build-mcp

Build MCP Server on Cloudflare

Arguments

The user invoked this command with: $ARGUMENTS

Instructions

When this command is invoked:

1. Read the skill file at agents-sdk/SKILL.md for core SDK guidance
2. Read agents-sdk/references/mcp.md for MCP client and server APIs, transports, and securing
3. Read agents-sdk/references/configuration.md for wrangler setup
4. Fetch https://developers.cloudflare.com/agents/api-reference/mcp-agent-api/ for the latest McpAgent API
5. For OAuth/security, fetch https://developers.cloudflare.com/agents/api-reference/securing-mcp-servers/

Scaffold Steps

1. Create project: npx create-cloudflare@latest --template cloudflare/agents-starter (or start fresh)
2. Install MCP SDK: npm install @modelcontextprotocol/sdk zod
3. Configure wrangler.jsonc: DO binding + new_sqlite_classes migration for the McpAgent class
4. Implement McpAgent: extend McpAgent, create McpServer, register tools in init()
5. Serve transport: MyMCP.serve("/mcp", { binding: "MyMCP" }) (Streamable HTTP, recommended)
6. Test: npx @modelcontextprotocol/inspector@latest
7. Deploy: npx wrangler deploy

Quick Reference

import { McpServer } from "@modelcontextprotocol/sdk/server/mcp.js";
import { McpAgent } from "agents/mcp";
import { z } from "zod";

export class MyMCP extends McpAgent<Env, State, {}> {
  server = new McpServer({ name: "my-mcp", version: "1.0.0" });
  initialState = { counter: 0 };

  async init() {
    this.server.registerTool("my_tool", {
      description: "Does something useful",
      inputSchema: { query: z.string() }
    }, async ({ query }) => ({
      content: [{ text: `Result: ${query}`, type: "text" }]
    }));
  }
}

// Entry point
export default {
  fetch(request: Request, env: Env, ctx: ExecutionContext) {
    return MyMCP.serve("/mcp", { binding: "MyMCP" }).fetch(request, env, ctx);
  }
};

Transport Options

Transport	Method	Use for
Streamable HTTP	MyMCP.serve("/mcp")	External/public clients (recommended)
SSE	MyMCP.serveSSE("/sse")	Legacy clients only (deprecated)
RPC	addMcpServer(name, env.Binding)	Same-Worker internal calls