re.search`. It has zero overhead and no index to build, making it a good default when the LLM knows roughly what it's looking for. + +```python +from fastmcp import FastMCP +from fastmcp.server.transforms.search import RegexSearchTransform + +mcp = FastMCP("My Server", transforms=[RegexSearchTransform()]) + +@mcp.tool +def search_database(query: str, limit: int = 10) -> list[dict]: + """Search the database for records matching the query.""" + ... + +@mcp.tool +def delete_record(record_id: str) -> bool: + """Delete a record from the database by its ID.""" + ... + +@mcp.tool +def send_email(to: str, subject: str, body: str) -> bool: + """Send an email to the given recipient.""" + ... +``` + +The LLM's `search_tools` call takes a `pattern` parameter — a regex string: + +```python +# Exact substring match +result = await client.call_tool("search_tools", {"pattern": "database"}) +# Returns: search_database, delete_record + +# Regex pattern +result = await client.call_tool("search_tools", {"pattern": "send.*email|notify"}) +# Returns: send_email +``` + +Results are returned in catalog order. If the pattern is invalid regex, the search returns an empty list rather than raising an error. + +### BM25 Search + +`BM25SearchTransform` ranks tools by relevance using the [BM25 Okapi](https://en.wikipedia.org/wiki/Okapi_BM25) algorithm. It's better for natural language queries because it scores each tool based on term frequency and document rarity, returning results ranked by relevance rather than filtering by match/no-match. + +```python +from fastmcp import FastMCP +from fastmcp.server.transforms.search import BM25SearchTransform + +mcp = FastMCP("My Server", transforms=[BM25SearchTransform()]) + +# ... define tools ... +``` + +The LLM's `search_tools` call takes a `query` parameter — natural language: + +```python +result = await client.call_tool("search_tools", { + "query": "tools for deleting things from the database" +}) +# Returns: delete_record ranked first, search_database second +``` + +BM25 builds an in-memory index from the searchable text of all tools. The index is created lazily on the first search and automatically rebuilt whenever the tool catalog changes — for example, when tools are added, removed, or have their descriptions updated. The staleness check is based on a hash of all searchable text, so description changes are detected even when tool names stay the same. + +### Which to Choose + +Use **regex** when your LLM is good at constructing targeted patterns and you want deterministic, predictable results. Regex is also simpler to debug — you can see exactly what pattern was sent. + +Use **BM25** when your LLM tends to describe what it needs in natural language, or when your tool catalog has nuanced descriptions where relevance ranking adds value. BM25 handles partial matches and synonyms better because it scores on individual terms rather than requiring a single pattern to match. + +## Configuration + +Both search transforms accept the same configuration options. + +### Limiting Results + +By default, search returns at most 5 tools. Adjust `max_results` based on your catalog size and how much context you want the LLM to receive per search: + +```python +mcp.add_transform(RegexSearchTransform(max_results=10)) +mcp.add_transform(BM25SearchTransform(max_results=3)) +``` + +With regex, results stop as soon as the limit is reached (first N matches in catalog order). With BM25, all tools are scored and the top N by relevance are returned. + +### Pinning Tools + +Some tools should always be visible regardless of search. Use `always_visible` to pin them in the listing alongside the synthetic tools: + +```python +mcp.add_transform(RegexSearchTransform( + always_visible=["help", "status"], +)) + +# list_tools returns: help, status, search_tools, call_tool +``` + +Pinned tools appear directly in `list_tools` so the LLM can call them without searching. They're excluded from search results to avoid duplication. + +### Custom Tool Names + +The default names `search_tools` and `call_tool` can be changed to avoid conflicts with real tools: + +```python +mcp.add_transform(RegexSearchTransform( + search_tool_name="find_tools", + call_tool_name="run_tool", +)) +``` + +## The `call_tool` Proxy + +The `call_tool` proxy forwards calls to the real tool. When a client calls `call_tool(name="search_database", arguments={...})`, the proxy resolves `search_database` through the server's normal tool pipeline — including transforms and middleware — and executes it. + +The proxy rejects attempts to call the synthetic tools themselves. `call_tool(name="call_tool")` raises an error rather than recursing. + + +Tools discovered through search can also be called directly via `client.call_tool("search_database", {...})` without going through the proxy. The proxy exists for LLMs that only know about the tools returned by `list_tools` and need a way to invoke discovered tools through a tool they can see. + + +## Auth and Visibility + +Search results respect the full authorization pipeline. Tools filtered by middleware, visibility transforms, or component-level auth checks won't appear in search results. + +The search tool queries `list_tools()` through the complete pipeline at search time, so the same filtering that controls what a client sees in the listing also controls what they can discover through search. + +```python +from fastmcp.server.transforms import Visibility +from fastmcp.server.transforms.search import RegexSearchTransform + +mcp = FastMCP("My Server") + +# ... define tools ... + +# Disable admin tools globally +mcp.add_transform(Visibility(False, tags={"admin"})) + +# Add search — admin tools won't appear in results +mcp.add_transform(RegexSearchTransform()) +``` + +Session-level visibility changes (via `ctx.disable_components()`) are also reflected immediately in search results. diff --git a/docs/servers/transforms/tool-transformation.mdx b/docs/servers/transforms/tool-transformation.mdx new file mode 100644 index 000000000..393b47b5a --- /dev/null +++ b/docs/servers/transforms/tool-transformation.mdx @@ -0,0 +1,231 @@ +--- +title: Tool Transformation +sidebarTitle: Tool Transformation +description: Modify tool schemas - rename, reshape arguments, and customize behavior +icon: wrench +tag: NEW +--- + +import { VersionBadge } from '/snippets/version-badge.mdx' + + + +Tool transformation lets you modify tool schemas - renaming tools, changing descriptions, adjusting tags, and reshaping argument schemas. FastMCP provides two mechanisms that share the same configuration options but differ in timing. + +**Deferred transformation** with `ToolTransform` applies modifications when tools flow through a transform chain. Use this for tools from mounted servers, proxies, or other providers where you don't control the source directly. + +**Immediate transformation** with `Tool.from_tool()` creates a modified tool object right away. Use this when you have direct access to a tool and want to transform it before registration. + +## ToolTransform + +The `ToolTransform` class is a transform that modifies tools as they flow through a provider. Provide a dictionary mapping original tool names to their transformation configuration. + +```python +from fastmcp import FastMCP +from fastmcp.server.transforms import ToolTransform +from fastmcp.tools.tool_transform import ToolTransformConfig + +mcp = FastMCP("Server") + +@mcp.tool +def verbose_internal_data_fetcher(query: str) -> str: + """Fetches data from the internal database.""" + return f"Results for: {query}" + +# Rename the tool to something simpler +mcp.add_transform(ToolTransform({ + "verbose_internal_data_fetcher": ToolTransformConfig( + name="search", + description="Search the database.", + ) +})) + +# Clients see "search" with the cleaner description +``` + +`ToolTransform` is useful when you want to modify tools from mounted or proxied servers without changing the original source. + +## Tool.from_tool() + +Use `Tool.from_tool()` when you have the tool object and want to create a transformed version for registration. + +```python +from fastmcp import FastMCP +from fastmcp.tools import Tool, tool +from fastmcp.tools.tool_transform import ArgTransform + +# Create a tool without registering it +@tool +def search(q: str, limit: int = 10) -> list[str]: + """Search for items.""" + return [f"Result {i} for {q}" for i in range(limit)] + +# Transform it before registration +better_search = Tool.from_tool( + search, + name="find_items", + description="Find items matching your search query.", + transform_args={ + "q": ArgTransform( + name="query", + description="The search terms to look for.", + ), + }, +) + +mcp = FastMCP("Server") +mcp.add_tool(better_search) +``` + +The standalone `@tool` decorator (from `fastmcp.tools`) creates a Tool object without registering it to any server. This separates creation from registration, letting you transform tools before deciding where they go. + +## Modification Options + +Both mechanisms support the same modifications. + +**Tool-level options:** + +| Option | Description | +|--------|-------------| +| `name` | New name for the tool | +| `description` | New description | +| `title` | Human-readable title | +| `tags` | Set of tags for categorization | +| `annotations` | MCP ToolAnnotations | +| `meta` | Custom metadata dictionary | +| `enabled` | Whether the tool is visible to clients (default `True`) | + +**Argument-level options** (via `ArgTransform` or `ArgTransformConfig`): + +| Option | Description | +|--------|-------------| +| `name` | Rename the argument | +| `description` | New description for the argument | +| `default` | New default value | +| `default_factory` | Callable that generates a default (requires `hide=True`) | +| `hide` | Remove from client-visible schema | +| `required` | Make an optional argument required | +| `type` | Change the argument's type | +| `examples` | Example values for the argument | + +## Hiding Arguments + +Hide arguments to simplify the interface or inject values the client shouldn't control. + +```python +from fastmcp.tools.tool_transform import ArgTransform + +# Hide with a constant value +transform_args = { + "api_key": ArgTransform(hide=True, default="secret-key"), +} + +# Hide with a dynamic value +import uuid +transform_args = { + "request_id": ArgTransform(hide=True, default_factory=lambda: str(uuid.uuid4())), +} +``` + +Hidden arguments disappear from the tool's schema. The client never sees them, but the underlying function receives the configured value. + + +`default_factory` requires `hide=True`. Visible arguments need static defaults that can be represented in JSON Schema. + + +## Renaming Arguments + +Rename arguments to make them more intuitive for LLMs or match your API conventions. + +```python +from fastmcp.tools import Tool, tool +from fastmcp.tools.tool_transform import ArgTransform + +@tool +def search(q: str, n: int = 10) -> list[str]: + """Search for items.""" + return [] + +better_search = Tool.from_tool( + search, + transform_args={ + "q": ArgTransform(name="query", description="Search terms"), + "n": ArgTransform(name="max_results", description="Maximum results to return"), + }, +) +``` + +## Custom Transform Functions + +For advanced scenarios, provide a `transform_fn` that intercepts tool execution. The function can validate inputs, modify outputs, or add custom logic while still calling the original tool via `forward()`. + +```python +from fastmcp import FastMCP +from fastmcp.tools import Tool, tool +from fastmcp.tools.tool_transform import forward, ArgTransform + +@tool +def divide(a: float, b: float) -> float: + """Divide a by b.""" + return a / b + +async def safe_divide(numerator: float, denominator: float) -> float: + if denominator == 0: + raise ValueError("Cannot divide by zero") + return await forward(numerator=numerator, denominator=denominator) + +safe_division = Tool.from_tool( + divide, + name="safe_divide", + transform_fn=safe_divide, + transform_args={ + "a": ArgTransform(name="numerator"), + "b": ArgTransform(name="denominator"), + }, +) + +mcp = FastMCP("Server") +mcp.add_tool(safe_division) +``` + +The `forward()` function handles argument mapping automatically. Call it with the transformed argument names, and it maps them back to the original function's parameters. + +For direct access to the original function without mapping, use `forward_raw()` with the original parameter names. + +## Context-Aware Tool Factories + +You can write functions that act as "factories," generating specialized versions of a tool for different contexts. For example, create a `get_my_data` tool for the current user by hiding the `user_id` parameter and providing it automatically. + +```python +from fastmcp import FastMCP +from fastmcp.tools import Tool, tool +from fastmcp.tools.tool_transform import ArgTransform + +# A generic tool that requires a user_id +@tool +def get_user_data(user_id: str, query: str) -> str: + """Fetch data for a specific user.""" + return f"Data for user {user_id}: {query}" + + +def create_user_tool(user_id: str) -> Tool: + """Factory that creates a user-specific version of get_user_data.""" + return Tool.from_tool( + get_user_data, + name="get_my_data", + description="Fetch your data. No need to specify a user ID.", + transform_args={ + "user_id": ArgTransform(hide=True, default=user_id), + }, + ) + + +# Create a server with a tool customized for the current user +mcp = FastMCP("User Server") +current_user_id = "user-123" # e.g., from auth context +mcp.add_tool(create_user_tool(current_user_id)) + +# Clients see "get_my_data(query: str)" — user_id is injected automatically +``` + +This pattern is useful for multi-tenant servers where each connection gets tools pre-configured with their identity, or for wrapping generic tools with environment-specific defaults. diff --git a/docs/servers/transforms/transforms.mdx b/docs/servers/transforms/transforms.mdx new file mode 100644 index 000000000..4008f86b4 --- /dev/null +++ b/docs/servers/transforms/transforms.mdx @@ -0,0 +1,174 @@ +--- +title: Transforms Overview +sidebarTitle: Overview +description: Modify components as they flow through your server +icon: wand-magic-sparkles +tag: NEW +--- + +import { VersionBadge } from '/snippets/version-badge.mdx' + + + +Transforms modify components as they flow from providers to clients. When a client asks "what tools do you have?", the request passes through each transform in the chain. Each transform can modify the components before passing them along. + +## Mental Model + +Think of transforms as filters in a pipeline. Components flow from providers through transforms to reach clients: + +``` +Provider → [Transform A] → [Transform B] → Client +``` + +When listing components, transforms receive sequences and return transformed sequences—a pure function pattern. When getting a specific component by name, transforms use a middleware pattern with `call_next`, working in reverse: mapping the client's requested name back to the original, then transforming the result. + +## Built-in Transforms + +FastMCP provides several transforms for common use cases: + +- **[Namespace](/servers/transforms/namespace)** - Prefix component names to prevent conflicts when composing servers +- **[Tool Transformation](/servers/transforms/tool-transformation)** - Rename tools, modify descriptions, reshape arguments +- **[Enabled](/servers/visibility)** - Control which components are visible at runtime +- **[Tool Search](/servers/transforms/tool-search)** - Replace large tool catalogs with on-demand search +- **[Resources as Tools](/servers/transforms/resources-as-tools)** - Expose resources to tool-only clients +- **[Prompts as Tools](/servers/transforms/prompts-as-tools)** - Expose prompts to tool-only clients +- **[Code Mode (Experimental)](/servers/transforms/code-mode)** - Replace many tools with programmable `search` + `execute` + +## Server vs Provider Transforms + +Transforms can be added at two levels, each serving different purposes. + +### Provider-Level Transforms + +Provider transforms apply to components from a specific provider. They run first, modifying components before they reach the server level. + +```python +from fastmcp import FastMCP +from fastmcp.server.providers import FastMCPProvider +from fastmcp.server.transforms import Namespace, ToolTransform +from fastmcp.tools.tool_transform import ToolTransformConfig + +sub_server = FastMCP("Sub") + +@sub_server.tool +def process(data: str) -> str: + return f"Processed: {data}" + +# Create provider and add transforms +provider = FastMCPProvider(sub_server) +provider.add_transform(Namespace("api")) +provider.add_transform(ToolTransform({ + "api_process": ToolTransformConfig(description="Process data through the API"), +})) + +main = FastMCP("Main", providers=[provider]) +# Tool is now: api_process with updated description +``` + +When using `mount()`, the returned provider reference lets you add transforms directly. + +```python +main = FastMCP("Main") +mount = main.mount(sub_server, namespace="api") +mount.add_transform(ToolTransform({...})) +``` + +### Server-Level Transforms + +Server transforms apply to all components from all providers. They run after provider transforms, seeing the already-transformed names. + +```python +from fastmcp import FastMCP +from fastmcp.server.transforms import Namespace + +mcp = FastMCP("Server", transforms=[Namespace("v1")]) + +@mcp.tool +def greet(name: str) -> str: + return f"Hello, {name}!" + +# All tools become v1_toolname +``` + +Server-level transforms are useful for API versioning or applying consistent naming across your entire server. + +### Transform Order + +Transforms stack in the order they're added. The first transform added is innermost (closest to the provider), and subsequent transforms wrap it. + +```python +from fastmcp.server.providers import FastMCPProvider +from fastmcp.server.transforms import Namespace, ToolTransform +from fastmcp.tools.tool_transform import ToolTransformConfig + +provider = FastMCPProvider(server) +provider.add_transform(Namespace("api")) # Applied first +provider.add_transform(ToolTransform({ # Sees namespaced names + "api_verbose_name": ToolTransformConfig(name="short"), +})) + +# Flow: "verbose_name" -> "api_verbose_name" -> "short" +``` + +When a client requests "short", the transforms reverse the mapping: ToolTransform maps "short" to "api_verbose_name", then Namespace strips the prefix to find "verbose_name" in the provider. + +## Custom Transforms + +Create custom transforms by subclassing `Transform` and overriding the methods you need. + +```python +from collections.abc import Sequence +from fastmcp.server.transforms import Transform, GetToolNext +from fastmcp.tools.tool import Tool + +class TagFilter(Transform): + """Filter tools to only those with specific tags.""" + + def __init__(self, required_tags: set[str]): + self.required_tags = required_tags + + async def list_tools(self, tools: Sequence[Tool]) -> Sequence[Tool]: + return [t for t in tools if t.tags & self.required_tags] + + async def get_tool(self, name: str, call_next: GetToolNext) -> Tool | None: + tool = await call_next(name) + if tool and tool.tags & self.required_tags: + return tool + return None +``` + +The `Transform` base class provides default implementations that pass through unchanged. Override only the methods relevant to your transform. + +Each component type has two methods with different patterns: + +| Method | Pattern | Purpose | +|--------|---------|---------| +| `list_tools(tools)` | Pure function | Transform the sequence of tools | +| `get_tool(name, call_next)` | Middleware | Transform lookup by name | +| `list_resources(resources)` | Pure function | Transform the sequence of resources | +| `get_resource(uri, call_next)` | Middleware | Transform lookup by URI | +| `list_resource_templates(templates)` | Pure function | Transform the sequence of templates | +| `get_resource_template(uri, call_next)` | Middleware | Transform template lookup by URI | +| `list_prompts(prompts)` | Pure function | Transform the sequence of prompts | +| `get_prompt(name, call_next)` | Middleware | Transform lookup by name | + +List methods receive sequences directly and return transformed sequences. Get methods use `call_next` for routing flexibility—when a client requests "new_name", your transform maps it back to "original_name" before calling `call_next()`. + +```python +class PrefixTransform(Transform): + def __init__(self, prefix: str): + self.prefix = prefix + + async def list_tools(self, tools: Sequence[Tool]) -> Sequence[Tool]: + return [t.model_copy(update={"name": f"{self.prefix}_{t.name}"}) for t in tools] + + async def get_tool(self, name: str, call_next: GetToolNext) -> Tool | None: + # Reverse the prefix to find the original + if not name.startswith(f"{self.prefix}_"): + return None + original = name[len(self.prefix) + 1:] + tool = await call_next(original) + if tool: + return tool.model_copy(update={"name": name}) + return None +``` diff --git a/docs/servers/versioning.mdx b/docs/servers/versioning.mdx new file mode 100644 index 000000000..4c44a73bd --- /dev/null +++ b/docs/servers/versioning.mdx @@ -0,0 +1,336 @@ +--- +title: Versioning +sidebarTitle: Versioning +description: Serve multiple API versions from a single codebase +icon: code-branch +tag: NEW +--- + +import { VersionBadge } from '/snippets/version-badge.mdx' + + + +Component versioning lets you maintain multiple implementations of the same tool, resource, or prompt under a single identifier. You register each version, and FastMCP handles the rest: clients see the highest version by default, but you can filter to expose exactly the versions you want. + +The primary use case is serving different API versions from one codebase. Instead of maintaining separate deployments for v1 and v2 clients, you version your components and use `VersionFilter` to create distinct API surfaces. + +## Versioned API Surfaces + +Consider a server that needs to support both v1 and v2 clients. The v2 API adds new parameters to existing tools, and you want both versions to coexist cleanly. Define your components on a shared provider, then create separate servers with different version filters. + +```python +from fastmcp import FastMCP +from fastmcp.server.providers import LocalProvider +from fastmcp.server.transforms import VersionFilter + +# Define versioned components on a shared provider +components = LocalProvider() + +@components.tool(version="1.0") +def calculate(x: int, y: int) -> int: + """Add two numbers.""" + return x + y + +@components.tool(version="2.0") +def calculate(x: int, y: int, z: int = 0) -> int: + """Add two or three numbers.""" + return x + y + z + +# Create servers that share the provider with different filters +api_v1 = FastMCP("API v1", providers=[components]) +api_v1.add_transform(VersionFilter(version_lt="2.0")) + +api_v2 = FastMCP("API v2", providers=[components]) +api_v2.add_transform(VersionFilter(version_gte="2.0")) +``` + +Clients connecting to `api_v1` see the two-argument `calculate`. Clients connecting to `api_v2` see the three-argument version. Both servers share the same component definitions. + +`VersionFilter` accepts two keyword-only parameters that mirror comparison operators: `version_gte` (greater than or equal) and `version_lt` (less than). You can use either or both to define your version range. + +```python +# Versions < 3.0 (v1.x and v2.x) +VersionFilter(version_lt="3.0") + +# Versions >= 2.0 (v2.x and later) +VersionFilter(version_gte="2.0") + +# Versions in range [2.0, 3.0) (only v2.x) +VersionFilter(version_gte="2.0", version_lt="3.0") +``` + + +**Unversioned components are exempt from version filtering by default.** Set `include_unversioned=False` to exclude them. Including them by default ensures that adding version filtering to a server with mixed versioned and unversioned components doesn't accidentally hide the unversioned ones. To prevent confusion, FastMCP forbids mixing versioned and unversioned components with the same name. + + +### Filtering Mounted Servers + +When you mount child servers and apply a `VersionFilter` to the parent, the filter applies to components from mounted servers as well. Range filtering (`version_gte` and `version_lt`) is handled at the provider level, meaning mounted servers don't need to know about the parent's version constraints. + +```python +from fastmcp import FastMCP +from fastmcp.server.transforms import VersionFilter + +# Child server with versioned components +child = FastMCP("Child") + +@child.tool(version="1.0") +def process(data: str) -> str: + return data.upper() + +@child.tool(version="2.0") +def process(data: str, mode: str = "default") -> str: + return data.upper() if mode == "default" else data.lower() + +# Parent server mounts child and applies version filter +parent = FastMCP("Parent") +parent.mount(child, namespace="child") +parent.add_transform(VersionFilter(version_lt="2.0")) + +# Clients see only child_process v1.0 +``` + +The parent's `VersionFilter` sees components after they've been namespaced, but filters based on version regardless of namespace. This lets you apply version policies consistently across your entire server hierarchy. + +## Declaring Versions + +Add a `version` parameter to any component decorator. FastMCP stores versions as strings and groups components by their identifier (name for tools and prompts, URI for resources). + +```python +from fastmcp import FastMCP + +mcp = FastMCP() + +@mcp.tool(version="1.0") +def process(data: str) -> str: + """Original processing.""" + return data.upper() + +@mcp.tool(version="2.0") +def process(data: str, mode: str = "default") -> str: + """Enhanced processing with mode selection.""" + if mode == "reverse": + return data[::-1].upper() + return data.upper() +``` + +Both versions are registered. When a client lists tools, they see only `process` with version 2.0 (the highest). When they invoke `process`, version 2.0 executes. The same pattern applies to resources and prompts. + +### Versioned vs Unversioned Components + +For any given component name, you must choose one approach: either version all implementations or version none of them. Mixing versioned and unversioned components with the same name raises an error at registration time. + +```python +from fastmcp import FastMCP + +mcp = FastMCP() + +@mcp.tool +def calculate(x: int, y: int) -> int: + """Unversioned tool.""" + return x + y + +@mcp.tool(version="2.0") # Raises ValueError +def calculate(x: int, y: int, z: int = 0) -> int: + """Cannot mix versioned with unversioned.""" + return x + y + z +``` + +The error message explains the conflict: "Cannot add versioned tool 'calculate' (version='2.0'): an unversioned tool with this name already exists. Either version all components or none." + +This restriction helps keep version filtering behavior predictable. + +Resources and prompts follow the same pattern. + +```python +@mcp.resource("config://app", version="1.0") +def config_v1() -> str: + return '{"format": "legacy"}' + +@mcp.resource("config://app", version="2.0") +def config_v2() -> str: + return '{"format": "modern", "schema": "v2"}' + +@mcp.prompt(version="1.0") +def summarize(text: str) -> str: + return f"Summarize: {text}" + +@mcp.prompt(version="2.0") +def summarize(text: str, style: str = "concise") -> str: + return f"Summarize in a {style} style: {text}" +``` + +### Version Discovery + +When clients list components, each versioned component includes metadata about all available versions. This lets clients discover what versions exist before deciding which to use. The `meta.fastmcp.versions` field contains all registered versions sorted from highest to lowest. + +```python +from fastmcp import Client + +async with Client(server) as client: + tools = await client.list_tools() + + for tool in tools: + if tool.meta: + fastmcp_meta = tool.meta.get("fastmcp", {}) + # Current version being returned (highest by default) + print(f"Version: {fastmcp_meta.get('version')}") + # All available versions for this component + print(f"Available: {fastmcp_meta.get('versions')}") +``` + +For a tool with versions `"1.0"` and `"2.0"`, listing returns the `2.0` implementation with `meta.fastmcp.version` set to `"2.0"` and `meta.fastmcp.versions` set to `["2.0", "1.0"]`. Unversioned components omit these fields entirely. + +This discovery mechanism enables clients to make informed decisions about which version to request, support graceful degradation when newer versions introduce breaking changes, or display version information in developer tools. + +## Requesting Specific Versions + +By default, clients receive and invoke the highest version of each component. When you need a specific version, FastMCP provides two approaches: the FastMCP client API for Python applications, and the MCP protocol mechanism for any MCP-compatible client. + +### FastMCP Client + +The FastMCP client's `call_tool` and `get_prompt` methods accept an optional `version` parameter. When specified, the server executes that exact version instead of the highest. + +```python +from fastmcp import Client + +async with Client(server) as client: + # Call the highest version (default behavior) + result = await client.call_tool("calculate", {"x": 1, "y": 2}) + + # Call a specific version + result_v1 = await client.call_tool("calculate", {"x": 1, "y": 2}, version="1.0") + + # Get a specific prompt version + prompt = await client.get_prompt("summarize", {"text": "..."}, version="1.0") +``` + +If the requested version doesn't exist, the server raises a `NotFoundError`. This ensures you get exactly what you asked for rather than silently falling back to a different version. + +### MCP Protocol + +For generic MCP clients that don't have built-in version support, pass the version through the `_meta` field in arguments. FastMCP servers extract the version from `_meta.fastmcp.version` before processing. + + +```json Tool Call Arguments +{ + "x": 1, + "y": 2, + "_meta": { + "fastmcp": { + "version": "1.0" + } + } +} +``` + +```json Prompt Arguments +{ + "text": "Summarize this document...", + "_meta": { + "fastmcp": { + "version": "1.0" + } + } +} +``` + + +The `_meta` field is part of the MCP request params, not arguments, so your component implementation never sees it. This convention allows version selection to work across any MCP client without requiring protocol changes. The FastMCP client handles this automatically when you pass the `version` parameter. + +## Version Comparison + +FastMCP compares versions to determine which is "highest" when multiple versions share an identifier. The comparison behavior depends on the version format. + +For [PEP 440](https://peps.python.org/pep-0440/) versions (like `"1.0"`, `"2.1.3"`, `"1.0a1"`), FastMCP uses semantic comparison where numeric segments are compared as numbers. + +```python +# PEP 440 versions compare semantically +"1" < "2" < "10" # Numeric order (not "1" < "10" < "2") +"1.9" < "1.10" # Numeric order (not "1.10" < "1.9") +"1.0a1" < "1.0b1" < "1.0" # Pre-releases sort before releases +``` + +For other formats (dates, custom schemes), FastMCP falls back to lexicographic string comparison. This works well for ISO dates and other naturally sortable formats. + +```python +# Non-PEP 440 versions compare as strings +"2025-01-15" < "2025-02-01" # ISO dates sort correctly +"alpha" < "beta" # Alphabetical order +``` + +The `v` prefix is stripped before comparison, so `"v1.0"` and `"1.0"` are treated as equal for sorting purposes. + +## Retrieving Specific Versions + +Server-side code can retrieve specific versions rather than just the highest. This is useful during migrations when you need to compare behavior between versions or access legacy implementations. + +The `get_tool`, `get_resource`, and `get_prompt` methods accept an optional `version` parameter. Without it, they return the highest version. With it, they return exactly that version. + +```python +from fastmcp import FastMCP + +mcp = FastMCP() + +@mcp.tool(version="1.0") +def add(x: int, y: int) -> int: + return x + y + +@mcp.tool(version="2.0") +def add(x: int, y: int) -> int: + return x + y + 100 # Different behavior + +# Get highest version (default) +tool = await mcp.get_tool("add") +print(tool.version) # "2.0" + +# Get specific version +tool_v1 = await mcp.get_tool("add", version="1.0") +print(tool_v1.version) # "1.0" +``` + +If the requested version doesn't exist, a `NotFoundError` is raised. + +## Removing Versions + +The `remove_tool`, `remove_resource`, and `remove_prompt` methods on the server's [local provider](/servers/providers/local) accept an optional `version` parameter that controls what gets removed. + +```python +# Remove ALL versions of a component +mcp.local_provider.remove_tool("calculate") + +# Remove only a specific version +mcp.local_provider.remove_tool("calculate", version="1.0") +``` + +When you remove a specific version, other versions remain registered. When you remove without specifying a version, all versions are removed. + +## Migration Workflow + +Versioning supports gradual migration when updating component behavior. You can deploy new versions alongside old ones, verify the new behavior works correctly, then clean up. + +When migrating an existing unversioned component to use versioning, start by assigning an initial version to your existing implementation. Then add the new version alongside it. + +```python +from fastmcp import FastMCP + +mcp = FastMCP() + +@mcp.tool(version="1.0") +def process_data(input: str) -> str: + """Original implementation, now versioned.""" + return legacy_process(input) + +@mcp.tool(version="2.0") +def process_data(input: str, options: dict | None = None) -> str: + """Updated implementation with new options parameter.""" + return modern_process(input, options or {}) +``` + +Clients automatically see version 2.0 (the highest). During the transition, your server code can still access the original implementation via `get_tool("process_data", version="1.0")`. + +Once the migration is complete, remove the old version. + +```python +mcp.local_provider.remove_tool("process_data", version="1.0") +``` diff --git a/docs/servers/visibility.mdx b/docs/servers/visibility.mdx new file mode 100644 index 000000000..509bd7068 --- /dev/null +++ b/docs/servers/visibility.mdx @@ -0,0 +1,452 @@ +--- +title: Component Visibility +sidebarTitle: Visibility +description: Control which components are available to clients +icon: toggle-on +tag: NEW +--- + +import { VersionBadge } from '/snippets/version-badge.mdx' + + + +Components can be dynamically enabled or disabled at runtime. A disabled tool disappears from listings and cannot be called. This enables runtime access control, feature flags, and context-aware component exposure. + +## Component Visibility + +Every FastMCP server provides `enable()` and `disable()` methods for controlling component availability. + +### Disabling Components + +The `disable()` method marks components as disabled. Disabled components are filtered out from all client queries. + +```python +from fastmcp import FastMCP + +mcp = FastMCP("Server") + +@mcp.tool(tags={"admin"}) +def delete_everything() -> str: + """Delete all data.""" + return "Deleted" + +@mcp.tool(tags={"admin"}) +def reset_system() -> str: + """Reset the system.""" + return "Reset" + +@mcp.tool +def get_status() -> str: + """Get system status.""" + return "OK" + +# Disable admin tools +mcp.disable(tags={"admin"}) + +# Clients only see: get_status +``` + +### Enabling Components + +The `enable()` method re-enables previously disabled components. + +```python +# Re-enable admin tools +mcp.enable(tags={"admin"}) + +# Clients now see all three tools +``` + +## Keys and Tags + +Visibility filtering works with two identifiers: keys (for specific components) and tags (for groups). + +### Component Keys + +Every component has a unique key in the format `{type}:{identifier}`. + +| Component | Key Format | Example | +|-----------|------------|---------| +| Tool | `tool:{name}` | `tool:delete_everything` | +| Resource | `resource:{uri}` | `resource:data://config` | +| Template | `template:{uri}` | `template:file://{path}` | +| Prompt | `prompt:{name}` | `prompt:analyze` | + +Use keys to target specific components. + +```python +# Disable a specific tool +mcp.disable(keys={"tool:delete_everything"}) + +# Disable multiple specific components +mcp.disable(keys={"tool:reset_system", "resource:data://secrets"}) +``` + +### Tags + +Tags group components for bulk operations. Define tags when creating components, then filter by them. + +```python +from fastmcp import FastMCP + +mcp = FastMCP("Server") + +@mcp.tool(tags={"public", "read"}) +def get_data() -> str: + return "data" + +@mcp.tool(tags={"admin", "write"}) +def set_data(value: str) -> str: + return f"Set: {value}" + +@mcp.tool(tags={"admin", "dangerous"}) +def delete_data() -> str: + return "Deleted" + +# Disable all admin tools +mcp.disable(tags={"admin"}) + +# Disable all dangerous tools (some overlap with admin) +mcp.disable(tags={"dangerous"}) +``` + +A component is disabled if it has **any** of the disabled tags. The component doesn't need all the tags; one match is enough. + +### Combining Keys and Tags + +You can specify both keys and tags in a single call. The filters combine additively. + +```python +# Disable specific tools AND all dangerous-tagged components +mcp.disable(keys={"tool:debug_info"}, tags={"dangerous"}) +``` + +## Allowlist Mode + +By default, visibility filtering uses blocklist mode: everything is enabled unless explicitly disabled. The `only=True` parameter switches to allowlist mode, where **only** specified components are enabled. + +```python +from fastmcp import FastMCP + +mcp = FastMCP("Server") + +@mcp.tool(tags={"safe"}) +def read_only_operation() -> str: + return "Read" + +@mcp.tool(tags={"safe"}) +def list_items() -> list[str]: + return ["a", "b", "c"] + +@mcp.tool(tags={"dangerous"}) +def delete_all() -> str: + return "Deleted" + +@mcp.tool +def untagged_tool() -> str: + return "Untagged" + +# Only enable safe tools - everything else is disabled +mcp.enable(tags={"safe"}, only=True) + +# Clients see: read_only_operation, list_items +# Disabled: delete_all, untagged_tool +``` + +Allowlist mode is useful for restrictive environments where you want to explicitly opt-in components rather than opt-out. + +### Allowlist Behavior + +When you call `enable(only=True)`: + +1. Default visibility state switches to "disabled" +2. Previous allowlists are cleared +3. Only specified keys/tags become enabled + +```python +# Start fresh - only enable these specific tools +mcp.enable(keys={"tool:safe_read", "tool:safe_write"}, only=True) + +# Later, switch to a different allowlist +mcp.enable(tags={"production"}, only=True) +``` + +### Ordering and Overrides + +Later `enable()` and `disable()` calls override earlier ones. This lets you create broad rules with specific exceptions. + +```python +mcp.enable(tags={"api"}, only=True) # Allow all api-tagged +mcp.disable(keys={"tool:api_admin"}) # Later disable overrides for this tool + +# api_admin is disabled because the later disable() overrides the allowlist +``` + +You can always re-enable something that was disabled by adding another `enable()` call after it. + +## Server vs Provider + +Visibility state operates at two levels: the server and individual providers. + +### Server-Level + +Server-level visibility state applies to all components from all providers. When you call `mcp.enable()` or `mcp.disable()`, you're filtering the final view that clients see. + +```python +from fastmcp import FastMCP + +main = FastMCP("Main") +main.mount(sub_server, namespace="api") + +@main.tool(tags={"internal"}) +def local_debug() -> str: + return "Debug" + +# Disable internal tools from ALL sources +main.disable(tags={"internal"}) +``` + +### Provider-Level + +Each provider can add its own visibility transforms. These run before server-level transforms, so the server can override provider-level disables. + +```python +from fastmcp import FastMCP +from fastmcp.server.providers import LocalProvider + +# Create provider with visibility control +admin_tools = LocalProvider() + +@admin_tools.tool(tags={"admin"}) +def admin_action() -> str: + return "Admin" + +@admin_tools.tool +def regular_action() -> str: + return "Regular" + +# Disable at provider level +admin_tools.disable(tags={"admin"}) + +# Server can override if needed +mcp = FastMCP("Server", providers=[admin_tools]) +mcp.enable(names={"admin_action"}) # Re-enables despite provider disable +``` + +Provider-level transforms are useful for setting default visibility that servers can selectively override. + +### Layered Transforms + +Provider transforms run first, then server transforms. Later transforms override earlier ones, so the server has final say. + +```python +from fastmcp import FastMCP +from fastmcp.server.providers import LocalProvider + +provider = LocalProvider() + +@provider.tool(tags={"feature", "beta"}) +def new_feature() -> str: + return "New" + +# Provider enables feature-tagged +provider.enable(tags={"feature"}, only=True) + +# Server disables beta-tagged (runs after provider) +mcp = FastMCP("Server", providers=[provider]) +mcp.disable(tags={"beta"}) + +# new_feature is disabled (server's later disable overrides provider's enable) +``` + +## Per-Session Visibility + +Server-level visibility changes affect all connected clients simultaneously. When you need different clients to see different components, use per-session visibility instead. + +Session visibility lets individual sessions customize their view of available components. When a tool calls `ctx.enable_components()` or `ctx.disable_components()`, those rules apply only to the current session. Other sessions continue to see the global defaults. This enables patterns like progressive disclosure, role-based access, and on-demand feature activation. + +```python +from fastmcp import FastMCP +from fastmcp.server.context import Context + +mcp = FastMCP("Session-Aware Server") + +@mcp.tool(tags={"premium"}) +def premium_analysis(data: str) -> str: + """Advanced analysis available to premium users.""" + return f"Premium analysis of: {data}" + +@mcp.tool +async def unlock_premium(ctx: Context) -> str: + """Unlock premium features for this session.""" + await ctx.enable_components(tags={"premium"}) + return "Premium features unlocked" + +@mcp.tool +async def reset_features(ctx: Context) -> str: + """Reset to default feature set.""" + await ctx.reset_visibility() + return "Features reset to defaults" + +# Premium tools are disabled globally by default +mcp.disable(tags={"premium"}) +``` + +All sessions start with `premium_analysis` hidden. When a session calls `unlock_premium`, that session gains access to premium tools while other sessions remain unaffected. Calling `reset_features` returns the session to the global defaults. + +### How Session Rules Work + +Session rules override global transforms. When listing components, FastMCP first applies global enable/disable rules, then applies session-specific rules on top. Rules within a session accumulate, and later rules override earlier ones for the same component. + +```python +@mcp.tool +async def customize_session(ctx: Context) -> str: + # Enable finance tools for this session + await ctx.enable_components(tags={"finance"}) + + # Also enable admin tools + await ctx.enable_components(tags={"admin"}) + + # Later: disable a specific admin tool + await ctx.disable_components(names={"dangerous_admin_tool"}) + + return "Session customized" +``` + +Each call adds a rule to the session. The `dangerous_admin_tool` ends up disabled because its disable rule was added after the admin enable rule. + +### Filter Criteria + +The session visibility methods accept the same filter criteria as `server.enable()` and `server.disable()`: + +| Parameter | Description | +|-----------|-------------| +| `names` | Component names or URIs to match | +| `keys` | Component keys (e.g., `{"tool:my_tool"}`) | +| `tags` | Tags to match (component must have at least one) | +| `version` | Version specification to match | +| `components` | Component types (`{"tool"}`, `{"resource"}`, `{"prompt"}`, `{"template"}`) | +| `match_all` | If `True`, matches all components regardless of other criteria | + +```python +from fastmcp.utilities.versions import VersionSpec + +@mcp.tool +async def enable_recent_tools(ctx: Context) -> str: + """Enable only tools from version 2.0.0 or later.""" + await ctx.enable_components( + version=VersionSpec(gte="2.0.0"), + components={"tool"} + ) + return "Recent tools enabled" +``` + +### Automatic Notifications + +When session visibility changes, FastMCP automatically sends notifications to that session. Clients receive `ToolListChangedNotification`, `ResourceListChangedNotification`, and `PromptListChangedNotification` so they can refresh their component lists. These notifications go only to the affected session. + +When you specify the `components` parameter, FastMCP optimizes by sending only the relevant notifications: + +```python +# Only sends ToolListChangedNotification +await ctx.enable_components(tags={"finance"}, components={"tool"}) + +# Sends all three notifications (no components filter) +await ctx.enable_components(tags={"finance"}) +``` + +### Namespace Activation Pattern + +A common pattern organizes tools into namespaces using tag prefixes, disables them globally, then provides activation tools that unlock namespaces on demand: + +```python +from fastmcp import FastMCP +from fastmcp.server.context import Context + +server = FastMCP("Multi-Domain Assistant") + +# Finance namespace +@server.tool(tags={"namespace:finance"}) +def analyze_portfolio(symbols: list[str]) -> str: + return f"Analysis for: {', '.join(symbols)}" + +@server.tool(tags={"namespace:finance"}) +def get_market_data(symbol: str) -> dict: + return {"symbol": symbol, "price": 150.25} + +# Admin namespace +@server.tool(tags={"namespace:admin"}) +def list_users() -> list[str]: + return ["alice", "bob", "charlie"] + +# Activation tools - always visible +@server.tool +async def activate_finance(ctx: Context) -> str: + await ctx.enable_components(tags={"namespace:finance"}) + return "Finance tools activated" + +@server.tool +async def activate_admin(ctx: Context) -> str: + await ctx.enable_components(tags={"namespace:admin"}) + return "Admin tools activated" + +@server.tool +async def deactivate_all(ctx: Context) -> str: + await ctx.reset_visibility() + return "All namespaces deactivated" + +# Disable namespace tools globally +server.disable(tags={"namespace:finance", "namespace:admin"}) +``` + +Sessions start seeing only the activation tools. Calling `activate_finance` reveals finance tools for that session only. Multiple namespaces can be activated independently, and `deactivate_all` returns to the initial state. + +### Method Reference + +- **`await ctx.enable_components(...) -> None`**: Enable matching components for this session +- **`await ctx.disable_components(...) -> None`**: Disable matching components for this session +- **`await ctx.reset_visibility() -> None`**: Clear all session rules, returning to global defaults + +## Client Notifications + +When visibility state changes, FastMCP automatically notifies connected clients. Clients supporting the MCP notification protocol receive `list_changed` events and can refresh their component lists. + +This happens automatically. You don't need to trigger notifications manually. + +```python +# This automatically notifies clients +mcp.disable(tags={"maintenance"}) + +# Clients receive: tools/list_changed, resources/list_changed, etc. +``` + +## Filtering Logic + +Understanding the filtering logic helps when debugging visibility state issues. + +The `is_enabled()` function checks a component's internal metadata: + +1. If the component has `meta.fastmcp._internal.visibility = False`, it's disabled +2. If the component has `meta.fastmcp._internal.visibility = True`, it's enabled +3. If no visibility state is set, the component is enabled by default + +When multiple `enable()` and `disable()` calls are made, transforms are applied in order. **Later transforms override earlier ones**, so the last matching transform wins. + +## The Visibility Transform + +Under the hood, `enable()` and `disable()` add `Visibility` transforms to the server or provider. The `Visibility` transform marks components with visibility metadata, and the server applies the final filter after all provider and server transforms complete. + +```python +from fastmcp import FastMCP +from fastmcp.server.transforms import Visibility + +mcp = FastMCP("Server") + +# Using the convenience method (recommended) +mcp.disable(names={"secret_tool"}) + +# Equivalent to: +mcp.add_transform(Visibility(False, names={"secret_tool"})) +``` + +Server-level transforms override provider-level transforms. If a component is disabled at the provider level but enabled at the server level, the server-level `enable()` can re-enable it. diff --git a/docs/snippets/local-focus.mdx b/docs/snippets/local-focus.mdx new file mode 100644 index 000000000..4da6ac752 --- /dev/null +++ b/docs/snippets/local-focus.mdx @@ -0,0 +1,7 @@ +export const LocalFocusTip = () => { + return ( + + This integration focuses on running local FastMCP server files with STDIO transport. For remote servers running with HTTP or SSE transport, use your client's native configuration - FastMCP's integrations focus on simplifying the complex local setup with dependencies and uv commands. + + ); +}; \ No newline at end of file diff --git a/docs/snippets/version-badge.mdx b/docs/snippets/version-badge.mdx new file mode 100644 index 000000000..3442524b8 --- /dev/null +++ b/docs/snippets/version-badge.mdx @@ -0,0 +1,7 @@ +export const VersionBadge = ({ version }) => { + return ( + + New in version {version} + + ); +}; \ No newline at end of file diff --git a/docs/snippets/youtube-embed.mdx b/docs/snippets/youtube-embed.mdx new file mode 100644 index 000000000..1c36e6cfd --- /dev/null +++ b/docs/snippets/youtube-embed.mdx @@ -0,0 +1,12 @@ +export const YouTubeEmbed = ({ videoId, title }) => { + return ( + " + html = create_info_box(xss_content) + assert "<iframe" in html + assert "