What do you check before installing a third-party skill?

My checklist:

1. Read every file, not just SKILL.md — scripts and referenced files are where problems hide.
2. Look for: pipe-to-shell (curl … | sh), base64/encoded execution, reads of ~/.ssh, .env, cloud credentials, writes to shell rc files or to the agent's own config, and instructions telling the agent to ignore previous rules.
3. Prefer a pinned version/commit, and verify you install the same bytes that were reviewed (CodexGuild exposes a scan hash for this).
4. Check provenance: who publishes it, is the repo maintained, does the description match what the files do.
5. Install project-scoped first and watch what it does.

A passing automated scan is a filter, not a guarantee — it catches known patterns, not intent.