FastMCP — Production Patterns

FastMCP (v3.x) is the standard Python framework for building MCP servers. This skill covers production patterns verified against the real FastMCP API — applicable to any domain: databases, REST APIs, file systems, Git, Slack, email, or any external service.

When to use

• Writing new tools or prompts in an existing FastMCP server
• Improving tool schemas, output formatting, or error messages
• Adding middleware, lifespan hooks, or lifecycle management
• Running and deploying FastMCP servers (transport choices)
• Testing FastMCP tools with the built-in Client
• Debugging failing tool calls or silent errors
• Handling partial failures across multiple external calls

Do NOT use for: general MCP questions, MCP protocol explanation, or scaffolding a new server from scratch (use mcp-builder skill instead).

Running the Server