This is only a problem with OpenAI Chat Completions API. With OpenAI Responses API and Anthropic Messages API a tool output can be text, image or file.

Oh, you're right! From the responses API reference:

> For function_call_output / custom_tool_call_output items. The output of the tool call, either a plain string or a

> list of input_text / input_image content parts. With the deepseek-v4-flash-vision-exp model, input_image parts in

> the output are processed as real images; with other models they are replaced with a placeholder text.