Remote MCP Server On Cloudflare S0d

🚀 Building a Remote MCP Server on Cloudflare

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

🚀 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 a browser window at http://localhost:8787/.

🔗 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.
• Inside 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.
• You should be redirected back to the MCP Inspector, and you can now 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 the Anthropic's Quick Start Guide, go to Settings > Developer > Edit Configuration in Claude Desktop, and find your 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 the available tools in the bottom right corner. As prompted, Claude should call the MCP addition tool to answer questions.

🚀 Deployment to Cloudflare

1. npx wrangler kv namespace create OAUTH_KV
2. Follow the guide to add the KV space 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 Worker's workers.dev URL (e.g., worker-name.account-name.workers.dev/sse) as the MCP server address in the inspector and click "Connect". You are now connected to your MCP server through 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 directly connecting to your MCP server via the following command may be helpful.

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

In rare cases, you may need to clear the files in the ~/.mcp-auth directory:

rm -rf ~/.mcp