Would a tool manufacturer need a different marketing strategy for a
big retail chain like Home Dep[ot than for a singlr hardware store run
by its owner? Why?

I think I would need more info.
Is it a specialty-type of tool that is complex- that only
professionals ie. carpenters, builders, etc. would use....or would it
be a tool that the "weekend warrior" would use in order to save money
from paying someone else to do the work.
My thought would be that the mom and pop hardware store...would pay
more for product...but would likely be a "dealer" or distributor of
that product...and need to attend training...and would spend the time
with their customer to consult the use with them.
I think that a Home Depot would be a mass seller..who would likely get
the best price...for buying the most....but the consumer would be on
his own....as he/she is now for the most part with any Home Depot
purchase.
I suppose it depends on how this manufacturer wants it's product
viewed....and the importance of it in the marketplace.
good luck