Audit an installed Agent Skills inventory against real session history — find skills that never fire, descriptions that never match actual work, duplicate installs across roots, and near-misses where a skill should have triggered but didn't. Use when the user asks to review, prune, clean up, or improve their skills; asks "which of my skills are useless / never used / worth keeping"; asks why a skill never triggers or isn't being picked up; or wants to know whether a new skill is worth installing. Also use before writing a new skill, to check whether one already covers the need.
