Does Buddhism have a model of practical rationality? A standard model of human practical reasoning is the belief-desire-intention model of action. 

Very simply put: The agent has a desire (“I want to be a doctor”) and a set of beliefs (“Studying medicine will get me there”) on the basis of which s/he forms an intention to act in a certain way (“I’ll study hard and try to get in to medical school”). When you ask a person, the intention and the desire is what the person refers to as her or his reasons for doing (and not doing) what s/he does. F.ex. staying home and reading instead of going to the pub. 

Does Buddhism have a model of practical rationality that can be extracted on the basis of canonical texts? And if so, is the Buddhist practical rationality model normative (what's beneficial/not beneficial) or descriptive, based on the agents subjective rationality like the belief-desire-intention model of action? 

Here is more on the model (as ascribed to D. Davidson, the idea is pretty much all over western philosophy and goes goes back - hold fast! - to Plato).
the belief-desire-intention model of action


Are the "four noble truths" an example of that?


I "believe" the first three truths
I "desire" the end of suffering
Therefore I "intend" the fourth noble truth


Or "ethics":


I believe that immorality causes or doesn't alleviate suffering
I wish to avoid causing suffering
Therefore I intend to avoid immorality


Or "compassion":


I believe I am able to suffer (and want to avoid that)
I believe other people are like me (able to suffer and wanting to avoid that)
Therefore I intend other people to be free from suffering



  the idea is pretty much all over western philosophy and goes back - hold fast! - to Plato


Have you read Zen and the Art of Motorcycle Maintenance? I liked it. I'd rather not spoiler it but I was remembering it earlier today: towards the climax (which isn't at the end of the book), he goes back to Homer and the Sophists. He quite loses his cool over Aristotle, which is funny at the time, sadder later.