Animation Only When Requested
NEVER: Add animation unless it is explicitly requested. Gratuitous animation slows perceived performance and can cause motion sickness. Animation should serve purpose.
Never add animations unless explicitly requested - they can hurt UX if overused
Bad
Good
Why it matters
Read this as what it is: agent-facing guidance. It is a default for the party that was not asked — a coding agent handed "build me a settings panel" should not decide on its own that the panel slides. It is not a claim that animation is bad. A human designer choosing to animate has, by definition, explicitly requested it. The failure it prevents is real: animation added because it looks cool taxes every future use of a control, slows perceived performance, and is the single loudest tell of generated UI. Where motion IS wanted, animations-necessity-check gives the test it has to pass.