I understand I can open the Info panel and Tag something; I understand I can drag files and folders into a tag in the Tag Smart Folder. Both are too much trouble. I have a suggestion:

Decades ago, I was an avid user of Mitch Kapor’s superb relational database, Agenda. It used automatic tagging, although I don’t remember it being called that at the time. I loved that program (and I think anybody who used it remembers it fondly).

The user could create a list of tags. Then, say you opened a Text File and began to enter text. Whenever you typed one of the words that was in the tag list, it would link to it automatically. If you were typing along and thought some word should become a tag, you could add it immediately. It was an interesting exercise to establish the tag list because it forced you to think about the categories you were working with – and the list started dictating what you wrote in the note so a tag would be established.

Agenda was absolutely fabulous for taking notes when doing research – you could concentrate on your ideas and let the linkages be set up automatically as you wrote – of course, you had to watch your spelling.

Because DTPro contains filetypes other than user entered text, it would be ideal if there was a script to generate a “tag find” on any imported text document, to create the links retrospectively.

This feature is available already. If you right-click on any word in a document, you can add that word as a tag.

While not auto-tagging, something else that may help your workflow now is if you right-click on a tag in the Tag bar, DEVONthink will give you a list of suggested tags based on the tag combinations already used in the database.