Claude Opus 5.5 — reviews, specs & pricing
Anthropic's first Claude 5.5 model, released 22 September 2026 for long-running agentic coding and knowledge work. 1M-token context, 128k max output, adaptive thinking always on, and about 40% cheaper to run than Opus 5 at $4/$20 per million tokens.
Summary
Claude Opus 5.5 is Anthropic's premier model built specifically for advanced agentic coding and complex knowledge-work workflows. Featuring a massive 1-million-token input context and a 128k token output capacity, it operates with always-on adaptive thinking for deep, autonomous problem-solving. Despite these heavy reasoning capabilities, it is highly cost-effective, running about 40% cheaper than its predecessor at $4 per million input tokens and $20 per million output tokens.
Sample use case
A software engineering team can deploy Claude Opus 5.5 to autonomously refactor a legacy enterprise codebase. By loading the entire repository of code and documentation into the model's 1-million-token context window, the model can use its adaptive reasoning to map intricate system dependencies, identify security vulnerabilities, and generate tens of thousands of lines of optimized, modern code in a single execution using its massive 128k token output capacity.
Specifications
- Provider: anthropic
- License: closed
- Context: 1000k tokens
- Input price: $4/M tok
- Output price: $20/M tok
- Released: 2026-09-22
Pros
- Massive 1M-token input context window
- Unprecedented 128k maximum output capacity
- 40% cheaper than the previous Opus generation
- Powerful always-on adaptive reasoning capabilities
Cons
- Slower generation speeds due to continuous thinking
- Lacks native vision or audio modalities
- Still premium-priced compared to lightweight models
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