The toolbit system is the new standard for tool description and management starting with FreeCAD version 0.19. This video goes through the user interface and data structure of toolbits and libraries.
Official Toolbit documentation: https://wiki.freecadweb.org/Path_Tools
Patreon: https://www.patreon.com/sliptonic
FreeCAD For Inventors book: https://www.kobo.com/us/en/ebook/freecad-for-inventors