A meta-skill for building and refining other skills through structured iteration. Walk through the full cycle: draft the skill, write test prompts, run evaluations both qualitative and quantitative, then rewrite based on results. It handles users at any entry point, whether they're starting from scratch or already have a draft to optimize. The eval-viewer scripts give you concrete metrics to improve against, and there's a separate flow for tuning skill descriptions to fix undertriggering. Worth noting the guidance on progressive disclosure: keep the main SKILL.md under 500 lines and push reference material into bundled files. Most useful when you're serious about iteration rather than one-shot skill writing.
npx skills add https://github.com/anthropics/claude-plugins-official --skill skill-creator