VulcanBench VulcanBench
Model results · Anthropic

Claude Fable 5

Every published VulcanBench measurement of Claude Fable 5, newest first: accuracy, cost, tokens, and time, graded by deterministic hidden tests on real tasks.

Report08
Kimi K3 vs Grok 4.5, Claude Fable 5 & GPT-5.6 Sol benchmark
Kimi K3 joins the VulcanBench v3 field: Grok 4.5 leads all eleven configurations at 91.3% with the lowest cost per solved task; K3 debuts at 74%, rising to 87% under an extended-budget ablation.
2026-07-19
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Report07
Grok 4.5 vs Claude Fable 5 vs GPT-5.6 Sol benchmark
Grok 4.5 leads at 91% from medium effort onward on the v3 suite; only GPT-5.6 Sol rewards the effort knob; two frontier-hard tasks go 0-for-27.
2026-07-12
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Report05
Claude Fable 5 vs Opus 4.8 frontier-hard benchmark
Two models, two effort levels, on a suite with five frontier-hard tasks. Binary pass@1 is a four-way tie; effort helps Opus and backfires for Fable.
2026-07-04
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Report04
Claude Fable 5 vs Opus 4.8 vs GPT-5.5 benchmark
Four frontier configurations on 15 real engineering evals. All score 14/15 but each misses a different task; cost spans 4x.
2026-07-02
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Report03
Claude Fable 5 vs Sonnet 5 vs GLM-5.2 benchmark
Accuracy converges across three models while efficiency spans an order of magnitude. Fable 5 at low effort matches Sonnet 5 at high effort for a quarter of the cost.
2026-07-01
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How would Claude Fable 5 do on your stack?

Public results answer "which model is stronger on this suite." Whether Claude Fable 5 belongs in your routing table depends on your languages, your codebases, and your task mix — that gets measured, not guessed. Grading rules are in the methodology.

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