I am not 100% positive, but I am 90% sure that a tip is only enough to watch a person until they find enough evidence for probable cause. For example, if someone gives a tip that you are selling drugs they cannot afaik immediately raid you but rather have to wait for you to do something like throw out drug packaging supplies with residue on them. Or they could pull you over for a traffic violation. If an anonymous tip was enough to raid someone, it would turn into a tool to get people who piss you off raided for no reason.