Conciseness

Roughly half the body restates standard SQL knowledge Claude already has — the JOIN/CTE/window-function examples under "Query Generation Patterns", the Connection Pooling and Read Replicas sections, the Sharding & Replication tables, and Best Practices bullets like "Use meaningful names" and "Validate inputs: Prevent SQL injection attacks". That is several padded sections of unnecessary explanation, matching anchor 2 rather than 3, where only isolated instances would remain after trimming.

Actionability

The tool-workflow commands are formatted as copy-paste ready ("python3 schema_analyzer.py --input schema.sql --generate-erd --output-format json -o analysis.json"), but the three scripts they invoke — schema_analyzer.py, index_optimizer.py, migration_generator.py — do not exist anywhere in the bundle, so the core workflow cannot actually be executed; the remaining SQL snippets are executable but generic. This is anchor 3: concrete-looking guidance with a critical missing piece, not the executable-and-complete anchor 4.

Workflow Clarity

The four-step tool workflow is clearly sequenced and includes a genuine validation loop ("Re-run step 1 on the *target* schema and assert the issues found in the first pass are gone; run migration_generator.py --validate-only before handing over"), satisfying the database-operations feedback-loop requirement. It falls short of anchor 5 because there is no error-recovery guidance (what to do when the analyzer flags issues that cannot be fixed, or when a migration fails --validate-only).

Progressive Disclosure

Only one of the four reference files is signaled from the body ("→ See references/database-design-reference.md for details"); database_selection_decision_tree.md, index_strategy_patterns.md, and normalization_guide.md are never mentioned and are effectively undiscoverable, while ~120 lines of sharding, replication, and query-pattern content that belongs in those references is inlined in SKILL.md. Buried references plus inlined reference-grade content matches anchor 2; structure does exist, but the reference wiring failure is well below the midpoint.

Specificity

The description lists five concrete actions ("design database schemas, plan data migrations, optimize queries, choose between SQL and NoSQL, or model data relationships") at a granularity comparable to the top anchor, but coverage has minor gaps — the body's index-optimization and ERD-generation competencies are only loosely covered by "optimize queries" — matching anchor 4 rather than 5.

Completeness

The 'when' is fully explicit ("Use when the user asks to...") and each trigger verb doubles as a 'what', but the 'what' is only implied by the fused trigger list rather than stated separately, so it sits at anchor 4 ('both present; one could be more explicit') rather than the clearly-separated what+when of anchor 5.

Trigger Term Quality

Natural phrases users would actually say are present ("optimize queries", "plan data migrations", "choose between SQL and NoSQL"), but common synonyms and variations are missing — "indexing", "normalization", "ERD", "schema design", "performance tuning" — which is anchor 4's 'good keyword coverage; a few natural terms missing', not the comprehensive synonym coverage of anchor 5.

Distinctiveness Conflict Risk

A clear database-design niche with distinct, domain-specific triggers; minor overlap risk comes from "optimize queries", which a general SQL/query-writing skill would also claim — anchor 4 ('mostly distinct; minor overlap risk with closely related skills'), above anchor 3 because the remaining triggers are unambiguous.