{
    "action": "tool_call",
    "reasoning": "I have already gathered most common values for several key categorical columns (job_logs.phase, column_tags.tag, job_logs.dataset_id, job_logs.function_name, job_logs.job_id) in step-9. Now I need to get the most common values for other important categorical columns identified in step-7, particularly: llm_calls.purpose, batches.status, llm_calls.dataset_id, and tag_lineage_edges.table_name. I'll query these one at a time since UNION ALL failed in step-10.",
    "tool": "query_sql",
    "args": {
        "sql": "SELECT purpose, COUNT(*) as frequency FROM raw.llm_calls WHERE purpose IS NOT NULL GROUP BY purpose ORDER BY frequency DESC LIMIT 10",
        "purpose": "Get most common values for llm_calls.purpose",
        "source": "raw"
    }
}