The following call, will result in all components In Nexus being tagged. The reason is that by accident, the URL with was not escaped within quotes "".
This is a very simple mistake to make and could cause Nexus to become unresponsive.
To prevent these type of accidents, if no search criteria is provided then Nexus should not tag. There could be a specific parameter call for tagging all components if someone really wanted to intentionally tag all components in Nexus (seems unlikely).