One of the goals with these plugins is that they should adhere to the Nagios Plugin Development Guidlines as far as possible. This means that they should work with all the monitoring tools related to Nagios and Icinga.
Documentation and specific information about the plugins can be found under its own section on this page, and in the actual plugin.
All the plugins are all released under the Apache software license version 2, which means that you are free to use them without any restrictions. Any feedback about the plugins is much appreciated.