Unless your designers are a 3rd party, bring them over to the dev team. Throwing material over the wall is almost always going to lead to a bad time when there are not experts on both sides handing off from one to the other. The designers should be working with the developers to implement their vision. In essence, from the developer perspective, the designer is the customer (at least up to a point). Your developers having to "infer" suggests that they aren't in a position (either aren't aware of who to ask or explicitly barred from asking) to ask the designers for clarification, that's a communication barrier that will cause harm to the project.
Barriers like this (silos in general) are a great way to isolate separate groups, but also greatly reduce the effectiveness of everyone.