The model will reportedly be made available to enterprise customers and paid subscribers. 

Just two months after rolling out Mythos to a limited pool of high-level users, Anthropic has announced the release of Claude Fable 5, an AI model similar to Mythos but with significant safeguards and blocks to prevent deliberate misuse and security breaches, according to the company. 

Unlike Mythos, which is currently only available to a select number of organisations and institutions due to major concerns about securing critical infrastructure, Claude Fable 5 will be made available to enterprise customers and paid subscribers. 

The model has built-in barriers that aim to block responses in high-risk areas such as cybersecurity, chemistry and biology, with such interactions automatically handled instead, the company said, by its Opus 4.8 model.

Fable 5, Anthropic claimed, shows strong capabilities in software engineering, knowledge work, vision, scientific research and similar fields.

In a statement, Anthropic explained that over the course of the past few months, the organisation has worked to improve safeguards that would make Claude Fable 5 “robust enough for a general release”, adding that in prioritising safety, some measures are “stricter than would be ideal” and some benign requests may be classified as risky. However, there are plans to further refine the model’s regulation systems. 

Anthropic has also announced an updated version of the Mythos model, Claude Mythos 5, reportedly similar to Fable 5 but with the cyber safeguards lifted. 

The organisation said, “In consultation with the US government, we plan to steadily expand access to Claude Mythos 5, continuing our periodic addition of new partners, as well as pursuing a trusted access programme that allows cybersecurity organisations to apply in a more systematic manner.”

In early June, Anthropic unveiled plans for a historic initial public offering that could take the company’s valuation soaring above $1trn. The proposal came less than a week after Anthropic overtook OpenAI’s valuation with a $65bn Series H funding round that valued it at $965bn.

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