The tools directory that comes with the mpatrol distribution contains the source code for tools that are built on top of the mpatrol library. The functions that are defined in these files are intended to be useful for specific applications as well as providing real-world examples of how to extend mpatrol. If you wish to use one of the source files in the tools directory then you should first compile it and then link it into your program along with the mpatrol library.
Alternatively, if you've already installed mpatrol on your system then there should be an mpatrol subdirectory within the include directory where mpatrol.h is installed that contains all of the header files in the tools directory. There should also be a libmptools library within the library directory where libmpatrol is installed that contains an object file for each of the source files in the tools directory. You can then make use of a particular tool by including its header file from the mpatrol include subdirectory and then linking with the libmptools library.
If you've written a useful extension to mpatrol then you might wish to submit it for inclusion in the next release of mpatrol. Even if it's just for a specific application, there might be other users out there that may benefit from it. You'll even get a credit in the manual! Note that any documentation should also be written in the associated header file.