Anthropic · Claude Fable
Claude Fable 5
Anthropic’s most capable widely released model for demanding reasoning and long-horizon agentic work, with stricter safety classifiers than Mythos.
Keep it for the jobs that break cheaper options. Capability without a cost and review baseline is not a recommendation.
Use it for
- Very long and difficult agentic projects
- Hard reasoning with auditable outputs
- Tasks that can justify a premium model
It is slow and expensive for ordinary work, requires careful refusal handling in integrations and has data-retention conditions that matter to organisations.
Effort without the jargon
The task is genuinely long-horizon and the value is high enough to measure against cheaper models.
Advanced recordCost, limits, privacy and operations
Fable is the premium Claude option: reserve it for work with a clear scorecard because its input and output prices make vague experimentation expensive.
- API cost
- Officially disclosedClaude API list price: US$10 per million input tokens and US$50 per million output tokens; caching, batch and cloud-platform rates can differ.
- Context window
- Officially disclosed1,000,000 tokens
- Maximum output
- Officially disclosed128,000 tokens (synchronous Messages API)
- Knowledge cutoff
- Officially disclosedReliable knowledge: January 2026; training data: January 2026
- Recorded inputs
- Text · Images
- Recorded output
- Text
Data handling is a product decision
Depends on surfaceAnthropic says commercial API inputs and outputs are deleted from its backend within 30 days by default, with exceptions for stored services, agreed controls, safety enforcement and law. Consumer Claude and cloud platforms have separate terms.
Operational constraints
- Adaptive thinking is always on; extended thinking is not exposed as a separate mode.
- The dateless API ID is a pinned snapshot rather than an automatically moving alias.
- Long-running agents still need cost ceilings, stop conditions and review checkpoints.
Unknown means the cited official record does not disclose a safe value. It is not an estimate. Prices are provider list prices in USD where stated and can change before this record's review date.
Keep the evidence separate
Anthropic calls Fable 5 its most capable widely released model for demanding reasoning and long-running agents.
After several hours of hands-on use he described it as powerful, slow and expensive: exactly the combination that demands a task-level value test.
Read the independent source ↗No Human Bit result is claimed; use this as evaluation guidance only.
Not scheduled
No Human Bit result is claimed for this model yet.