This paper shows that existing software metric tools interpret and implement the

definitions of object-oriented software metrics differently. This

delivers tool-dependent metrics results and has even implications on the results

of analyses based on these metrics results. In short, the metrics-based assessment

of a software system and measures taken to improve its design differ considerably

from tool to tool. To support our case, we conducted an

experiment with a number of commercial and free metrics tools. We calculated metrics values using

the same set of standard metrics for three software systems of different sizes.

Measurements show that, for the same software

system and metrics, the metrics values are tool depended. We also defined a

(simple) software quality model for "maintainability" based on the metrics

selected. It defines a ranking of the classes that are most critical wrt.

maintainability. Measurements show that even the ranking of classes in a software

system is metrics tool dependent.