Claude Opus 4.5

Claude Opus 4.5, released on 24 November 2025, was Anthropic's flagship model of the Claude 4 generation and the direct predecessor of the Claude 5 family. It works with a 200,000-token context window and returns up to 64,000 tokens per response, taking text and images as input. Two things made it a turning point. The first was price: Anthropic cut Opus rates from fifteen and seventy-five dollars per million tokens down to five and twenty-five — the level Opus 5 still charges today — which moved the most capable Claude out of the occasional-use bracket and into everyday coding and agent work. The second was the effort parameter, first shipped here, which let callers trade tokens for depth of reasoning instead of choosing between separate models; adaptive thinking in Claude Opus 5 grew directly out of that idea. On capability, Opus 4.5 was the first model to pass eighty percent on SWE-bench Verified, and it paired that with extended thinking, tool use, computer use and context compaction for long agent sessions. Anthropic deployed it under ASL-3 of the Responsible Scaling Policy and shipped it on the Claude API, Amazon Bedrock, Google Vertex AI and Microsoft Foundry, as well as in Claude.ai and Claude Code. It remains documented and available as a previous-generation model; wujec.ai keeps its profile alongside the newer releases rather than replacing it.

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