Checks ContentCatalog.txt file automatically when launched.

The tool works automatically. Run it before going to the Creations menu and after exiting the Creations menu - quit the game and run the tool before loading a saved game if you've installed new mods or updated mods in the Creations menu. No need to use the tool if you're just playing the game normally.

Check button re-checks the file.

Clean button repairs the file. It may take a while with a large mod list.

Backup button copies ContentCatalog.txt to ContentCatalog.txt.bak. A previous backup if it exists will be overwritten without warning. Use the backup function before loading your saved game since this is when the corruption may occur. It's best to exit the game after making modifications to your installed mods, updating mods or changing the load order.

Restore button copies ContentCatalog.txt.bak to ContentCatalog.txt

Edit buttons are for opening ContentCatalog.txt or Plugins.txt files for editing with your default text editor.

Explore button opens the folder with your plugin and catalog files. You could manually edit the Plugins.txt file to enable or disable mods if needed. A * character indicates that a mod is enabled.

Load Order button shows a list of mods and allows them to be turned on or off or moved up or down in the load order.

You can alt-tab from the game to check the ContentCatalog file to see if corruption has occurred by pressing the Check button.

The launch Starfield button is hard coded to the default Steam installation path at the moment and is only intended for quick testing.
Quit the game if it's running before using the Clean or Edit buttons.

Source code link on GitHub