Skip to main content

Documentation Index

Fetch the complete documentation index at: https://gofastmcp.com/llms.txt

Use this file to discover all available pages before exploring further.

New in version 3.1.0 This guide shows you how to secure your FastMCP server using PropelAuth, a complete authentication and user management solution. This integration uses the 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 account
  2. Your FastMCP server’s base URL (can be localhost for development, e.g., http://localhost:8000)

​
Step 1: Configure PropelAuth

1

Enable MCP Authentication

Navigate to the MCP section in your PropelAuth dashboard, click Enable MCP, and choose which environments to enable it for (Test, Staging, Prod).
2

Configure Allowed MCP Clients

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.
3

Configure Scopes

Under MCP > Scopes, define the permissions available to MCP clients (e.g., read:user_data).
4

Choose How Users Create OAuth Clients

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.
5

Generate Introspection Credentials

Go to MCP > Request Validation and click Create Credentials. Note the Client ID and Client Secret - you’ll need these to validate tokens.
6

Note Your Auth URL

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.

​
Step 2: Environment Setup

Create a .env file with your PropelAuth configuration: 
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:
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: 
fastmcp run server.py --transport http --port 8000
Then use a FastMCP client to verify authentication works: 
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:
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:
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)