Remote MCP Server On Cloudflare S4k

🚀 Setting Up a Remote MCP Server on Cloudflare

Let's get a remote MCP server up and running on Cloudflare Workers and integrate OAuth login!

🚀 Quick Start

Local Development

# Clone the repository
git clone git@github.com:cloudflare/ai.git

# Install dependencies
cd ai
npm install

# Run locally
npx nx dev remote-mcp-server

You should be able to open http://localhost:8787/ in your browser.

Connecting the MCP Inspector to Your Server

To explore the new MCP API, you can use the MCP Inspector.

• Start it using npx @modelcontextprotocol/inspector.
• In the inspector (http://localhost:5173), switch the transport type to SSE, enter http://localhost:8787/sse as the MCP server address in the URL, and click "Connect".
• You'll be redirected to a (simulated) user/password login page. Enter any email and password to log in.
• After successful login, you should be redirected back to the MCP inspector, and you can list and call any defined tools!

Connecting Claude Desktop to Your Local MCP Server

The MCP inspector is great, but what we really want to do is connect it to Claude! Follow Anthropic's Quick Start Guide, go to Settings > Developer > Edit Configuration in Claude Desktop to find the configuration file. Open the file with a text editor and replace it with the following content:

{
  "mcpServers": {
    "math": {
      "command": "npx",
      "args": [
        "mcp-remote",
        "http://localhost:8787/sse"
      ]
    }
  }
}

This will run a local proxy that allows Claude to communicate with your MCP server over HTTP. When you open Claude, a browser window should open and allow you to log in. You should see available tools in the bottom right corner. Given an appropriate prompt, Claude should request to call a tool.

Deployment to Cloudflare

1. npx wrangler kv namespace create OAUTH_KV
2. Follow the instructions to add the kv namespace ID to wrangler.jsonc.
3. npm run deploy

Calling Your Newly Deployed Remote MCP Server from a Remote MCP Client

Just as you did in "Local Development" above, run the MCP inspector: npx @modelcontextprotocol/inspector@latest Then enter your Cloudflare Worker URL (e.g., worker-name.account-name.workers.dev/sse) as the MCP server address in the inspector and click "Connect". You've successfully connected the MCP server from a remote MCP client.

Connecting Claude Desktop to Your Remote MCP Server

Update the Claude configuration file to point to your workers.dev URL (e.g., https://worker-name.account-name.workers.dev/sse), and then restart Claude.

{
  "mcpServers": {
    "math": {
      "command": "npx",
      "args": [
        "mcp-remote",
        "https://worker-name.account-name.workers.dev/sse"
      ]
    }
  }
}

Debugging

If you encounter any issues, restarting Claude or connecting directly to your MCP server via the following command may help.

npx mcp-remote http://localhost:8787/sse

In rare cases, clearing the files in the ~/.mcp-auth directory may be helpful:

rm -rf ~/.mcp-auth