Build Model Context Protocol (MCP) servers that expose tools, resources, and prompts to LLM clients. Covers the official Python SDK (FastMCP) and the Node/TypeScript SDK, transports (stdio vs HTTP), registering servers with clients, and tool-design best practices. Use this skill whenever the user wants to create an MCP server, wrap an API or service as MCP tools, or connect a custom backend to Claude/other MCP clients.