Yesterday, Anthropic officially introduced Claude Fable 5.2 and Claude Mythos 5.2 models that showed improvements in areas like coding, reasoning and vision. Testers have found that Fable 5.2 and Mythos 5.2 communicate more clearly than past Fable and Mythos models.
Fable 5.2 is now available in the Claude Platform and Claude Code.
It’s up to 30% faster than Fable 5.1, and costs $8/$40 per 1M tokens, down from $10/$50. https://t.co/mHGJNRbIZS
— ClaudeDevs (@ClaudeDevs) November 9, 2026
Claude Fable 5.2 & Mythos 5.2
These models generate outputs up to 30% faster than Claude Fable 5.1 and Claude Mythos 5.1 models. Fable 5.2 and Mythos 5.2 also come with an optional fast mode, which speeds up token generation by up to 2.5 times. Fast mode is available for $16 per million input tokens and $80 per million output tokens.
During evaluation, it was revealed that Claude Fable 5.2 and Mythos 5.2 models were a step above Opus 5.5 in almost all the capabilities evaluated: Coding, Cybersecurity, Protein design, Agentic Search, Computer use, Robotics, Knowledge work, Multidisciplinary reasoning and visual chart recognition.
For the model underlying Claude Fable 5.2 and Claude Mythos 5.2, Anthropic’s pre-deployment safety work included alignment training and testing, newly designed evaluations on the model’s propensity to take unhelpful actions, building stronger safeguards against misuse, and scaling up our behavioural monitoring.
The company tested Claude Mythos 5.2 on its automated behavioral audit, which tests how a model behaves across approximately 1900 scenarios. Claude Mythos 5.2 performed as well as, or better than, Opus 5.5, Sonnet 5.5, and Claude Mythos 5.1 on most measures. Hallucinating inputs, falsely claiming to have completed a task, omitting important information, and failing to disclose bad or lazy work were all lower in Claude Mythos 5.2.
Safeguards
- Cybersecurity and biology safeguards: Consistent with previous Claude Fable models, Fable 5.2 comes with safety classifiers that block high-risk cyber activities, including penetration testing, exploit generation and binary-based vulnerability, as well as most tasks in research biology. Based on early testing across claude.ai, Claude Code, and Cowork, the company observed about 55% fewer blocks with Fable 5.2 compared with Fable 5.1- about 60% fewer in cybersecurity and 40% fewer in biology. Claude Mythos 5.2 is available to vetted organisations that work in these dual-use areas.
- AI Research and development: The model that underlies Claude Fable 5.2 and Claude Mythos 5.2 is a step forward in general capabilities. In relevant areas, including accelerator kernel optimisation and improving large language model architectures, Fable 5.2 and Claude Mythos 5.2 perform at about the level of Opus 5.5. The models also include transparent fallbacks to Opus 5 for a small set of topics in this domain, including kernel development on certain nonstandard accelerators.
- Anti-distillation: Fable 5.2 has the strongest protections against distillation of any model the company released.
Powerful models like Claude Fable 5.2 and Mythos 5.2 rely on safeguards that monitor a window of usage data. Eligible customers can continue using Claude Fable 5.2 and Mythos 5.2 with zero data retention before implementing safety monitoring with Enterprise Frontier Safeguards. For other customers, the company has 30-day retention for safety monitoring.
Availability
Claude Fable 5.2 is available on all platforms including Amazon Web Services, Google Cloud, and Microsoft Azure. Developers can get started with claude-fable-5-2 on the Claude Platform.
The company is giving subscribers this week on eligible paid plans extra Fable usage. Plans and seats that include Fable models get one to three Fable resets based on how long they’ve subscribed, and Fable is included for up to 50% of weekly usage limits for Pro plans and standard seats on the Team plan.
Fast mode for Claude Fable 5.2 and Claude Mythos 5.2 is available on Claude Code, the Claude Platform, Claude Models on Google Cloud, and Microsoft Foundry. Access to Claude Mythos fast mode is available only to organisations who are past of Anthropic’s Verification Programs.
The models are available for $8 per million input tokens and $40 per million output tokens.
