Introduction to Claude Fable 5
Anthropic has begun rolling out a new model called 'Fable,' which is based on the same underlying model as Mythos, its most powerful AI model class. The company previously developed a model called 'Mythos,' which is a state-of-the-art model that poses security risks to companies around the world.
Security Risks and Safeguards
At the time of the Mythos model announcement, Anthropic noted that it was powerful enough to potentially help bad actors attack public and private software. The company warned that 'the advantage will belong to the side that can get the most out of these tools,' and that 'in the short term, this could be attackers, if frontier labs aren’t careful about how they release these models.'
Because of these risks, Anthropic decided to limit access to models like Mythos and offer them only to cybersecurity experts and trusted companies. Now, the company says it has developed strong guardrails for the same model class, which means these powerful AI models can no longer be easily exploited by bad actors.
Claude Fable 5 and Its Limitations
As a result, Anthropic is launching a safer version called 'Fable 5.' This model has strict safeguards in place that will block or divert sensitive queries, like those involving offensive cybersecurity, biology, or chemistry, to its previous model, Opus 4.8. Claude Mythos 5 is the unrestricted version of that same model, with those safeguards lifted.
Because of the risks involved, Claude Mythos 5 is only available to a highly vetted group of trusted partners, such as government cyberdefenders and specific life sciences researchers. Fable 5, on the other hand, is free for a limited time, and it consumes tokens faster than any other model.
Anthropic says Fable 5 is an expensive model because it requires a lot of compute, which means the company cannot afford to make it available as easily as Opus 4.8 or its previous models. However, until June 22, Anthropic says Fable 5 will be offered to all Pro, Max, and Enterprise customers, but after the window expires, it'll switch to usage-based pricing.
Testing Fable 5
In tests, BleepingComputer observed that Fable 5 uses a massive amount of tokens in a span of minutes. Fable used approximately 1 million tokens in 8 minutes. This behavior was particularly noticeable when using Workflow, a new execution system that allows Claude to break complex prompts into smaller tasks and spin up parallel subagents to implement them.
Claude Fable 5 exhausted a $100 Max subscription's daily usage in just 9 minutes. This doesn't happen when casually interacting with Claude Fable 5, but if you switch to Workflow mode and change model thinking to high, you're going to consume all your tokens in minutes. However, even if you don't use Fable 5 with workflow in high effort, you're still going to consume it 2 times faster than the Opus model.
This explains why Anthropic is hesitating to unlock Fable 5 in the same capacity as Opus and other models, but that could change in the coming weeks, as the company is known for nerfing its models and increasing the capacity later.
Conclusion
Anthropic's Claude Fable 5 AI model is a powerful tool with strict safeguards in place to prevent exploitation by bad actors. While it is available for a limited time to Pro, Max, and Enterprise customers, its high token consumption rate may limit its accessibility to some users.
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Source: BleepingComputer