While building a skill index I almost recommended a repo with sixteen thousand stars. Looked great. Then I checked when it was last touched: January 2023. Three years dead. If an agent had loaded its instructions it would have followed them confidently, and they're wrong now. That's the whole problem nobody talks about with these skill libraries.
If you've used Claude Code or any agent setup recently, you've seen the pattern. There's a folder of SKILL.md files, or an MCP registry, or some awesome-agent-skills repo, and the agent reaches into it when it needs to do a thing. Everyone is building the library. The library is easy. It's a folder of markdown.
The part nobody builds is the part that actually matters: how does the agent know which skill in the pile won't lie to it?
A skill is instructions an AI follows. Confidently. That's different from code. When code is wrong it crashes, loud, you notice. When a skill is wrong the agent just does the wrong thing and tells you it went great. So a stale or subtly-broken skill isn't neutral. It's negative. It produces a confident wrong answer instead of making the agent stop and think. No skill at all would have been safer.
I went looking for the existing solution and what I found was a hundred link lists. They tell you a skill exists. They do not tell you the one thing you need before you load it: can I trust this, and is it still true.
