Three tools with basic schemas and descriptions, but significant gaps in parameter documentation and output schema clarity. Tool names follow verb_noun convention (query_database, list_tables, describe_table), which is good. However, descriptions are minimal (10-40 chars), parameter descriptions lack detail on constraints and formats, and output schemas are not documented. No error handling guidance. The query_database tool accepts arbitrary SQL with args array but lacks validation constraints or injection warnings. Missing idempotency guidance for write operations.

• Expand query_database description to 100-150 chars: 'Execute a parameterized SQL query. Use ? placeholders in query and pass values in args array to prevent SQL injection. Supports SELECT, INSERT, UPDATE, DELETE. Not idempotent, retries may cause duplicates.'
• Document output schemas for all tools. E.g., query_database returns {columns: string[], rows: any[][], rowCount: number}; list_tables returns {tables: {name: string, schema: string}[], total: number}.
• Add constraint details to parameters: 'schema: Database schema name (default: public). Must be 1-63 chars, alphanumeric + underscore.'
• Add error recovery guidance: 'If query fails with syntax error, check SQL syntax. If connection fails, verify DB_HOST, DB_PORT, DB_USER, DB_PASSWORD environment variables.'
• Add tool annotations (destructiveHint for query_database, readOnlyHint for list_tables/describe_table) to clarify which tools modify state.