Anthropic Introduces Claude Opus 5.5 and Announces Sonnet and Haiku 5.5

Model Introduction

Anthropic is introducing Claude Opus 5.5, the first model in its new Claude 5.5 family. The company states that Opus 5.5 performs at the level of Claude Fable 5.1 on most work and costs 40% less to run than Opus 5. Claude Sonnet 5.5 and Claude Haiku 5.5 will follow in the coming weeks, with many of the same improvements to performance, efficiency, and safety.

Performance and Pricing

Opus 5.5 is a major step up from Opus 5. Early testers saw large jumps in performance on complex work, including one tester who completed a 680,000-line code migration in less than a day. In a test to cut load times across every page of a web app, Opus 5.5 succeeded 39 of 40 times.

The model is priced at $4 per million input tokens and $20 per million output tokens, which is 20% less than Opus 5. Cache reads are $0.20 per million tokens, 60% less than Opus 5. Anthropic's tests show that at default settings, it will cost 40% less than Opus 5 on typical workloads. Opus 5.5 also generates output more than 30% faster than Opus 5.

Safety and Communication

Opus 5.5 achieves the best scores of any model to date on Anthropic's automated behavioral audit, its alignment suite that tests Claude across thousands of simulated scenarios. It is much less likely than recent models to take hard-to-reverse actions or act outside the boundaries it has been given, and it is more resistant than Opus 5 to prompt injection.

The model communicates more naturally than prior models. Early testers found its writing clearer and easier to follow. It puts the most important information up front and is less likely to use jargon or idiosyncratic phrases.

Why it matters

The release of Claude Opus 5.5 introduces a new tier of AI models from Anthropic focused on efficiency and safety, with broader availability of the Claude 5.5 family expected soon through the release of Sonnet 5.5 and Haiku 5.5.

Sources

• anthropic.com: Introducing Claude Opus 5.5 \ Anthropic

This article was drafted with AI assistance and checked against the sources above. Company claims are reported as claims. Cover image is AI-generated.