At a Glance
| Vendor | Anthropic |
| Family | Claude 5 series |
| Launched | Anthropic released Claude Opus 5.5 on September 22, 2026, about two months after Opus 5. It is the first model in the Claude 5.5 family, and Anthropic says it performs at the level of Claude Fable 5.1 on most work. It is also the model behind Claude Duet. |
| Context window | 1,000,000 tokens with 128,000 maximum output tokens, or 300,000 through the Message Batches API with a beta header. The reliable knowledge cutoff is June 2026. Adaptive thinking is always on, and the default effort is medium. |
| Pricing | $4 per million input tokens and $20 per million output tokens, 20 percent below Opus 5. Cache reads cost $0.20 per million, five-minute cache writes $5, and the Batch API is 50 percent off. Fast mode costs $8 / $40 and runs up to 2.5x faster. Anthropic says typical workloads cost 40 percent less than Opus 5 at default settings. |
| Access channels | Claude API (claude-opus-5-5), Claude apps, Amazon Bedrock (anthropic.claude-opus-5-5), Google Cloud, Microsoft Foundry, and Claude Platform on AWS. |
Notable Benchmarks
At max effort, Anthropic reports 66.4 percent on Terminal-Bench 4.0 (Fable 5.1 55.8, GPT-6 Astra 57.9), 54.4 percent on FrontierCode v1.1, 57.8 percent on CursorBench 4.0, and 1846 Elo on GDPval-AA v2.1. GPT-6 Astra leads on AutomationBench (41.4 against 40.0) and Terminal-Bench-Science 0.1 (64.6 against 58.7). At default medium effort, Anthropic reports 54.6 percent on FrontierCode and 52.5 percent on CursorBench, so check the effort level when comparing. Independently, Artificial Analysis is reported at an Intelligence Index of 58.4.
Strengths
Long-running agentic coding and knowledge work, Fable-level results on most tasks at 40 percent of its list price, and a recent June 2026 cutoff. Anthropic says it ties Fable 5.1 for the lowest prompt injection success rate on a Gray Swan benchmark.
Limitations
Four breaking changes affect Opus 5 code: thinking cannot be disabled, forced tool use returns an error, thinking blocks are tied to the model and conversation, and the older computer_20251124 tool is rejected on some platforms. Most scores above are vendor-reported.
Brand-Visibility Implications
Opus 5.5 matters for two reasons. Its June 2026 cutoff brings a further month of coverage into recall, compared with the May cutoff of Opus 5. And its price makes it a likely default for agents built on Claude, including Anthropic's own Claude Duet. Re-run Claude baselines from September 22, and record the model with each result, because Fable, Opus, and Sonnet can all sit behind what users call Claude. See Claude Duet, Claude family lineage, and Claude brand visibility.
How Presenc AI Tracks This Model
Presenc AI monitors brand visibility on Anthropic's Claude 5 series as part of continuous multi-platform AI visibility tracking. We sample Claude Opus 5.5 across representative prompt sets daily, compare against competitor performance on the same prompts, and flag material mention-rate changes so brand teams can respond quickly when AI representation shifts.