Single tool 'query' has critical definition gaps. Description is minimal (28 chars, below 20-char floor). Input schema present but parameter 'sql' lacks description entirely, violates pattern:tool-description requirement that every parameter needs explanation. No output schema documented. No error handling guidance. Tool lacks context on when to use it vs alternatives, prerequisites, or what fields to expect in results. Naming is acceptable (verb_noun form) but insufficient to overcome missing parameter documentation.

• Expand tool description to 100-200 chars: 'Execute read-only SQL queries against the connected PostgreSQL database. Returns query results as JSON. Use for SELECT statements only; INSERT/UPDATE/DELETE are blocked. Call list_tables() first to discover available tables and schemas.'
• Add description to 'sql' parameter: 'SQL SELECT query to execute. Must be read-only (no INSERT, UPDATE, DELETE, DROP). Max 10,000 characters. Examples: SELECT * FROM users LIMIT 10; SELECT COUNT(*) FROM orders WHERE created_at > NOW() - INTERVAL 7 days'
• Document output schema in tool description or as a separate schema field: 'Returns {rows: [{column1: value, column2: value, ...}], rowCount: number}. Each row is a JSON object with column names as keys.'
• Add error handling that returns actionable messages: catch SQL syntax errors and suggest 'Invalid SQL. Check table names with list_tables() or column names with describe_table(table_name).' Catch timeouts and suggest 'Query exceeded 30s timeout. Add LIMIT clause or filter by date range.'
• Add parameter constraints to description: specify max query length, timeout duration, result row limit, and forbidden keywords. Example: 'Max 10,000 chars, 30s timeout, max 1,000 rows returned. Forbidden: INSERT, UPDATE, DELETE, DROP, TRUNCATE.'