curl -X POST 'https://api.openai.com/v1/threads/runs' \
  -H "Authorization: Bearer $OPENAI_API_KEY" \
  -H 'Content-Type: application/json' \
  -d '{
  "assistant_id": "assistant-id"
}'

# POST /threads/runs (OpenAI API)
Base URL: https://api.openai.com/v1
Auth: Authorization; OpenAI API key; required.
Request formats: application/json.
Last verified: 2026-10-20

> Create thread and run

## Critical Gotchas
* The Responses API is the primary interface for new text and tool workflows; Chat Completions remains a separate compatibility API.
* Audio transcription uploads use multipart form data rather than a JSON request body.

## cURL
curl -X POST 'https://api.openai.com/v1/threads/runs' \
  -H "Authorization: Bearer $OPENAI_API_KEY" \
  -H 'Content-Type: application/json' \
  -d '{
  "assistant_id": "assistant-id"
}'

## Parameters
| Name | In | Type | Required | Description |
| :--- | :--- | :--- | :--- | :--- |
| assistant_id | body | string | Yes | The ID of the [assistant](https://developers.openai.com/api/docs/assistants/m... |
| thread | body | object | No | Options to create a new thread. If no thread is provided when running a reque... |
| model | body | string | No | The ID of the [Model](https://developers.openai.com/api/reference/resources/m... |
| instructions | body | string | No | Override the default system message of the assistant. This is useful for modi... |
| tools | body | object[] | No | Override the tools the assistant can use for this run. This is useful for mod... |
| tool_resources | body | object | No | A set of resources that are used by the assistant's tools. The resources are... |
| metadata | body | object | No | Set of 16 key-value pairs that can be attached to an object. This can be usef... |
| temperature | body | number | No | What sampling temperature to use, between 0 and 2. Higher values like 0.8 wil... |
Other params: top_p, stream, max_prompt_tokens, max_completion_tokens, truncation_strategy, tool_choice, parallel_tool_calls, response_format

## Response example
{"id":"string","object":"thread.run"}

---
Need an API key? Get one at https://platform.openai.com/api-keys

POST

POST /threads/runs — OpenAI API

OpenAI API key (required); https://api.openai.com/v1

OpenAI API

Create thread and run

Base URL: https://api.openai.com/v1
Auth: Authorization: Bearer <OPENAI_API_KEY>
Last verified: 2026-10-20 · upstream hash matched

Actions Try in browser→

Agents: curl -H "Accept: text/markdown" this URL
→ 401 tokens · Vary: Accept

Critical gotchas

The Responses API is the primary interface for new text and tool workflows; Chat Completions remains a separate compatibility API.

Audio transcription uploads use multipart form data rather than a JSON request body.

cURL

curl -X POST 'https://api.openai.com/v1/threads/runs' \  -H "Authorization: Bearer $OPENAI_API_KEY" \  -H 'Content-Type: application/json' \  -d '{  "assistant_id": "assistant-id"}'

Parameters

Name	In	Type	Required	Description
assistant_id	body	string	Yes	The ID of the [assistant](https://developers.openai.com/api/docs/assistants/migration) to use to execute this run.
thread	body	object	No	Options to create a new thread. If no thread is provided when running a request, an empty thread will be created.
model	body	string	No	The ID of the [Model](https://developers.openai.com/api/reference/resources/models) 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.
instructions	body	string	No	Override the default system message of the assistant. This is useful for modifying the behavior on a per-run basis.
tools	body	object[]	No	Override the tools the assistant can use for this run. This is useful for modifying the behavior on a per-run basis.
tool_resources	body	object	No	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.
metadata	body	object	No	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.
temperature	body	number	No	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_p	body	number	No	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.
stream	body	boolean	No	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.
max_prompt_tokens	body	integer	No	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.
max_completion_tokens	body	integer	No	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.
truncation_strategy	body	object	No	Controls for how a thread will be truncated prior to the run. Use this to control the initial context window of the run.
tool_choice	body	string	No	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.
parallel_tool_calls	body	boolean	No	Whether to enable [parallel function calling](https://developers.openai.com/api/docs/guides/function-calling#parallel-function-calling) during tool use.
response_format	body	string	No	Specifies the format that the model must output. Compatible with [GPT-4o](https://developers.openai.com/api/docs/models/gpt-4o), [GPT-4 Turbo](https://developers.openai.com/api/docs/models/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](https://developers.openai.com/api/docs/guides/structured-outputs). 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.

Response 200 OK

{
  "id": "string",
  "object": "thread.run",
  "created_at": 0,
  "thread_id": "string",
  "assistant_id": "string",
  "status": "queued",
  "required_action": {
    "type": "submit_tool_outputs",
    "submit_tool_outputs": {
      "tool_calls": [
        {
          "id": "string",
          "type": "function",
          "function": {
            "name": "[recursive or deeply nested schema]",
            "arguments": "[recursive or deeply nested schema]"
          }
        }
      ]
    }
  },
  "last_error": {
    "code": "server_error",
    "message": "string"
  },
  "expires_at": 0,
  "started_at": 0,
  "cancelled_at": 0,
  "failed_at": 0,
  "completed_at": 0,
  "incomplete_details": {
    "reason": "max_completion_tokens"
  },
  "model": "string",
  "instructions": "string",
  "tools": [],
  "metadata": {},
  "usage": {
    "completion_tokens": 0,
    "prompt_tokens": 0,
    "total_tokens": 0
  },
  "temperature": 0,
  "top_p": 0,
  "max_prompt_tokens": 0,
  "max_completion_tokens": 0,
  "truncation_strategy": {
    "type": "auto",
    "last_messages": 0
  },
  "tool_choice": "none",
  "parallel_tool_calls": true,
  "response_format": "auto"
}

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