Update: We wrote this post on June 11 and published it on June 13. Anthropic has since disabled access to Claude Fable 5 after a US government directive, which makes some of these results even more relevant. Fable 5 was a strong model, especially at planning, but our testing did not show a massive jump on coding ability when it came to execution (many people were hyping this on social media). Once we had a detailed plan, GPT-5.5 performed similarly on execution.The post: Anthropic released Claud...