SkillsBench: Curated Skills Beat AI-Generated Skills 16.2% to Zero

SkillsBench is the first standardized benchmark for evaluating agent skills — 86 tasks across 11 domains, 7,308 test trajectories. The critical finding: curated skills boost agent pass rates by 16.2%, but self-generated skills provide zero benefit on average. Smaller models with good skills can match larger models without them. This validates investing time in hand-crafted skills over auto-generated ones and scientifically justifies the value of skill marketplaces.