All benchmarks

FrontierCode (Diamond)

Agentic coding

Cognition’s FrontierCode evaluation tests whether models can complete difficult coding tasks while meeting the standards of high-quality production codebases — code that is correct, maintainable and reviewable, not merely passing tests. Diamond is the hardest tier.

Model scores

  • Fable 529.3%
  • Opus 5—
  • Opus 4.813.4%
  • Sonnet 5—
  • GPT-5.6 Sol—
  • GPT-5.55.7%
  • Composer 2.5—
  • Opus 4.7—
  • Gemini 3.1 Pro—
  • Mythos Preview—

Official source: Anthropic — Fable 5 / Mythos 5 announcement

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