What is your experience from real-life, who should be responsible for a choice of agile planning tools to be used by the agile/scrum team?
Team should decide whether a tool is to be used; but I think suggestion most commonly comes from the Scrum Master as (s)he is most likely to have experience using tools. Any team member can suggest tools of course.
Anyway, my feeling is that given Scrum philosophy, the whole team needs to agree on this in my opinion. Usually things start with "let's try this, see if it works", and is refined along the way, just like anything else in Scrum. It should not be top-down enforcement, same way as using Scrum methodology should be team decision, not handed down from top.