This entry is a serving variant of Anthropic: Claude Opus 4.1. A variant shares its base model's tokenizer by construction, so the measurement lives on the base record and this page inherits it.
| Signal | Result | Reference |
|---|---|---|
| Tokenizer signature | Not measured | – |
| API surface | No other entry shares this exact contract | api_bccca5cb |
| Context and output | 200,000 context · 32,000 max output | declared |
| Reasoning contract | Optional | declared |
| Serving providers observed | None recorded yet | – |
Claude Opus 4.1 is an updated version of Anthropic’s flagship model, offering improved performance in coding, reasoning, and agentic tasks. It achieves 74.5% on SWE-bench Verified and shows notable gains...
Supported parameters
include_reasoningmax_tokensreasoningresponse_formatstopstructured_outputstemperaturetool_choicetools
defaults: {"temperature":null,"top_p":null,"top_k":null,"frequency_penalty":null,"presence_penalty":null,"repetition_penalty":null}
Cite this page as the evidence record for Anthropic: Claude Opus 4.1 (batch): the URL is stable, measurements are dated, and revisions append to the history above. Method: tokenizer fingerprinting, v1, 50 strings. The raw data behind every figure is on the data page.
