Introducing Claude Fable 5.1, the world's most advanced model for coding and knowledge work. It excels at complex, long-running tasks, like a long mathematical proof or a contract with hundreds of cross-references. It avoids shortcuts and is smart enough to fix the root causes of an issue. Its research capabilities also offer an early glimpse of how AI will contribute to scientific progress. Fable 5.1 is available everywhere today. Read more at anthropic.com/claude-fable-and-mythos-5-1

Today we're releasing Fable 5.1, the latest upgrade to our most capable model class. Whatever you already hand-clod, it can take on more, and do the hardest parts better. That's possible because of how it handles multi-step work. It's like a complex financial model, a long mathematical proof, or a contract with hundreds of cross-references. These are the kinds of tasks where a small mistake in step two messes things up in step 40. In Fable 5.1 holds up the whole way. Give it a software project, and it can take on more of it than ever. From code review to performance work, features that cut across an entire code base. Sessions you can step away from and come back to. If it hits a wall, it tells you what it tried and where it got stuck, and it doesn't stop at code. Give Fable 5.1 an open question, and it comes back with something polished, ready for you to review. The research, the spreadsheet, the memo, the deck, all with the numbers and sources laid out so that you can check them. And this model is great at science. Give it a hard problem, and it works with you by reading the literature, proposing a hypothesis, and designing an experiment, so that your research happens faster. Fable 5.1 is out today, available everywhere. Hand it something big, and see what it brings back. We think it's the best model we've made for complex work, and it's ready for yours. (gentle music)