The skill is generally efficient and avoids explaining basic concepts Claude already knows, but it's quite long (~500+ lines) with some sections that could be tightened. The Common Mistakes table at the end is extensive and some entries repeat guidance already covered in earlier sections (e.g., snake_case, domains, timestamptz). However, most content earns its place as domain-specific conventions Claude wouldn't inherently know.

The skill provides concrete, executable SQL examples throughout — CREATE DOMAIN definitions, RLS policies, trigger functions, queue claim CTEs, migration DDL with IF NOT EXISTS, and reference table seeding. Code is copy-paste ready PostgreSQL, not pseudocode, and covers real production patterns with specific syntax.

The skill covers many individual patterns clearly but lacks explicit multi-step workflow sequences with validation checkpoints. For example, the migration section shows idempotent DDL but doesn't provide a step-by-step migration workflow with validation. The base/subtype section references triggers but doesn't show the full creation sequence with verification. For a skill involving destructive operations (migrations, schema changes), explicit validation steps would strengthen this.

The skill excels at progressive disclosure — the main body provides concise overviews with key examples for each topic, then consistently links to dedicated reference files (e.g., 'read [Naming Conventions](references/naming-conventions.md)'). References are one level deep, clearly signaled with descriptive link text, and the main document serves as a navigable overview. However, no bundle files were provided to verify the references actually exist.

Lists multiple specific concrete actions: writing/reviewing PostgreSQL/PL-pgSQL, designing table schemas, writing functions and procedures, building migrations, defining domains, RAISE EXCEPTION patterns, BEFORE/AFTER triggers, base/subtype hierarchies, composite key designs, row-level security policies, idempotent DDL scripts.

Clearly answers both 'what' (PostgreSQL schema design, functions, triggers, migrations, etc.) and 'when' with explicit trigger guidance ('Use when writing or reviewing PostgreSQL...', 'Also use when...', 'If you are touching Postgres for an application database, use this skill').

Excellent coverage of natural terms users would say: PostgreSQL, PL-pgSQL, Postgres, table schemas, functions, procedures, migrations, triggers, row-level security, DDL scripts, domains, composite keys. These are terms a developer would naturally use when seeking help with PostgreSQL.

Clearly scoped to PostgreSQL/Postgres specifically, with the explicit note 'PostgreSQL-specific — examples will not run on other engines.' This creates a distinct niche that would not conflict with general SQL or other database engine skills.