Astra vs Fable 5.1 on Meta ads: Astra wins the body, Fable wins the hook
In a same-script, same-renderer test of ad prompts, Astra produced steadier, more complete videos while Fable 5.1 had stronger opening hooks, and the author shares a prompt guide to patch Astra's default style.
GPT-6 Astra just dropped, and it's INSANE for making meta ads BUT Fable 5.1 still does 1 thing better. We ran both through the same harness. Same brief, same product, same renderer — Seedance 2.5. Each model writes the prompt. We render both. We compare. Astra won the body. Not close. Cleaner scene transitions. Product stays consistent shot to shot. Pacing holds all the way through. The last 7 seconds of an Astra ad look like something an agency actually shipped. Then you watch the first 3. Fable's hooks stop the scroll. Astra's hooks start the ad. Our best read on why: Astra is built to complete work. OpenAI's own launch post says it's their best model at following templates and producing structured narratives. Polished. Thorough. Even. That's exactly what a body needs. It's the opposite of what a hook needs. A hook is unfinished on purpose. It's a question, not an answer. Thoroughness kills it. Give Astra a 4-beat brief and it writes 4 equal beats. Beat 1 has to be disproportionately loud. It isn't. Good news: it's fixable in the prompt. We wrote a prompting guide for Astra that patches the defaults it ships with. Hook-first structure. Asymmetry rules. The exact brief format that works with Seedance 2.5 for Meta ads. Comment "hook" and I'll send it. Both ran on HeyOz — every model, side by side, same product.