Yes, spying should be monitored by an international agency because it is unfair for some countries to be spied on by others. Why do we need to know what one politician writes in an email? This should be kept private, and spying should be punished for violating a person's rights.
No, I do not believe there should be an international agency that monitors spies. Most countries use spying as a method of keeping an eye on other countries. Although this seems to be dishonest, it is a practicals means of getting information. As of now each country monitors their own spies and tries to ensure their safety. If there was international agency that monitored spying, it would no longer be a secret who these spies are and where they are. This would basically end the entire practice.
I think a fair question is: Who is accountable?
If The Verge wants to be what I believe it to want to be, critical – then ask that question and complain when no answer is given in a big way.
Explain why whistle blowing is then the only way to get information or accept that rouge departments is the reality.
Intelligence agencies are so secretive when it comes to any form of international cooperation that they often hold information back from even their closest allies. Therefore the idea that an international body charged with oversight of the world’s intelligence services would be effective is complete nonsense. It would be nothing more than a waste of time, manpower and money.