Conciseness

Prose is minimal and code dominates, which is good, but much of the ~640 lines restates textbook React knowledge Claude already has (composition over inheritance, useDebounce, ErrorBoundary, React.memo/useCallback basics), and the closing '覚えておいてください...' paragraph is pure motivational padding. This fits 'mostly efficient but includes some unnecessary explanation or could be tightened' rather than the lean anchor 4.

Actionability

Every section gives concrete, executable TypeScript with usage snippets (e.g. the full useQuery implementation with refs to keep refetch referentially stable, the virtualizer list, the keyboard-navigation Dropdown). Minor gaps keep it below fully copy-paste-ready: usage examples reference undeclared helpers (MarketCard, Spinner, performSearch) and some imports/props types (ModalProps, DropdownProps) are omitted — matching 'mostly executable guidance with minor gaps'.

Workflow Clarity

This is a pattern catalog, not a multi-step process: sections are independent lookups with no sequencing and no guidance on when to choose one pattern over another beyond a single vague closing sentence. It exceeds the 50-line simple-skill exception, and although no destructive/batch operations are involved, there are no decision checkpoints ('use X when...') — fitting 'steps listed but checkpoints missing or implicit' at best.

Progressive Disclosure

Section headers are clear and consistent (component patterns → hooks → state → performance → forms → errors → a11y), but the entire ~640-line pattern library is inlined in SKILL.md with no references/, scripts/, or assets/ bundle. A library of this size clearly belongs partly in separate reference files ('content that should be separate is inline'), though the good in-file structure keeps it above anchor 2's 'no structure' example.

Specificity

The description names the domain ('React、Next.js、状態管理、パフォーマンス最適化、UIベストプラクティス') but the only action stated is generic 'フロントエンド開発パターン' (frontend development patterns) with no concrete verbs. This matches the anchor 'names the domain but actions are minimal or generic'; it does not reach 3 because no concrete actions like 'build components' or 'optimize rendering' are stated.

Completeness

The 'what' is present (frontend development patterns for React/Next.js), but there is no 'Use when...' clause or equivalent trigger guidance, which the guidelines cap at 3. It is not a 2 because the 'what' is clearly stated, not vague.

Trigger Term Quality

'React', 'Next.js', and '状態管理' (state management) are natural terms a user might say, but common trigger phrases and synonyms are missing — e.g. 'component', 'hook', 'form', '再レンダリング' (re-render), 'パフォーマンスチューニング'. This fits 'some relevant keywords but missing common variations or synonyms' rather than the good-coverage anchor 4.

Distinctiveness Conflict Risk

'React、Next.js' anchors it to a specific niche, but 'フロントエンド開発パターン' (frontend development patterns) and 'UIベストプラクティス' are broad enough to overlap with general web-development and coding skills. This is 'somewhat specific but could still overlap with similar skills'; not 4 because no distinct trigger phrases separate it from neighboring frontend skills.