meta_ads_audiences_create_lookalike
Create a lookalike audience from a source audience, targeting a specific country with a similarity ratio between 1% and 20% to expand reach while maintaining match quality.
Instructions
Creates a Lookalike Audience from an existing source audience. Returns the new audience_id. Mutating — not automatically reversible; record before-state with mureo_state_action_log_append if you may need to roll back. Lookalikes typically populate within 24–72h; the approximate_count remains 0 until Meta finishes the similarity build. ratio=0.01 gives the top 1% most similar users in the target country (smallest, highest match); ratio=0.10 gives top 10% (larger reach, looser match). For the base audience list use meta_ads_audiences_list.
Input Schema
TableJSON Schema
| Name | Required | Description | Default |
|---|---|---|---|
| name | Yes | Audience name shown in Ads Manager. Must be unique within the account. | |
| ratio | Yes | Similarity ratio — fraction of the target country's population to include. 0.01 = top 1% (tightest match, smallest audience); 0.20 = top 20% (loosest, largest). Meta caps at 0.20. | |
| country | Yes | Target country ISO code(s) for the lookalike expansion. Accepts a single code string (e.g. 'JP') or a list (e.g. ['JP', 'KR']). Lookalike reach is always scoped to the specified country/countries. | |
| account_id | No | Meta Ads account ID in the format 'act_XXXXXXXXXX' (e.g. 'act_1234567890'). Optional — falls back to META_ADS_ACCOUNT_ID from the configured credentials. The leading 'act_' prefix is required. | |
| starting_ratio | No | Lower bound of the ratio range. Default 0.0. Advanced: set > 0 to carve out a tiered lookalike that excludes the top-similarity slice (e.g. starting_ratio=0.01, ratio=0.05 = users ranked 1–5% in similarity, excluding the top 1%). | |
| source_audience_id | Yes | Source Custom Audience to build the lookalike from. Meta recommends a source of at least 1,000–10,000 users for good match quality. |