Quite a few versions back MacVector used to have an old, but well loved, Test PCR Primer Pairs algorithm. Its interface was clunky and it did not take into account modern algorithms for calculating Tm. However, the results were useful. If you liked this tool then you will be pleased to know that the functionality is still in MacVector.
When you enter a pair of primers into Primer Design/Test (pairs) (previously called Design Primers) the interface switches to a new testing mode, TEST PRIMER PAIRS. This tool lets you test pairs of primers using an updated variant of the Test PCR Primer Pairs algorithm.