# Claude Fable 5.1 launches; Mythos 5.1 stays restricted — QANATONE

> Anthropic announced Fable 5.1 and Mythos 5.1 on September 1. They are the same model with different safeguards and access.

Kaynak: https://www.qanatone.com/en/haber/claude-fable-5-1-mythos-5-1/

---

[News](https://www.qanatone.com/en/haber/)

# Claude Fable 5.1 launches; Mythos 5.1 stays restricted

1 Sep 2026 1 min read News · Models

Anthropic announced Fable 5.1 and Mythos 5.1 on September 1. They are the same model with different safeguards and access.

## Two names, one model

Fable 5.1 is generally available with Anthropic's production safeguards, on the Claude API, AWS, Google Cloud and Microsoft Azure. Mythos 5.1 is limited to vetted cybersecurity and life-sciences organisations in restricted-access programs, currently in the US; Anthropic says it is working with the US government to expand access.

## Performance and price

On Anthropic's published evaluations, Fable 5.1 more than doubles Fable 5 on agentic scientific research and nearly doubles it on business workflows. Pricing stays at $10 per million input tokens and $50 per million output tokens, while cache reads are 75% cheaper.

## More articles

[News · Ads ### ChatGPT ads hit a $1 billion annual run rate in under 200 days 31 Aug 2026 · 1 min](https://www.qanatone.com/en/haber/chatgpt-reklamlari-1-milyar-dolar/)[News · Funding ### a16z raises a $1.1 billion fund for the physical side of AI 28 Aug 2026 · 1 min](https://www.qanatone.com/en/haber/a16z-machine-age-fonu/)[News · Payments ### Coinbase x402: AI agents made 14 million payments in 30 days 27 Aug 2026 · 1 min](https://www.qanatone.com/en/haber/coinbase-x402-ajan-odemeleri/)[News · Models ### Ask Gemini arrives in Google Chat as a single command line 26 Aug 2026 · 1 min](https://www.qanatone.com/en/haber/google-chat-ask-gemini/)[News · Funding ### AI agent Instinct, built by a 23-year-old, hits $2.5 billion 26 Aug 2026 · 1 min](https://www.qanatone.com/en/haber/instinct-2-5-milyar-dolar/)[News · Infrastructure ### Nvidia reports $96.2 billion in quarterly revenue 26 Aug 2026 · 1 min](https://www.qanatone.com/en/haber/nvidia-96-milyar-dolar-ceyrek/)[News · Funding ### Salesforce's Agentforce passes $1.5 billion in ARR 26 Aug 2026 · 1 min](https://www.qanatone.com/en/haber/salesforce-agentforce-1-5-milyar/)[News · Infrastructure ### Emerald AI raises $150 million for grid-flexible data centers 25 Aug 2026 · 1 min](https://www.qanatone.com/en/haber/emerald-ai-esnek-veri-merkezi/)