Change focus to *Help* buffer after running describe-mode

Question

When I type C-h m for describe-mode the frame splits into two windows with the current buffer on top and the *Help* buffer below. But the focus stays in the current buffer, so I usually have to type C-x o to move focus to the *Help* buffer, and then scroll down with the page-down key to find what I am looking for.

I tried to improve this work flow by automatically give focus to the *Help* buffer:

(advice-add 'describe-mode :after 'other-window)

But now I get error:

Debugger entered--Lisp error: (wrong-type-argument stringp 1)

when I type C-h m.

Answer 1

Customize the variable help-window-select:

    "Non-nil means select help window for viewing.
Choices are:
 never (nil) Select help window only if there is no other window
             on its frame.
 other       Select help window unless the selected window is the
             only other window on the help window's frame.
 always (t)  Always select the help window.

This option has effect if and only if the help window was created
by `with-help-window'"

Answer 2

Forgot to use call-interactively on other-window. This seems to work better:

(advice-add 'describe-mode :after '(lambda (&rest args) (call-interactively 'other-window)))