revertbot.py is a script that helps you clean up after your bot if it does undesirable things. It goes through your bot's list of contributions, from most recent to most ancient, and reverts the last revision your bot made on each page — provided, of course, that your bot made the most recent revision on the page.
It is therefore most effectively used immediately after you notice your bot has gone astray.
It is invoked by typing
python revertbot.py, and it appears to have no parameters, options or other settings.
It should almost certainly not be run unattended, as it does not ask permission to make changes. In at least version 7957 from February 2010, its default — and unalterable — mode is just to automatically make changes.