Claude Opus 4.6

Claude Opus 4.6 is Anthropic's frontier model, released on February 5, 2026. It is a hybrid reasoning model: it can answer quickly or engage extended thinking, and with adaptive thinking it decides for itself when deeper reasoning is worthwhile, controlled through four effort levels (low, medium, high, and max). Opus 4.6 is the first Opus-class model with a 1 million token context window (in beta), which Anthropic says marks a qualitative shift in how much context a model can actually use while maintaining peak performance.

Key Features

• Hybrid reasoning with adaptive thinking: Developers tune four effort levels, trading intelligence against speed and cost; the model chooses automatically how deeply to reason.
• 1M token context (beta): Available on the Claude Developer Platform, with up to 128k output tokens and premium pricing above 200k tokens.
• Anti context rot: On the 8-needle 1M variant of MRCR v2, Opus 4.6 scores 76%, versus 18.5% for Sonnet 4.5, meaning it can retrieve information hidden in very long conversations without degrading.
• Long-horizon autonomy: Plans more carefully and stays on task longer, reducing the back-and-forth needed for complex, multi-step workflows.
• Broad platform availability: claude.ai, the Claude API (model ID claude-opus-4-6), and all major clouds (AWS, Google Cloud, Microsoft Foundry).

Performance Highlights

• Terminal-Bench 2.0: Highest score among frontier models on the agentic coding evaluation
• SWE-bench Verified: 81.42% (prompt-modified, 25-trial average)
• Humanity's Last Exam (with tools): 53.0%, leading all other frontier models
• BrowseComp: 83.7% (86.8% with a multi-agent harness)
• MCP Atlas: 62.7% at high effort, an industry-leading result
• GDPval-AA: Outperforms OpenAI's GPT-5.2 by roughly 144 Elo points

Pricing

Use Cases

• Agentic coding: State-of-the-art on Terminal-Bench 2.0 and SWE-bench Verified, making it a strong default for autonomous software engineering.
• Enterprise knowledge work: Leads on GDPval-AA across finance, legal, and other professional domains; a popular choice for the workflows of firms like Harvey (BigLaw Bench 90.2%).
• Long-context analysis: Its MRCR v2 results make it practical for analyzing massive codebases, legal documents, and research corpora in a single pass.
• Computer use and tool use: Strong performance across computer-use, web search, and programmatic tool calling evaluations.

Getting Started

1. Access Opus 4.6 on claude.ai, or through the Claude API and SDKs in the Claude Code tool.
2. In the API, use the model identifier claude-opus-4-6.
3. Set the thinking budget via effort levels (low, medium, high, max) or enable adaptive thinking to let the model choose.
4. For contexts above 200k tokens, plan for the higher long-context pricing tier.

Advantages & Comparison

Opus 4.6 addresses the industry's "context rot" problem directly, where other models degrade as conversations grow long. Its combination of adaptive thinking, agentic coding leadership, and 1M-token context makes it a natural choice for teams that run long, autonomous workflows and need consistent performance throughout. Compared to its predecessor Opus 4.5, it gains roughly 190 Elo points on GDPval-AA and dramatically better long-context retrieval.

Frequently Asked Questions

What is the difference between Opus 4.6 and Opus 5?

Opus 5, released later, is Anthropic's newest flagship, while Opus 4.6 remains available and is preferred by some users for its more coherent plain-language output and stable behavior in long agentic sessions.

Is Opus 4.6 open source?

No. It is proprietary and available only through Anthropic's apps, API, and cloud partners.

Does it support multimodal input?

Yes, Opus 4.6 accepts both text and vision inputs.

Alternatives

• GPT-5.6: OpenAI's frontier reasoning family: /en/items/models/gpt-5.6
• Gemini 3 Pro: Google's frontier model: /en/items/models/google-gemini-3-pro
• GLM-5.3: Zhipu's open-weight coding and agentic flagship: /en/items/models/glm-5-3

Conclusion

Claude Opus 4.6 is a serious upgrade for anyone running long-horizon agentic coding or enterprise knowledge work. Its adaptive thinking, industry-leading Terminal-Bench and GDPval-AA results, and first Opus-class 1M context window make it a top-tier default for autonomous workflows that demand sustained performance over long sessions.

Usage Terms

Usage is subject to Anthropic's Commercial Terms of Service.