Conciseness

The ~35-line body is lean and assumes Claude's competence: 'Review the requested scope for concrete, reproducible defects. The nearest `AGENTS.md` owns package facts and commands' adds only skill-specific constraints, with zero padding or explanation of concepts Claude already knows.

Actionability

Every instruction is executable and specific: diff-area-to-file routing ('Models or migrations: references/db-schema-rule.md'), an exact P0-P3 severity taxonomy, and a complete output contract including the literal string 'No issues found.' and required elements ('a tight file and line reference, the failing contract or reproduction path, impact, and a concrete fix direction').

Workflow Clarity

The 'Evidence First' section gives a clear 4-step sequence with an explicit reporting gate ('Report only findings tied to an observable failure, violated contract, security boundary...') and a fallback path ('When no pack applies, review correctness, security, behavior changes, and test evidence directly'). It falls short of 5 only because there is no explicit verify-or-reproduce step per finding before reporting, though the gate in step 4 partially covers this; it is above 3 because checkpoints are explicit rather than implicit.

Progressive Disclosure

The body is a concise overview that routes to four well-signaled, one-level-deep references ('Read only the packs matched by the diff'), each keyed to a concrete diff area; all four referenced files (architecture-rule.md, db-schema-rule.md, repositories-rule.md, sqlalchemy-rule.md) exist in references/ and are substantive, with detail appropriately split out of SKILL.md.

Specificity

'Supports pending-change, file-focused, and pasted-diff reviews' lists several concrete review modes within a clearly bounded domain, matching the 'several specific actions; minor gaps' anchor. It is not 5 because it never states what the review produces (e.g., severity-ranked defect findings), and not 3 because it goes beyond naming the domain with 1-2 actions.

Completeness

Both questions are answered explicitly: the 'what' ('Supports pending-change, file-focused, and pasted-diff reviews' of backend code under `api/`) and an exceptionally explicit 'when' with concrete trigger phrases and boundaries ('Use only when the user explicitly requests a review or audit... Do not use for implementation-only requests, diagnosis without review intent, frontend code, or backend code outside `api/`'). The score-4 anchor ('when' could be more explicit) clearly does not fit, since the when includes both positive triggers and an exclusion list.

Trigger Term Quality

Natural trigger terms are present ('review or audit of backend code', 'diff'), matching 'good keyword coverage; a few natural terms missing'. It is not 5 because common user phrasings like 'code review', 'PR review', or 'pull request' are absent, and not 3 because the coverage of the core request vocabulary is solid rather than partial.

Distinctiveness Conflict Risk

The description carves out a clear niche with minimal conflict risk: it is scoped to 'backend code under `api/`' and explicitly excludes overlapping cases ('implementation-only requests, diagnosis without review intent, frontend code, or backend code outside `api/`'), so it is unlikely to trigger for the wrong skill.