Guides agents through creating, validating, and optimizing Agent Skills (SKILL.md files) from user requests. Covers all YAML frontmatter fields, directory layout, progressive disclosure, scripts, quality patterns, and evaluation workflows. Use when a user asks you to create, edit, audit, or improve an Agent Skill, even if they don't use the word "skill" — any request about reusable agent instructions, workflow packaging, or capability extension should trigger this skill.
