Make a description of custom function to be visible in the standard popup dialog

I would like to have small description on routines in code completion.    

Currently you cannot create a description and attach to your own routines, such that it will pop-up while code completion.

This is useful if you have a library of routines specially you work in team environment and you have considerable amount of code in the library.

Script-extensions are not suitable for evolving/changing library .