A list of File IDs that the message should use. There can be a maximum of 10 files attached to a message. Useful for tools like retrieval and code interpreter that can access and use files.
Set of 16 key-value pairs that can be attached to a message. This can be useful for storing additional information about the message in a structured format. Keys can be a maximum of 64 characters long, and values can be a maximum of 512 characters long.