npm install
npm run build

claude mcp add system-info node /path/to/mcp-demo/dist/index.js

{
  "mcpServers": {
    "system-info": {
      "type": "stdio",
      "command": "node",
      "args": ["/absolute/path/to/mcp-demo/dist/index.js"],
      "env": {}
    }
  }
}

┌─────────────┐         JSON-RPC          ┌─────────────┐
│ Claude Code │ ────────────────────────> │  MCP Server │
│  (Client)   │   stdio (stdin/stdout)    │ (this repo) │
│             │ <──────────────────────── │             │
└─────────────┘                          └─────────────┘
                                                 │
                                                 ↓
                                         ┌──────────────┐
                                         │ ipify API    │
                                         │ ip-api.com   │
                                         │ Node.js os   │
                                         └──────────────┘

mcp-demo/
├── src/
│   └── index.ts          # MCP server implementation
├── dist/                 # Compiled JavaScript
├── package.json
└── tsconfig.json

# List available tools
echo '{"jsonrpc":"2.0","id":1,"method":"tools/list","params":{}}' | node dist/index.js

# Call a tool
echo '{"jsonrpc":"2.0","id":2,"method":"tools/call","params":{"name":"get_public_ip","arguments":{}}}' | node dist/index.js

// 1. Add to tool list
{
  name: "get_weather",
  description: "Get current weather",
  inputSchema: {
    type: "object",
    properties: {
      city: { type: "string" }
    },
    required: ["city"]
  }
}

// 2. Handle the call
if (name === "get_weather") {
  const { city } = request.params.arguments;
  const response = await axios.get(`https://api.weather.com/${city}`);
  return {
    content: [{ type: "text", text: JSON.stringify(response.data) }]
  };
}