Why do commands behave inconsistently?

[Orome]

If I have a list in Home and choose List > REVERSE from the toolbox, I get a reversed list as a result, but if I have a list and choose List > SORT, I get the list followed by SORT(), which can't be evaluated.

For example, if I have
{2, 5, 8, 3, 6, 9}
and choose List > REVERSE I get
{9, 6, 3, 8, 5, 2}
but if I instead choose List > SORT I get
{2, 5, 8, 3, 6, 9} SORT()
which is unusable.

Why do these behave differently, and how am I supposed to know that they do?