Create a model response

Creates a model response using the OpenAI-compatible Responses API. The request accepts either a single text input or a list of input items (allowing batched, multi-turn input in one request), and the result can be streamed to the client as it is generated.

Not every provider implements the Responses API. Requests routed to a provider that does not support it return 400 Bad Request with an explanatory error message; use /chat/completions for those providers.

Specific provider to use (default determined by model)

Request body

modelstring required

Model ID used to generate the response.

instructionsstring nullable

A system (or developer) message inserted into the model's context. When used with previous_response_id, instructions from previous responses are not carried over.

max_output_tokensinteger nullable

An upper bound for the number of tokens that can be generated for a response, including visible output tokens and reasoning tokens.

streamboolean

If set to true, the model response data is streamed to the client as it is generated using server-sent events.

temperaturenumber float nullable

What sampling temperature to use, between 0 and 2. Higher values make the output more random; lower values make it more focused.

top_pnumber float nullable

An alternative to sampling with temperature, called nucleus sampling, where the model considers the tokens with top_p probability mass.

previous_response_idstring nullable

The unique ID of the previous response to the model. Use this to create multi-turn conversations.

storeboolean

Whether to store the generated model response for later retrieval.

backgroundboolean

Whether to run the model response in the background. Useful for long-running or batched requests.

parallel_tool_callsboolean

Whether to allow the model to run tool calls in parallel.

metadataobject

Set of up to 16 key-value pairs that can be attached to the object and returned when retrieving the response.

userstring

A stable identifier for your end-users, used to help detect and prevent abuse.

Response

Successful response

idstring required

Unique identifier for this response.

objectstring required

The object type, which is always response.

created_atinteger required

Unix timestamp (in seconds) of when the response was created.

The status of the response generation.

modelstring required

The model used to generate the response.

instructionsstring nullable

The system/developer message used to generate the response.