https://resources.anthropic.com/hubfs/The-Complete-Guide-to-Building-Skill-for-Claude.pdf
checklist
Folder named in kebab-case
SKILL.md file exists (exact spelling)
YAML frontmatter has --- delimiters
name field: kebab-case, no spaces, no capitals
description includes WHAT and WHEN
No XML tags (< >) anywhere
Instructions are clear and actionable
Error handling included
Examples provided
References clearly linked
