WebMCP plugin

Agent skill for making websites WebMCP-compatible: ping-pong which paths to expose, then ship Declarative vs Imperative vs Bridge.

Surface support today: Codex, Chrome 149 and Edge 150 origin trials, experimental Brave Leo; Firefox and Safari are still positions-only (implementation status).

The repo is packaged as a plugin for Claude Code, Codex, and as a skills.sh skill.

Install

Cursor / skills.sh

npx skills add alpic-ai/webmcp --skill webmcp

Claude Code

claude plugin marketplace add alpic-ai/webmcp
claude plugin install webmcp@webmcp

Validate before submitting:

claude plugin validate .

Codex

Add this repo as a marketplace source, then install WebMCP from the Plugins Directory.

codex plugin marketplace add alpic-ai/webmcp

What’s inside

skills/webmcp/
├── SKILL.md                         # Ping-pong + Declarative vs Imperative vs Bridge
└── references/
    ├── strategies.md                # Declarative vs Imperative vs Bridge
    ├── declarative-forms.md         # toolname / tooldescription on existing forms
    ├── tool-design.md               # Dedicated imperative paths
    ├── runtime.md                   # Native vs polyfill, iframes
    ├── frameworks.md                # Vanilla, React/usewebmcp, Next, Vue
    ├── proxy-existing-mcp.md        # webmcp-proxy for existing MCP servers
    ├── verify.md                    # Chrome DevTools MCP dogfood
    └── security.md                  # Session inheritance, injection

Why this exists

1. Spec-aligned — document.modelContext first, navigator fallback
2. Path-first — agent ping-pongs strategies and paths before coding
3. Three strategies — Declarative vs Imperative vs Bridge (webmcp-proxy)
4. Verification-first — Chrome DevTools MCP list_webmcp_tools / execute_webmcp_tool

Example prompts after install

• “Make this site WebMCP compatible — help me choose what to expose”
• “Annotate our existing forms as WebMCP tools”
• “Put our MCP server on the website with webmcp-proxy”
• “Expose checkout as one dedicated WebMCP tool from step 1”

References

• W3C WebMCP draft
• Chrome Imperative API
• Chrome Declarative API
• Chrome best practices
• webmcp-proxy
• usewebmcp

License

MIT