Claude Opus 4.6: Anthropic reasoning model
1M tokens · Text / Vision / Code · Prompt cache
Okou no longer runs Claude Opus 4.6. This page is kept as a reference for its specs, pricing and benchmarks. For the same kind of work, use GPT 5.6 Luna.
See GPT 5.6 LunaClaude Opus 4.6 was Anthropic's flagship before Opus 4.7 and introduced most of what now defines the Claude 4 family: the 1M-token context window in beta, adaptive thinking at four effort levels, and the highest agentic-coding scores Anthropic had shipped at the time (vendor-reported SWE-bench Verified 80.8%, Terminal-Bench 2.0 65.4%, OSWorld 72.7%).
Vendor list price is the same $5 / $25 per 1M tokens as 4.7. The only good reason to stay on 4.6 is behaviour stability for an agent that's already been validated against this version; anything new should start on 4.7.
What is Claude Opus 4.6?
February 5, 2026 · Previous top-tier of the Claude 4 family. Superseded by Claude Opus 4.7.
Claude Opus 4.6 was Anthropic's frontier model before Opus 4.7. It was released on February 5, 2026 and introduced several capabilities that defined the Claude 4 family. Adaptive thinking with four effort levels, the 1M-token context window in beta, and Anthropic's highest agentic-coding scores at release.
Specs at a glance
Claude Opus 4.6 benchmarks
Vendor-reported scores from Anthropic's Opus 4.6 release materials and Artificial Analysis. Treat absolute SWE-bench numbers cautiously. OpenAI flagged training-data contamination on SWE-bench Verified across all frontier models.
Claude Opus 4.6 pricing
Provider list price, per 1M tokens.
How Claude Opus 4.6 behaves in practice
Observed behaviour from production agent runs.
Reasoning
Strong on hard reasoning steps. Opus 4.7 is incrementally better at slightly lower vendor cost. There is no benchmark category where 4.6 leads.
Tool use
Reliable across multi-tool agent flows. Same ballpark as Sonnet 4.6 on routing accuracy with extra robustness on edge cases.
Long context
1M-token context with 76% MRCR v2 recall. Actually usable across the full window, not just nominal.
Speed
Slower than Sonnet 4.6 and Kimi K2.7 Code; comparable to Opus 4.7. Around 41 tokens/sec at max effort per Artificial Analysis.
Best agent tasks for Claude Opus 4.6
The production agent that's already paying its way
Your team spent two weeks tuning prompts and tool schemas against Opus 4.6, the agent has been live for a month, and customers are happy. Pinning to 4.6 keeps the behaviour identical while you decide whether the 4.7 upgrade is worth a re-validation cycle, instead of letting Anthropic auto-upgrade your traffic and quietly shifting outputs underneath you.
Claude Opus 4.6 vs other models
Claude Opus 4.6 vs Claude Sonnet 4.6
Sonnet 4.6 is ×1 and handles most agent loops. Reach for Opus only when Sonnet visibly fails. Usually for orchestration or hard code edits.
Bottom line: should you use Claude Opus 4.6?
Pin if you've already validated against it; otherwise start on Opus 4.7. The migration is a setting change, not a rewrite.
Frequently asked questions
When was Claude Opus 4.6 released?
Anthropic released Opus 4.6 on February 5, 2026. Opus 4.7 followed shortly after.
What is Claude Opus 4.6's context window?
1 million tokens (beta) with up to 128K tokens of output per response.
What's adaptive thinking?
A scheduling layer that lets Claude decide how much reasoning compute to spend per turn. Four levels. Low, medium, high, max. With high as the default. Replaced Opus 4.5's extended-thinking toggle.
Alternatives
Availability of Claude Opus 4.6 on Okou
Claude Opus 4.6 has been removed from the Okou lineup, so it can no longer be selected in chat or in a workflow, and it is not available with your own API key. GPT 5.6 Luna covers the same cost-saving tier.
