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v1

latestOpenAPI 3.1.0MIT2026-07-132429592.7 MB
Assistants

Modifies an assistant.

post/assistants/{assistant_id}

Path parameters

assistant_idstring required

The ID of the assistant to modify.

Request body

reasoning_effort'none' | 'minimal' | 'low' | 'medium' | 'high' | 'xhigh' nullable

Constrains effort on reasoning for reasoning models. Currently supported values are none, minimal, low, medium, high, and xhigh. Reducing reasoning effort can result in faster responses and fewer tokens used on reasoning in a response.

  • gpt-5.1 defaults to none, which does not perform reasoning. The supported reasoning values for gpt-5.1 are none, low, medium, and high. Tool calls are supported for all reasoning values in gpt-5.1.
  • All models before gpt-5.1 default to medium reasoning effort, and do not support none.
  • The gpt-5-pro model defaults to (and only supports) high reasoning effort.
  • xhigh is supported for all models after gpt-5.1-codex-max.
namestring nullable

The name of the assistant. The maximum length is 256 characters.

descriptionstring nullable

The description of the assistant. The maximum length is 512 characters.

instructionsstring nullable

The system instructions that the assistant uses. The maximum length is 256,000 characters.

metadataMetadata nullable

Set of 16 key-value pairs that can be attached to an object. This can be useful for storing additional information about the object in a structured format, and querying for objects via API or the dashboard.

Keys are strings with a maximum length of 64 characters. Values are strings with a maximum length of 512 characters.

temperaturenumber nullable

What sampling temperature to use, between 0 and 2. Higher values like 0.8 will make the output more random, while lower values like 0.2 will make it more focused and deterministic.

top_pnumber nullable

An alternative to sampling with temperature, called nucleus sampling, where the model considers the results of the tokens with top_p probability mass. So 0.1 means only the tokens comprising the top 10% probability mass are considered.

We generally recommend altering this or temperature but not both.

Example request

{
  "temperature": 1,
  "top_p": 1
}

Response

OK

idstring required

The identifier, which can be referenced in API endpoints.

object'assistant' required

The object type, which is always assistant.

created_atinteger required

The Unix timestamp (in seconds) for when the assistant was created.

namestring nullable required

The name of the assistant. The maximum length is 256 characters.

descriptionstring nullable required

The description of the assistant. The maximum length is 512 characters.

modelstring required

ID of the model to use. You can use the List models API to see all of your available models, or see our Model overview for descriptions of them.

instructionsstring nullable required

The system instructions that the assistant uses. The maximum length is 256,000 characters.

metadataMetadata nullable required

Set of 16 key-value pairs that can be attached to an object. This can be useful for storing additional information about the object in a structured format, and querying for objects via API or the dashboard.

Keys are strings with a maximum length of 64 characters. Values are strings with a maximum length of 512 characters.

temperaturenumber nullable

What sampling temperature to use, between 0 and 2. Higher values like 0.8 will make the output more random, while lower values like 0.2 will make it more focused and deterministic.

top_pnumber nullable

An alternative to sampling with temperature, called nucleus sampling, where the model considers the results of the tokens with top_p probability mass. So 0.1 means only the tokens comprising the top 10% probability mass are considered.

We generally recommend altering this or temperature but not both.

Example response

{
  "temperature": 1,
  "top_p": 1
}