Claude Fable 5.1
Claude Fable 5.1 is a general-purpose Claude model tuned for long-running agentic coding, knowledge work, and research with a default 1M token context window, large max output length, and adaptive thinking features. It includes API features for preserved thinking blocks, prompt caching behavior changes, per-message effort controls, and beta turn-scoped system messages and thinking display modes.
What it does
Use it for long-running coding agents, knowledge-work tasks, and research.
- Availability
- Available on the Claude API and listed cloud platforms
- Pricing model
- $10 / $50 USD per MTok; prompt cache reads $0.25 USD per million tokens
- Deployment
- Hosted through the Claude API and listed cloud platforms
- Privacy
- Requires 30-day data retention; unavailable under zero data retention unless expressly authorized by Anthropic
- Licence
- Not established
Capability
Modality
Access
Deployment
Pricing
Target user
Evidence
5 claims- Claude Fable 5.1 is for long-running agentic coding, knowledge work, and research. [1]
We’ve launched Claude Fable 5.1 ( claude-fable-5-1 ), the successor to Claude Fable 5 for long-running agentic coding, knowledge work, and research, alongside Claude Mythos 5.1 ( claude-mythos-5-1 ) for Project Glasswing participants.
Anthropic. Quoted text is outside CC BY 4.0 and keeps its original rights. - It supports a 1M-token context window by default and 128k max output tokens. [1]
Both models support a 1M token context window by default, 128k max output tokens, and always-on adaptive thinking , at $10 / $50 USD per MTok, the same as Claude Fable 5, with cache reads cut to $0.25 USD per MTok.
Anthropic. Quoted text is outside CC BY 4.0 and keeps its original rights. - It is available on the Claude API, Claude in Amazon Bedrock, Claude Platform on AWS, Claude on Google Cloud, and Claude in Microsoft Foundry. [1]
Claude Fable 5.1 is available on the Claude API, Claude in Amazon Bedrock , Claude Platform on AWS , Claude on Google Cloud , and Claude in Microsoft Foundry .
Anthropic. Quoted text is outside CC BY 4.0 and keeps its original rights. - Its listed price is $10 / $50 USD per MTok, with prompt cache reads at $0.25 USD per million tokens. [1]
Prompt cache reads on Claude Fable 5.1 and Claude Mythos 5.1 cost $0.25 USD per million tokens: 0.025x the base input price, compared with 0.1x on other models.
Anthropic. Quoted text is outside CC BY 4.0 and keeps its original rights. - It requires 30-day data retention and is not available under zero data retention unless expressly authorized by Anthropic. [1]
Like Claude Fable 5, both models require 30-day data retention and aren’t available under zero data retention unless expressly authorized by Anthropic.
Anthropic. Quoted text is outside CC BY 4.0 and keeps its original rights.
Sources
1
1
AnthropicOwner-controlled
https://docs.claude.com/en/release-notes/overview#2026-09-01
Retrieved 2026-10-28 00:27 UTC
Verified
Versions
4| Version | Effective | Change | Changed fields | State |
|---|---|---|---|---|
| 4 | 2026-10-28 00:27 UTC | material change | availability, pricing model, deployment, privacy | Current |
| 3 | 2026-10-24 02:04 UTC | material change | capability, modality, access, availability, pricing model, deployment, privacy | Current |
| 2 | 2026-10-01 21:40 UTC | evidence update | score | Current |
| 1 | 2026-09-01 00:00 UTC | publication | None | Current |
In briefs
2- WeatherNext 2 leads 13 AI developments in week 36, 2026 Weekly brief 2026-W36
- WeatherNext 2 leads 9 AI developments on 1 September 2026 Daily brief 2026-09-01
Original catalog content is licensed under CC BY 4.0, attributed to wowsuchai. Source quotations and linked content keep their original rights.