FastAPI-MCP

A zero-configuration tool for integrating Model Context Protocol (MCP) servers with FastAPI applications.

Features

• 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
• Type-safe conversion from FastAPI endpoints to MCP tools
• Documentation preservation from FastAPI to MCP
• Custom tools - Add custom MCP tools alongside your API endpoints

Installation

We recommend using uv, a fast Python package installer:

uv add fastapi-mcp

Alternatively, you can install with pip:

pip install fastapi-mcp

For detailed installation instructions and alternative methods, see INSTALL.md.

Basic Usage

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 add_mcp_server

# Your FastAPI app
app = FastAPI()

# Mount the MCP server to your app
add_mcp_server(
    app,                    # Your FastAPI app
    mount_path="/mcp",      # Where to mount the MCP server
    name="My API MCP",      # Name for the MCP server
)

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

Advanced Usage

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 add_mcp_server

app = FastAPI()

mcp_server = add_mcp_server(
    app,                                    # Your FastAPI app
    mount_path="/mcp",                      # Where to mount the MCP server
    name="My API MCP",                      # Name for the MCP server
    describe_all_responses=True,            # False by default. Include all possible response schemas in tool descriptions, instead of just the successful response.
    describe_full_response_schema=True      # False by default. Include full JSON schema in tool descriptions, instead of just an LLM-friendly response example.
)

# Add custom tools in addition to existing APIs.
@mcp_server.tool()
async def get_server_time() -> str:
    """Get the current server time."""
    from datetime import datetime
    return datetime.now().isoformat()

Examples

See the examples directory for complete examples.

Simple integration example:

from fastapi import FastAPI
from fastapi_mcp import add_mcp_server

app = FastAPI(title="Simple API")

@app.get("/hello/{name}")
async def hello(name: str):
    """Say hello to someone"""
    return {"message": f"Hello, {name}!"}

# Add MCP server
mcp_server = add_mcp_server(app, mount_path="/mcp")

# Optionally add custom tools
@mcp_server.tool()
async def get_current_time():
    """Get the current server time"""
    from datetime import datetime
    return datetime.now().isoformat()

if __name__ == "__main__":
    import uvicorn
    uvicorn.run(app, host="127.0.0.1", port=8000)

Connecting to the MCP Server

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

1. Run your application
2. In Claude, use the URL of your MCP server endpoint (e.g., http://localhost:8000/mcp)
3. Claude will discover all available tools and resources automatically

Development and Contributing

If you're interested in contributing to FastAPI-MCP:

# Clone the repository
git clone https://github.com/tadata-org/fastapi_mcp.git
cd fastapi_mcp

# Create a virtual environment and install dependencies with uv
uv venv
source .venv/bin/activate  # On Windows: .venv\Scripts\activate
uv add -e ".[dev]"

# Run tests
uv run pytest

For more details about contributing, see CONTRIBUTING.md.

Requirements

• Python 3.10+
• uv

License

MIT License. Copyright (c) 2024 Tadata Inc.

About

Developed and maintained by Tadata Inc.