Claude Opus 5.5
Anthropic released Claude Opus 5.5, matching Fable 5.1 on most work at about 40% lower cost with stronger safeguards.
Anthropic introduced Claude Opus 5.5, the first model in the Claude 5.5 family, saying it matches Claude Fable 5.1 on most work and costs about 40% less to run than Opus 5. Input and output are priced at $4 and $20 per million tokens, cache reads at $0.20 per million, and output is more than 30% faster. It scores 66.4% on Terminal-Bench 4.0, compared with 55.8% for Fable 5.1 and 57.9% for GPT-6 Astra, with further results on FrontierCode, CursorBench, and OSWorld. Because it is comparable to Claude Mythos 5.1 on biology and cybersecurity, safeguards route those tasks to Opus 4.8 or Opus 5; Anthropic says it resists prompt injection better than Opus 5 and posts its best automated behavioral-audit score.
- Opus 5.5 matches Fable 5.1 on most work and costs about 40% less than Opus 5.
- Prices are $4 input and $20 output per million tokens; cache reads are $0.20.
- Terminal-Bench 4.0 score is 66.4%, ahead of Fable 5.1 and GPT-6 Astra.
- Cyber and biology safeguards reroute tasks to Opus 4.8 or Opus 5.
- Anthropic reports stronger prompt-injection resistance and its best behavioral-audit score.
- Organizations
- AnthropicOpenAIFrontier DesignMETRZapier
From the original article
14 min read at anthropic.com
We’re introducing Claude Opus 5. 5, the first model in our new Claude 5. 5 family.
By throwaway371647 · anthropic.com
A short excerpt; the article and its images belong to the publisher. Summary, key facts and assessment above are AI-written from the article and can be wrong.