Walking that line between being a good neighbor and being an
abused neighbor can be tricky. Asking "helpful" questions like
"What are you going to do with this tool?" can short circuit
its abuse. In the cutting through comp shingles example, you
could then point out that a circular saw is the wrong tool for
the job and that a sawz all/ bayonet saw would be the tool for
the job - with the right blade of course. Then you can offer
to go with him to buy one - along with the proper bladeS -
plural - for the job he's got in mind. Now you're in Helpful
Advisor mode rather than the less desireable Lender mode.

Also make a point of asking how long he'll need the tool.
Explain that you often do things very early in the morning
and late at night and you'd hate to wake him up to get
your tool when you need it. So stress that you need your
tool(s) back by sundown. Now you're the Helpful Neighbor
who is also the Considerate Neighbor. It also make him
schedule things for a week end.

I HAD a brother in law living acrossed the street and two
doors down. His wife wanted to remodel their house and
he, being an auto mechanic, had few tools for that type
of work. In no time at all he had
- my pick up truck with the bed full of 2x4s
- my worm drive circular saw, with blades
- my sawz all with blades
- two of my electric hand drills with bits
- my crow bars
- two or three of my hammers (ball peen hammers
are useless on remodels)
- a couple of my extension cords (the ones his sister
hadn't "modified" - with the hedge trimmer!)
- my framing square and regular square
- my palm nailer (he had a compressor)
- my 6 and 8 foot ladders
:
:
:

If I needed one of my tools back it'd take days to
"borrow it back" and this went on for over a
month.

Things came to a head after a couple of weeks when
I heard my skill saw cutting something - at 10:30
at night. Our neighborhood gets quiet after about
nine pm and folks call the cops after that.

Now knowing that this guy had a problem with
"authority figures" (he'd chased his father around
the back yard with a baseball bat when he was
a teen, and tried to back his bug eyed Sprite over
a county sheriff in his early twenties) I went over
to suggest he knock off work for the night and
offered to give him a hand when he got home from
work the next day.

That lead to a lot of yelling on his part and me
demanding my truck and tools back. When he
was about to THROW my skill saw into the bed
of MY truck - from his porch - things got a bit
testy. That incident ended with him pulling a
knife on me and my 6' 6" neighbor, who'd come
out of no where, taking the knife away in a less
than gentle manner.

Needless to say, I became a little tighter with
my tools. Fortunately, he lost the house,
but only after I, being the husband of his sister,
had to deal with sheriffs and bail bondsmen and
one of his ex-wives/girl friends and a sheriff,
on a cold rainy morning around 6 am.

NEVER LOAN TOOLS TO IN LAWS.

Recapping
Ask helpful questions
Offer helpful suggestions - like lets go over to
The Borg and get you the tools you're gonna need
Need the tool(s) back by sundown - the OR ELSE
can be implied as subtly or as forcefully as you
feel necessary.

charlie b
who just got his four, four foot bessys back
from his eldest and his youngest still has his
hammer drill and masonry bits.