Text, image, or audio input to the model, used to generate a response. Can also contain previous assistant responses.
A text input to the model.
An image input to the model. Learn about image inputs.
The detail level of the image to be sent to the model. One of high, low, auto, or original. Defaults to auto.
The URL of the image to be sent to the model. A fully qualified URL or base64 encoded image in a data URL.
A file input to the model.
The detail level of the file to be sent to the model. Use auto to let the system select the detail level; for GPT-5.6 and later models, auto uses high-quality rendering, which may increase input token usage. Use low for lower-cost rendering, or high to render the file at higher quality. Defaults to auto.
The role of the message input. One of user, assistant, system, or
developer.
Labels an assistant message as intermediate commentary (commentary) or the final answer (final_answer).
For models like gpt-5.3-codex and beyond, when sending follow-up requests, preserve and resend
phase on all assistant messages — dropping it can degrade performance. Not used for user messages.