MCP Server on Cloudflare Workers

# MCP Server on Cloudflare Workers with Bearer Auth This repository demonstrates a proof of concept implementation of a Model Context Protocol (MCP) server running on Cloudflare Workers with simple bearer token authentication. ## Overview This project shows how to: - Deploy an MCP server on Cloudflare's edge network - Implement basic bearer token authentication - Create and expose MCP tools via a serverless architecture ## Local Development ```bash # Install dependencies npm install # Run the server locally npm run dev ``` After starting the server, it will be available at http://localhost:8787 ## Authentication This implementation uses a simple bearer token authentication scheme. Clients must provide an Authorization header with their requests. The server passes this token to the MCP tools, allowing tools to perform actions based on the authenticated user. ## Testing with MCP Inspector You can use the [MCP Inspector](https://modelcontextprotocol.io/docs/tools/inspector) to test your MCP server: 1. Install and start the inspector: ```bash npx @modelcontextprotocol/inspector ``` 2. Configure the inspector: - Switch the Transport Type to `SSE` - Enter the URL of your MCP server (local: `http://localhost:8787/sse` or deployed: `https://your-worker.workers.dev/sse`) - Add a bearer token in the Authorization field - Click "Connect" 3. Test the functionality: - Click "List Tools" to see available tools - Try running the "getToken" tool, which will return your authorization header - Try the "add" tool with two numbers to test basic functionality <div align="center"> <img src="img/mcp-inspector-sse-config.png" alt="MCP Inspector configuration" width="600"/> </div> <div align="center"> <img src="img/mcp-inspector-successful-tool-call.png" alt="Successful MCP tool call" width="600"/> </div> ## Deploying to Cloudflare Deploy your MCP server to Cloudflare Workers: ```bash npm run deploy ``` After deployment, your server will be available at `https://your-worker.workers.dev` ## Project Structure - `src/index.ts` - Main server implementation with MCP tools definition - `src/utils.ts` - Helper utilities for rendering the web interface - `wrangler.jsonc` - Cloudflare Workers configuration ## Important Notes This is a proof of concept implementation meant to demonstrate how MCP can run in a serverless environment. In a production setting, you would want to implement: - More robust authentication (OAuth, token validation, etc.) - Rate limiting and additional security measures - Proper error handling and monitoring ## Troubleshooting If you encounter issues: 1. Make sure your bearer token is properly formatted in the Authorization header 2. Check the worker logs in the Cloudflare dashboard 3. Try restarting your local development server For persistent authentication issues, you may need to clear any cached credentials: ```bash rm -rf ~/.mcp-auth ```