Yes, this is correct - they're kind of like sleeve dowels. I thought of the starter locator pin, but that's present and accounted for. I haven't noticed any of my tools not functioning due to a lack of a pin like this. I have a few breaker bars that pivot, but no pivoting ratchets. I still haven't cleaned and put my tools away so I'll go through the pile and see if anything looks amiss. Thanks for the ideas!

Looked at my tools, and nothing looks amiss there, but I did have another thought on what this is - it looks like it could be a roller from a needle bearing. It looks chromed and hardened with some scoring on it. I still have no idea where it came from or how it ended up in the webbing in the engine block near the oil filter housing...