Anthropic · Frontier
Claude Fable 5.1
Anthropic's most capable generally available model, the successor to Fable 5 for long-running agentic coding, knowledge work and research. Thinking is adaptive and always on. Same $10 / $50 price as Fable 5, with cache reads cut to $0.25 per million tokens.
Model ID: claude-fable-5-1
What that means
A worked example
Per-token pricing is hard to feel. Take a moderately chatty production workload: 100 calls a day, roughly 10,000 tokens in and 2,000 out each time. On Claude Fable 5.1 that comes to about:
$600 / month
Before caching, batching or volume discounts, all of which move this number a long way. Illustrative only.
Strong at
- -Long-horizon agentic work
- -Hard reasoning
- -Research synthesis
Typical use
- -Multi-hour agent runs
- -Complex research
- -Large refactors
Watch out for
- -tool_choice any and tool return a 400 error; use auto with strict tool use
- -Uses the newer tokenizer: roughly 30% more tokens for the same text than pre-4.7 models
Same tier
What else to look at
| Model | Developer | Context | In / 1M | Out / 1M |
|---|---|---|---|---|
| Claude Opus 5.5 | Anthropic | 1M | $4 | $20 |
| Claude Fable 5 | Anthropic | 1M | $10 | $50 |
| Claude Opus 5 | Anthropic | 1M | $5 | $25 |
| Claude Opus 4.8 | Anthropic | 1M | $5 | $25 |
| GPT-6 Astra | OpenAI | 1.05M | $10 | $50 |
Verified 2026-10-11.