{
    "action": "tool_call",
    "reasoning": "The earlier draft cited numbers, but the evidence in this turn doesn't show them. I'll re-run one aggregate query over raw.raw_kaggle by surface (average aces, average double faults, rank stats, serve-stat coverage) so the answer rests on an executed result.",
    "tool": "query_sql",
    "args": {
        "sql": "SELECT Surface, COUNT(*) AS player_matches, COUNT(Aces) AS rows_with_serve_stats, ROUND(100.0*COUNT(Aces)/COUNT(*),1) AS pct_with_serve_stats, ROUND(AVG(TRY_CAST(Aces AS DOUBLE)),2) AS avg_aces, ROUND(AVG(TRY_CAST(DFs AS DOUBLE)),2) AS avg_dfs, ROUND(AVG(TRY_CAST(Rk AS DOUBLE)),0) AS mean_rank, ROUND(MEDIAN(TRY_CAST(Rk AS DOUBLE)),0) AS median_rank FROM raw.raw_kaggle GROUP BY Surface ORDER BY avg_aces DESC",
        "purpose": "Verify surface differences in aces, double faults, player rank and serve-stat coverage",
        "source": "raw"
    }
}