"Make my tool look up required dependencies and ask politely to install them if missing."
This is exactly how i solved a similar problem i had with Spreadsheet::HTML. If the client does not use certain features that require dependencies, why require those dependencies. I do this via eval and as such, i lost the ability to import methods/functions, but always found a work around. You can see more here, but the edited version is:
eval "use Spreadsheet::Read";
our $NO_READER = $@;
# and then later
return [[ "cannot load $file" ],[ 'please install Spreadsheet::Read'
+]] if $NO_READER;
Which is presented back to the client. Hope this helps.
(the triplet paradiddle with high-hat)