Reading :help 'tags' and scrolling a little bit down finds the following sentence:

The *tagfiles()* function can be used to get a list of the file names
actually used.

Accordingly, :echo tagfiles() will show the name(s) of found tagfile(s).

An easy way to test this is in any of Vim's help files. It will pick up the helptags in <whatever>/doc/tags.

Reading :help 'tags' and scrolling a little bit down finds the following sentence:

The tagfiles() function can be used to get a list of the file names
actually used.

Accordingly, :echo tagfiles() will show the name(s) of found tagfile(s).

An easy way to test this is in any of Vim's help files. It will pick up the helptags in <whatever>/doc/tags.

Reading :help 'tags' and scrolling a little bit down finds the following sentence:

The tagfiles() function can be used to get a list of the file names actually used.

Accordingly, :echo tagfiles() will show the name(s) of found tagfile(s).

An easy way to test this is in any of Vim's help files. It will pick up the helptags in <whatever>/doc/tags.

Reading :help 'tags' and scrolling a little bit down finds the following sentence:

The *tagfiles()* function can be used to get a list of the file names
actually used.

Accordingly, :echo tagfiles() will show the name(s) of found tagfile(s).

An easy way to test this is in any of Vim's help files. It will pick up the helptags in <whatever>/doc/tags.