I use "right click - add page as a task in Doit.im" all the time and I found the pop up "Success" window annoying: it interrupts my attention and I have to click the confirm button.

I think it is better to have it as a soft notification, i.e. instead of popping a new window that I need to click, it shows a small notification bubble on the edge of the screen, and I don't have to do anything with it, itself will go away after few seconds.