{
    "action": "tool_call",
    "reasoning": "To find duplicates, I need to check for rows that repeat across key identifying columns. The columns_catalog table is the largest (74.6% of data), so I'll start there. From the column inspection, I can see that 'id' is the primary identifier, 'tables_catalog_id' links to the parent table, and 'column_name' + 'ordinal' define the column within that table. I'll check for exact duplicates on the natural key (tables_catalog_id, column_name, ordinal) and also check other major tables like job_logs and llm_calls for duplicates on their likely natural keys.",
    "tool": "query_sql",
    "args": {
        "sql": "SELECT tables_catalog_id, column_name, ordinal, COUNT(*) as duplicate_count FROM raw.columns_catalog GROUP BY tables_catalog_id, column_name, ordinal HAVING COUNT(*) > 1 ORDER BY duplicate_count DESC LIMIT 50",
        "purpose": "Check for duplicate rows in columns_catalog based on natural key (tables_catalog_id, column_name, ordinal)"
    }
}