The correct syntax for accessing a variable inside another package is $pkgname::varname, but note that this only works if varname is a package variable. If it's lexical (my $varname), then you can't get to it at all from outside the package.

Given that you have the package name inside a variable, things get a little messy. I couldn't find a way to do it without "eval":

print eval("\$${module_name}::description"), "\n";
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