Anthropic Launches Claude Fable 5.2 and Mythos 5.2
Anthropic has released Claude Fable 5.2 and Claude Mythos 5.2, two new frontier models designed for coding and agentic tasks, sharing the same base architecture but featuring distinct security filters.
What happened?
Anthropic has launched Claude Fable 5.2 and Claude Mythos 5.2, two new frontier models based on the same underlying architecture. Fable 5.2 is optimised for long-term coding, research, and agent-based workflows, while Mythos 5.2 features fewer built-in security guardrails for cyber and biological domains. The models feature a one-million-token context window and a maximum output capacity of 128,000 tokens, and are available via the Claude Platform, AWS, Google Cloud, and Microsoft Azure.
Key facts
| Kontextfönster | 1 000 000 tokens |
|---|---|
| Maximal utdata | 128 000 tokens |
| RoboDojo Sim-resultat | 64,9 % |
| AutomationBench-resultat | 51,4 % |
| Lanseringsdatum | 10 november 2026 |
Why it matters
Fable 5.2 outperforms the previous Opus 5.5 in almost all benchmarks reported by Anthropic, while providing that performance at approximately half the cost compared to the 5.1 models. The launch also demonstrates a segmented safety strategy, where the same foundation model is provided with varying levels of restrictions based on the intended use case.
Who is affected?
The launch concerns developers, researchers, and enterprises building advanced coding agents or managing large research databases. Customers on major cloud platforms including AWS, Google Cloud, and Azure can access the models via API.
Impact on the EU
Not applicable to EU status. The source does not specify if or how the distribution of Claude Fable 5.2 or Mythos 5.2 differs within the European Union.
What else you should know
The models are provided as a hosted API without open weights. According to Anthropic, Fable 5.2 reached 64.9 per cent in RoboDojo Sim, surpassing GPT-6 Astra at 29.8 per cent, but finished at 51.4 per cent in AutomationBench, behind Gemini 4 Carbon at 53.9 per cent.
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