Conciseness

The ~26-line body is lean and instructional throughout: three concrete commands and six tersely labeled steps with zero padding or explanation of concepts Claude already knows. Even "The index is NOT the goal — it points you to the actual guideline files" earns its place by guarding a real failure mode, matching 'every token earns its place'.

Actionability

Steps 1–3 give copy-paste-ready commands ("git diff --name-only HEAD", "python3 ./.trellis/scripts/get_context.py --mode packages", "cat .trellis/spec/<package>/<layer>/index.md"), but step 5 "Run lint and typecheck for the affected package" provides no specific command or pointer to where it is defined. This is 'mostly executable guidance; concrete code or commands with minor gaps' rather than the fully copy-paste-ready profile of score 5.

Workflow Clarity

The six steps are clearly numbered and sequenced, and the lint/typecheck run plus "Report any violations" act as checkpoints. It falls short of score 5 because "fix them if found" lacks an explicit re-validation loop (fix, then re-run lint/typecheck), leaving a minor validation gap; it is above score 3 since checkpoints are present and explicit, not merely implied.

Progressive Disclosure

This is a simple skill under 50 lines with no bundle files and no content that belongs in separate reference files, so the simple-skill exception applies: the well-organized numbered structure with bold step labels suffices. The dynamic pointers into ".trellis/spec/" are one level deep (index.md to the guideline files it names) and explicitly signaled.

Specificity

"Identifies changed files via git diff, discovers applicable spec modules, runs lint and typecheck, and reports guideline violations" lists five concrete actions covering every stage of the validation pipeline. This matches the anchor for multiple specific concrete actions with comprehensive coverage; score 4 would require minor gaps, but no workflow stage is missing.

Completeness

The 'what' is explicit ("Validates recently written code against project-specific development guidelines from .trellis/spec/" with concrete mechanisms) and the 'when' is an explicit "Use when..." clause with three concrete trigger conditions ("needs quality verification, to catch context drift during long sessions, or before committing changes"). Both are clearly and explicitly answered, matching the top anchor.

Trigger Term Quality

Natural phrases like "needs quality verification", "context drift during long sessions", and "before committing changes" are terms a user would plausibly say. A few common variations are missing (e.g., "check my code", "code review"), so it fits 'good keyword coverage; a few natural terms missing' rather than the comprehensive synonym coverage of score 5.

Distinctiveness Conflict Risk

The niche is anchored to project-specific guidelines from ".trellis/spec/" and tooling like "get_context.py", making it mostly distinct. However, the trigger "code is written and needs quality verification" could overlap with generic code-review or lint skills, so it fits 'mostly distinct; minor overlap risk' rather than the minimal-conflict profile of score 5.