Temperature MCP Server Example

This project demonstrates how to build a simple MCP (Model Context Protocol) server in Go that provides temperature data for a given location. The server exposes a get_temperature tool via MCP, which proxies requests to an underlying HTTP temperature service.

Features

• Implements an MCP server using the mark3labs/mcp-go library.
• Registers a tool (get_temperature) that accepts a location parameter.
• Proxies temperature requests to a local or remote HTTP service.
• Well-documented code for educational purposes.

Project Structure

• main.go: Main entry point. Sets up the MCP server, registers the tool, and implements the handler logic.
• go.mod, go.sum: Go module files for dependency management.

Usage

Prerequisites

• Go 1.18 or newer
• An HTTP temperature service running locally on http://localhost:8080/temperature?location=<LOCATION> (you can use your own implementation or go-temperature-server)

Running the MCP Server

1. Clone the repository or copy the source files to your Go workspace.

2. Install dependencies:

   go mod tidy
   

3. Build the MCP server:

   go build -o mcp-temperature-server main.go
   

4. Ensure your HTTP temperature service is running on port 8080.

5. Start the MCP server:

   ./mcp-temperature-server
   

Example Request

You can use an MCP-compatible client or integration to call the get_temperature tool with a location parameter, e.g.:

{
  "tool": "get_temperature",
  "params": { "location": "Chapel Hill" }
}

Example Response

The response will be in plain text, containing a JSON object with the location and temperature:

Temperature for Chapel Hill: {"location":"Chapel Hill","temperature":18.25}

Example mcp_config.json for Windsurf IDE

To use this project with the Windsurf IDE, create a .codeium/windsurf/mcp_config.json file in your home directory (or project root) with the following content:

{
  "mcpServers": {
    "temperature": {
      "command": "./ABSOLUTE/PATH/TO/YOUR/REPO/go-mcp-temperature-server/go-mcp-temperature-server",
      // <-- Modify this to match your checkout location and leave the initial ./ alone
      "args": [],
      "env": {
        "WEATHER_API_KEY": "YOUR_API_KEY_HERE"
      }
    }
  }
}

• Replace YOUR_API_KEY_HERE with your actual weather API key.
• The path to the server binary should match your project structure.
• This configuration ensures the MCP server is started with the correct environment variable for authentication.

How It Works

• The MCP server defines a tool called get_temperature.
• When invoked, it extracts the location argument, then queries the HTTP service at http://localhost:8080/temperature?location=<LOCATION>&units=metric&appid=<YOUR_API_KEY>.
• The result is returned as plain text (with JSON content) to the MCP client.

Customization

• To use a different HTTP temperature service, modify the endpoint variable in main.go.
• The backend temperature service expects the API key as the appid query parameter (e.g., ...&appid=YOUR_API_KEY). If you receive a 500 Internal Server Error, check the backend service logs and ensure the API key is valid and passed as a query parameter.
• To add more tools or capabilities, register additional tools and handlers using the MCP server API.

License

MIT or as specified in your project.

For more information on MCP, see mark3labs/mcp-go.