Anthropic unveils Claude Opus 5.5

Sept 22 : Anthropic on Tuesday launched Claude Opus 5.5, a new AI model that it says delivers performance comparable to its top-tier Fable 5.1 while costing 40 per cent less to run than its predecessor.

The release lands amid growing debate over AI risks. CEO Dario Amodei earlier this month called on the global AI community to slow down the pace of releasing new capabilities to address safety concerns.

Anthropic said Opus 5.5 underwent external testing by independent AI safety research groups Frontier Design and METR before launch and includes safeguards previously reserved for its most capable systems.

According to Anthropic, Opus 5.5 outscored rival OpenAI's GPT-5.6 Sol on a software development benchmark while costing roughly one-third as much to run.

Opus 5.5 is priced at $4 per million input tokens and $20 per million output tokens, 20 per cent below Opus 5, Anthropic said. The model is available on platforms including Amazon Web Services, Google Cloud and Microsoft Azure.

The model also scored better than previous systems in internal safety tests and was about 85 per cent less likely than Opus 5 or Mythos 5.1 to attempt to bypass containment boundaries in a dedicated evaluation, the company said.

Claude Sonnet 5.5 and Claude Haiku 5.5 will be released in the coming weeks, the company said, bringing many of the same performance, speed and safety improvements. 

Anthropic is also expanding programs that give vetted cybersecurity and life-sciences researchers broader access to the model.