Conciseness

The body is dense and assumes Claude's competence — "Never invent an API, a pattern or a behaviour" — with no basic-concept explanations, matching the efficient anchor. It falls short of lean because of minor redundancy that could be trimmed: approvals are restated in three places (Critical Rule 1, the gate table's "--execute" row, and the Before Execute section), and the sub-agent batching budget is explained twice (Before Execute and Sub-Agent Delegation).

Actionability

Guidance is fully executable: a gate table gives copy-paste-ready commands per moment ("check_commit.py --message \"<msg>\"", "check_proofs.py <feature> [--mutations <mutations.json>]") with the path convention pinned earlier ("python3 <skill-dir>/scripts/<name>.py"), plus an exact .specs file tree and exact output formats like "**Approved**: <date> - user: \"<their words>\"". Placeholders are parameterized deliberately, and the rule "Skip a script only when no code-execution tool is available; then perform the same checks by reading the artifact" covers the fallback case.

Workflow Clarity

The multi-step process is clearly sequenced (Specify → Design → Tasks → Execute with an auto-sizing matrix) and validation is explicit with feedback loops: "A non-zero exit means STOP and fix", a safety valve ("If that listing reveals >5 steps or complex dependencies, STOP and create a formal tasks.md"), and resume conflict rules ("continue when the files and git agree; stop only on a conflict"). Checkpoints are tied to concrete moments in a When/Command table.

Progressive Disclosure

The body is an overview with all detail pushed one level deep: every one of the 11 unique reference paths cited (specify.md, implement.md, verify-screens.md, etc.) exists in references/, every script named exists in scripts/, and the Commands tables map trigger patterns to their reference file. References are clearly signaled at their decision points, not buried.

Specificity

Lists multiple concrete, specific actions with comprehensive coverage: "writes testable requirements in EARS notation, atomic tasks with a gate and a commit each", "Ships deterministic Python scripts", "an independent Verifier (author != verifier) spends its time on mutations". There is no vague filler — every clause names a concrete behavior, matching the top anchor rather than the 'several specific actions with minor gaps' of 4.

Completeness

Explicitly answers both questions: the 'what' opens with "Feature planning and implementation with 4 adaptive phases (Specify, Design, Tasks, Execute)" and details behaviors, and the 'when' is fully explicit with "Use when (1) planning features, (2) implementing with verification and atomic commits, (3) validating an implementation against a spec" plus a concrete Triggers list. It even adds negative scope ("Do NOT use for pure architecture decomposition analysis"), going beyond the 4 anchor's weaker 'when'.

Trigger Term Quality

Natural trigger phrases users would actually say are covered comprehensively with synonyms: "specify feature", "discuss feature", "verify work", "UAT", "record decision", "pause work", "resume work", plus "validate"/"verify work" variations for the same intent. Not a 4 because the multi-word phrases are exactly what a user would say when needing this skill, not the generic single keywords the 4 anchor tolerates alongside gaps.

Distinctiveness Conflict Risk

The spec-driven niche is clear and the explicit exclusion "Do NOT use for pure architecture decomposition analysis or standalone technical design documents" plus multi-word triggers keep it mostly distinct. Not a 5 because the bare single-word triggers "design", "tasks", "implement", "validate" are generic and would overlap with general coding/design skills; not a 3 because the exclusion clause and the distinctive multi-word phrases substantially reduce overlap.