Introducing Claude Fable 5.1 and Claude Mythos 5.1
Our most advanced models for coding and knowledge work. Their research capabilities also offer an early glimpse of how AI models will contribute to scientific progress.
Anthropic
Claude Mythos 5.1
Anthropic
Mythos 5.1 is available only through our trusted access programs; its safeguards are specifically designed to support work in cybersecurity and the life sciences.
Specs
Model
- Family
- Claude
- Variant
- Mythos 5.1
- Weights
- Proprietary
Limits
- Context
- 1,000,000 tokens
- Max output
- 128,000 tokens
Modalities
- Input
- Text Image PDF
- Output
- Text
Pricing
- Input
- $10 / 1M
- Output
- $50 / 1M
- Cache read
- $0.25 / 1M
- Cache write
- $12.5 / 1M
Capabilities
- Reasoning
- Yes
- Reasoning control
- Effort levels
- Tool calling
- Yes
- Attachments
- Yes
Dates
- Released
- 1 Sept 2026
- Knowledge cutoff
- Jun 2026
Articles
All articlesanthropic.com
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