The spec should be typed. Those other users should not just be giving you typed data, they should be giving you a type signature.
I'm referring to a general situation. You're referring to a specific situation of http apis sharing what I assume is untyped data and the typing is lost during transport. The solution is to develop protocols on top of http where the type signature isn't lost.
I'm referring to a general situation. You're referring to a specific situation of http apis sharing what I assume is untyped data and the typing is lost during transport. The solution is to develop protocols on top of http where the type signature isn't lost.