Claude Sonnet 4.6

Arena ranked GLM-5.1 third on Code Arena and first among open models, putting it on par with Claude Sonnet 4.6 and within about 20 points of the overall lead. The update gives the open model a new frontier coding benchmark after its initial release and hosting wave.

Anthropic added a beta advisor tool to the Messages API so Sonnet or Haiku can call Opus mid-run inside one request. Anthropic says Sonnet plus Opus scored 2.7 points higher on SWE-bench Multilingual while cutting per-task cost 11.9%.

LLM Debate Benchmark ran 1,162 side-swapped debates across 21 models and ranked Sonnet 4.6 first, ahead of GPT-5.4 high. It adds a stronger adversarial eval pattern for judge or debate systems, but you should still inspect content-block rates and judge selection when reading the leaderboard.

Third-party MRCR v2 results put Claude Opus 4.6 at a 78.3% match ratio at 1M tokens, ahead of Sonnet 4.6, GPT-5.4, and Gemini 3.1 Pro. If you are testing long-context agents, measure retrieval quality and task completion, not just advertised context window size.

Anthropic made 1M-token context generally available for Opus 4.6 and Sonnet 4.6, removed the long-context premium, and raised media limits to 600 images or PDF pages. Use it for retrieval-heavy and codebase-scale workflows that previously needed beta headers or special long-context pricing.