SkillCheck (Free)

Check skills against Anthropic guidelines and the agentskills specification. This file contains Free tier validation rules.

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Prerequisites

• Any AI assistant with file Read capability (Claude Code, Cursor, Windsurf, Codex CLI)
• Works on any platform (Unix/macOS/Windows)
• No special tools required (Read-only)
• No environment variables or API keys required; the checks run fully offline

Interface

• Input: path(s) to SKILL.md files, plus any references/*.md files in the same skill folder
• Output: a validation report listing each issue with check ID, severity (Critical / Warning / Suggestion), line number, and fix; strengths reported in a separate list
• Modes: runs standalone on a single skill or over a directory of skills, one report per skill