Claude Opus 4.1

Anthropic Generally Available

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...

Context
200K
tokens
Input
$15.00
per MTok
Output
$75.00
per MTok

About

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...

Modalities

Input
Vision Text file
Output
Text

Code Examples

curl https://api.anthropic.com/v1/messages \
  -H "x-api-key: $ANTHROPIC_API_KEY" \
  -H "anthropic-version: 2023-06-01" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "claude-opus-4.1",
    "max_tokens": 1024,
    "messages": [
      { "role": "user", "content": "Explain quantum entanglement in one sentence." }
    ]
  }'

API Parameters

Name Type Description
include_reasoning boolean Include the model's internal reasoning trace in the response.
max_tokens deprecated integer Deprecated. Use max_completion_tokens.
reasoning object Configuration for extended-thinking / reasoning mode.
response_format one of Constrain output to a JSON schema or an enum (structured outputs).
stop array Up to 4 sequences where the API will stop generating tokens.
structured_outputs boolean Enable JSON-schema-constrained output.
temperature number Sampling temperature; higher values produce more random output. 0 is deterministic.
tool_choice one of Controls which (if any) tool is called: "none", "auto", "required", or a specific tool.
tools array List of tools (functions) the model may call.
top_k integer Limit sampling to the top-k most likely tokens at each step.
top_p number Nucleus sampling: consider only tokens whose cumulative probability ≥ top_p.

Standard OpenAI-compatible parameters. Consult the provider docs for model-specific behaviour.