MPC with Transport streamable-http not sending custom headers.

[Bernardoow]

Hi everyone, good morning!

I have an app that relies on Authorization and a custom header for AuthN/AuthZ.

I’m using the fastapi-mcp [1] library along with an Agent that uses MCP Tools.

The issue is: when I use the tool with Agno, it only sends the Authorization header, but not my custom one.

Is there a way to configure or send additional custom headers?

Thanks in advance!

MCP

      server_params = StreamableHTTPClientParams(
            url=SERVER_URL,
            headers={
                "Authorization": "Bearer YOUR_ACCESS_TOKEN",
                "x-operation": "123",
                "X-operation": "value",
                "x_operation": "1234",
                "X_operation": "value22",
                "Xoperation": "value2",
                "X-Request-ID": "teste",
            },
        )
        self.mcp_tools = MCPTools(
            server_params=server_params,
            transport="streamable-http",
            env={
                "x-operation": "123",
                "X-operation": "value",
                "x_operation": "1234",
                "X_operation": "value22",
                "Xoperation": "value2",
                "X-Request-ID": "teste",
            },
        )

FastAPI app

app = FastAPI(title="Users API", version="1.0.0")

@app.get("/users", response_model=list[User])
def get_users(
    request: Request,
    x_custom_header: Annotated[str | None, Header()] = None,
    x_operation: Annotated[str | None, Header()] = None,
    X_Request_ID: Annotated[str | None, Header()] = None,
) -> list[User]:
    teste = User(
        username=f"test{request.headers.items()}",
        full_name=f"Test User F{x_custom_header}F F{x_operation}F {X_Request_ID}",
    )
    return [teste]

mcp = FastApiMCP(app, describe_all_responses=True)

mcp.mount_http()
    

AGNO Response

Here is the retrieved user data from the API:                                             ┃
┃                                                                                           ┃
┃                                     User Information                                      ┃
┃                                                                                           ┃
┃  • Username: test[('host', 'apiserver'), ('accept', '*/*'), ('accept-encoding', 'gzip,    ┃
┃    deflate'), ('connection', 'keep-alive'), ('user-agent', 'python-httpx/0.28.1'),        ┃
┃    ('authorization', 'Bearer YOUR_ACCESS_TOKEN')]                                         ┃                                                         ┃
┃  • Full Name: Test User FNoneF FNoneF None                                                ┃

Curl request and response

curl -X GET "http://localhost:8001/users" -H "x_custom_header: your-value" -H "x_operation: your-operation" -H "X_Request_ID: your-request-id"
[{"username":"test[('host', 'localhost:8001'), ('user-agent', 'curl/7.81.0'), ('accept', '*/*'), ('x_custom_header', 'your-value'), ('x_operation', 'your-operation'), ('x_request_id', 'your-request-id')]","full_name":"Test User FNoneF FNoneF None"}]%           

pyproject.toml

[project]
name = "agent"
version = "0.1.0"
description = "Add your description here"
readme = "README.md"
requires-python = ">=3.13"
dependencies = [
    "agno>=v1.7.12",
    "anthropic>=0.59.0",
    "fastapi[standard]>=0.116.1",
    "google-genai>=1.27.0",
    "mcp>=1.12.2",
    "ollama>=0.5.1",
    "openai>=1.97.1",
    "pgvector>=0.4.1",
    "psycopg[binary]>=3.2.9",
    "sqlalchemy>=2.0.41",
]

[Bernardoow]

I found the problem. I need add more headers at the fastapi-mcp.

https://github.com/tadata-org/fastapi_mcp/blob/e5cad13cabfc725bbcb047e526816d887d96da62/fastapi_mcp/server.py#L78