# Anthropic releases Claude Fable and Mythos 5.2 with benchmark results

> Original title: We're releasing Claude Fable & Mythos 5.2! They're good models, I have some demos and tips for you.

- Source: Felix Rieseberg
- Published: 2026-11-09T19:00:52.000Z
- Bad Influence: https://badinfluence.news/items/ckghvfj93c6a91vhie5c7n1st
- Original: https://x.com/felixrieseberg/status/2119867837296857361

## Summary

Anthropic says it is releasing Claude Fable and Mythos 5.2 and that Fable beats Opus on large, long tasks such as rewriting a whole codebase. The accompanying table reports Fable 5.2 leading most listed benchmarks, including SWE-bench Pro at 93.0 and OSWorld 2.1 at 89.3, while Opus 5.5 scores higher on GDPval-AA and AA-Briefcase ELO. The author says he still often prefers Opus 5.5 for everyday work.

## Post

We're releasing Claude Fable & Mythos 5.2! They're good models, I have some demos and tips for you.

Fable beats Opus on big, long tasks. Good examples are rewriting an entire codebase, creating an excellent first draft of a large artifact, or exploring ambiguous scenarios.

I expect to see it used to port a lot of stuff to Rust, support journalists in large-scale investigations, and help with research & science. I often still prefer Opus 5.5 for everyday work. Fable's got a big brain and thinks a little slower.

![](https://badinfluence.news/api/img-proxy?u=https%3A%2F%2Fpbs.twimg.com%2Fmedia%2FHWtGmDiaUAA85Hz.jpg&mode=thumb&exp=1794528000&sig=4e48d5137b54c3af)