Apply this skill when the request involves:
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"hard to use", "high drop-off", "difficult input", "confusing", "accessibility issues", "too many errors"
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使いにくい、離脱が多い、入力が難しい、迷う、アクセシビリティ、エラーが多い
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UI design review, or working on forms, onboarding, settings screens
Core Principles
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Usability is cost, not preference. Reduce confusion, memory burden, operation count, and error rate.
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Cognitive load. Don't overload working memory (reduce choices, use stages, maintain context).
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Accessibility. Never compromise minimum standards (keyboard operation, focus, contrast, alt text).
Design Philosophy (Decision Rules)
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Don't break the user's current context. Avoid abrupt screen transitions, information loss, and modal abuse.
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Prevent errors. Use input constraints, immediate feedback, and sensible defaults.
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Don't make users memorize. Show, don't ask them to choose (recognition over recall).
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Keep operations consistent. Same things behave the same way.
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Accessibility is not an afterthought. Include it in specs from the start.
Initial Questions to Clarify
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Where is failure happening? (Step / screen / operation)
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What can't be done? (Understanding / deciding / operating / inputting / waiting)
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Who is struggling? (Novice / expert / assistive tech user / slow connection)
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What defines success? (Completion rate, time, error rate, satisfaction)
Output Format (Follow This Order)
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Problem summary (observations, facts, hypotheses)
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Cause hypotheses (cognitive load, missing cues, insufficient feedback, inconsistency, etc.)
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Improvement proposals (with priorities)
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Accessibility check (minimum)
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Validation plan (metrics, user testing, A/B, etc.)
Minimum Accessibility Checklist
Can complete main operations with keyboard only Focus is visible Contrast is sufficient Forms have labels and error descriptions Images have alt text (when needed)
Common Pitfalls
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Assuming "users will get used to it" and ignoring first-time confusion
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Error messages too abstract to guide next action
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Adding accessibility last and breaking the experience