Mcp Builder

What it does

This skill provides a comprehensive guide for building high-quality MCP (Model Context Protocol) servers. These servers enable Large Language Models (LLMs) to interact with external services and APIs, allowing them to accomplish real-world tasks. The skill guides users through a four-phase workflow – research, implementation, review, and evaluation – offering checklists and best practices for each stage. It also includes language-specific implementation guides for Python (FastMCP) and Node/TypeScript.

When to use it

• When you need to create tools that allow an LLM to access external services or APIs.
• When designing AI agent workflows beyond simple API endpoint calls, focusing on consolidating related operations into high-impact tools.
• When optimizing tool responses for limited context windows within the LLM.
• When developing MCP servers in either Python (using FastMCP) or Node/TypeScript and needing SDK documentation and project structure templates.

Key capabilities

• Four-phase workflow guide: Research, Implementation, Review, Evaluation.
• Agent-centric design principles for tool creation.
• Language-specific implementation guides for Python (FastMCP) and Node/TypeScript.
• Tool design patterns including input validation, response formatting, pagination, error handling, and annotations.

Example prompts

• "Guide me through the research phase of building an MCP server."
• "What are some best practices for optimizing tool responses within a limited context window?"
• "Show me the project structure template for a Node/TypeScript MCP server."

Tips & gotchas

• This skill focuses on building MCP servers, not using them. It's geared towards developers creating tools for LLMs.
• Prioritize designing tools that enable complete workflows rather than just wrapping existing API endpoints.
• Be mindful of the limited context windows in LLMs and strive to return concise, high-signal information.