{
    "action": "tool_call",
    "reasoning": "No evidence is in context yet, so I will compute the key correlations and the blue-light filter comparison in a single query before answering.",
    "tool": "query_sql",
    "args": {
        "sql": "SELECT COUNT(*) AS n, SUM(blue_light_filter_active) AS filter_users, CORR(bedtime_phone_minutes, sleep_latency_min) AS r_phone_latency, CORR(bedtime_phone_minutes, next_day_fatigue_score) AS r_phone_fatigue, CORR(bedtime_phone_minutes, total_sleep_hours) AS r_phone_sleep, CORR(total_sleep_hours, next_day_fatigue_score) AS r_sleep_fatigue, CORR(morning_alarm_snoozes, next_day_fatigue_score) AS r_snooze_fatigue, CORR(blue_light_filter_active, sleep_latency_min) AS r_filter_latency, CORR(blue_light_filter_active, total_sleep_hours) AS r_filter_sleep, CORR(screen_brightness_pct, sleep_latency_min) AS r_bright_latency, CORR(physical_activity_min, total_sleep_hours) AS r_activity_sleep, CORR(physical_activity_min, next_day_fatigue_score) AS r_activity_fatigue, CORR(caffeine_post_5pm_mg, total_sleep_hours) AS r_caff_sleep, CORR(caffeine_post_5pm_mg, deep_sleep_pct) AS r_caff_deep, CORR(caffeine_post_5pm_mg, sleep_latency_min) AS r_caff_latency, CORR(caffeine_post_5pm_mg, next_day_fatigue_score) AS r_caff_fatigue FROM raw.bedtime_screentime_sleep_debt",
        "purpose": "Compute correlations among bedtime behaviours, sleep outcomes and fatigue",
        "source": "raw"
    }
}