Anthropic releases Claude Fable 5.2 and Mythos 5.2 models
Anthropic released Claude Fable 5.2 and Claude Mythos 5.2, stating that both have improvements in coding, reasoning, and vision, with output speeds up to 30% faster than Fable 5.1 and Mythos 5.1, priced at $8 per million input tokens and $40 per million output tokens. Anthropic stated that Fable and Mythos are aimed at the most complex, open-ended technical work, and that for most coding and knowledge tasks it recommends starting with Claude Opus 5.5, then switching to higher or lower models as needed. Anthropic also stated that over 90% of merged changes in its core codebase were written by Claude, and that an agent team used an early version of Fable 5.2 to migrate a critical production service from Python to Rust, improving startup speed by about 26 times.
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The original text lists the new versions' improvements in coding, reasoning, and vision, and provides speed and pricing changes for easy comparison of the upgrade magnitude against the previous generation.
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Anthropic is out with its second big update to Claude Fable 5 since introducing the model class back in June. Here’s what’s new with Claude Fable 5.2.
Claude Fable 5.2 arrives today
Anthropic first released Fable 5, its Mythos-class AI model for Claude, over the summer. In September, Anthropic enhanced Claude with its more capable Fable 5.1 model upgrade.
In Anthropic’s world, Fable is Claude’s most capable model. Haiku, Sonnet, and Opus are the small, medium, and large models below Fable.
Starting today, Claude Fable 5.2 and Mythos 5.2 are the latest best-in-class models.
The new Fable and Mythos models are faster and cheaper
Here’s what Anthropic says about the newest Claude Fable and Mythos versions:
Claude Fable 5.2 and Claude Mythos 5.2 show 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. They generate outputs up to 30% faster than Claude Fable 5.1 and Claude Mythos 5.1, and they’re available at a lower price: $8 per million input tokens and $40 per million output tokens. […]
Fable and Mythos are best for the most ambitious, open-ended technical work. For most coding and knowledge tasks, we recommend that users start with Claude Opus 5.5, our strongest daily driver, and then switch to a different model as required, depending on the scope and complexity of their work—upward to Fable or Mythos, or downward to Claude Sonnet 5.5 or Claude Haiku 5.5.
For coding specifically, this is how Anthropic describes Claude Fable 5.2:
Over 90% of the changes merged into Anthropic’s core codebase are now written by Claude (with human guidance). We’ve used Fable 5.2 to fix stubborn bugs in minutes, optimize performance across all of our services, and complete high-value software projects that would otherwise have been too slow or too costly to attempt. A team of agents running an earlier version of Fable 5.2 migrated a critical production service from Python to Rust—the service is now more efficient, more reliable, and starts about 26 times faster. We’ve found that Fable 5.2 exercises strong engineering judgement and can produce high-quality results from even ambiguous requests.
As part of the launch, Anthropic is getting users additional Fable usage:
You can learn much more about Claude Fable 5.2 here.
Related Claude stories:
Anthropic upgrades Claude with new Personal Finance feature
Anthropic takes on ChatGPT Dots and Meta Muse with Claude Duet
Anthropic just released a brand-new Claude Science app for Mac
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