Check an agent skill before you install it

Paste the GitHub link to a SKILL.md, AGENTS.md, CLAUDE.md, DESIGN.md, llms.txt or Cursor rule file. The registry runs the same fixed checks it gives every file it holds, including curl or wget piped into a shell, hidden zero-width characters and, for a skill, a missing frontmatter block, and shows the grade from A to F with each check it passed or failed.

Public files on github.com only, up to 512 KB. The registry does not save the file or its grade.

What the checks look for

Every check is a fixed pattern, so the same file always gets the same grade. The checks read the one file you link, not the scripts or other files beside it, so an A means that file passed, not that a skill is safe to run. A critical check, such as a hidden zero-width or bidirectional control character, fails the file outright; an advisory one, such as a command that pipes a download into a shell, lowers the grade from A. What each grade means, and how often each happens across the registry, is on the badge page, and what to look for beyond the checks is in what to check before you install a skill.