Let Me Rest, Seriously

Restriction-based spy detection.

The Restriction's rule is that if it activates when I give the other party (the enemy) information I know will be useful to them, that person must belong to the enemy faction.

Moreover, since the enemy faction can be identified based on what information I convey, it must seem absurdly overpowered.

...No, it really is overpowered.

After all, I can detect a spy with nothing more than a single word.

However.

"It isn't completely overpowered, though."

Spy detection through the Restriction?

It sounds incredibly useful, but it clearly comes with several risks as well.

Naturally, the enemy has to give me information that benefits them in response to the information I offered...