Hello,
I'm sorry for the delay :), I have a lot of work with my other addons currently.
The explanation for %s and %f can be seen in the Settings page / Context menu options / (?) - the question-mark icon.
I should have probably write it on a better place.

Also, with this addon you can access your previous queries by pressing arrow UP, which can be super handy :).
Best Regards,
Juraj Mäsiar