Fix: Propagate isError flag from ScreenAsMcpTool to ToolsCall result

@@ -500,7 +500,7 @@
                     
                     result.result = [
                         content: content,
-                        isError: false
+                        isError: serviceResult?.result?.isError ?: false
                     ]
                     return
                 }
@@ -1596,4 +1596,4 @@ ${truncatedOutput}
 
     <!-- NOTE: handle#McpRequest service removed - functionality moved to screen/webapp.xml for unified handling -->
 
-</services>
\ No newline at end of file
+</services>