Create a ChatGPT Ads ad group

Adds one paused ad group to a campaign that already exists, with its own bidding configuration and optional context hints. Nothing delivers until the user resumes it, and creating it spends nothing. Use when: the user wants to test a different audience, context or bid inside a campaign they already have. Get the campaign id from chatgpt_list_campaigns first. Do not use it to set a budget — budgets live on the campaign on this platform, so a "budget for this ad group" is really chatgpt_update_campaign. Do not use it to build a whole campaign from scratch: that is chatgpt_launch_ad. Do not pass a place name in geo_location_ids. Resolve every place with chatgpt_geo_lookup first; ids only. Because geo targeting is a campaign setting here, passing locations rewrites where the whole campaign runs — the preview says so explicitly, so read it to the user before they approve. max_bid is required: this tool creates a fixed-bid ad group, which the platform will not accept without a maximum bid, so a call without one is refused before anything is created. Its unit follows the campaign objective — a CPM (per 1,000 impressions) for reach, per click for clicks, per conversion for conversions — and the preview shows it with that unit. Returns the new ad group id, read back from the platform with its paused state and its bid confirmed. If the user has not said what the ad group is for or what to bid, ask. Do not invent a bid.