Extension mechanisms offered by UML 2.0 are often explored in order to define UML profiles that serve specific modeling purposes. These UML 2.0 profiles should be effectively accommodated by standard UML-based modeling tools, which provide the means for applying them in practice. Almost every UML 2.0 modeling tool supports the definition of stereotypes and the description of constraints in Object Constraint Language. However, implementing a profile in practice often entails the development of additional functionality. This requirement mainly stems from the fact that when dealing with complex models it is more efficient for end-users to help them enforce a constraint rather than notify them when it is broken. Such issues, encountered when developing a UML 2.0 profile for enterprise information systems engineering using Rational Software Modeler as a standard UML 2.0 modeling tool, are discussed in the paper.