Lean and token-efficient — a compact DO/DON'T table, a tight ASCII decision tree, and bullet lists with one inline example; it assumes Claude knows React rather than re-explaining it. It is not a 2 because the opening 'escape hatch' framing is the skill's thesis and earns its place rather than padding concepts Claude already knows.

Provides concrete, specific guidance — names exact React primitives (useMemo, key prop, useSyncExternalStore, event handlers), routes each situation via the decision tree, and shows one worked example ('const fullName = firstName + ' ' + lastName'). It is not a 2 because, per the instruction-skill carve-out, the guidance is actionable and specific even though most alternatives are demonstrated at pattern level rather than with full code.

A single-purpose, under-50-line skill whose decision tree sequences the logic clearly and is well-organized, meeting the simple-skill allowance for a 3. It is not a 2 because no destructive/batch operations are involved, so the missing-validation cap does not apply, and the routing is unambiguous.

The overview is concise and the 'Detailed Guidance' references are clearly signaled and one level deep, but the referenced files './anti-patterns.md' and './alternatives.md' do not exist in the bundle (no references/ directory or matching files), so the promised detail is not actually delivered. It is not a 3 because the disclosure chain is broken by dangling references, and not a 1 because the SKILL.md itself is well structured rather than a monolithic wall of text.

Lists multiple concrete actions — 'writing/reviewing useEffect, useState for derived values, data fetching, or state synchronization' and 'Teaches when NOT to use Effect and better alternatives' — matching the score-3 anchor for several specific concrete actions. It is not a 2 because the action coverage is comprehensive rather than partial, and the verb 'Teaches' is third person with no first/second-person voice to penalize.

Clearly answers both 'what' ('React useEffect best practices from official docs') and 'when' with an explicit trigger clause ('Use when writing/reviewing useEffect, useState for derived values, data fetching, or state synchronization'). It is not a 2 because the 'when' guidance is explicit, not merely implied.

Natural developer-facing terms — 'useEffect', 'useState', 'data fetching', 'state synchronization', 'derived values' — give good coverage of what a user would actually say, matching the score-3 anchor. It is not a 2 because common variations are well represented rather than missing.

Occupies a clear niche (React useEffect best practices) with distinct, React-specific triggers, making it unlikely to fire for unrelated skills. It is not a 2 because the scope is tightly bounded to useEffect rather than overlapping broadly with other skills.