compute function cyclomatic complexity...
...and issue message if above a threshold.
Since you're already analyzing the functions, it would seem to be a relatively minor addition to compute a cyclomatic complexity for the function (he said, while signing up someone else to do all the work).
Then, similarly to the "-size" option, the user could be allowed to set a max complexity, above which an info message could be generated.
This would help reduce our reliance on additional tools.
please also consider nesting complexity