MCP Server Builder

This skill provides comprehensive guidance for building MCP (Model Context Protocol) servers that expose external services and APIs to language models through standardized tool interfaces. It covers designing intuitive tool schemas with clear names and descriptions, implementing tool handlers that execute operations reliably, exposing resources like documentation and configuration that models can query, following MCP best practices for error handling and response formatting, supporting multiple implementation languages including Python with FastMCP, Node.js and TypeScript with the official MCP SDK, and C# with Microsoft's .NET SDK. The agent learns architectural patterns for MCP servers including when to expose capabilities as tools versus resources, how to structure tool parameters for optimal model usage, and how to handle authentication and rate limiting for underlying APIs. The skill establishes boundaries between what belongs in an MCP server versus client-side logic, emphasizing that servers expose capabilities while clients orchestrate their usage. Trade-offs include granularity of tool design—many small tools versus fewer comprehensive tools—balancing between exposing raw API access versus higher-level abstractions, and choosing between synchronous responses for quick operations versus async patterns for long-running tasks. The skill emphasizes that well-designed MCP servers make external capabilities accessible to models in intuitive, reliable ways.