Anthropic Ships Opus 5.5 With Lower Prices and Fable-Level Performance

Anthropic released Opus 5.5 on Tuesday, billing the update as a new state of the art for coding and knowledge work. Opus is the top tier of the company's three-level Claude lineup, above Sonnet and Haiku, and the new version manages a rare feat: it outpaces Anthropic's own larger Fable model on many benchmarks and completes several informal tasks that Fable could not finish.

The pricing story is just as notable. Output tokens on Opus 5.5 cost $20 per million tokens, down from $25 for the previous generation, with similar reductions across other usage metrics. The model also runs faster, reflecting a broader drop in the compute needed to serve it.

Communication style gets an overhaul too. Anthropic says Opus 5.5 is less likely to lean on jargon and now places the most important information at the start of its responses rather than burying it.

The release comes only two months after Opus 5 launched in late July. Anthropic says Sonnet 5.5 and Haiku 5.5, the next tiers in the refresh cycle, will follow in the coming weeks with comparable improvements.

On safety, Anthropic rates Opus 5.5 as comparable to Mythos in biology and cybersecurity capability, which places it under the same safeguards as Fable. Those controls restrict how far the models can go in hunting exploits in compiled software or assisting with the development of biological weapons. Alignment testing followed the company's usual pattern, with pre-release evaluation by outside groups including METR and Frontier Design, and Anthropic says more advanced security and monitoring systems are already being prepared for future models.

Opus 5.5 is also the first new Anthropic model since CEO Dario Amodei publicly endorsed slowing the pace of frontier capabilities so that safety work can catch up. 'Fully addressing the risks requires even more prudence,' Amodei wrote earlier this month, arguing that capability advancement should be paced against the rate of progress in risk prevention. The company's blog post hints that public policy will play a growing role in that effort, promising more details soon.