A zero-configuration tool for automatically exposing FastAPI endpoints as Model Context Protocol (MCP) tools.

• Direct integration - Mount an MCP server directly to your FastAPI app
• Zero configuration required - just point it at your FastAPI app and it works
• Automatic discovery of all FastAPI endpoints and conversion to MCP tools
• Preserving schemas of your request models and response models
• Preserve documentation of all your endpoints, just as it is in Swagger
• Flexible deployment - Mount your MCP server to the same app, or deploy separately
• ASGI transport - Uses FastAPI's ASGI interface directly by default for efficient communication

We recommend using uv, a fast Python package installer:

uv add fastapi-mcp

Alternatively, you can install with pip:

pip install fastapi-mcp

The simplest way to use FastAPI-MCP is to add an MCP server directly to your FastAPI application:

from fastapi import FastAPI from fastapi_mcp import FastApiMCP app = FastAPI() mcp = FastApiMCP(app) # Mount the MCP server directly to your FastAPI app mcp.mount()

That's it! Your auto-generated MCP server is now available at https://app.base.url/mcp.

FastAPI-MCP uses the operation_id from your FastAPI routes as the MCP tool names. When you don't specify an operation_id, FastAPI auto-generates one, but these can be cryptic.

Compare these two endpoint definitions:

# Auto-generated operation_id (something like "read_user_users__user_id__get") @app.get("/users/{user_id}") async def read_user(user_id: int): return {"user_id": user_id} # Explicit operation_id (tool will be named "get_user_info") @app.get("/users/{user_id}", operation_id="get_user_info") async def read_user(user_id: int): return {"user_id": user_id}

For clearer, more intuitive tool names, we recommend adding explicit operation_id parameters to your FastAPI route definitions.

To find out more, read FastAPI's official docs about advanced config of path operations.

FastAPI-MCP provides several ways to customize and control how your MCP server is created and configured. Here are some advanced usage patterns:

from fastapi import FastAPI from fastapi_mcp import FastApiMCP app = FastAPI() mcp = FastApiMCP( app, name="My API MCP", describe_all_responses=True, # Include all possible response schemas in tool descriptions describe_full_response_schema=True # Include full JSON schema in tool descriptions ) mcp.mount()

You can control which FastAPI endpoints are exposed as MCP tools using Open API operation IDs or tags:

from fastapi import FastAPI from fastapi_mcp import FastApiMCP app = FastAPI() # Only include specific operations mcp = FastApiMCP( app, include_operations=["get_user", "create_user"] ) # Exclude specific operations mcp = FastApiMCP( app, exclude_operations=["delete_user"] ) # Only include operations with specific tags mcp = FastApiMCP( app, include_tags=["users", "public"] ) # Exclude operations with specific tags mcp = FastApiMCP( app, exclude_tags=["admin", "internal"] ) # Combine operation IDs and tags (include mode) mcp = FastApiMCP( app, include_operations=["user_login"], include_tags=["public"] ) mcp.mount()

Notes on filtering:

• You cannot use both include_operations and exclude_operations at the same time
• You cannot use both include_tags and exclude_tags at the same time
• You can combine operation filtering with tag filtering (e.g., use include_operations with include_tags)
• When combining filters, a greedy approach will be taken. Endpoints matching either criteria will be included

You are not limited to serving the MCP on the same FastAPI app from which it was created.

You can create an MCP server from one FastAPI app, and mount it to a different app:

from fastapi import FastAPI from fastapi_mcp import FastApiMCP # Your API app api_app = FastAPI() # ... define your API endpoints on api_app ... # A separate app for the MCP server mcp_app = FastAPI() # Create MCP server from the API app mcp = FastApiMCP(api_app) # Mount the MCP server to the separate app mcp.mount(mcp_app) # Now you can run both apps separately: # uvicorn main:api_app --host api-host --port 8001 # uvicorn main:mcp_app --host mcp-host --port 8000

If you add endpoints to your FastAPI app after creating the MCP server, you'll need to refresh the server to include them:

from fastapi import FastAPI from fastapi_mcp import FastApiMCP app = FastAPI() # ... define initial endpoints ... # Create MCP server mcp = FastApiMCP(app) mcp.mount() # Add new endpoints after MCP server creation @app.get("/new/endpoint/", operation_id="new_endpoint") async def new_endpoint(): return {"message": "Hello, world!"} # Refresh the MCP server to include the new endpoint mcp.setup_server()

FastAPI-MCP uses ASGI transport by default, which means it communicates directly with your FastAPI app without making HTTP requests. This is more efficient and doesn't require a base URL.

It's not even necessary that the FastAPI server will run. See the examples folder for more.

If you need to specify a custom base URL or use a different transport method, you can provide your own httpx.AsyncClient:

import httpx from fastapi import FastAPI from fastapi_mcp import FastApiMCP app = FastAPI() # Use a custom HTTP client with a specific base URL custom_client = httpx.AsyncClient( base_url="https://api.example.com", timeout=30.0 ) mcp = FastApiMCP( app, http_client=custom_client ) mcp.mount()

See the examples directory for complete examples.

Once your FastAPI app with MCP integration is running, you can connect to it with any MCP client supporting SSE, such as Cursor:

1. Run your application.

2. In Cursor -> Settings -> MCP, use the URL of your MCP server endpoint (e.g., http://localhost:8000/mcp) as sse.

3. Cursor will discover all available tools and resources automatically.

If your MCP client does not support SSE, for example Claude Desktop:

1. Run your application.

2. Install mcp-proxy, for example: uv tool install mcp-proxy.

3. Add in Claude Desktop MCP config file (claude_desktop_config.json):

On Windows:

{ "mcpServers": { "my-api-mcp-proxy": { "command": "mcp-proxy", "args": ["http://127.0.0.1:8000/mcp"] } } }

On MacOS:

{ "mcpServers": { "my-api-mcp-proxy": { "command": "/Full/Path/To/Your/Executable/mcp-proxy", "args": ["http://127.0.0.1:8000/mcp"] } } }

Find the path to mcp-proxy by running in Terminal: which mcp-proxy.

4. Claude Desktop will discover all available tools and resources automatically

Thank you for considering contributing to FastAPI-MCP! We encourage the community to post Issues and Pull Requests.

Before you get started, please see our Contribution Guide.

Join MCParty Slack community to connect with other MCP enthusiasts, ask questions, and share your experiences with FastAPI-MCP.

• Python 3.10+ (Recommended 3.12)
• uv

MIT License. Copyright (c) 2024 Tadata Inc.