If someone asks me to ϕ, typically that informs me that they want me to ϕ. But the normative effect of the request cannot be reduced to the normative effect of learning about the requester’s desires.
First, when you request that I ϕ, you also consent to my ϕ, and hence the request has the normative effects of consent. But one can want something done without consenting to it. For instance, if I have a lot of things on my plate, I might desire that a student give me their major paper late so that I don’t have to start grading yet, but that desire is very different in normative consequences from my agreeing to the lateness of the paper, much less my requesting that it be late.
Second, considerate people often have desires that they do not wish to impose on others. A request creates a special kind of moral reason, and hence imposes in a way that merely learning of a desire does not.
Moreover, we cannot understand requests apart from these moral normative effects. A request seems to be in part or whole defined as the kind of speech act that typically has such normative effects: the creating of a permission and of a reason. Moreover, that reason is a sui generis one: it is a reason-of-request, rather than a reason-of-desire, a reason-of-need, etc.
There is something rather impressive in this creation of reasons. A complete stranger has the power to come up to me and make me have a new moral reason just by asking a question, since a question is in part a request for an answer (and in part the creation of a context for the speech acts that would be constitute the answer). Typically, this reason is not conclusive, but it is still a real moral reason that imposes on me.
Consider the first time anybody ever requested anything. In requesting, they exercised their power to create a moral reason for their interlocutor. This was a power they already had, and the meaningfulness of the speech act of requesting must have already been in place. How? How could that speech act have already been defined, already understandable? The speech act was largely defined by the kinds of reasons it gives rise to. But the kinds of reasons it gave rise to were ones that had never previously existed! For before the first request there were no reasons-of-request. So the speech act had a meaningfulness without anybody ever having encountered the kinds of reasons that came from it.
This is deeply mysterious. It suggests an innate power of the human nature, a power to request and thereby create reasons. This power seems hard to reconcile with naturalism, though I do not have any knock-down argument here.