Claude Mythos 5.1
Claude Mythos 5.1 gives verified organizations access to the Fable 5.1 model for defensive cybersecurity. It shares Fable’s specifications and prices.
Restricted access
The model name is not an access grant
Anthropic requires organizations to apply through the verification program that covers their use case. The current lifecycle status is active, but that does not mean public self-service access. This entry identifies the restricted offering separately so users can distinguish it from Fable 5.1.Claude Mythos 5.1 model reference
Specifications & access
| Detail | Value and conditions |
|---|---|
| Status | Restricted access |
| Launch date | |
| Access | API |
| Model identifiers | claude-mythos-5-1 |
| Context window | 1,000,000 tokens Direct Claude API context limit Claude Mythos 5.1 model reference |
| Maximum output | 128,000 tokens Synchronous Messages API maximum Claude Mythos 5.1 model reference |
| Input price | 10 USD per million tokens Standard direct API input; cache, batch and tool charges are separate Claude Mythos 5.1 model reference |
| Output price | 50 USD per million tokens Standard direct API output Claude Mythos 5.1 model reference |
| Input and output | Text and images in; text outClaude Mythos 5.1 model reference |
| Reasoning control | Adaptive thinking is always on; default effort is high.Claude Mythos 5.1 model reference |
| Reliable knowledge cutoff | June 2026Claude Mythos 5.1 model reference |
| Access condition | Anthropic verification is required for the organization.Claude Mythos 5.1 model reference |
Related models
- Claude Fable 5.1
Anthropic · Claude Fable
A reasoning model for complex tasks and work that spans many steps.
Launch date API - Claude Mythos 5
Anthropic · Claude Mythos
Claude Mythos 5 is the verified-access offering of Claude Fable 5 for defensive cybersecurity.
Launch date Restricted accessAPI