Lean and efficient — feature table, security bullets, copy-paste commands, and parameter tables with no explanations of concepts Claude already knows; every section earns its place rather than the 'mostly efficient but could be tightened' level.

Fully executable copy-paste commands with real flags and subcommands, plus concrete JSON/Mermaid output examples; the referenced scripts/db_explorer.py exists and exposes matching argparse subcommands, making guidance copy-paste ready.

A simple single-purpose CLI where each subcommand is one unambiguous read-only action; the tool itself enforces safety (read-only mode, keyword/multi-statement blocking), so no manual destructive-validation checkpoint is needed, satisfying the simple-skills allowance for a 3.

Well-organized into clear sections with one bundle file (scripts/db_explorer.py) referenced by real relative paths and verified present — references are one level deep and clearly signaled, with no nested reference chains.

Lists five concrete actions — list tables, inspect schemas (columns/types/constraints), preview data, generate Mermaid ER diagrams, and run safe read-only queries — matching the 'multiple specific concrete actions' anchor rather than the partial-coverage anchor below.

Explicitly answers both what it does (the five actions) and when to use it ('Triggered by requests to explore a database... and by keywords like...'), satisfying the both-what-and-when anchor with explicit triggers.

Provides varied natural keywords users would say — 'describe tables', 'view table structures', 'ER diagram', 'schema', 'SQL query' — giving good coverage of common phrasings rather than only jargon or a single keyword.

Scoped narrowly to SQLite/PostgreSQL read-only database exploration with distinct triggers (ER diagram, schema inspection, safe queries), making it unlikely to fire for unrelated skills.