claude-sonnet-4-5-think · Anthropic
Claude Sonnet 4.5 does not enable reasoning mode by default. To access its deep reasoning capabilities, users would typically need to call the native Claude API. To make this capability available through an OpenAI-compatible interface, the claude-sonnet-4-5-think model is provided with reasoning mode pre-enabled and a default 64k-token context window, allowing it to be called directly via the OpenAI unified API. Claude Sonnet 4.5 Think is a reasoning-focused variant of Claude Sonnet 4.5 designed for advanced tasks that require rigorous reasoning, complex decision-making, and long-chain analysis; aside from its enhanced reasoning mechanism, all other capabilities remain consistent with the standard Claude Sonnet 4.5 model, making it well suited for complex problem decomposition, multi-step planning, and logic-intensive analysis.
Claude Sonnet 4.5 does not enable reasoning mode by default. To access its deep reasoning capabilities, users would typically need to call the native Claude API. To make this capability available through an OpenAI-compatible interface, the claude-sonnet-4-5-think model is provided with reasoning mode pre-enabled and a default 64k-token context window, allowing it to be called directly via the OpenAI unified API. Claude Sonnet 4.5 Think is a reasoning-focused variant of Claude Sonnet 4.5 designed for advanced tasks that require rigorous reasoning, complex decision-making, and long-chain analysis; aside from its enhanced reasoning mechanism, all other capabilities remain consistent with the standard Claude Sonnet 4.5 model, making it well suited for complex problem decomposition, multi-step planning, and logic-intensive analysis.
Claude Sonnet 4.5 Thinking has a 200,000 token context window.
On AIHubMix, Claude Sonnet 4.5 Thinking costs $3.3 per million input tokens and $16.5 per million output tokens.
Claude Sonnet 4.5 Thinking accepts text, image and PDF input.
Claude Sonnet 4.5 Thinking supports thinking, tool calling, function calling and structured outputs. Per-protocol parameter support is listed in the capability table on this page.
Claude Sonnet 4.5 Thinking is available through the AIHubMix unified API. The API is OpenAI-compatible: point your OpenAI SDK at https://aihubmix.com/v1, use your AIHubMix API key, and set the model name to claude-sonnet-4-5-think — no other code changes needed.
Claude Sonnet 4.5 Thinking is developed by Anthropic. AIHubMix aggregates it alongside models from other providers behind one API and one bill.
Claude Sonnet 4.5 Thinking was released on September 29, 2025 by Anthropic.
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Use Claude Sonnet 4.5 Thinking via the AIHubMix unified API — one interface for every major LLM.