HDRI Loader is a V-Ray for Maya script.
It helps you with setting your scene up for rendering your object with the help of an hdri.
It creates a dome light and configures the render globals and makes all necessary connections and when enabling the sun light you have also the possibility to specify the shadow softness.
You can also let it create render layers that split the scene up into a background, shadow and an object layer for later compositing.
In the script field you can specify commands that will be executed after setting up the scene to automatically set default settings. For example: setAttr “vraySettings.sys_regsgen_xc” 32;
This sets the render region devision to 32 pixel.