Tool Design

It covers writing tool descriptions that agents actually route on, designing schemas and error messages, MCP server design, and deciding when to consolidate or split tools. The core principle is consolidation: if you can't definitively say which tool applies in a situation, the agent won't either. The skill pushes toward fewer, more comprehensive tools rather than sprawling catalogs where agents pick wrong half the time. Use it when the unit of work is a single tool or tool set. It explicitly doesn't cover project architecture decisions or whether to use sub-agents, which route to other skills.