Claude Opus 5.5 takes the top spot on the Artificial Analysis Intelligence Index, along with a 20% price cut and larger cache hit discount
Claude Opus 5.5 brings Anthropic to parity with GPT-6 Astra on evaluations like Terminal-Bench 4.0 and AutomationBench-AA, while extending Anthropic’s lead in agentic knowledge work.
At max effort it scores 58 on the Artificial Analysis Intelligence Index, the highest score we have measured by several points. Anthropic has cut Opus pricing to $4/$20 per 1M input/output tokens (Opus 5: $5/$25) and cache reads from $0.50 to $0.20.
Key takeaways:
➤ Consistent strong performance, with leading scores on six of the ten Intelligence Index evaluations: Humanity's Last Exam 61.4% (previous best 59.1%, Claude Fable 5.1), SciCode 66.9% (63.1%, Fable 5.1), GDPval-AA v2.1, AA-Briefcase v1.1, AA-Omniscience and AutomationBench-AA. On Terminal-Bench 4.0 it scores 59.6%, level with the leader GPT-6 Astra (xhigh) and +11 points over Opus 5. It remains slightly behind on CritPt, AA-LCR, and GDP.pdf
➤ Leads in agentic knowledge work: On AA-Briefcase, our private frontier knowledge work evaluation, it reaches an Elo of 1822. This is +143 over Fable 5.1, ahead…
At max effort, Claude Opus 5.5 scores 58 on Artificial Analysis's Intelligence Index, the highest score the firm says it has measured.
Opus 5.5 hits 61.4% on Humanity's Last Exam (up from a prior best of 59.1% set by Claude Fable 5.1) and 66.9% on SciCode (up from 63.1%), per Artificial Analysis.
On Artificial Analysis's private AA-Briefcase knowledge-work benchmarkA standard public test set for comparing AI models — the shared scoreboards behind every "model X beats model Y" claim.Full definition →, Opus 5.5 reaches an Elo of 1822, +143 over Fable 5.1, the first time an Anthropic model has topped GPT-5.6 Sol on presentation quality there.
Despite scoring higher, Opus 5.5 (max) uses about 119k output tokenThe chunk of text a model reads and writes in — roughly three-quarters of a word — and the unit AI usage is billed in.Full definition → per Intelligence Index task versus roughly 73k for Opus 5, 78k for Fable 5.1, and 27k for GPT-6 Astra, per Artificial Analysis.
Anthropic cut Opus 5.5 pricing 20% to $4/$20 per million input/output tokens and cut cache-read pricing 60% to $0.20 per million tokens, a 95% discount versus uncached input.
Terms in this piece · Glossary
eval — A repeatable test for AI quality — a set of tasks plus scoring — used the way software teams use test suites, because model output is too variable to judge by eyeballing.
benchmark — A standard public test set for comparing AI models — the shared scoreboards behind every "model X beats model Y" claim.
token — The chunk of text a model reads and writes in — roughly three-quarters of a word — and the unit AI usage is billed in.
Why it matters
Artificial Analysis puts hard numbers on Opus 5.5: top Intelligence Index score, parity with GPT-6 Astra on Terminal-Bench 4.0, and a 20% price cut, giving engineers concrete grounds to compare frontier models.
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