Anyone with a basic grasp on interpersonal skills wouldn't be posting this question.
This title is unequivocally rude. Just to be clear, this is not my real answer, it's the example that proves the point.
You were intending to send your short message to this person, likely with no surrounding context. When you read this title, before you read the rest of the answer, you were in a similar position of having no surrounding context.
In the absence of a further elaboration, the title (and your suggested phrasing) comes across as not just rude, but also hostile.
Your phrasing is the issue.
I understand what you are trying to say. Your statement is objectively correct. You're seeing your words as well-meaning, correct and tersely efficient. But you're not seeing that the other person cannot inherently know that you are not upset with them.
You left no markers to suggest that your reply is well intended (and you're not just annoyed), and it also contains pieces that imply the opposite (that you are indeed annoyed and close to calling them stupid).
Anyone with basic understanding of how Y works
The rest of the reply doesn't even matter, this immediately puts the other person on the defensive. You're reprimanding them for not having a basic understanding of how Y works.
"Anyone" suggests that this person is being unusually ignorant, and that pretty much everyone else is better at it than them.
"Basic" suggests that the problem is hilariously trivial (and implies that it's not worth your time or effort).
would be able to infer that from the examples.
"would be able" is a conditional. In the current context, it is understood as "this should be the case, but apparently not for you". You're not just calling their abilities into question, you're almost explicitly stating that you know that they're unable to understand the examples.
"Infer" is the problem here. Inferences happen privately (and in silence), so you're inherently berating the person for contacting you.
"From the examples" is making a similar claim. It states that the examples are clear and obvious and implies that asking a question is unwarranted (which again labels the person as unusually ignorant).
I can’t teach you how Y works.
What you're trying to say is that you can't teach Y. However, what you're actually saying is that you can't teach this person (about the workings of Y).
Again, this allows for the inference that you're calling the person ignorant, incapable of understanding it even if you were to teach them.
What you told the person:
- This is a trivial problem.
- Anyone else would understand this, but you seemingly don't.
- You should read the examples in silence, instead of asking me questions.
- Even if I were to teach you, you wouldn't get it.
What you should tell them:
- My tool cannot solve this particular problem, it only helps with X.
- To solve the problem when using my tool, you can use Y.
- Alternatively, you can also use Z instead of my tool, which avoids your current issue and doesn't require Y.
- The best resource for information on Y is the official Y documentation.
- The best resource for information on Z is the official Z documentation.
Putting that information in a reply:
My tool does not feature a solution for your current problem. It's only intended to help with X.
In order to fix your problem when using my tool, I would suggest you take a look at Y on their official website. There, you can also find examples on how to fix your current problem.
Alternatively, you can use Z as an alternative to my tool. Z does not have the current problem, so you won't need to work around it using Y. For information on Z, I suggest you take a look at their official website.
I used "your problem" a lot, the repetition is a bit grating. But this is because I don't know what the problem is. You do, when you're writing your reply.
Try to refer to it with a concrete description of the problem, don't just call it "your problem".
Why is my version more polite?
Maybe it helps to compare the differences:
- I have not called this person's knowledge into question.
- I haven't implied that anyone else would already know what I'm telling them.
- I stuck to the facts. You need Y to work around the problem. Whether this person already understands Y or not is irrelevant, they are capable of looking up a tutorial by themselves if they feel they need it. There's no need for me to make a statement about their aptitude.
- I never suggested teaching them; which means I also never had to explicitly refuse teaching them. You don't want to teach this person, then never mention teaching them. Stick to the facts.
- I offered Z as an alternative, but I did not explain why I think this person may prefer Z over X+Y. There's no need for me to tell him that I think he's not skilled enough. This person can look at Z and X+Y, and can decide for themselves which route they choose to take.
Think about why this person contacted you. He wasn't asking you to assess his aptitude; he was only asking for your experienced feedback (since you're the developer of your tool).
As it turns out, you can't help with what he's asking, it's simply not part of your tool and it's not your job to teach them other skills.
However, this does not justify calling their lack of these skills into question. The polite thing to do is to refer them to someone/some resources that explains it better than you can.