"If you're lending it they're on their own. You've no liability. But
add a
disclaimer to the clipboard mentioned above. "

I wouldn't be too sure about that. I don;t know of any specific law
here in NJ that limits your liability because you just lent someone a
tool. Say I lent a stepladder to someone, it's a little wobbly, and
they fall off it. I don't believe there is anything to prevent them
from suing me, claiming I knew the ladder was defective, etc.

Granted, this isn't a big issue with a wrench, but if you start lending
out circular saws and think you can't be sued, I think you are making a
big mistake.