Field Guide 29: 28 rules for organizing Agent Skills, covering folder layout, SKILL.md frontmatter, descriptions that trigger reliably, progressive disclosure and evaluation. Each rule says whether it comes from the Agent Skills specification or from Claude Code. The kit has a worked create-component skill for a design system (scaffold script, contract and token references, 20 trigger queries, output evals) and a zero-dependency validator with 34 checks and a portable profile for claude.ai and Skills API uploads.
When a skill never triggers or triggers on the wrong requests, when you are converting flat Markdown commands into skills, or before sharing a skills folder with a team or uploading it outside Claude Code.