validate_skill_line
Use this when drafting or reviewing a ## Skills entry. Pass the EXACT
markdown bullet line; you get back valid, the parsed fields, and precise
errors / warnings (missing sha256, tool without tool_sha256, non-semver
version, short description). Fix errors before publishing; warnings are
adoption-ladder hints, not blockers. For whole-file validation use
npx @rckflr/llms-skills validate <llms.txt>.