Inverse world has a tag for Hazards called Social. (This hazard is human [-oid] in nature. Social hazards are often unable to be solved with violence, for one reason or another.) That book suggests that Social threats don't need the intelligent tag because they are assumed to already have it. I think it would be fair to swap "unable to be solved with violence" with "almost always solvable without violence." then add "Social creatures have sufficiently advanced societies that that some individuals pick up other skills. The GM can adapt the monster by adding tags to reflect specific training, like a mage or warrior." With these changes, the Intelligent tag can be removed entirely.
By default, the Social tag otherwise doesn't give any incentive to be non-violent except players acceptance that you shouldn't kill certain people. combining it with Friendly (This hazard does not mean you any harm. This doesn’t mean it isn’t dangerous, of course, but it doesn’t intend to be.) probably helps with that incentive, but I think it fair to offer players a chance to mark XP for a Social threat of any kind to be dealt with peacefully.
