I can't explain why it's not catching the -k parameter. I tried it with similar result. There is one interesting thing I discovered when I dumped the object through Data::Dumper though: The paramaters '-k' and 'foo' are enumerated in @{$args->{_internal}{unused}}. So we know they were in @ARGV to begin with, and that Getopt::Declare found them, but the module doesn't seem to be using them.

I like what Damian Conway says in the docs under the BUGS section: "If nothing else, it shouldn't take 1500 lines to explain a package that was designed for intuitive ease of use!"