MCP Server

Developed with Claude Code

A minimal Model Context Protocol server written in Python, with two example tools:

Tool	Description
get_weather	Live weather for any city (powered by wttr.in — no API key needed)
calculate	Safe evaluation of math expressions (sqrt, sin, pi, **, …)

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Requirements

• Python 3.10+
• pip

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Setup

1. Create and activate a virtual environment

python3 -m venv .venv
source .venv/bin/activate   # Windows: .venv\Scripts\activate

2. Install dependencies

pip install -r requirements.txt

3. Run the server

MCP servers communicate over stdio, so you normally don't run the server directly — your MCP client launches it. See the client configuration section below.

To verify the server starts without errors:

python server.py
# The process will block waiting for MCP messages — that's expected.
# Press Ctrl+C to quit.

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Connecting to Claude Desktop

Add the server to Claude Desktop's config file:

• macOS: ~/Library/Application Support/Claude/claude_desktop_config.json
• Windows: %APPDATA%\Claude\claude_desktop_config.json

{
  "mcpServers": {
    "example-server": {
      "command": "/absolute/path/to/MCP-Server/.venv/bin/python",
      "args": ["/absolute/path/to/MCP-Server/server.py"]
    }
  }
}

Replace the paths with the actual absolute paths on your machine. Restart Claude Desktop after saving.

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Connecting via Claude Code (CLI)

claude mcp add example-server \
  /absolute/path/to/MCP-Server/.venv/bin/python \
  -- /absolute/path/to/MCP-Server/server.py

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Tool reference

get_weather

Input:  { "city": "Tokyo" }
Output: Weather for Tokyo, Japan:
          Condition : Partly cloudy
          Temp      : 18°C / 64°F
          Feels like: 17°C
          Humidity  : 60%
          Wind      : 15 km/h NE

calculate

Supported operators: +, -, *, /, **, %, //

Supported functions: abs, round, sqrt, ceil, floor, log, log10, sin, cos, tan

Constants: pi, e

Input:  { "expression": "sqrt(2) * pi" }
Output: 4.442882938158366

Input:  { "expression": "2 ** 10" }
Output: 1024

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Project structure

MCP-Server/
├── server.py          # MCP server with tool implementations
├── requirements.txt   # Python dependencies
└── README.md

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Extending the server

To add a new tool:

1. Add a types.Tool(...) entry inside handle_list_tools().
2. Add a matching elif name == "your_tool": branch inside handle_call_tool().
3. Implement the tool logic as a plain function (sync) or async coroutine.