Felix Rieseberg(@felixrieseberg):Today, we're releasing Fable 5.1 and Mythos 5.1. While the model is getting slightly better at a lot of things, I expect many users to appreciate that Fable 5.1 solves agentic coding tasks at roughly half the cost of Fable 5. I personally also really like it's writing style, which imho sounds a lot more natural then our previous models did. Some other personal highlights below!

Felix Rieseberg

@felixrieseberg

I build things @AnthropicAI, Co-Maintainer

Joined April 2009

721 Following 72.3K Followers

Felix Rieseberg@felixrieseberg

2026.09.01 18:07

Today, we're releasing Fable 5.1 and Mythos 5.1. While the model is getting slightly better at a lot of things, I expect many users to appreciate that Fable 5.1 solves agentic coding tasks at roughly half the cost of Fable 5. I personally also really like it's writing style, which imho sounds a lot more natural then our previous models did. Some other personal highlights below!