No, you're wrong (in my opinion). For the simple reason that however long to spend trying to think out the API, you'll never come up with all of the requirements - and new requirements will always emerge as soon as you think you've finished tying them down.

APIs will always change. Your best bet is to design an API that is flexible enough to accept the changes without breaking existing code. Perl is particularly good at this as it's easy to add new parameters to a function and set up defaults for ones that aren't passed. This is even easier if you use hashes to simulate named parameters.

"Perl makes the fun jobs fun
and the boring jobs bearable" - me