Anthropic launches faster Claude Fable and Mythos AI models

Summarised from 3 outlets · Updated 9 Nov, 19:37 · Archive

Anthropic has released Claude Fable 5.2 and Claude Mythos 5.2, claiming improvements in coding, reasoning and vision.

Anthropic released Claude Fable 5.2 and Claude Mythos 5.2 on Monday, saying the new models show improvements in coding, reasoning and vision. Fable 5.2 is available today while Mythos 5.2 access is restricted to vetted organisations. The company claims the models can handle complex technical challenges and have solved open theoretical physics problems during testing, including two open problems in black hole physics and formalized the proof of Fermat's Last Theorem in 30 hours.

Fable 5.2 returns responses 30 per cent faster than the previous version, according to Anthropic. The company has also reduced Fable's cost from $10 to $8 per million input tokens. TechCrunch reports that Fable 5.2 is now cheaper than its primary competitor, GPT-6 Astra. Fable 5.2 is compatible with zero data retention policies through the Enterprise Frontier Safeguards system.

TechCrunch notes this is Anthropic's first model release since a third-party assessment group called METR published a report suggesting the lab might be approaching recursive self-improvement, where AI models could carry on training independently. The report found internal models were speeding up Anthropic's progress by roughly 2x, though uncertainties remain. Anthropic's release notes that both new models 'voice suspicion that they are being evaluated more often than any of our recent models', which the company says challenges its ability to assess how they will perform in real-world settings.

How it is being reported

• Anthropic Launches Claude Fable 5.2 and Mythos 5.2Anthropic today introduced its latest models, Claude Fable 5.2 and Claude Mythos 5.2, which have improvements in coding, reasoning, and vision. Anthropic says Fable 5.2 and Mythos 5.2 communicate more clearly than the 5.1 versions, with outputs generated up to 30 percent faster. Fable 5.2 uses fewer tokens than Fable 5.1 on challenging tasks when set to medium effort. The company suggests using Fable and Mythos for "the most ambitious, open-ended technical work." Anthropic recommends starting with Opus 5.5 for most coding and knowledge tasks, then switching to a model like Fable or Mythos…MacRumors · 9 Nov, 19:38
• Anthropic releases new Mythos and Fable models amid RSI concernsAnthropic says the new models "show improvements in areas like coding, reasoning, and vision," as well as in communicating more clearly with users.TechCrunch · 9 Nov, 19:24
• Anthropic launches new Claude Fable and Mythos 5.2 modelsAnthropic is announcing two new models today: Claude Fable 5.2 and Claude Mythos 5.2, which it says are designed to take on "daunting" technical challenges. The company claims the new models show improvements in coding, reasoning, and vision, and can generate outputs faster than the 5.1 versions of the Fable and Mythos models. Claude Fable […]The Verge · 9 Nov, 19:00

In this story: Anthropic · METR · OpenAI

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