mcp-rpc-transport

MCP RPC Transport

An Agent calling an McpAgent within the same Worker using RPC transport -- no HTTP, no network overhead. Uses Workers AI so no API keys are needed.

How to run

npm install && npm start

What this demonstrates

The RPC transport connects an Agent to an McpAgent via Durable Object bindings. Both live in the same Worker. The Agent passes the DO namespace directly to addMcpServer:

export class Chat extends AIChatAgent<Env> {
  async onStart() {
    await this.addMcpServer("my-mcp", this.env.MyMCP, {
      props: { userId: "demo-user-123", role: "admin" }
    });
  }
}

The McpAgent defines tools that become available to the chat:

export class MyMCP extends McpAgent<Env, State, Props> {
  server = new McpServer({ name: "Demo", version: "1.0.0" });

  async init() {
    this.server.tool(
      "add",
      "Add to counter",
      { a: z.number() },
      async ({ a }) => {
        this.setState({ counter: this.state.counter + a });
        return {
          content: [{ type: "text", text: `Total: ${this.state.counter}` }]
        };
      }
    );
  }
}

Try asking the AI to add numbers to the counter or check who you are.

Related

• MCP Client -- connecting to remote MCP servers with OAuth
• MCP Transports docs -- all transport options