A vision-enabled Chat Completions request must represent the user message as a multimodal content array. One item contains the prompt with " type " : " text " , while another contains the image reference with " type " : " image_url " and an image_url.url property:
" content " : [
{ " type " : " text " , " text " : " Analyze this image. " },
{ " type " : " image_url " , " image_url " : { " url " : " < image-url > " }}
]
This structure explicitly identifies each modality, allowing the deployed model to route the text and image through the appropriate processing paths. A URL embedded in an ordinary string remains text and is not interpreted as visual input. Microsoft’s documented Chat Completions schema shows the text and image objects inside the user message’s content array.
Request metadata does not define model input, and a system message should contain behavioral instructions rather than the user’s image attachment. Base64 images are supported, but the encoded value must be formatted as a data URL and supplied through the structured image item—not inserted into a plain content string.
Study Guide alignment: deploy and consume multimodal models, integrate generative workflows into applications, and design multimodal-understanding workflows .
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