By reading again what are on-topic questions, I found that discussing security tools are among on-topic subjects; but then I see many questions closed as being tools recommendations.
Why this contradiction?
A: "I'm using this tool to do X, but I have general questions about its use."
B: "What tool do I use to do X?"
C: "Tool X isn't working. How do I use it?"
A is on-topic. It shows knowledge, understanding, and context. It is possible for questions to survive the use of the tool into more general tool use.
B is off-topic because tools go in and out of favour, new tools rise, questions go stale.
C is the big debate. Theoretically, they could be on topic, but in practice, questions of this type have needed to go to product-specific forums or the vendor/dev's support page. Alternatively, I've seen a lot of questions that should go to SuperUser as a general software config question. Most of the questions I've seen are answered by RTFM.
Personally, if C cannot be answered by RTFM or the vendor support page, and the question shows an understanding of the technology and the problem, it is on-topic here.
With the death of Hackoverflow, the community might need to assess how much of C we need to take on.