Sonnet 4.5 is Anthropic's most capable Sonnet-class model yet, with frontier performance across coding, agents, and professional work. It excels at iterative development, complex codebase navigation, end-to-end project management with memory, polished document creation, and confident computer use for web QA and workflow automation.
Claude 4.5 Sonnet is Anthropic’s most capable Sonnet-class model, offering a powerful combination of low-latency high throughput and frontier intelligence. Built for stateful agentic workflows, iterative development, and desktop automation, it maintains precise logical execution and exceptional contextual memory across complex, multi-step professional tasks.
To interact with this model via an OpenAI-compatible gateway or OpenRouter endpoint:
| Parameter | Type | Required | Description |
|---|---|---|---|
model |
string |
Yes | Use "claude-sonnet-4-5" . |
messages |
array |
Yes | Array of standard conversation objects (role/content) supporting multi-modal payloads. |
max_tokens |
integer |
No | Limits generation length. Supports a massively expanded maximum output of up to 64,000 tokens. |
temperature |
float |
No | Recommended: 0.0 or 0.2 for deterministic coding and infrastructure logic; 0.7 for document creation. |
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