Anthropic launched Claude Opus 5.5 on September 22 as its first Claude 5.5 family model. The company targets developers and enterprises with stronger coding, reasoning, and computer-use capabilities.
The model reaches Claude Fable 5.1-level performance across most workflows while costing 40% less overall. Anthropic achieved this through lower token usage, faster output generation, and improved computational efficiency.
Anthropic also positioned Claude Opus 5.5 against OpenAI’s GPT-6 Astra through several published benchmark comparisons. The company reported higher scores across coding, knowledge work, and multidisciplinary reasoning tests.
Terminal-Bench 4.0 gave Claude Opus 5.5 a 66.4% score, ahead of GPT-6 Astra’s 57.9%. FrontierCode also showed Opus 5.5 slightly ahead with a 54.4% score.
GDPval-AA measured knowledge work performance, where Opus 5.5 reached 1,846 Elo against Astra’s 1,542. Humanity’s Last Exam also favored Opus 5.5 with tools enabled.
GPT-6 Astra still scored higher on specialized tests covering scientific research and business workflow automation. Astra reached 64.6% on Terminal-Bench Science against Opus 5.5’s 58.7%.
Cost efficiency forms another major part of Anthropic’s Claude Opus 5.5 pitch for large-scale AI coding. The model costs USD 4 per million input tokens and USD 20 per million output tokens.
Anthropic says Opus 5.5 costs nearly 20% of Astra’s task cost on FrontierCode at default settings. Terminal-Bench performance can also match Astra while using around 40% of its task cost.
The coding improvements extend beyond benchmark scores to long, complex software engineering workflows. An early tester completed a 680,000-line migration in less than a day.
Another test showed Opus 5.5 improving page load times across a web application during 39 of 40 attempts. Anthropic also reported output generation more than 30% faster than Opus 5.
Safety remains another focus, with Anthropic reporting its strongest automated behavioral audit performance so far. The company said Opus 5.5 showed fewer attempts to cross containment boundaries during testing.
Anthropic also highlighted communication improvements, saying the model places important information first and follows writing instructions more closely. An early tester described the AI model as one that ‘writes the way I do.’
Claude Opus 5.5 now reaches developers through Anthropic’s Claude Platform under the model name claude-opus-5-5. Amazon Web Services, Google Cloud, and Microsoft Azure also provide access.
Anthropic plans to expand the Claude 5.5 lineup with Sonnet 5.5 and Haiku 5.5 in coming weeks. The tech giant said both models will bring similar improvements across performance, efficiency, and safety.
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