Upload does not include photo Description/Caption

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Regarding eshmu's upload.py, line 160:
create_body = json.dumps({"albumId":album_id, "newMediaItems":[{"description":"","simpleMediaItem":{"uploadToken":upload_token.content.decode()}}]}, indent=4)

I am trying to upload JPGs to Google Photos with a description. However, when I set the description, this field is entirely ignored by Google Photos:
create_body = json.dumps({"albumId":album_id, "newMediaItems":[{"description":"THIS TEXT IS IGNORED","simpleMediaItem":{"uploadToken":upload_token.content.decode()}}]}, indent=4)

How can this very helpful python script be modified to include the photo captions?
This is the issue to be addressed (but in python):
https://stackoverflow.com/questions/72639040/programmatically-set-a-google-photos-caption

Thank you!