openai/gpt-5-nano

Fastest, most cost-effective GPT-5 model from OpenAI

Capabilities

Reference ImagesSystem Prompt

Cost

Community model (estimated from hardware time)

Input Parameters

Name	Type	Description	Default	Constraints
`image_input`	array	List of images to send to the model		—
`max_completion_tokens`	integer	Maximum number of completion tokens to generate. For higher reasoning efforts you may need to increase your max_completion_tokens to avoid empty responses (where all the tokens are used on reasoning).	`—`	—
`messages`	array	A JSON string representing a list of messages. For example: [{"role": "user", "content": "Hello, how are you?"}]. If provided, prompt and system_prompt are ignored.		—
`prompt`	string	The prompt to send to the model. Do not use if using messages.	`—`	—
`reasoning_effort`	string	Constrains effort on reasoning for GPT-5 models. Currently supported values are minimal, low, medium, and high. The minimal value gets answers back faster without extensive reasoning first. Reducing reasoning effort can result in faster responses and fewer tokens used on reasoning in a response. For higher reasoning efforts you may need to increase your max_completion_tokens to avoid empty responses (where all the tokens are used on reasoning).	`"minimal"`	minimallowmediumhigh
`system_prompt`	string	System prompt to set the assistant's behavior	`—`	—
`verbosity`	string	Constrains the verbosity of the model's response. Lower values will result in more concise responses, while higher values will result in more verbose responses. Currently supported values are low, medium, and high. GPT-5 supports this parameter to help control whether answers are short and to the point or long and comprehensive.	`"medium"`	lowmediumhigh

image_inputarray

List of images to send to the model

Default:

max_completion_tokensinteger

Maximum number of completion tokens to generate. For higher reasoning efforts you may need to increase your max_completion_tokens to avoid empty responses (where all the tokens are used on reasoning).

messagesarray

A JSON string representing a list of messages. For example: [{"role": "user", "content": "Hello, how are you?"}]. If provided, prompt and system_prompt are ignored.

Default:

promptstring

The prompt to send to the model. Do not use if using messages.

reasoning_effortstring

Constrains effort on reasoning for GPT-5 models. Currently supported values are minimal, low, medium, and high. The minimal value gets answers back faster without extensive reasoning first. Reducing reasoning effort can result in faster responses and fewer tokens used on reasoning in a response. For higher reasoning efforts you may need to increase your max_completion_tokens to avoid empty responses (where all the tokens are used on reasoning).

Default: "minimal"

minimallowmediumhigh

system_promptstring

System prompt to set the assistant's behavior

verbositystring

Constrains the verbosity of the model's response. Lower values will result in more concise responses, while higher values will result in more verbose responses. Currently supported values are low, medium, and high. GPT-5 supports this parameter to help control whether answers are short and to the point or long and comprehensive.

Default: "medium"

lowmediumhigh

Version: 034fc01c1d16Updated: 7/25/20264.8M runs