That module is only 30 lines of actual code and it is broken.

There is a FIXME note in the source

$opt->{doc} || ' ', # FIXME new GLD shouldn't need this hack
[download]

which lead me to try

#!/usr/bin/perl --
BEGIN {
    package My::App;
    BEGIN { $INC{'My/App.pm'} = __FILE__; }
    use Moose;
    with 'MooseX::Getopt::GLD';
    has 'out' => (is => 'rw', isa => 'Str', required => 1, doc => "yo"
+, );
    has 'in'  => (is => 'rw', isa => 'Str', required => 1, doc => "yo 
+ho", );
}

#!/usr/bin/perl --
use My::App;
my $app = My::App->new_with_options();
[download]

but that doesn't work (Found unknown argument(s) passed to 'in' attribute constructor in 'Moose::Meta::Attribute': doc)

Related bug #47865: Help and usage don't seem to work with Getopt::Long::Descriptive