‘It feels like working with another staff-level engineer’: Anthropic lifts the veil on the latest features for Fable 5.2 and Mythos 5.2 built ‘for the most ambitious, open-ended technical work’ — and it's already built an operating system from scratch

The latest Fable and Mythos releases are cheaper and more accurate

News By Benedict Collins Published 10 November 2026

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• Anthropic releases Fable 5.2 and Mythos 5.2 designed to help solve complex problems and ambitious projects
• Both offer a 20% cheaper token cost than previous versions
• The models are highly capable across coding, biology scientific and mathematics research

Anthropic’s latest Fable and Mythos releases have been unveiled, offering users superior outputs that are more accurate at a cheaper token cost than previous versions.

Fable 5.2 is available for all users and couples its improved inference with an improved set of cybersecurity and biology safeguards. But to get your hands on the expanded capabilities of Mythos 5.2, you’ll have to apply through Anthropic’s Life Sciences and Cyber Verification Programs.

Anthropic totes the new Fable and Mythos versions as being perfect for “ambitious, open-ended technical work” rather than as a “daily driver” — for which Anthropic recommends sticking to Opus 5.5.

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Cheaper, quicker, and more accurate

The latest Fable release promises more bang for your buck over the 5.1 release. Anthropic says that 5.2 usage will sit at $8 per million input tokens and $40 per million output tokens — around 20% cheaper than the previous version.

But if you’re on a deadline or just want something done quickly, Anthropic is introducing an optional “fast mode” that increases token generation speed by up to 2.5 times at an increased cost of $16 (input) and $80 (output) per million tokens.

Across almost every benchmark task, Anthropic says Fable 5.2 is more accurate than Opus 5.5, delivering results faster and more accurately with a significantly reduced token cost per task.

But Anthropic says users will be best served by taking a balanced approach to model use, using Opus 5.5 to get tasks started with Fable 5.2 coming on board as an “advisor” for more difficult tasks.

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