Conciseness

The guidance is codebase-specific (real file paths, index names, failure modes) with no basic-concept padding, but steps 3, 7, and 10 are run-on paragraphs of 150+ words with embedded multi-sentence anecdotes ('A real case: a settings still applying indicator went through three full implementation-and-break cycles...'). Mostly efficient but could be tightened — the score-3 anchor; not 4, whose over-explanation is only 'minor instances', and not 2, since the anecdotes are concrete justifications rather than unnecessary explanations.

Actionability

Fully actionable instruction-only guidance: 'cite file:line for every claim', 'Grep CREATE INDEX for every index on the tables involved', 'EXPLAIN QUERY PLAN at a realistic row count', a concrete save path ('.gemini/internal-docs/PRDs/<kebab-case-name>.md'), a status-line format, a three-box implementation checklist, and named real functions (current_scan_presence_condition(), test/db_test_helpers.py). Matches the score-5 anchor's 'fully executable... specific examples cover the common cases'.

Workflow Clarity

A 13-step numbered process with explicit validation checkpoints (step 11's dedicated final-check bullet list, step 7's confirm-the-test-fails-red-for-the-right-reason), an error-recovery feedback loop ('revert the implementation, confirm the test fails red against the reverted code, and only then reapply the fix'), and checklists — an exact match for the score-5 anchor; no validation cap applies since verification is pervasive.

Progressive Disclosure

Single-file skill with no bundle (no references/, scripts/, or assets/ exist) and clear section headers throughout, so nothing is buried or nested. However, extended real-case anecdotes (the sse_manager.js story, the index examples) and codebase-specific details are inlined in dense paragraph steps, and one pointer ('see scan-pipeline Gotcha 8') resolves to nothing shipped with the skill. Good structure with minor organization gaps — the score-4 anchor; not 5, which expects a lean overview split across files, and not 3, since the inline material is justification rather than clearly-separate reference content.

Specificity

Lists seven concrete actions — 'challenge the idea', 'verify every claim against actual code', 'trace every downstream consumer of a mechanism', 'evaluate performance impact against the schema/indexes that actually exist', 'record rejected alternatives and open-issue decisions explicitly', 'do a dedicated final-check pass' — comprehensive coverage of the PRD-writing process. Fits the score-5 anchor ('multiple specific concrete actions; comprehensive coverage'), not score 4's 'minor gaps in coverage', since every phase of the methodology is named.

Completeness

Explicitly answers both what ('Rigorous PRD-writing methodology — challenge the idea, verify every claim against actual code...') and when ('Use this when asked to write, draft, or review a PRD, design doc, or feature proposal for this codebase') with concrete trigger phrases — an exact match for the score-5 anchor; not 4, whose 'when' is less explicit.

Trigger Term Quality

'write, draft, or review a PRD, design doc, or feature proposal' gives good natural verb and noun coverage, but misses common variations the skill body itself lists as triggers ('spec out this feature', 'product requirements document'). Good coverage with a few natural terms missing — the score-4 anchor, not 5's comprehensive synonym coverage.

Distinctiveness Conflict Risk

'PRD', 'design doc', and 'feature proposal' form a clear niche with distinct, unlikely-to-misfire triggers; minimal overlap risk with generic writing or documentation skills — the score-5 anchor rather than 4's 'minor overlap risk with closely related skills'.