SkillCheck Free validates Claude Code SKILL.md files against ~25 contract rules covering structure, naming, semantic consistency, and quality patterns. It catches missing frontmatter, weak or ambiguous descriptions, trigger collisions, anti-pattern formatting (prose where tables belong), naming smells, and contradictions before users encounter them. Runs locally — it's itself a SKILL.md the agent reads, with no API calls, binaries, or external services. MIT-licensed. Works in Claude Code, Claude Desktop/Web (Projects), and Cursor. The Free tier covers structural, semantic, and naming checks plus quality-pattern recognition. SkillCheck Pro (separate product at getskillcheck.com) adds anti-slop detection, security scanning, token budget analysis, WCAG accessibility, and enterprise readiness checks.