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

mcp_server