Return type standardization

tools/read_image.py

@@ -25,6 +25,6 @@ async def handle(args: Dict[str, Any]):
     
     try:
         data = base64.b64encode(path.read_bytes()).decode("utf-8")
-        return {"type": "image", "data": data, "mimeType": mime_type}
+        return [{"type": "image", "data": data, "mimeType": mime_type}]
     except Exception as e:
         raise ToolError(f"Error reading image: {str(e)}")