Add an ad to a TikTok ad group (paused)

Creates one more ad inside an existing TikTok ad group, PAUSED, from a video already in the library or an organic post (Spark Ad). Use when: testing a second creative, or replacing one that tiktok_detect_creative_fatigue has flagged. Adding a fresh ad to a working ad group is the right way to handle fatigue: it keeps the ad group's learning, which pausing and rebuilding would throw away. Do not upload a video here — this tool takes a video_id. Upload happens in tiktok_create_video_campaign, or the user uploads in Ads Manager and tiktok_list_ad_videos finds the id. Do not add more than two or three ads to one ad group. TikTok concentrates delivery on whichever wins early, so extra ads mostly divide the learning rather than expand the test. Do not guess the identity. TikTok requires one on every ad; list them with tiktok_list_identities and ask the user which account the ad appears as. A video_id ad also needs exactly one cover image (tiktok_upload_images). Do not assume the new ad delivers immediately: it is created paused and, once resumed, TikTok reviews it first — usually a few hours. Validates before creating: the identity (it must exist on the advertiser, be available, and be able to carry the post), the cover image, the ad text (no emoji; Chinese and Japanese characters count double), and the landing page the campaign's objective requires. Returns the new ad id, read back from TikTok with its review status.