Free-form READ of the Meta Marketing API Insights edge — any metric, breakdown and filter Meta supports, for data the ready-made reports do not cover. fields: Insights field names (e.g. spend, impressions, reach, frequency, clicks, inline_link_clicks, actions, cost_per_action_type, action_values, purchase_roas, video_p75_watched_actions, campaign_id, campaign_name, adset_id, ad_id). level: account | campaign | adset | ad. breakdowns: e.g. age, gender, country, region, publisher_platform, platform_position, device_platform, impression_device, hourly_stats_aggregated_by_advertiser_time_zone (Meta allows only certain combinations). action_breakdowns: e.g. action_type, action_destination. time_increment: 1 = one row per day, 'monthly', or a number of days. filtering: Meta filter objects, e.g. [{"field": "campaign.id", "operator": "IN", "value": ["123"]}] or [{"field": "spend", "operator": "GREATER_THAN", "value": 0}]. days = last N full days excluding today, or give start_date/end_date (YYYY-MM-DD); Meta keeps insights for 37 months. Reference: https://developers.facebook.com/docs/marketing-api/insights/parameters. Meta rejects invalid field/breakdown combinations with an explanatory error. Read-only; reply carries the exact period.