{ "type": "object", "description": "Represents a file attachment on a message.", "name": "Attachment", "properties": { "id": { "type": "string", "description": "Unique identifier for the attachment" }, "type": { "type": "string", "description": "MIME type of the attachment" }, "url": { "type": "uri", "description": "URL to access the attachment" }, "filename": { "type": "string", "description": "Original filename" }, "size": { "type": "integer", "description": "File size in bytes" } }, "$schema": "https://json-structure.org/draft/2020-12/schema" }