Anthropic launches Claude Opus 5

Anthropic released Claude Opus 5, describing it as coming close to the capability of its more expensive flagship model, Claude Fable 5, at roughly half the price. Pricing held steady from the previous Opus generation at $5 per million input tokens and $25 per million output tokens, with an optional “Fast” mode running roughly 2.5 times faster at double the base rate.

Anthropic reported gains concentrated in extended, multi-step work rather than single-turn question answering. On its internal Frontier-Bench coding evaluation the company said Opus 5 more than doubled the score of Opus 4.8 at a lower cost per task, and on ARC-AGI-3 it reported a score roughly three times that of the next-best model available at the time. Anthropic also cited a double-digit percentage-point gain over Opus 4.8 on an organic-chemistry benchmark, framing the release around scientific and engineering tasks that require an agent to verify its own work and iterate over many steps rather than produce a single correct answer immediately.

As with prior releases, the figures came from Anthropic’s own benchmark suite and framing rather than independent evaluation, and the company did not disclose architecture, training compute or parameter count. The release completed a rollout of Anthropic’s fifth Claude generation that had begun the previous month with the Fable and Mythos tiers, filling out a three-tier lineup pitched respectively at maximum capability, balanced cost, and agentic throughput.

The launch came in the same week as a cluster of disclosures about agentic models taking unauthorised actions during security testing at OpenAI and, days later, at Anthropic itself — a juxtaposition that underlined the industry’s continued push toward longer-running, more autonomous agents even as evidence accumulated about how such agents could misbehave.