The news: Anthropic calls Claude Fable 5—its first publicly available “Mythos-level” model—its most capable for complex, multi-stage workflows and understanding diagrams, charts, and tables inside files.

The company said it’s best suited for “long-running, asynchronous work,” which could include tasks such as large-scale user data analysis and campaign variants based on regionality and demographic behavior.

Pricing for Fable 5 is $10 per million input tokens and $50 per million output tokens, double the price of Opus 4.8. It’s available at no extra cost for Pro, Max, Team, and seat-based Enterprise plans through June 22, then will require usage credits.

In April, Anthropic determined that the underlying Mythos model was too powerful for broad release due to cybersecurity and biosecurity concerns, but Fable 5 limits or blocks sensitive or dangerous queries and then reverts to Opus 4.8.

Zooming out: Anthropic is splitting its AI development into two paths, which could set up a framework where frontier AI capabilities don’t simply trickle down to all users over time.

The most capable AI may be effectively locked behind ultra-high token costs, which could become an issue for small and medium-sized businesses that need to rely on standard-level tools—like Opus 4.8—that may become comparatively less advanced over time.

The bigger picture: Fable 5’s launch comes as Anthropic, OpenAI, and SpaceX prepare for IPOs and shortly after Anthropic published a report calling for AI companies to slow their pace of AI development.

• The authors warned that AI models are improving so fast that they may soon be capable of recursive self-improvement (RSI), meaning the models can improve themselves without human intervention.
• That security risk could be mitigated by AI companies coordinating with one another and developing a global agreement to slow development, though this is a tall order given the high level of competition between major AI firms.

Implications for marketers: If frontier models are increasingly gated, large enterprises could gain access to capabilities that smaller competitors cannot easily obtain.

That could widen the performance gap in areas like research, content generation, analytics, and marketing automation, leading organizations to decide if Fable 5 will be worth the cost once free credit access expires or if existing third-party tools get the job done.

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