GPT-5.6 Sol vs. Claude Fable: Why OpenAI’s new model crushes my benchmark

GPT-5.6 Sol is back, and I ran it through my full How I AI vibe benchmark against GPT-5.6 Terra, Luna, Claude Fable 5, and Sonnet 5 across five categories: PRDs, prototypes, wireframes, debugging, and agentic voice. Sol won by a meaningful margin on my Claire Weighted Index (70% my taste, 30% Terminal Bench 2.1), and I also tested two use cases I can't stop thinking about: building a gamified homework tracking app for my kids in one shot with Codex, and browser automation with Chrome that burned through 500 LinkedIn replies while I did literally nothing.What you’ll learn:How I scored five AI models (including GPT 5.6 Sol, Fable 5, and Sonnet 5) using my “Claire Weighted Index” benchmark across PRDs, prototypes, code, and agentic voiceThe difference between GPT-5.6 Sol (Terra) and Sol for PRD writingHow Fable’s precision and pedantry made it harder to collaborate with, and the exact moment Sol broke through where Fable got stuckWhy Sonnet 5 is still my go-to for agentic voice in OpenClaw, even after this whole benchmarkHow I used GPT-5.6 Sol in Codex to build a fully gamified homework tracking app for my kids in one shotThe video editing use case that saved me hours clipping a talk I gave at Cursor’s eventHow to use Codex plus GPT-5.6 and Chrome for browser automation, and why this is my single most-loved use case right now—In this episode, I cover:(00:00) Intro(01:10) The three GPT-5.6 models: Sol, Terra, Luna(02:17) Pricing: Sol vs. Fable API costs(03:24) The How I AI benchmark(05:03) Claire-weighted Index results(07:00) Per-task winners: prototypes, PRDs, agentic voice(11:59) What Claire actually rewards(13:20) Full-fidelity prototype side-by-sides (Sol vs. Fable)(17:45) Wireframes(18:19) Agentic voice(19:15) Where Sol is better than other models(23:56) Gamified kids’ homework app, built in one shot(28:02) Fable’s pedantry problem and how Sol broke through it(31:49) Two bonus use cases: video editing and browser use(35:08) Final summary and model recommendations—Tools referenced:• GPT 5.6 (Sol, Terra, Luna): https://help.openai.com/en/articles/20001325-a-preview-of-gpt-56-sol-terra-and-luna• Codex: https://openai.com/codex• ChatPRD: https://www.chatprd.ai/• CapCut: https://www.capcut.com/• Math Academy: https://www.mathacademy.com/—Other references:• Cursor event where Claire spoke on the future of PM: https://www.youtube.com/watch?v=4CAFK-rc26A• ChatPRD blog (where benchmark outputs will be published): https://www.chatprd.ai/—Where to find Claire Vo:ChatPRD: https://www.chatprd.ai/Website: https://clairevo.com/LinkedIn: https://www.linkedin.com/in/clairevo/X: https://x.com/clairevo—Production and marketing by https://penname.co/. For inquiries about sponsoring the podcast, email [email protected].