No, it's not too short at all! Shorter is always better—and if you can directly address 1) what you do, and 2) what your target customer values in the same sentence, that would be optimal.

You're definitely getting there, it seems. We had an accountant client several years ago, and we came up with this little line for a piece that was never used: "Save time and money, and skip the stress, and focus on what you do best." Obviously you would need to include some kind of extra services line or value prop statement, but you are free to use that as a headline if you like. 😉