This will create the folders for the .gma files (addon archives) from which extraction will be done. Once you have added your addons to the folders just run the tool basically raw: ...
gmod-addon-test/ ├── addon.json # Workshop metadata ├── LICENSE # License file ├── README.md # This file ├── lua/ # Lua code directory │ ├── autorun/ # Auto-executed scripts │ │ ├── sh_example.lua # ...