Tags and keywords
Some of the MAll methods and supporting All` package functions can be used with a PatternTest (? query) to address this slight shortcoming of out-of-the-box MTools:
The Webel MTools extensions of course just use MTools function to achieve this, but they offer them in a more convenient way.
Notes
[ANTI-PATTERN, GOTCHA, ISSUE, LIMITATION, WARNING]{INFORMATIVE} Mathematica: MTools: Argument Pattern strong type matching does not intrinsically respect inheritance (makes implementing design-by-contract and some Design Patterns less convenient). But you can use PatternTests with Webel MAll extensions.