Conciseness

The body is lean and dense — configuration schema, env-var and exit-code tables, and four canonical examples with no padding and no explanation of concepts Claude already knows (e.g., no tutorial on regex, JSON, or shell scripting). It matches the score-5 anchor ('lean and efficient; assumes Claude's competence; every token earns its place'); score 4 would require identifiable instances of over-explanation to trim, and none stand out.

Actionability

Three of the four canonical examples are copy-paste executable (the rm -rf blocker, the inline allow echo, the Go context injector), and the config snippets are concrete. It falls short of the score-5 anchor because the rewrite example pipes through an unexplained placeholder — `jq -r '.tool_input.command' | some-rewriter` — so that example is not executable as written; the user-specific rewriting logic is implicitly but not explicitly justified, which is exactly the 'minor gaps' of the score-4 anchor.

Workflow Clarity

The Authoring Checklist gives a clear 5-step sequence (shebang/set flags, chmod, config entry, intent decision, shallow-merge reminder) and the Debugging section supplies error-recovery guidance (timeout behavior, non-2/49 exits, stderr logging, matcher regex). It does not reach 5 because there is no explicit verification checkpoint such as testing the hook against a sample stdin payload before wiring it into crush.json — the 'minor validation gaps' of the score-4 anchor. The destructive-operations cap does not apply since the workflow authors hooks rather than performing destructive/batch operations.

Progressive Disclosure

The single file (~205 lines) is well organized into scannable sections (Events, Configuration, Input, Output, Aggregation, Examples, Checklist, Debugging, Compatibility) with a one-level pointer to the full reference ('For the full reference, see docs/hooks/README.md'). It stops short of the score-5 anchor because that pointer is not a proper link and no bundle file exists, so reference-grade detail (env-var/exit-code tables) is inlined rather than split out — the 'minor organization gaps' and 'references mostly clear' of the score-4 anchor; it is well above score 3, where structure would be weak or references buried.

Specificity

The description lists multiple specific concrete actions — "add, write, debug, or configure a Crush hook", "gating or blocking tool calls, approving or rewriting tool input before execution, injecting context into tool results, or troubleshooting hook behavior" — giving comprehensive coverage of the skill's capabilities with no vague filler. It matches the score-5 anchor ('lists multiple specific concrete actions; comprehensive coverage') and exceeds score 4, which permits minor coverage gaps; none are evident.

Completeness

Both 'what' and 'when' are explicitly answered: the 'Use when the user wants to...' clause gives concrete trigger conditions, and the em-dash clause states what the skill does (gating/blocking, approving/rewriting, injecting context, troubleshooting). It mirrors the score-5 anchor example structure; it is above score 4 because the 'when' is fully explicit with concrete trigger phrases rather than merely present.

Trigger Term Quality

Natural trigger terms are comprehensive and include synonyms: "add, write, debug, or configure" (authoring synonyms), "gating or blocking" (blocking synonyms), "troubleshooting", plus the concrete artifact names "Crush hook" and "crush.json". This matches the score-5 anchor's requirement for synonym coverage; score 4 ('a few natural terms missing') would apply only if common phrasings were absent, and a user asking to write, block with, or troubleshoot a hook would phrase it in terms already covered.

Distinctiveness Conflict Risk

The description names a clear niche — Crush hooks in crush.json — with distinct triggers ('Crush hook', 'crush.json', 'tool input'), giving minimal conflict risk with other skills. Even against a closely related Claude Code hooks skill, the repeated 'Crush' qualifier disambiguates, fitting the score-5 anchor ('clear niche with distinct triggers; minimal conflict risk').