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Overview Models Agents Tools Audio & voice Production API reference

Create thread and run

POST
/threads/runs

Create a thread and run it in one request.

Create thread and run

curl https://api.openai.com/v1/threads/runs \
  -H "Authorization: Bearer $OPENAI_API_KEY" \
  -H "Content-Type: application/json" \
  -H "OpenAI-Beta: assistants=v2" \
  -d '{
      "assistant_id": "asst_abc123",
      "thread": {
        "messages": [
          {"role": "user", "content": "Explain deep learning to a 5 year old."}
        ]
      }
    }'
Response example
{
  "id": "run_abc123",
  "object": "thread.run",
  "created_at": 1699076792,
  "assistant_id": "asst_abc123",
  "thread_id": "thread_abc123",
  "status": "queued",
  "started_at": null,
  "expires_at": 1699077392,
  "cancelled_at": null,
  "failed_at": null,
  "completed_at": null,
  "required_action": null,
  "last_error": null,
  "model": "gpt-4.1",
  "instructions": "You are a helpful assistant.",
  "tools": [],
  "tool_resources": {},
  "metadata": {},
  "temperature": 1.0,
  "top_p": 1.0,
  "max_completion_tokens": null,
  "max_prompt_tokens": null,
  "truncation_strategy": {
    "type": "auto",
    "last_messages": null
  },
  "incomplete_details": null,
  "usage": null,
  "response_format": "auto",
  "tool_choice": "auto",
  "parallel_tool_calls": true
}
Body Parameters
JSON
assistant_id: string

The ID of the assistant to use to execute this run.

instructions: optional string or null

Override the default system message of the assistant. This is useful for modifying the behavior on a per-run basis.

max_completion_tokens: optional integer or null

The maximum number of completion tokens that may be used over the course of the run. The run will make a best effort to use only the number of completion tokens specified, across multiple turns of the run. If the run exceeds the number of completion tokens specified, the run will end with status incomplete. See incomplete_details for more info.

minimum256
max_prompt_tokens: optional integer or null

The maximum number of prompt tokens that may be used over the course of the run. The run will make a best effort to use only the number of prompt tokens specified, across multiple turns of the run. If the run exceeds the number of prompt tokens specified, the run will end with status incomplete. See incomplete_details for more info.

minimum256
metadata: optional Metadata or null

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.

model: optional string or "gpt-5" or "gpt-5-mini" or "gpt-5-nano" or 35 more or null

The ID of the Model to be used to execute this run. If a value is provided here, it will override the model associated with the assistant. If not, the model associated with the assistant will be used.

One of the following:
string
"gpt-5" or "gpt-5-mini" or "gpt-5-nano" or 35 more

The ID of the Model to be used to execute this run. If a value is provided here, it will override the model associated with the assistant. If not, the model associated with the assistant will be used.

One of the following:
"gpt-4.1"
"gpt-4.1-mini"
"gpt-4.1-nano"
"gpt-4.1-2025-04-14"
"gpt-4.1-mini-2025-04-14"
"gpt-4.1-nano-2025-04-14"
"gpt-4o"
"gpt-4o-2024-11-20"
"gpt-4o-2024-08-06"
"gpt-4o-2024-05-13"
"gpt-4o-mini"
"gpt-4o-mini-2024-07-18"
"gpt-4.5-preview"
"gpt-4.5-preview-2025-02-27"
"gpt-4-turbo"
"gpt-4-turbo-2024-04-09"
"gpt-4-0125-preview"
"gpt-4-turbo-preview"
"gpt-4-1106-preview"
"gpt-4-vision-preview"
"gpt-4"
"gpt-4-0314"
"gpt-4-0613"
"gpt-4-32k"
"gpt-4-32k-0314"
"gpt-4-32k-0613"
"gpt-3.5-turbo"
"gpt-3.5-turbo-16k"
"gpt-3.5-turbo-0613"
"gpt-3.5-turbo-1106"
"gpt-3.5-turbo-0125"
"gpt-3.5-turbo-16k-0613"
"gpt-5"

Deprecated. Announced shutdown date: 2026-12-11. See https://developers.openai.com/api/docs/deprecations for details and recommended replacements.

"gpt-5-mini"

Deprecated. Announced shutdown date: 2026-12-11. See https://developers.openai.com/api/docs/deprecations for details and recommended replacements.

"gpt-5-nano"

Deprecated. Announced shutdown date: 2026-12-11. See https://developers.openai.com/api/docs/deprecations for details and recommended replacements.

"gpt-5-2025-08-07"

Deprecated. Announced shutdown date: 2026-12-11. See https://developers.openai.com/api/docs/deprecations for details and recommended replacements.

"gpt-5-mini-2025-08-07"

Deprecated. Announced shutdown date: 2026-12-11. See https://developers.openai.com/api/docs/deprecations for details and recommended replacements.

"gpt-5-nano-2025-08-07"

Deprecated. Announced shutdown date: 2026-12-11. See https://developers.openai.com/api/docs/deprecations for details and recommended replacements.

parallel_tool_calls: optional boolean (default: true)

Whether to enable parallel function calling during tool use.

response_format: optional AssistantResponseFormatOption or null

Specifies the format that the model must output. Compatible with GPT-4o, GPT-4 Turbo, and all GPT-3.5 Turbo models since gpt-3.5-turbo-1106.

Setting to { "type": "json_schema", "json_schema": {...} } enables Structured Outputs which ensures the model will match your supplied JSON schema. Learn more in the Structured Outputs guide.

Setting to { "type": "json_object" } enables JSON mode, which ensures the message the model generates is valid JSON.

Important: when using JSON mode, you must also instruct the model to produce JSON yourself via a system or user message. Without this, the model may generate an unending stream of whitespace until the generation reaches the token limit, resulting in a long-running and seemingly “stuck” request. Also note that the message content may be partially cut off if finish_reason="length", which indicates the generation exceeded max_tokens or the conversation exceeded the max context length.

One of the following:
"auto"

auto is the default value

ResponseFormatText object { type }

Default response format. Used to generate text responses.

type: "text"

The type of response format being defined. Always text.

ResponseFormatJSONObject object { type }

JSON object response format. An older method of generating JSON responses. Using json_schema is recommended for models that support it. Note that the model will not generate JSON without a system or user message instructing it to do so.

type: "json_object"

The type of response format being defined. Always json_object.

ResponseFormatJSONSchema object { json_schema, type }

JSON Schema response format. Used to generate structured JSON responses. Learn more about Structured Outputs.

json_schema: object { name, description, schema, strict }

Structured Outputs configuration options, including a JSON Schema.

name: string

The name of the response format. Must be a-z, A-Z, 0-9, or contain underscores and dashes, with a maximum length of 64.

description: optional string

A description of what the response format is for, used by the model to determine how to respond in the format.

schema: optional map[unknown]

The schema for the response format, described as a JSON Schema object. Learn how to build JSON schemas here.

strict: optional boolean or null (default: false)

Whether to enable strict schema adherence when generating the output. If set to true, the model will always follow the exact schema defined in the schema field. Only a subset of JSON Schema is supported when strict is true. To learn more, read the Structured Outputs guide.

type: "json_schema"

The type of response format being defined. Always json_schema.

stream: optional boolean or null

If true, returns a stream of events that happen during the Run as server-sent events, terminating when the Run enters a terminal state with a data: [DONE] message.

temperature: optional number or null (default: 1)

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.

minimum0
maximum2
thread: optional object { messages, metadata, tool_resources }

Options to create a new thread. If no thread is provided when running a request, an empty thread will be created.

messages: optional array of object { content, role, attachments, metadata }

A list of messages to start the thread with.

content: string or array of ImageFileContentBlock { image_file, type } or ImageURLContentBlock { image_url, type } or TextContentBlockParam { text, type }

The text contents of the message.

One of the following:
TextContent = string

The text contents of the message.

ArrayOfContentParts = array of ImageFileContentBlock { image_file, type } or ImageURLContentBlock { image_url, type } or TextContentBlockParam { text, type }

An array of content parts with a defined type, each can be of type text or images can be passed with image_url or image_file. Image types are only supported on Vision-compatible models.

minItems1
One of the following:
ImageFileContentBlock object { image_file, type }

References an image File in the content of a message.

image_file: ImageFile { file_id, detail }
file_id: string

The File ID of the image in the message content. Set purpose="vision" when uploading the File if you need to later display the file content.

detail: optional "auto" or "low" or "high" (default: "auto")

Specifies the detail level of the image if specified by the user. low uses fewer tokens, you can opt in to high resolution using high.

One of the following:
"auto"
"low"
"high"
type: "image_file"

Always image_file.

ImageURLContentBlock object { image_url, type }

References an image URL in the content of a message.

image_url: ImageURL { url, detail }
url: string

The external URL of the image, must be a supported image types: jpeg, jpg, png, gif, webp.

formaturi
detail: optional "auto" or "low" or "high" (default: "auto")

Specifies the detail level of the image. low uses fewer tokens, you can opt in to high resolution using high. Default value is auto

One of the following:
"auto"
"low"
"high"
type: "image_url"

The type of the content part.

TextContentBlockParam object { text, type }

The text content that is part of a message.

text: string

Text content to be sent to the model

type: "text"

Always text.

role: "user" or "assistant"

The role of the entity that is creating the message. Allowed values include:

  • user: Indicates the message is sent by an actual user and should be used in most cases to represent user-generated messages.
  • assistant: Indicates the message is generated by the assistant. Use this value to insert messages from the assistant into the conversation.
One of the following:
"user"
"assistant"
attachments: optional array of object { file_id, tools } or null

A list of files attached to the message, and the tools they should be added to.

file_id: optional string

The ID of the file to attach to the message.

tools: optional array of CodeInterpreterTool { type } or FileSearchTool { type }

The tools to add this file to.

One of the following:
CodeInterpreterTool object { type }
type: "code_interpreter"

The type of tool being defined: code_interpreter

FileSearchTool object { type }
type: "file_search"

The type of tool being defined: file_search

metadata: optional Metadata or null

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.

metadata: optional Metadata or null

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.

tool_resources: optional object { code_interpreter, file_search } or null

A set of resources that are made available to the assistant’s tools in this thread. The resources are specific to the type of tool. For example, the code_interpreter tool requires a list of file IDs, while the file_search tool requires a list of vector store IDs.

code_interpreter: optional object { file_ids }
file_ids: optional array of string (default: [])

A list of file IDs made available to the code_interpreter tool. There can be a maximum of 20 files associated with the tool.

maxItems20
file_search: optional object { vector_store_ids, vector_stores }
vector_store_ids: optional array of string

The vector store attached to this thread. There can be a maximum of 1 vector store attached to the thread.

maxItems1
vector_stores: optional array of object { chunking_strategy, file_ids, metadata }

A helper to create a vector store with file_ids and attach it to this thread. There can be a maximum of 1 vector store attached to the thread.

maxItems1
chunking_strategy: optional Auto { type } or Static { static, type }

The chunking strategy used to chunk the file(s). If not set, will use the auto strategy.

One of the following:
Auto object { type }

The default strategy. This strategy currently uses a max_chunk_size_tokens of 800 and chunk_overlap_tokens of 400.

type: "auto"

Always auto.

Static object { static, type }
static: object { chunk_overlap_tokens, max_chunk_size_tokens }
chunk_overlap_tokens: integer

The number of tokens that overlap between chunks. The default value is 400.

Note that the overlap must not exceed half of max_chunk_size_tokens.

max_chunk_size_tokens: integer

The maximum number of tokens in each chunk. The default value is 800. The minimum value is 100 and the maximum value is 4096.

minimum100
maximum4096
type: "static"

Always static.

file_ids: optional array of string

A list of file IDs to add to the vector store. For vector stores created before Nov 2025, there can be a maximum of 10,000 files in a vector store. For vector stores created starting in Nov 2025, the limit is 100,000,000 files.

maxItems100000000
metadata: optional Metadata or null

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.

tool_choice: optional AssistantToolChoiceOption or null

Controls which (if any) tool is called by the model. none means the model will not call any tools and instead generates a message. auto is the default value and means the model can pick between generating a message or calling one or more tools. required means the model must call one or more tools before responding to the user. Specifying a particular tool like {"type": "file_search"} or {"type": "function", "function": {"name": "my_function"}} forces the model to call that tool.

One of the following:
"none" or "auto" or "required"

none means the model will not call any tools and instead generates a message. auto means the model can pick between generating a message or calling one or more tools. required means the model must call one or more tools before responding to the user.

One of the following:
"none"
"auto"
"required"
AssistantToolChoice object { type, function }

Specifies a tool the model should use. Use to force the model to call a specific tool.

type: "function" or "code_interpreter" or "file_search"

The type of the tool. If type is function, the function name must be set

One of the following:
"function"
"code_interpreter"
"file_search"
function: optional AssistantToolChoiceFunction { name }
name: string

The name of the function to call.

tool_resources: optional object { code_interpreter, file_search } or null

A set of resources that are used by the assistant’s tools. The resources are specific to the type of tool. For example, the code_interpreter tool requires a list of file IDs, while the file_search tool requires a list of vector store IDs.

code_interpreter: optional object { file_ids }
file_ids: optional array of string (default: [])

A list of file IDs made available to the code_interpreter tool. There can be a maximum of 20 files associated with the tool.

maxItems20
file_search: optional object { vector_store_ids }
vector_store_ids: optional array of string

The ID of the vector store attached to this assistant. There can be a maximum of 1 vector store attached to the assistant.

maxItems1
tools: optional array of CodeInterpreterTool { type } or FileSearchTool { type, file_search } or FunctionTool { function, type } or null

Override the tools the assistant can use for this run. This is useful for modifying the behavior on a per-run basis.

maxItems20
One of the following:
CodeInterpreterTool object { type }
type: "code_interpreter"

The type of tool being defined: code_interpreter

FileSearchTool object { type, file_search }
type: "file_search"

The type of tool being defined: file_search

file_search: optional object { max_num_results, ranking_options }

Overrides for the file search tool.

max_num_results: optional integer

The maximum number of results the file search tool should output. The default is 20 for gpt-4* models and 5 for gpt-3.5-turbo. This number should be between 1 and 50 inclusive.

Note that the file search tool may output fewer than max_num_results results. See the file search tool documentation for more information.

minimum1
maximum50
ranking_options: optional object { score_threshold, ranker }

The ranking options for the file search. If not specified, the file search tool will use the auto ranker and a score_threshold of 0.

See the file search tool documentation for more information.

score_threshold: number

The score threshold for the file search. All values must be a floating point number between 0 and 1.

minimum0
maximum1
ranker: optional "auto" or "default_2024_08_21"

The ranker to use for the file search. If not specified will use the auto ranker.

One of the following:
"auto"
"default_2024_08_21"
FunctionTool object { function, type }
function: FunctionDefinition { name, description, parameters, strict }
name: string

The name of the function to be called. Must be a-z, A-Z, 0-9, or contain underscores and dashes, with a maximum length of 64.

description: optional string

A description of what the function does, used by the model to choose when and how to call the function.

parameters: optional FunctionParameters

The parameters the functions accepts, described as a JSON Schema object. See the guide for examples, and the JSON Schema reference for documentation about the format.

Omitting parameters defines a function with an empty parameter list.

strict: optional boolean or null (default: false)

Whether to enable strict schema adherence when generating the function call. If set to true, the model will follow the exact schema defined in the parameters field. Only a subset of JSON Schema is supported when strict is true. Learn more about Structured Outputs in the function calling guide.

type: "function"

The type of tool being defined: function

top_p: optional number or null (default: 1)

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.

minimum0
maximum1
truncation_strategy: optional object { type, last_messages } or null

Controls for how a thread will be truncated prior to the run. Use this to control the initial context window of the run.

type: "auto" or "last_messages"

The truncation strategy to use for the thread. The default is auto. If set to last_messages, the thread will be truncated to the n most recent messages in the thread. When set to auto, messages in the middle of the thread will be dropped to fit the context length of the model, max_prompt_tokens.

One of the following:
"auto"
"last_messages"
last_messages: optional integer or null

The number of most recent messages from the thread when constructing the context for the run.

minimum1
Returns
Run object { id, assistant_id, cancelled_at, 24 more }

Represents an execution run on a thread.

id: string

The identifier, which can be referenced in API endpoints.

assistant_id: string

The ID of the assistant used for execution of this run.

cancelled_at: integer or null

The Unix timestamp (in seconds) for when the run was cancelled.

formatunixtime
completed_at: integer or null

The Unix timestamp (in seconds) for when the run was completed.

formatunixtime
created_at: integer

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

formatunixtime
expires_at: integer or null

The Unix timestamp (in seconds) for when the run will expire.

formatunixtime
failed_at: integer or null

The Unix timestamp (in seconds) for when the run failed.

formatunixtime
incomplete_details: object { reason } or null

Details on why the run is incomplete. Will be null if the run is not incomplete.

reason: optional "max_completion_tokens" or "max_prompt_tokens"

The reason why the run is incomplete. This will point to which specific token limit was reached over the course of the run.

One of the following:
"max_completion_tokens"
"max_prompt_tokens"
instructions: string

The instructions that the assistant used for this run.

last_error: object { code, message } or null

The last error associated with this run. Will be null if there are no errors.

code: "server_error" or "rate_limit_exceeded" or "invalid_prompt"

One of server_error, rate_limit_exceeded, or invalid_prompt.

One of the following:
"server_error"
"rate_limit_exceeded"
"invalid_prompt"
message: string

A human-readable description of the error.

max_completion_tokens: integer or null

The maximum number of completion tokens specified to have been used over the course of the run.

minimum256
max_prompt_tokens: integer or null

The maximum number of prompt tokens specified to have been used over the course of the run.

minimum256
metadata: Metadata or null

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.

model: string

The model that the assistant used for this run.

object: "thread.run"

The object type, which is always thread.run.

parallel_tool_calls: boolean (default: true)

Whether to enable parallel function calling during tool use.

required_action: object { submit_tool_outputs, type } or null

Details on the action required to continue the run. Will be null if no action is required.

submit_tool_outputs: object { tool_calls }

Details on the tool outputs needed for this run to continue.

tool_calls: array of RequiredActionFunctionToolCall { id, function, type }

A list of the relevant tool calls.

id: string

The ID of the tool call. This ID must be referenced when you submit the tool outputs in using the Submit tool outputs to run endpoint.

function: object { arguments, name }

The function definition.

arguments: string

The arguments that the model expects you to pass to the function.

name: string

The name of the function.

type: "function"

The type of tool call the output is required for. For now, this is always function.

type: "submit_tool_outputs"

For now, this is always submit_tool_outputs.

response_format: AssistantResponseFormatOption or null

Specifies the format that the model must output. Compatible with GPT-4o, GPT-4 Turbo, and all GPT-3.5 Turbo models since gpt-3.5-turbo-1106.

Setting to { "type": "json_schema", "json_schema": {...} } enables Structured Outputs which ensures the model will match your supplied JSON schema. Learn more in the Structured Outputs guide.

Setting to { "type": "json_object" } enables JSON mode, which ensures the message the model generates is valid JSON.

Important: when using JSON mode, you must also instruct the model to produce JSON yourself via a system or user message. Without this, the model may generate an unending stream of whitespace until the generation reaches the token limit, resulting in a long-running and seemingly “stuck” request. Also note that the message content may be partially cut off if finish_reason="length", which indicates the generation exceeded max_tokens or the conversation exceeded the max context length.

One of the following:
"auto"

auto is the default value

ResponseFormatText object { type }

Default response format. Used to generate text responses.

type: "text"

The type of response format being defined. Always text.

ResponseFormatJSONObject object { type }

JSON object response format. An older method of generating JSON responses. Using json_schema is recommended for models that support it. Note that the model will not generate JSON without a system or user message instructing it to do so.

type: "json_object"

The type of response format being defined. Always json_object.

ResponseFormatJSONSchema object { json_schema, type }

JSON Schema response format. Used to generate structured JSON responses. Learn more about Structured Outputs.

json_schema: object { name, description, schema, strict }

Structured Outputs configuration options, including a JSON Schema.

name: string

The name of the response format. Must be a-z, A-Z, 0-9, or contain underscores and dashes, with a maximum length of 64.

description: optional string

A description of what the response format is for, used by the model to determine how to respond in the format.

schema: optional map[unknown]

The schema for the response format, described as a JSON Schema object. Learn how to build JSON schemas here.

strict: optional boolean or null (default: false)

Whether to enable strict schema adherence when generating the output. If set to true, the model will always follow the exact schema defined in the schema field. Only a subset of JSON Schema is supported when strict is true. To learn more, read the Structured Outputs guide.

type: "json_schema"

The type of response format being defined. Always json_schema.

started_at: integer or null

The Unix timestamp (in seconds) for when the run was started.

formatunixtime
status: "queued" or "in_progress" or "requires_action" or 6 more

The status of the run, which can be either queued, in_progress, requires_action, cancelling, cancelled, failed, completed, incomplete, or expired.

One of the following:
"queued"
"in_progress"
"requires_action"
"cancelling"
"cancelled"
"failed"
"completed"
"incomplete"
"expired"
thread_id: string

The ID of the thread that was executed on as a part of this run.

tool_choice: AssistantToolChoiceOption or null

Controls which (if any) tool is called by the model. none means the model will not call any tools and instead generates a message. auto is the default value and means the model can pick between generating a message or calling one or more tools. required means the model must call one or more tools before responding to the user. Specifying a particular tool like {"type": "file_search"} or {"type": "function", "function": {"name": "my_function"}} forces the model to call that tool.

One of the following:
"none" or "auto" or "required"

none means the model will not call any tools and instead generates a message. auto means the model can pick between generating a message or calling one or more tools. required means the model must call one or more tools before responding to the user.

One of the following:
"none"
"auto"
"required"
AssistantToolChoice object { type, function }

Specifies a tool the model should use. Use to force the model to call a specific tool.

type: "function" or "code_interpreter" or "file_search"

The type of the tool. If type is function, the function name must be set

One of the following:
"function"
"code_interpreter"
"file_search"
function: optional AssistantToolChoiceFunction { name }
name: string

The name of the function to call.

tools: array of CodeInterpreterTool { type } or FileSearchTool { type, file_search } or FunctionTool { function, type } (default: [])

The list of tools that the assistant used for this run.

maxItems20
One of the following:
CodeInterpreterTool object { type }
type: "code_interpreter"

The type of tool being defined: code_interpreter

FileSearchTool object { type, file_search }
type: "file_search"

The type of tool being defined: file_search

file_search: optional object { max_num_results, ranking_options }

Overrides for the file search tool.

max_num_results: optional integer

The maximum number of results the file search tool should output. The default is 20 for gpt-4* models and 5 for gpt-3.5-turbo. This number should be between 1 and 50 inclusive.

Note that the file search tool may output fewer than max_num_results results. See the file search tool documentation for more information.

minimum1
maximum50
ranking_options: optional object { score_threshold, ranker }

The ranking options for the file search. If not specified, the file search tool will use the auto ranker and a score_threshold of 0.

See the file search tool documentation for more information.

score_threshold: number

The score threshold for the file search. All values must be a floating point number between 0 and 1.

minimum0
maximum1
ranker: optional "auto" or "default_2024_08_21"

The ranker to use for the file search. If not specified will use the auto ranker.

One of the following:
"auto"
"default_2024_08_21"
FunctionTool object { function, type }
function: FunctionDefinition { name, description, parameters, strict }
name: string

The name of the function to be called. Must be a-z, A-Z, 0-9, or contain underscores and dashes, with a maximum length of 64.

description: optional string

A description of what the function does, used by the model to choose when and how to call the function.

parameters: optional FunctionParameters

The parameters the functions accepts, described as a JSON Schema object. See the guide for examples, and the JSON Schema reference for documentation about the format.

Omitting parameters defines a function with an empty parameter list.

strict: optional boolean or null (default: false)

Whether to enable strict schema adherence when generating the function call. If set to true, the model will follow the exact schema defined in the parameters field. Only a subset of JSON Schema is supported when strict is true. Learn more about Structured Outputs in the function calling guide.

type: "function"

The type of tool being defined: function

truncation_strategy: object { type, last_messages } or null

Controls for how a thread will be truncated prior to the run. Use this to control the initial context window of the run.

type: "auto" or "last_messages"

The truncation strategy to use for the thread. The default is auto. If set to last_messages, the thread will be truncated to the n most recent messages in the thread. When set to auto, messages in the middle of the thread will be dropped to fit the context length of the model, max_prompt_tokens.

One of the following:
"auto"
"last_messages"
last_messages: optional integer or null

The number of most recent messages from the thread when constructing the context for the run.

minimum1
usage: object { completion_tokens, prompt_tokens, total_tokens } or null

Usage statistics related to the run. This value will be null if the run is not in a terminal state (i.e. in_progress, queued, etc.).

completion_tokens: integer

Number of completion tokens used over the course of the run.

prompt_tokens: integer

Number of prompt tokens used over the course of the run.

total_tokens: integer

Total number of tokens used (prompt + completion).

temperature: optional number or null

The sampling temperature used for this run. If not set, defaults to 1.

top_p: optional number or null

The nucleus sampling value used for this run. If not set, defaults to 1.

Returns Examples
Response example
{
  "id": "run_abc123",
  "object": "thread.run",
  "created_at": 1699076792,
  "assistant_id": "asst_abc123",
  "thread_id": "thread_abc123",
  "status": "queued",
  "started_at": null,
  "expires_at": 1699077392,
  "cancelled_at": null,
  "failed_at": null,
  "completed_at": null,
  "required_action": null,
  "last_error": null,
  "model": "gpt-4.1",
  "instructions": "You are a helpful assistant.",
  "tools": [],
  "tool_resources": {},
  "metadata": {},
  "temperature": 1.0,
  "top_p": 1.0,
  "max_completion_tokens": null,
  "max_prompt_tokens": null,
  "truncation_strategy": {
    "type": "auto",
    "last_messages": null
  },
  "incomplete_details": null,
  "usage": null,
  "response_format": "auto",
  "tool_choice": "auto",
  "parallel_tool_calls": true
}