I have an Ubuntu laptop that I've used for work for several years. I have SSH keys for a number of different clients on my machine, including some personal projects.

One day, when connecting to a machine over a jump server that utilized SSH forwarding the sysadmin was trying to help me debug something and sent me a list of all of my own keys. It wasn't just a list of the key I was using to connect to that machine but every single key on my laptop, complete with names.

Until he showed me that, I had no idea that the SSH Agent was quite literally sending the house. I was always under the impression that the only thing sent was what was needed to connect to the single machine.