Claude Opus 4.5
By Anthropic
5 is Anthropic's most capable large language model in the Claude 4 family, designed for the highest-difficulty reasoning, coding, and agentic tasks where maximum quality matters more than speed or cost.
Definition
Claude Opus 4.5 is Anthropic's most capable large language model in the Claude 4 family, designed for the highest-difficulty reasoning, coding, and agentic tasks where maximum quality matters more than speed or cost.
Overview
Claude Opus 4.5 sits at the top of Anthropic's model lineup, above the faster and cheaper Claude Sonnet and Claude Haiku tiers, and represents an incremental but meaningful upgrade over earlier Opus 4 releases in reasoning depth, coding accuracy, and reliability on long, multi-step agentic tasks. Like other Claude 4-generation models, Opus 4.5 supports extended thinking, where the model can allocate additional internal reasoning steps before producing a final answer, improving performance on complex math, coding, and multi-hop reasoning problems. Opus 4.5 is positioned specifically for workloads where task difficulty or the cost of an error is high enough to justify its higher price and slower throughput relative to Sonnet — for example, deep codebase refactors, complex agentic workflows involving many tool calls, or research-style analysis requiring sustained reasoning across a long context window. It supports the same core capabilities as the rest of the Claude 4 family, including a large context window, vision input, tool use and function calling, and computer use for controlling graphical interfaces, but with generally stronger performance on the hardest benchmark tasks in each category. As with prior Claude releases, Opus 4.5 is available through the Claude API, Claude.ai, and via major cloud marketplaces such as Amazon Bedrock and Google Cloud Vertex AI, and Anthropic pairs each release with a public model card detailing safety evaluations and a system card documenting known limitations, consistent with the company's stated approach to responsible scaling.
Key Features
- Anthropic's highest-capability model tier within the Claude 4 family
- Extended thinking mode for deeper reasoning on hard problems
- Strong performance on complex coding, math, and multi-step agentic tasks
- Large context window supporting long documents and extended conversations
- Vision input for interpreting images, charts, and screenshots
- Tool use, function calling, and computer use for controlling software interfaces
- Available via Claude API, Claude.ai, Amazon Bedrock, and Google Cloud Vertex AI
- Higher cost and lower throughput than Sonnet or Haiku tiers, reserved for hardest tasks
Use Cases
Alternatives
Frequently Asked Questions
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