LLM
GA
Proprietary
Claude Fable 5.1
Long-horizon software engineering and security analysis
Release2026-09-01
Context1M
Max output128,000 tokens
ParametersUndisclosed
Local / VRAMAPI only
LicenseProprietary
Overview
Claude Fable 5.1 is a model in the LLM category from Anthropic. It was released in 2026-09-01. The vendor is based in US. Best for: Long-horizon software engineering and security analysis.
Notes: Fable is the safety-restricted public version of Mythos.
Strengths
- One of the highest coding/agentic scores
- 1M context
- 25-45% more efficient than Fable 5
Limits
- High price
- Downgraded to Opus in high-risk areas
- No audio/image output
Specifications
| Vendor | Anthropic |
|---|---|
| Category | LLM |
| Release | 2026-09-01 |
| Status | GA |
| License | Proprietary |
| Commercial use | Not specified |
| Context window | 1M |
| Max output tokens | 128,000 |
| Input modalities | Text, Image |
| Output modalities | Text |
| Prompt types | Text |
| Negative prompts | No |
| Max outputs | 1 |
| Local deployment | No |
| API access | Yes |
| Pricing | $10 / $50 per 1M token |
| Confidence | High |
| Vendor country | US |
| Vendor type | Frontier lab |
Pricing & hardware
$10 / $50 per 1M token
API-only: local GPU memory is not applicable. API access is available.