{
    "action": "tool_call",
    "reasoning": "I need to identify the main categorical columns across the dataset by finding VARCHAR/TEXT columns with low distinct-to-row ratios, indicating categorical nature suitable for frequency analysis.",
    "tool": "query_sql",
    "purpose": "Identify main categorical columns by finding VARCHAR/TEXT columns with low distinct-to-row ratios",
    "sql": "SELECT c.table_name, c.column_name, c.phys_type, c.semantic_role, c.rough_kind, c.approx_distinct_count, ao.row_count, ROUND(CAST(c.approx_distinct_count AS DOUBLE) / NULLIF(ao.row_count, 0), 4) as cardinality_ratio FROM meta.columns c JOIN analytics.table_overview ao ON c.table_name = ao.table_name WHERE c.phys_type IN ('VARCHAR', 'TEXT') AND c.approx_distinct_count IS NOT NULL AND ao.row_count > 0 AND CAST(c.approx_distinct_count AS DOUBLE) / ao.row_count < 0.1 ORDER BY ao.row_count DESC, cardinality_ratio ASC LIMIT 50"
}