Clerk Authentication MCP server

This Cloudflare Worker allows Claude Desktop to interact with Clerk-protected APIs by acting as a Model Context Protocol (MCP) server that can impersonate a Clerk user. This creates a secure bridge between Claude and your authentication-protected application endpoints.

How It Works

For any application using Clerk for authentication, you can deploy a Cloudflare Worker that functions as an MCP Server. This worker impersonates a Clerk user, allowing Claude to interact with protected routes.

Installation Instructions

Prerequisites

Before setting up the MCP server, ensure you have:

• An active Cloudflare account
• Clerk authentication set up in your application
• Claude Desktop installed

Deployment Steps

1. Deploy the Cloudflare MCP server to Claude Desktop by following the instructions in the Cloudflare Workers MCP repository.

2. Configure your worker to handle Clerk authentication by implementing the necessary user impersonation logic.

3. Add any required environment variables or secrets in your Cloudflare Worker configuration.

Usage Guide

Basic Interaction

Once your MCP server is deployed and configured, you can test it with a simple prompt in Claude Desktop:

Say hello to [email protected]

The Cloudflare Worker will:

• Impersonate the specified Clerk user
• Generate an authentication JWT
• Return a greeting along with the JWT

Practical Applications

In real-world scenarios, you would configure the worker to:

• Take a user identifier from Claude
• Generate the appropriate Clerk authentication tokens
• Use those tokens to access protected API routes or server actions
• Return the results to Claude

Configuring for Different Routes

You can modify the worker to handle various API endpoints by:

1. Defining route patterns in your worker
2. Setting up appropriate authentication handling for each route
3. Implementing response formatting for Claude's consumption

Troubleshooting

• If Claude cannot connect to your MCP server, verify your Cloudflare Worker deployment is active
• Check that your Clerk authentication configuration is correct
• Ensure all required environment variables are properly set
• Review Cloudflare Worker logs for any execution errors

How to add this MCP server to Cursor

There are two ways to add an MCP server to Cursor. The most common way is to add the server globally in the ~/.cursor/mcp.json file so that it is available in all of your projects.

If you only need the server in a single project, you can add it to the project instead by creating or adding it to the .cursor/mcp.json file.

Adding an MCP server to Cursor globally

To add a global MCP server go to Cursor Settings > MCP and click "Add new global MCP server".

When you click that button the ~/.cursor/mcp.json file will be opened and you can add your server like this:

{
    "mcpServers": {
        "cursor-rules-mcp": {
            "command": "npx",
            "args": [
                "-y",
                "cursor-rules-mcp"
            ]
        }
    }
}

Adding an MCP server to a project

To add an MCP server to a project you can create a new .cursor/mcp.json file or add it to the existing one. This will look exactly the same as the global MCP server example above.

How to use the MCP server

Once the server is installed, you might need to head back to Settings > MCP and click the refresh button.

The Cursor agent will then be able to see the available tools the added MCP server has available and will call them when it needs to.

You can also explictly ask the agent to use the tool by mentioning the tool name and describing what the function does.