server.py
├── ToolRegistry          ← Reusable framework for tool registration
│   ├── tool() decorator  ← Auto-generates JSON Schema from type hints
│   ├── list_tools()      ← Full MCP tool listing
│   └── call_tool()       ← Dispatch with error handling
├── Tools                 ← Utility implementations (self-contained)
└── Server                ← MCP protocol binding (stdio / SSE)

@registry.tool("my_tool", "Description of what it does")
def my_tool(param1: str, param2: int = 42) -> dict:
    \"\"\"Docstring becomes tool description.\"\"\"
    return {"result": param1 * param2}

pip install "mcp[cli]"
python server.py                     # stdio mode (for Claude Desktop)
python server.py --transport sse     # HTTP mode (for remote access)