Build your first MCP server in Node

mkdir hello-mcp && cd hello-mcp
npm init -y
npm install @modelcontextprotocol/sdk zod
npm install -D typescript @types/node tsx

// src/index.ts
import { Server } from "@modelcontextprotocol/sdk/server/index.js";
import { StdioServerTransport } from "@modelcontextprotocol/sdk/server/stdio.js";
import { z } from "zod";

const server = new Server(
{ name: "hello-mcp", version: "0.1.0" },
{ capabilities: { tools: {} } }
);

server.setRequestHandler("tools/list", async () => ({
tools: [{
  name: "echo",
  description: "Echo a message back",
  inputSchema: { type: "object", properties: { msg: { type: "string" } } }
}]
}));

server.setRequestHandler("tools/call", async (req) => {
const { msg } = z.object({ msg: z.string() }).parse(req.params.arguments);
return { content: [{ type: "text", text: `echo: ${msg}` }] };
});

await server.connect(new StdioServerTransport());

npx tsx src/index.ts
# should sit silent waiting on stdin — that's correct

// ~/Library/Application Support/Claude/claude_desktop_config.json
{
"mcpServers": {
  "hello": {
    "command": "npx",
    "args": ["tsx", "/absolute/path/to/hello-mcp/src/index.ts"]
  }
}
}