Node MCP Server

Small example MCP (Model Context Protocol) server that exposes a weather tool using the @modelcontextprotocol/sdk.

Overview

• Provides a minimal Express-based HTTP server that connects an McpServer to a Streamable HTTP transport.

• Exposes endpoints: /mcp (MCP transport), /health, /status, and /.

Requirements

• Node.js 18+ recommended

• npm

Install

npm install

Run

npm start

Server listens on port 3000 by default.

Endpoints

• GET /health — returns OK.

• GET /status — returns a JSON status object.

• POST /mcp — Streamable HTTP MCP transport endpoint. The server expects clients to POST JSON-RPC messages.

Important: the Streamable HTTP transport expects clients to include the following headers for POSTs:

• Content-Type: application/json

• Accept: application/json, text/event-stream

Example curl (initialize):

curl --location 'http://localhost:3000/mcp' \
--header 'Content-Type: application/json' \
--header 'Accept: application/json, text/event-stream' \
--data '{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "tools/call",
  "params": {
    "name": "getWeather_Tool",
    "arguments": {
      "location":"New York"
    }
  }
}'

Notes

• The project uses @modelcontextprotocol/sdk (see package.json) and returns structured tool results. Tool callbacks must return objects matching the SDK's expected schema (not plain strings).

• If you see errors about Accept headers or tool result shapes, verify headers and that tool callbacks return an object with a content array.

License

MIT