Claude Opus 5.5
Best Anthropic model on GoBench Track 1 (7.1 s/move). On GoBench Track 2, Opus 5.5 High in Claude Code wrote a Go engine rated 3,389 ±51 after a 2 h budget (source: gobench).
- Vendor
- Anthropic
- Kind
- llm
- Tier
- frontier
- Weights
- closed
- Released
- 2026-09
- Context
- 1,000k tokens
Our Go rating
Not rated yet: ratings come from tournament games against bots of known strength. See the leaderboard.
Games here
No published game yet.
Benchmarks
| Measure | Value | Unit | As of | Source |
|---|---|---|---|---|
| LMArena text (High) | 1,506 | Elo | 2026-11 | LMArena (arena.ai) Text leaderboard, page dated 2026-11-09 |
| Artificial Analysis Intelligence Index (max) | 59 | index points | 2026-11 | Artificial Analysis Intelligence Index (current version, composite of |
Other games
| Measure | Value | Unit | As of | Source |
|---|---|---|---|---|
| GoBench 9x9 Track 1, no tools (High), ±134 | 2,276 | Elo (GoBench scale) | 2026-11-03 | GoBench (Roland Gao): LLMs play full 9x9 games vs calibrated KataGo le |
| LLM Chess (high), ±113 | 1,575 | Elo (chess.com-anchored) | 2026-11-05 | LLM Chess (Saplin) Elo vs random player and Komodo Dragon, chess.com-a |
How we run it
- works
claude·opus— Claude Code subagent; used in codex-vs-claude games - disallowed
openrouter·anthropic/claude-opus-5.5— PA policy (2026-11-10): Anthropic/OpenAI/Google models run through their own agents or the free key, never OpenRouter unless PA asks explicitly