The idea of the enterprise architecture (EA) has been active since 1980-ies. However, enterprises still lack a clear approach and tools for implementing it in practice. In most cases, enterprise models are fragmental and use domain specific frameworks that do not have appropriate support in industrial tools. We introduce a novel approach to customizing UML tools for domain-specific modeling needs. This approach was implemented in MagicDraw and has already started to gain enthusiastic adoption in industry. The possibility to customize UML makes it more suitable as a platform for EA. While simplifying complex UML language and focusing on domain modeling concepts, it enables modelers to reuse the powerful features of UML tools – standard-based model data repository, diagramming features, model elements relationships analysis and navigation, model comparison and merge, documentation engine. The presented ideas are illustrated by custom EA model samples.