`ImageGenerationCall` does not have all fields that API returns

[Shulyaka]

Confirm this is an issue with the Python library and not an underlying OpenAI API

• This is an issue with the Python library

Describe the bug

I am using the image generation built-in tool with responses API. In result, I receive the following output item:

ImageGenerationCall(
    id='ig_68a8b19841a481908236d1f910688218064c9e93b52be280',
    result='<base_64 string>',
    status='completed',
    type='image_generation_call',
    background='transparent',
    output_format='png',
    quality='high',
    revised_prompt='A high-quality illustration of a dog on a transparent background. The dog should be depicted in a playful stance, with a shiny coat and expressive eyes. The style should be realistic and detailed, capturing the fur texture and features of the dog.',
    size='1024x1024',
)

While in openai.types.responses.response_output_item only the following fields are defined:

class ImageGenerationCall(BaseModel):
    id: str
    """The unique ID of the image generation call."""

    result: Optional[str] = None
    """The generated image encoded in base64."""

    status: Literal["in_progress", "completed", "generating", "failed"]
    """The status of the image generation call."""

    type: Literal["image_generation_call"]
    """The type of the image generation call. Always `image_generation_call`."""

The background, output_format, quality, revised_prompt, and size are missing.

To Reproduce

from openai import OpenAI

client = OpenAI() 

response = client.responses.create(
    model="gpt-5",
    input="Generate a high quality square image of a dog on transparent background",
    tools=[{"type": "image_generation"}],
)

print(response)

Code snippets

OS

Fedora

Python version

3.13.5

Library version

openai==1.99.5