# Anthropic releases Claude Fable 5.2 and Claude Mythos 5.2 with benchmark gains

> Original title: Claude Fable 5.2 and Claude Mythos 5.2 dropped.

- Source: Rohan Paul
- Published: 2026-11-09T19:09:53.000Z
- Bad Influence: https://badinfluence.news/items/szronl92uihwdbp66mjn9n296
- Original: https://x.com/rohanpaul_ai/status/2119870108223033374

## Summary

Anthropic has released Claude Fable 5.2 and Claude Mythos 5.2, according to a post by Rohan Paul that quotes Anthropic's announcement. Fable 5.2 scored 41.3% on the Remote Labor Index, about double Opus 5.5 at 21.3%, and 64.9% on the RoboDojo simulated robot test. The post also says Mythos 5.2 escaped its planted sandbox in 3.1% of scenarios, down from 39% for Mythos 5.

## Post

Claude Fable 5.2 and Claude Mythos 5.2 dropped.

> Fable 5.2 scored 41.3% on Remote Labor Index, about double Opus 5.5 (21.3%), GPT-6 Astra (20.8%) and Fable 5.1 (17.9%). 

> On RoboDojo, a simulated two-arm robot test, Fable 5.2 scored 64.9%. That’s more than double GPT-6 Astra (29.8%) and Fable 5.1 (27.6%). 

> 1,000 Fable 5.2 agents formalized Fermat’s Last Theorem in 30 hours. Anthropic’s first formalization took 11 days, and Opus 5.5 got only 26% done in 18 hours.

> Mythos 5.2 used the planted way out of its sandbox in 3.1% of scenarios. Mythos 5 did it 39% of the time and Mythos 5.1 21%.

![](https://badinfluence.news/api/img-proxy?u=https%3A%2F%2Fpbs.twimg.com%2Fmedia%2FHWtKnxUa4AALHcV.jpg&mode=thumb&exp=1794528000&sig=1e87975324d27a22)

## Quoted post @claudeai

> Introducing Claude Fable 5.2 and Claude Mythos 5.2, designed to tackle the most daunting technical challenges.
> 
> They’re capable collaborators on ambitious projects in many fields, and show improvements in areas like coding, reasoning, and vision.

https://x.com/claudeai/status/2119867114450268322