Conciseness

The ~30-line body is efficient overall — a dense Quick Reference with concrete numbers and terse per-mode directives — but the opening sentence ('Coverage thresholds prevent code quality from degrading over time by failing builds when test coverage drops below safe levels') explains a concept Claude already knows, and the four mode sections partially restate the same review instruction. This matches 'efficient; minor instances of over-explanation that could be trimmed' rather than the every-token-earns-its-place level 5.

Actionability

Concrete guidance is present: exact threshold specs ('70% branches, 80% lines/functions/statements', 'stricter thresholds (90%+) to critical utility code'), exclusion categories, and a specific review directive ('Flag exact gaps where the rule is not automatically verified'). Fully executable configs exist one clearly-signaled hop away in references/rule.md, but the body itself contains no code or commands — the Fix section stays at 'Jest, Vitest, or your testing framework' — so it lands at 'mostly executable with minor gaps', not copy-paste-ready level 5.

Workflow Clarity

The Check/Fix/Explain/Code Review sections each give an unambiguous single directive, appropriate for this simple read-only review skill (no destructive or batch operations, so no validation cap applies). It falls short of level 5 because the body includes no verification checkpoint — confirming that CI actually fails when coverage drops is stated only in the reference file's Verification section, leaving the Fix workflow without an explicit feedback loop in the body.

Progressive Disclosure

The body is a concise overview that delegates implementation details to a single one-level-deep reference ('For full implementation details, code examples, and framework-specific guidance, see references/rule.md'), and that file exists and contains exactly what is promised — Jest/Vitest configs, CI/CD integration, threshold tables, and verification steps. This matches the clear-overview, well-signaled, one-level-deep anchor.

Specificity

The description names its domain ('CI coverage, automated checks, or test strategy') and one or two actions ('reviewing', 'Focus on whether the rule is continuously verified'), but never enumerates concrete capabilities such as configuring thresholds or wiring CI gates. It fits the 'names domain and 1-2 concrete actions' anchor, not the level-4 anchor requiring several specific actions.

Completeness

A clear 'when' is present ('Use when reviewing CI coverage, automated checks, or test strategy related to Maintain test coverage thresholds'), but the 'what' is only weakly implied by the 'Focus on whether the rule is continuously verified' directive — the skill's concrete purpose is never stated. It does not reach level 4, which requires both what and when explicitly.

Trigger Term Quality

Natural phrases like 'CI coverage', 'automated checks', 'test strategy', and 'test coverage thresholds' would be said by users needing this skill. However, common variations such as 'code coverage' — arguably the most frequent phrasing — and tool names (Jest, Vitest) are missing, so it stops short of the comprehensive-synonym level-5 anchor.

Distinctiveness Conflict Risk

The niche focus on coverage-threshold enforcement ('CI coverage', 'Maintain test coverage thresholds') is mostly distinct from other skills. Broad terms like 'test strategy' and 'automated checks' create minor overlap risk with general testing/CI skills, keeping it below the minimal-conflict level-5 anchor.