Remote MCP Server On Cloudflare Fn9

🚀 Set Up a Remote MCP Server on Cloudflare

Let's launch a remote MCP server on Cloudflare Workers and equip it with 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 the browser at http://localhost:8787/.

🔗 Connect the MCP Inspector to Your Server

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

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

🔗 Connect Claude Desktop to the Local MCP Server

The inspector is great, but we really want to connect it to Claude! Follow Anthropic's Quick Start and go to Settings > Developer > Edit Configuration in Claude Desktop to find your configuration file. Open the file in 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 via HTTP. When you open Claude, a browser window should open and allow you to log in. You should see the available tools in the bottom right corner. Given the correct prompt, Claude should ask to call the tools.

🚀 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

🔗 Call Your Newly Deployed Remote MCP Server from a Remote MCP Client

Just like what you did in "Local Development" above, run the MCP inspector: npx @modelcontextprotocol/inspector@latest Then enter your Worker's workers.dev URL (e.g., worker-name.account-name.workers.dev/sse) as the URL of the MCP server to connect in the inspector, and click "Connect". You are now connected to your MCP server via the remote MCP client.

🔗 Connect Claude Desktop to Your Remote MCP Server

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

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

🐞 Debugging

If anything goes wrong, restarting Claude or directly connecting to your MCP server via the following command may help.

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

In rare cases, clearing the file added to ~/.mcp-auth may be helpful.

rm -rf ~/.mcp-auth