The חפץ חיים writes מותר to ask people about this בחור in תורה, if he did not ask you directly, he just said tell me about this and this student, and you know he really wants better then that student who is asking you about, Is that considered asking you directly about this and this thing? You could answer him and you have to answer him, or he has to say exactly what he wants to know about the person and if he doesn’t you’re not allowed to offer information, even though its a תועלת for him, to know that (not talking about a case that has a serious problem)? Whatever the answer is can you please write where you got that from.
Before answering a question of this sort, we have to understand that this topic is very delicate and sensitive, and this answer is only a general answer, and a rov should be consulted in each instance because other factors can come into play regarding what may or may not be said based ion the individual situation. Therefore this answer is only a general guideline.
If we are not talking about a serious problem, then if you are not asked about it specifically, you should not give over the information. First of all, because it is only your opinion that he would want better than this boy. Secondly, the reason why we are not allowed to say things that are derogatory, unless they are serious is because when a person is asked a shidduch question, he is faced with a tricky situation, on one hand if he says negative information, then he is harming the person he spoke about, but on the other hand if he doesn’t say, then he is harming the person that is asking the information. Therefore unless it is a situation where the harm is clear, we are not allowed to say, because of the rule “mai somchis d’dama …” “who said that one person’s blood is redder than the other”, therefore we say don’t do anything and don’t say, unless it is clear that there will be damage from not saying, such as something serious. However if the person asked you specifically, then it shows that this is an important issue for him, and then you are obligated to say. Therefore the fact that the person just asked a general question, doesn’t give you the right to say things that are negative and not a serious problem.
This however would only apply if the person asking the question is not someone close to the person being asked, because then we have as if two people that are equal and then we can’t choose.such as a relative or close friend. However if the person asking is a relative or close friend, then there is a different aspect that comes into play, “mbsarcha al tisalem”, and then even if he asks a general question we should say.
Nesivos Chaim on Chofetz Chaim Rechilus perek 10, Conversation with numerous poskim including R’ Y. Wainman shlit”a and R’ Yitzchok Berkowitz shlit”a, Chofetz Chaim ( Dirshu) Tziurim ftnt. 17.