Anthropic’s new Fable release is cheaper, less restrictive

Anthropic released Fable and Mythos 5.1, twinned versions of the company’s most advanced AI model. In addition to performance upgrades, the new Fable release includes changes meant to reduce token cost and false-positive restrictions from the model’s safeguards. As with the previous Mythos model, Mythos 5.1 will only be available to registered Anthropic partners engaged in cybersecurity or life sciences research. Fable 5.1, the unrestricted version, is available starting today on cloud platforms or through the Anthropic API. One of the most significant changes is Anthropic’s embrace of zero data retention, allowing clients to run models on their own infrastructure without data outflows. A high-privacy service called Enterprise Frontier Safeguards will roll out in the fall, allowing clients to control how monitoring for misuse takes place. The models also set records in a range of benchmarks including Terminal-Bench 4.0 and Humanity’s Last Exam.