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Pyyan / Compare / Grok 4.20 Reasoning vs Claude Fable 5

Grok 4.20 Reasoning vs Claude Fable 5

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Language Models · verified 13 Aug 2026

Grok 4.20 ReasoningxAIcurrent
Claude Fable 5Anthropiccurrent
3 slots left
SpecificationGrok 4.20 ReasoningClaude Fable 5
SummaryAgentic reasoning SKU.Most capable widely released model, for the hardest reasoning and long-horizon agentic work.
Context1M1M
Input ($/Mtok)$1.25$10
Output ($/Mtok)$2.5$50
LicenceProprietaryProprietary
Max output—128K
Model IDgrok-4.20-0309-reasoningclaude-fable-5
CategoryLanguage ModelsLanguage Models
OfficialxAI ↗Anthropic ↗

Highlighted rows are where these differ.

Grok 4.20 Reasoning

Agentic reasoning SKU.

Best for multi-step agents.

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 →