Anthropic releases Claude Fable 5, first public Mythos-class model at $10/$50 per million tokens

Anthropic has released Claude Fable 5, marking the first time the company has made a Mythos-class model publicly available. The model is priced at $10 per million input tokens and $50 per million output tokens, less than half the cost of the restricted Claude Mythos Preview released in April 2026.

Pricing and Performance

Claude Fable 5 costs $10 per million input tokens and $50 per million output tokens. According to Anthropic, the model "exceeds the capabilities of any model we've ever made generally available" and demonstrates state-of-the-art performance across nearly all tested benchmarks, particularly in software engineering, knowledge work, vision, and scientific research.

Anthropic claims Fable 5 outperforms both Claude Opus 4.8 and GPT-5.5 in their internal testing. The company states that "the longer and more complex the task, the larger Fable 5's lead over our other models."

Built-in Safeguards

Given the model's capabilities in areas like cybersecurity, Anthropic has implemented safeguards that redirect certain queries to Claude Opus 4.8 instead of processing them through Fable 5. The company says these safeguards trigger in less than 5% of sessions on average, though they acknowledge the filters are "tuned conservatively" and may catch some harmless requests.

"Without safeguards, Fable 5's capabilities in areas like cybersecurity could be misused to cause serious damage," Anthropic states in its announcement.

Claude Mythos 5: The Unrestricted Version

Alongside Fable 5, Anthropic detailed Claude Mythos 5, which is essentially Fable 5 without the safeguards. Mythos 5 remains restricted to a small group of cyberdefenders and infrastructure providers, including those with existing Claude Mythos Preview access. Both models are priced identically at $10/$50 per million tokens.

Rollout Plan

Due to anticipated high demand, Anthropic is implementing a staged rollout. From June 9 through June 22, 2026, Claude Fable 5 will be included at no extra cost for Pro, Max, Team, and seat-based Enterprise plans. On June 23, the model will require usage credits unless capacity allows for an extension of the included access period.

The company says it aims to restore Fable 5 as a standard part of subscription plans "as quickly as we can" once sufficient capacity is available.

What This Means

Anthropic's pricing strategy positions Fable 5 significantly below its restricted Mythos Preview model while maintaining safeguards that may limit some use cases. The staged rollout and usage credit requirement signal genuine capacity constraints, a pattern seen with other frontier model releases. The safeguard layer that redirects 5% of queries to a less capable model represents a novel approach to AI safety, though the impact on real-world performance remains to be seen. Comparisons to GPT-5.5 suggest Fable 5 competes directly with OpenAI's latest offerings, though independent benchmarks are needed to verify Anthropic's claims.