Anthropic's Claude Fable 5 Brings Powerful AI Model to the Masses with Guardrails

Anthropic, the AI firm behind the popular Claude model, has released a more powerful version called Fable 5, which is now available to the public. However, this new model comes with guardrails in place to prevent misuse.

Anthropic's Mythos model was initially limited to a handful of partners due to cybersecurity concerns. However, the firm has now expanded access to hundreds of organizations across 15 countries, focusing on those that manage critical infrastructure. With the launch of Fable 5, a version of Mythos is now available to anyone through Anthropic's Claude API and consumption-based Enterprise plans.

The model excels at software engineering, knowledge work, and vision, but it blocks responses and falls back to Claude Opus 4.8 in high-risk areas like cybersecurity, biology, chemistry, and distillation. This means that users will not get Fable 5 answers in every question, as the model will defer to Opus 4.8 in certain cases.

Pricing for Fable 5 is $10 per million input tokens and $50 per million output tokens, double the price of Opus 4.8. This price point may serve as a deterrent for widespread use, as many enterprises are growing critical of AI costs.

Anthropic has stressed-tested its classifiers with jailbreak attempts before releasing Fable 5 and says it has implemented a 30-day retention on all traffic to defend against complex and novel attacks. The company will use the data to "defend against complex and novel attacks, including new jailbreaks," and "identify and reduce false positives."

Early data shows that at least 95% of Fable sessions run entirely on the model's own responses, with a small percentage deferring to Opus 4.8. Third-party testing has shown that Fable 5 excels in areas like software engineering, knowledge work, and vision, with strong judgment and attention to nuance.

However, not everyone is happy about the guardrails on Fable 5. Cybersecurity researchers have expressed concerns about the limitations, citing the potential for the model to be used for malicious purposes.

Anthropic expects demand for Fable 5 to be high, but difficult to predict. The company is rolling out access to the model in stages, with Fable 5 included in Pro, Max, Team, and seat-based Enterprise plans at no extra cost until June 22. After that, it will require usage credits, with plans to restore it as a standard subscription feature as soon as possible.