Argthtjtr

I have always been puzzled by some sentences people make that end in a no. For example, let's say someone instructed you not to leave your post before they arrive. Then they return but you're not there. When you finally meet them, they say:

So you decided to wait for me elsewhere than we had agreed, no?.

What is the meaning of no and what should I answer?

From what you've written, I think you are describing someone asking a rhetorical question.

"You decided to wait for me elsewhere, didn't you?" is equivalent to "You decided to wait for me elsewhere, no?"

Asking only with 'no' like that is usually something of a challenge or at the very least it indicates a strong expectation that the answer will be agreement. It is used commonly in argumentative rhetoric and emotional disagreements, but it can also just be used to indicate genuine confusion or surprise.

Answering 'no' to this kind of question is expressing disagreement. Answering 'yes' is expressing agreement. To avoid any chance of ambiguity, you can expressly state the disagreement.

"No, we did not agree to meet here. We were supposed to meet at the restaurant."

While I agree that appending the word no at the end of a statement – thereby making it a question – can indeed sound accusatory, condescending, or confrontational, I don't think that's necessarily the case.

As Charles mentioned, it can also be used to express self-doubt, as if to say: "at least I think that's the case, is it not?" or, "wouldn't you agree?" or, "I could be wrong about that, please correct me if I'm mistaken."

As with anything else, much depends on the context: the relationship between speaker and listener, the tone of voice, the preceding conversation, facial gestures, and the like. But here are a few examples where it wouldn't seem much more of a challenge than adding "eh?":

I'll bet you had a good time on vacation; the weather was good there, no?

That hotel has the nicest staff, no?

1955 was the year that Brooklyn finally won the World Series, no?

That said, I agree with Mitch: it's not a common construct. Being rather concise, it could easily be misconstued to sound very curt. Use it with caution, no?

I think it's a question tag that people generally use whose native language is other than English, and one in which such a question tag exists. So it's probably a case of direct translation. I know Indians use it when speaking English, and I think the French might also use it.

In American English, it's common to append "right?" to the end of statements to turn them into questions. The idea is the same.

It is not particularly common among AmE speakers (I don't know about other varieties).

The final 'no?' is a simplified question tag, meaning 'isn't that so?'. It has the feeling of 'I dare you to contradict me.' It sounds like the butler confronting the parlor maid after coming back from the scullery, because he just saw the chauffeur quickly leave and the maid has engine grease on her apron.

Instead, in real life, you almost only ever hear:

So you decided to wait for me elsewhere than we had agreed, didn't you?

Another option would be

We agreed you'd wait for me here, right?

expecting a confirmation.

Using '..., no?' as a question tag sounds...continental... like someone French trying to avoid the (admittedly difficult and convoluted) "didn't you?". I suppose it is 'grammatical' but it is rare and sounds very accusatory.