The official docs on this are at: https://docs.carbide3d.com/assembly/carbidecreate/video-tutorials/#toolpaths
Further notes:
If you select a tool before clicking on “Add Tool” the selected tool will be used as a template for the new one.
- Toolpath
- Edit Library
- Add Tool
- double-click on the new tool to go into edit mode
- edit as needed
- Ok
- close window
Further discussion at: Can CC make use of a diamond drag bit?