1. A method for extensible context based user interface simplification for a model driven development tool, the method comprising: executing a model driven development tool in memory of a host computer the tool comprising a multiplicity of user interface components including tool items and also model components of a model loaded for processing in the tool; registering different ones of the tool items in a tool item registry in association with corresponding contexts of the model driven development tool; detecting a context change to a new one of the contexts in the model driven development tool based upon a selection of a new one of the model components in the model driven development tool; locating ones of the tool items in the registry mapped to the new context; and, displaying the located tool items in the model driven development tool.