SIMPLE.
Speak plainly,
"I do NOT lend my tools, so please don't put me in an awkward situation by asking." :Stop:
I kind of like this one, diplamatic. It puts nice guys at disadvantage. But oh well.
I was spoiled by living in a wonderful area in the woods a few years back, there was 5 of us all with acreage and we borrowed tools from each other all the time and in 13 years none of us ever lost a thing, never a complaint nothing. When done things were returned exactly were they came from, if it was broke it was replaced with an apology.
Well where I'm at now it seems everyone needs something and as said by others I've had to retrieve tools i needed for work weeks later.