This morning, when I booted my Mac, it told me that “Android File Transfer Agent.app” was something I’d downloaded from the Internet and asked if I really wanted to open it. I’d recently installed Android File Transfer, but didn’t know what Android File Transfer Agent was, or why it should be launching even if it was related to what I’d installed, so I said no. Android File Transfer wasn’t doing me any good, since my Mac can’t see my Android phone over the USB cable, so I deleted it from the Applications folder and emptied the trash. (It may be something Tracfone did; Tracfone is cheap but does annoying things to limit its phones.)
After a reboot it did the same thing again. I searched for Android File Transfer Agent and found there was nothing by that name on my computer.
A web search turned up an article which explained what was happening. Android File Transfer Agent lives within Android File Transfer.app (which is actually a directory that functions as an event horizon), and I’d already deleted it, but it was still listed in my Login Items, and OS X was trying blindly to launch it even though it didn’t exist. I found there were seven items in my Login Items, three of which weren’t present on the computer, two were related to products I’ve stopped using, and one was totally mysterious. I got rid of all of them, leaving just the one reasonable-looking item, and rebooted.
Application installers can stick stuff into your Login Items without telling you. It’s a good idea to look there occasionally and see what shouldn’t be there. Some junk removal might help to improve system startup speed.