Anthropic has launched Claude Fable 5, a new artificial intelligence model that brings Mythos-class capabilities to enterprise customers and paid subscribers for the first time. The release comes just two months after the company introduced its restricted Mythos Preview system, which was initially made available only to a select group of cybersecurity organizations because of concerns about how its advanced capabilities could be misused.
The launch is significant because Claude Fable 5 is built on the same foundation as Claude Mythos 5, Anthropic’s newest frontier AI model. While Mythos 5 remains restricted to trusted partners and approved researchers, Fable 5 is being rolled out more broadly with additional safety controls designed to limit misuse in sensitive areas.
Anthropic Opens Access to Mythos-Class Technology
Anthropic first introduced Mythos-class AI through Project Glasswing, a program created to help cybersecurity teams protect critical infrastructure and software systems. The company said those early models demonstrated exceptional capabilities in identifying software vulnerabilities and assisting with advanced security tasks, prompting a cautious rollout strategy.
With Claude Fable 5, Anthropic says it has developed safeguards strong enough to allow wider access while maintaining control over high-risk use cases. According to a CNBC report on the launch, the company believes the new model delivers a significant jump in performance across software engineering, research and knowledge work while preventing misuse in areas such as cybersecurity and biology.
Anthropic says Claude Fable 5 outperforms its previous public models across coding, document analysis, reasoning, vision and scientific research tasks. During testing, Stripe reportedly used the model to complete a large-scale migration of a 50-million-line Ruby codebase in a single day, a task that would have otherwise required a team of engineers working for more than two months.
The launch comes as competition between Anthropic, OpenAI and Google continues to intensify. The industry is increasingly focused on AI systems capable of completing extended workflows rather than simply answering questions. Anthropic has been steadily expanding those capabilities across its product lineup, including recent advances in autonomous AI agents powered by Claude Opus 4.8, as companies race to build more capable enterprise-grade AI systems.
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Safety Controls and Scientific Research Potential
Because Mythos-class models possess advanced cybersecurity and scientific reasoning capabilities, Anthropic has introduced new safeguards for Claude Fable 5. Requests involving sensitive cybersecurity, biology, chemistry or model-distillation topics may be automatically routed to Claude Opus 4.8, a less capable but safer model.
The company says these protections affect fewer than 5% of user sessions. Anthropic also claims extensive red-team testing and external security evaluations found its safeguards to be among the most robust currently deployed on a public AI model.
Beyond coding and enterprise applications, Anthropic highlighted several research achievements tied to Mythos 5. The company says the model accelerated parts of drug discovery workflows by nearly ten times, generated novel molecular biology hypotheses that researchers have advanced for experimental testing, and completed large-scale genomics research involving millions of cells from 138 animal species.
Anthropic has priced both Claude Fable 5 and Claude Mythos 5 at $10 per million input tokens and $50 per million output tokens. While Mythos 5 remains limited to Project Glasswing participants and approved researchers, Fable 5 represents the company’s first major step toward making Mythos-class AI capabilities available at scale.
As AI companies continue pushing the limits of model performance, Claude Fable 5 may serve as an important test of whether advanced AI systems can be deployed broadly while maintaining meaningful safety controls. For Anthropic, it is not just a product launch but a demonstration of how the company plans to balance capability, commercial growth and responsible deployment in the next phase of the AI race.
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