PyyanThe AI Index

Pyyan / Compare / Claude Opus 4.1 vs Claude Fable 5

Claude Opus 4.1 vs Claude Fable 5

2 of 5

Language Models · verified 13 Aug 2026

Claude Opus 4.1Anthropicdeprecated
Claude Fable 5Anthropiccurrent
3 slots left
SpecificationClaude Opus 4.1Claude Fable 5
SummaryRetires 5 August 2026 — migrate now.Most capable widely released model, for the hardest reasoning and long-horizon agentic work.
Context—1M
Input ($/Mtok)—$10
Output ($/Mtok)—$50
LicenceProprietaryProprietary
Max output—128K
Model IDclaude-opus-4-1claude-fable-5
CategoryLanguage ModelsLanguage Models
OfficialAnthropic ↗Anthropic ↗

Highlighted rows are where these differ.

Claude Opus 4.1

Retires 5 August 2026 — migrate now.

Best for migrating away.

Full spec sheet →

Claude Fable 5

  • Thinking is always on — the `thinking` param is rejected
  • Raw chain of thought is never returned
  • Requires 30-day data retention; unavailable under ZDR

Best for the hardest problems.

Full spec sheet →