Conciseness

The body is ~24 lines with zero padding: 'Remain read-only. Never edit code, tests, plans, or state.' and 'Never bash, edit, or write.' assume Claude's competence and add only non-obvious protocol. Every token earns its place, matching anchor 5; there are no unnecessary explanations that would drop it to 4.

Actionability

Directives are exact and executable: the tool allowlist 'tools=read,grep,find,ls', the prohibition 'Never `bash`, `edit`, or `write`', the output contract 'Return only `factory.review.v4`', and the termination step 'After the template, call `subagent_done` and emit nothing else.' This fully matches anchor 5 for an instruction-only skill — guidance is specific and unambiguous, covering the common cases (model mismatch, mutation tools present, missing packet).

Workflow Clarity

Three clearly sequenced phases (isolate session → review the task → return the verdict), each with explicit validation checkpoints and named failure paths: 'If the model matches the work model, return `blocked`', 'If mutation tools are present, return `blocked`', 'If the packet or diff file is missing... return `blocked` and name the missing input.' Every gate has a defined recovery/report action, matching anchor 5; no validation gaps exist that would justify anchor 4.

Progressive Disclosure

The body is a clean overview with well-signaled, purposeful references ('Read [references/reviewer-prompt.md] and follow it', 'After behavior and acceptance criteria, apply [references/code-quality.md]'), and both referenced files exist with substantive content. However, review-contract.md is only reachable two hops away via reviewer-prompt.md and is never mentioned in the body, and verdict/severity definitions are duplicated between reviewer-prompt.md and review-contract.md — minor organization gaps that keep it at anchor 4 rather than the fully one-level-deep, cleanly split structure of anchor 5.

Specificity

Lists several concrete mechanisms — 'read-only Pi subagent', 'model different from the worker', 'return a structured markdown findings list and a verdict', 'never edits code or applies its own findings' — with minor gaps in coverage (verdict types and severity levels are not surfaced). It exceeds anchor 3 (only 1-2 actions) but is not the comprehensive coverage of anchor 5.

Completeness

Both parts are explicit: the 'what' ('Adversarially review one ready-for-review ticket task... return a structured markdown findings list and a verdict') and the 'when' ('Use only for the review stage'). It falls short of anchor 5 because the trigger guidance is a single clause rather than multiple concrete trigger phrases, so the 'when' could be more specific; it is well above anchor 3 since the 'when' is explicit, not implied.

Trigger Term Quality

Natural terms a user in this workflow would say are present: 'review', 'ready-for-review ticket task', 'review stage', 'findings', 'verdict'. Coverage is good but misses common variations like 'check the implementation' or 'verify the worker's output', placing it between anchors 3 and 4, noticeably above the midpoint.

Distinctiveness Conflict Risk

The description carves a clear niche with distinct triggers — 'read-only Pi subagent', 'review stage', 'model different from the worker', 'never edits code or applies its own findings' — making confusion with general code-review or editing skills very unlikely. This matches anchor 5 (clear niche, minimal conflict risk); anchor 4 would require some notable overlap with a closely related skill, which is absent.