Claude Fable 5
Mythos-class flagship Claude
Context Window
1.0M
1,000,000 tokens
Max Output
128K
128,000 tokens
About this model
Claude Fable 5 is Anthropic's Mythos-class publicly released model, launched on 2026-06-09 for the most demanding reasoning, long-horizon agentic workflows, professional analysis, and difficult coding tasks.
It supports a 1M token context window by default and up to 128K output tokens, accepting text, image, and PDF inputs. Fable 5 has adaptive thinking always enabled, making it suitable for long autonomous sessions that require investigation and careful verification.
Note that Fable 5 applies stricter safety classifiers for high-risk areas such as cybersecurity, biology, and chemistry; classified requests may trigger upstream fallback or refusal behavior.
Highlights
Best For
Capabilities
Pricing (per 1M tokens)
| Pricing (per 1M tokens) | / 1M tokens |
|---|---|
| Input / 1M | $10.50 |
| Output / 1M | $52.50 |
| Cache Read | $1.05 |
| Cache Write | $13.13 |
Final prices shown
Quick Start
import anthropic client = anthropic.Anthropic( base_url="https://api.chuizi.ai/anthropic", api_key="ck-your-key-here", ) message = client.messages.create( model="claude-fable-5", max_tokens=1024, messages=[{"role": "user", "content": "Hello!"}] ) print(message.content[0].text)