Claude Fable 5.1
claude-fable-5-1
Anthropic · reasoning · api
Intelligence
Context
1M
Max output
128K
Input $/1M
$10.00
Output $/1M
$50.00
Modalities
text · image · document
Released
28 Aug 2026
Intelligence Index via Artificial Analysis · 0–100, higher is better
AI summary
● machine-written
Claude Fable 5.1: Anthropic's reasoning model for complex agentic work
Claude Fable 5.1 is Anthropic's flagship reasoning model designed for demanding autonomous reasoning and long-horizon agentic tasks. It supports text, image, and document inputs with a 1M-token context window and up to 128K output tokens per request. The model is positioned for complex work that would otherwise require extended human oversight or multiple steps.
What's new
- Adaptive thinking enabled by default with high effort level
- Cache hits priced at 0.025x base input rate ($0.25/MTok) versus 0.1x for other models
- Supports text, image, and document modalities
- Released June 2026 with reliable knowledge cutoff through June 2026
Best for
Autonomous knowledge work and codingLong-running, complex, multi-step tasksEnd-to-end work requiring few mistakes and self-correctionTasks requiring extended reasoning and verification loops
Common questions about Claude Fable →
Source: https://docs.claude.com/en/docs/about-claude/models/overview