If you don't pass a folder to *ansible-doctor* your current working directory will be used. The first step is to identify if the given folder is an Ansible role. This check is very simple, if the folder contains a subfolder called `tasks` is MUST be an Ansible role! :)
After the successful check, *ansible-doctor* will try to read some static files into a dictionary:
* defaults/main.yml
* meta/main.yml
This will be the base result set which is used as data source for every output template. Without any work, you will get at least a documentation about available variables and some meta information. Theses basic information can be expanded with a set of available annotations. In general, an annotation is a comment with an identifier. This identifier is followed by colon separated options and ends with a value.