Weather MCP Server

A simple Model Context Protocol server for learning purposes. Wraps the free Open-Meteo weather API — no API key required.

Built with Java 21, Spring Boot 3.5, and Spring AI 1.1.

MCP Tools

| Tool | Description | |------|-------------| | get_coordinates | Resolve a city name to latitude, longitude, and country | | get_current_weather | Get current weather by latitude and longitude | | get_weather_by_city | Get current weather by city name (geocoding + forecast) |

Prerequisites

• Java 21+

Build

./mvnw clean package

Run

java -jar target/mcp-weather-server-0.0.1-SNAPSHOT.jar

The server communicates over STDIO (standard input/output).

Use with Claude Desktop

Add to ~/Library/Application Support/Claude/claude_desktop_config.json:

{
  "mcpServers": {
    "weather": {
      "command": "java",
      "args": ["-jar", "/absolute/path/to/target/mcp-weather-server-0.0.1-SNAPSHOT.jar"]
    }
  }
}

Restart Claude Desktop. You can then ask things like "What's the weather in Tokyo?"

Tech Stack

• Java 21 / Maven
• Spring Boot 3.5 — application framework
• Spring AI 1.1 — MCP server support (spring-ai-starter-mcp-server)
• Open-Meteo API — free weather and geocoding data, no API key needed
• STDIO transport — no web server, runs as a subprocess