Should you tell Tower you're departing IFR

"KP" nospam@please wrote:
But if 99.9% of the traffic a local controller handles is VFR spamcans then
99.9% of the time when a spamcan calls for takeoff the response is going to
be "Cleared for takeoff." Usually without even looking for a strip since
many towers don't make strips for VFR.

I fly out of HPN, a busy Class D with everything from scheduled airlines to
two flight schools doing primary training. CD generally tells spam cans to
"advise tower and ground you're IFR".

Should the tower already know I'm IFR without my having to remind them? Of
course they should. But it doesn't cost me anything to play along with
their request, so why make a big deal out of it?