{
    "action": "tool_call",
    "reasoning": "No query results are in my evidence, so I can't cite the correlations from the earlier draft. I'll compute them in one query over raw data before answering.",
    "tool": "query_sql",
    "args": {
        "sql": "SELECT COUNT(*) AS n, corr(bedtime_phone_minutes, sleep_latency_min) AS r_phone_latency, corr(bedtime_phone_minutes, total_sleep_hours) AS r_phone_sleep, corr(sleep_latency_min, next_day_fatigue_score) AS r_latency_fatigue, corr(total_sleep_hours, next_day_fatigue_score) AS r_sleep_fatigue, corr(blue_light_filter_active, sleep_latency_min) AS r_filter_latency, corr(screen_brightness_pct, sleep_latency_min) AS r_brightness_latency, corr(caffeine_post_5pm_mg, total_sleep_hours) AS r_caffeine_sleep FROM raw.bedtime_screentime_sleep_debt",
        "purpose": "Compute key correlations across all users to ground the analytical questions",
        "source": "raw"
    }
}