Anthropic released Opus 5.5 on Tuesday, saying the new model set a state-of-the-art in coding and knowledge work while beating the larger Fable model on many benchmarks.. The company called Opus 5.5 “the strongest-performing model we’ve tested to date” in its announcement. Anthropic also said the model completed several informal tasks that Fable failed to complete..
Anthropic cut pricing for the new model. Output tokens cost $20 per million tokens for Opus 5.5, down from $25 for the previous model.. Other pricing metrics also fell, and Anthropic said Opus 5.5 runs faster and needs less compute power than its predecessor..
The company also changed how the model communicates. Anthropic said Opus 5.5 is less likely to use jargon and more likely to place important information at the start of its responses.. The release comes two months after Anthropic launched Opus 5 on July 24.
Anthropic said Sonnet 5.5 and Haiku 5.5 will be released “in the coming weeks” with similar performance gains.. Anthropic said Opus 5.5 is comparable to Mythos in biology and cybersecurity capabilities, placing it under the same safeguards applied to the company’s Fable model..
Those safeguards restrict the model’s use for finding exploits in compiled programs and for developing recognizable biological weapons, among other tasks.. Opus 5.5 is Anthropic’s first model release since Chief Executive Dario Amodei said the company should slow the pace of frontier AI development to keep risk prevention aligned with capability gains..
“I have become convinced that fully addressing the risks requires even more prudence,” Amodei wrote earlier this month. “Not just investing in risk prevention, but pacing the rate of capabilities advancement so that risk prevention has time to keep up.”. Anthropic said Opus 5.5’s safety training was broadly similar to earlier models, including alignment testing and pre-release evaluations by outside groups such as METR and Frontier Design..
The company said it is preparing more advanced training and evaluation systems for future models, including improved security and monitoring. “As AI becomes more capable, public policy should play a larger role in making sure the systems people rely on are safe,” Anthropic said in the blog post..
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