Claude Opus 4.6

Summary

Claude Opus 4.6 improves on Opus 4.5 with stronger coding, planning, debugging, code review, long-running agentic work, and performance in large codebases. It is the first Opus-class model with a beta 1M-token context window, while API features include adaptive thinking, four effort levels, context compaction, and up to 128k output tokens. In reported evaluations, it achieves the highest score on Terminal-Bench 2.0, leads frontier models on Humanity’s Last Exam and BrowseComp, and exceeds GPT-5.2 by around 144 Elo points and Opus 4.5 by 190 points on GDPval-AA. The release also adds Claude Code agent teams, upgraded Excel capabilities, a PowerPoint research preview, and availability on claude.ai, the API, and major cloud platforms, with base pricing of $5/$25 per million tokens.

Takeaways

1. 1

   Opus 4.6 supports four API effort levels—low, medium, high, and max—and adaptive thinking lets it decide when extended reasoning is useful.

2. 2

   Context compaction beta automatically summarizes and replaces older context near a configurable threshold, helping long-running conversations and agentic tasks continue without hitting limits.

3. 3

   On GDPval-AA, Opus 4.6 outperforms GPT-5.2 by around 144 Elo points and Claude Opus 4.5 by 190 points; base pricing remains $5/$25 per million tokens.