GPT-5.1-Codex-Max is OpenAI’s latest agentic coding model, designed for long-running, high-context software development tasks. It is based on an updated version of the 5.1 reasoning stack and trained on agentic...
Specifications
- Provider
- OpenAI
- Type
- Vendor / proprietary
- Modality
- text+image->text
- Context window
- 400K
- Released
- December 4, 2025
Capabilities
Input: textInput: imageOutput: textReasoning requiredConfigurable reasoning effort
Strengths
include_reasoningmax_completion_tokensreasoningreasoning_effortresponse_formatseedstructured_outputstool_choicetools
