This agent check type monitors your system metrics with help form the Node Agent Daemon (NAD) available on github.
NAD is a lightweight, simply managed host agent written in Node.js. NAD is the first choice of Circonus due to its easy extensibility and its ability to work on almost any platform, including Windows, RHEL, Ubuntu, and Illumos derivatives. NAD comes with enough plugins to monitor the basics, while allowing you to add your own checks to fit your environment.
NAD runs scripts only from the config directory and not from any subdirectories. The best practice is to write scripts in subdirectories of the config dir and soft link to them to enable their execution.
Some scripts distributed with NAD need to be compiled. (They aren't actually scripts; they are ELF executables.) Since not all programs can be compiled on all platforms, you need to build them as needed. There are makefiles, and you can pick and choose which ones you want to run. If you write a set of scripts or programs, you can describe them in an .index.json file and they will be reported on when you run NAD.
More details on the setup and use of nad are in the user docs.