Tool Design

A tool that returns correct data can still fail in production because the agent could not tell when to call it, what to pass, or what to do with the result. "Working" is not the same as "agent-usable". This skill family treats the agent as the consumer and designs for it.

The guidance is framework-neutral: it applies to MCP servers, native function calling, Runtype runtime tools, and any custom loop. It is organized as 54 named patterns across ten questions; references/pattern-index.md maps every pattern to the skill that owns it.

The consumer changed, so the design rules changed