This gives Claude structured knowledge about motion design for UI work. Use it when you're implementing animations and want to avoid the common mistakes: durations that are too slow, easing curves that feel robotic, or motion that exists just because you can. It covers the practical stuff like which easing function to use when (ease-out for entrances, ease-in for exits), actual millisecond ranges for different interaction types, and how to stagger lists without making users wait. The prefers-reduced-motion reminder and performance notes are worth having in context. Honestly most useful for keeping animation work grounded in purpose rather than flourish.
npx skills add https://github.com/owl-listener/designer-skills --skill animation-principles