View on models.dev 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 Fable 5.1
Anthropic
Claude Fable 5.1 sets a new standard for coding, knowledge work, and long-running problem-solving tasks.
Specs
Model
- Family
- Claude
- Variant
- Fable 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 articlesMore from Anthropic
All modelsClaude Opus 5.5
Anthropic
Claude Opus 5.5 leads in agentic coding and knowledge work, and costs 40% less to run than Opus 5 on typical workloads.
$4 / $20 per 1M · $0.2 cached 7w ago
Claude Sonnet 5.5
Anthropic
Claude Sonnet 5.5 is a clear upgrade over Claude Sonnet 5, runs 30%+ faster, and costs up to 30% less for most work.
$2 / $10 per 1M · $0.2 cached 6w ago
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.
$10 / $50 per 1M · $0.25 cached 10w ago