WorkOS 🤝 FastMCP

New in version 2.12.0 Secure your FastMCP server with WorkOS Connect authentication. This integration uses the OAuth Proxy pattern to handle authentication through WorkOS Connect while maintaining compatibility with MCP clients.

This guide covers WorkOS Connect applications. For Dynamic Client Registration (DCR) with AuthKit, see the AuthKit integration instead.

Configuration

Prerequisites

Before you begin, you will need:

A WorkOS Account with access to create OAuth Apps
Your FastMCP server’s URL (can be localhost for development, e.g., http://localhost:8000)

Step 1: Create a WorkOS OAuth App

Create an OAuth App in your WorkOS dashboard to get the credentials needed for authentication:

Create OAuth Application

In your WorkOS dashboard:

Navigate to Applications
Click Create Application
Select OAuth Application
Name your application

Get Credentials

In your OAuth application settings:

Copy your Client ID (starts with client_)
Click Generate Client Secret and save it securely
Copy your AuthKit Domain (e.g., https://your-app.authkit.app)

Configure Redirect URI

In the Redirect URIs section:

Add: http://localhost:8000/auth/callback (for development)
For production, add your server’s public URL + /auth/callback

The callback URL must match exactly. The default path is /auth/callback, but you can customize it using the redirect_path parameter.

Step 2: FastMCP Configuration

Create your FastMCP server using the WorkOSProvider:

server.py

from fastmcp import FastMCP
from fastmcp.server.auth.providers.workos import WorkOSProvider

# Configure WorkOS OAuth
auth = WorkOSProvider(
    client_id="client_YOUR_CLIENT_ID",
    client_secret="YOUR_CLIENT_SECRET",
    authkit_domain="https://your-app.authkit.app",
    base_url="http://localhost:8000",
    required_scopes=["openid", "profile", "email"]
)

mcp = FastMCP("WorkOS Protected Server", auth=auth)

@mcp.tool
def protected_tool(message: str) -> str:
    """This tool requires authentication."""
    return f"Authenticated user says: {message}"

if __name__ == "__main__":
    mcp.run(transport="http", port=8000)

Testing

Running the Server

Start your FastMCP server with HTTP transport to enable OAuth flows:

fastmcp run server.py --transport http --port 8000

Your server is now running and protected by WorkOS OAuth authentication.

Testing with a Client

Create a test client that authenticates with your WorkOS-protected server:

client.py

from fastmcp import Client
import asyncio

async def main():    
    # The client will automatically handle WorkOS OAuth
    async with Client("http://localhost:8000/mcp", auth="oauth") as client:
        # First-time connection will open WorkOS login in your browser
        print("✓ Authenticated with WorkOS!")
        
        # Test the protected tool
        result = await client.call_tool("protected_tool", {"message": "Hello!"})
        print(result)

if __name__ == "__main__":
    asyncio.run(main())

When you run the client for the first time:

Your browser will open to WorkOS’s authorization page
After you authorize the app, you’ll be redirected back
The client receives the token and can make authenticated requests

The client caches tokens locally, so you won’t need to re-authenticate for subsequent runs unless the token expires or you explicitly clear the cache.

Production Configuration

New in version 2.13.0 For production deployments with persistent token management across server restarts, configure jwt_signing_key, and client_storage:

server.py

import os
from fastmcp import FastMCP
from fastmcp.server.auth.providers.workos import WorkOSProvider
from key_value.aio.stores.redis import RedisStore
from key_value.aio.wrappers.encryption import FernetEncryptionWrapper
from cryptography.fernet import Fernet

# Production setup with encrypted persistent token storage
auth = WorkOSProvider(
    client_id="client_YOUR_CLIENT_ID",
    client_secret="YOUR_CLIENT_SECRET",
    authkit_domain="https://your-app.authkit.app",
    base_url="https://your-production-domain.com",
    required_scopes=["openid", "profile", "email"],

    # Production token management
    jwt_signing_key=os.environ["JWT_SIGNING_KEY"],
    client_storage=FernetEncryptionWrapper(
        key_value=RedisStore(
            host=os.environ["REDIS_HOST"],
            port=int(os.environ["REDIS_PORT"])
        ),
        fernet=Fernet(os.environ["STORAGE_ENCRYPTION_KEY"])
    )
)

mcp = FastMCP(name="Production WorkOS App", auth=auth)

Parameters (jwt_signing_key and client_storage) work together to ensure tokens and client registrations survive server restarts. Wrap your storage in FernetEncryptionWrapper to encrypt sensitive OAuth tokens at rest - without it, tokens are stored in plaintext. Store secrets in environment variables and use a persistent storage backend like Redis for distributed deployments.For complete details on these parameters, see the OAuth Proxy documentation.

Configuration Options

client_id

required

WorkOS OAuth application client ID

client_secret

required

WorkOS OAuth application client secret

authkit_domain

required

Your WorkOS AuthKit domain URL (e.g., https://your-app.authkit.app)

base_url

required

Your FastMCP server’s public URL

required_scopes

default:"[]"

OAuth scopes to request

redirect_path

default:"/auth/callback"

OAuth callback path

timeout_seconds

default:"10"

API request timeout

Get Started

Servers

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WorkOS 🤝 FastMCP

Configuration

Prerequisites

Step 1: Create a WorkOS OAuth App

Step 2: FastMCP Configuration

Testing

Running the Server

Testing with a Client

Production Configuration

Configuration Options

​Configuration

​Prerequisites

​Step 1: Create a WorkOS OAuth App

​Step 2: FastMCP Configuration

​Testing

​Running the Server

​Testing with a Client

​Production Configuration

​Configuration Options

Configuration

Prerequisites

Step 1: Create a WorkOS OAuth App

Step 2: FastMCP Configuration

Testing

Running the Server

Testing with a Client

Production Configuration

Configuration Options