Conciseness

The ~35-line body is pure prescriptive guidance — conventions, a checklist, and an output format — with no explanation of concepts Claude already knows (e.g., it never explains what SQL or aggregation is) and no padding. This matches the anchor 'lean and efficient; assumes Claude's competence; every token earns its place'; a 4 would require minor instances of over-explanation, which are absent.

Actionability

Concrete, immediately executable rules like "Always SELECT explicit column names, never SELECT *", "Alias aggregates with snake_case names (order_count, not count(*))", and the fenced ```sql output format match 'mostly executable guidance; concrete code or commands with minor gaps'. It falls short of 5 because there is no worked example query, though the scoring note confirms absence of code in an instruction-only skill is not penalized when guidance is this actionable.

Workflow Clarity

For this simple single-purpose skill the sequence is unambiguous: apply the conventions, run the "Review Checklist (run before returning an answer)" as an explicit validation checkpoint, then produce the specified output. The explicit pre-return checklist matches the simple-skill exception and provides the validation step anchors look for; a 4 would require that checkpoint be merely implicit.

Progressive Disclosure

Per the guideline that skills under 50 lines with no need for external references can score 5 with just well-organized sections, the body's clean sections (When to Use, Conventions, Review Checklist, Output Format) qualify — there are no buried or nested references (no bundle files exist at all). It is not below 5 since there is no inlined content that belongs in a separate file.

Specificity

The description lists several concrete, domain-anchored actions — "writing analytics SQL against the warehouse", "querying tables", "building a report", "aggregating metrics" — comparable to the anchor 'lists several specific actions; minor gaps in coverage'. It falls short of a 5 because it never names what the conventions actually cover (e.g., SELECT hygiene, partition filtering), which is a minor coverage gap.

Completeness

It explicitly answers both parts with concrete trigger phrases: the 'what' ("Conventions and review steps for writing analytics SQL against the warehouse") and the 'when' ("Use whenever the task involves querying tables, building a report, or aggregating metrics"), matching the anchor 5 example structure. A 4 would require the 'when' to be less explicit or specific, which is not the case here.

Trigger Term Quality

Natural user phrasings like "querying tables", "building a report", and "aggregating metrics" give good keyword coverage, matching the anchor 'good keyword coverage; a few natural terms missing'. Not a 5: common variations users would say — "write a SQL query", "dashboard", "metrics query", warehouse name — are absent.

Distinctiveness Conflict Risk

The niche (analytics SQL against a warehouse) is mostly distinct with clear triggers, matching the anchor 'mostly distinct; minor overlap risk'. It is not a 5 because generic phrases like "building a report" and "aggregating metrics" could plausibly overlap with general data-analysis or BI skills.