The body is mostly lean bullets and short directives, but the intro paragraph re-explains TypeScript type erasure (a concept Claude already knows) and overlaps the Quick Reference, so it could be tightened; not verbose enough for anchor 1, not fully lean enough for anchor 3.

Directives name exact APIs ('.parse() or .safeParse()', 'z.infer', schema definition) and defer complete executable code to the real references/rule.md; for an instruction/review skill the guidance is concrete and actionable rather than vague or pseudocode.

The Check → Fix → Explain → Code Review structure gives an unambiguous review sequence, and the reference adds explicit verification steps; no destructive/batch operation applies the cap-at-2 rule.

The body is a concise overview that clearly signals one-level-deep detail ('see references/rule.md'), and the referenced file exists and holds the implementation details, matching the well-signaled one-level-deep anchor.

Lists multiple concrete entry points ('fetch(), localStorage, process.env, form submissions') plus a concrete condition ('without explicitly validating the incoming data shape'), matching the multi-action anchor rather than the partial anchor 2.

An explicit 'Use when...' clause states the trigger, and the action ('reviewing code ... without explicitly validating') states what the skill does, answering both what and when; not capped at 2 because the Use-when trigger is present.

Uses natural developer terms ('fetch()', 'localStorage', 'process.env', 'form submissions') that users would actually say, giving good coverage of common variations rather than jargon.

The JS/TS runtime-validation niche with distinct fetch/localStorage/env/form triggers is unlikely to fire for unrelated skills, matching the clear-niche anchor.