In order to understand how to extend Zend_Tool, you need to know a few things about its overall structure. The whole of the system was built with extensibility in mind. Each of the major functional parts of the system are abstracted in such a way that its easy to not only extend, but to replace with completely separate implementations. [...] But for our first order of business, we'll demonstrate how to add new commands to the Zend_Tool system.
He dives into the details of the Zend_Tool internals (including the Manifest component, the Provider_Version and the Provider_interface) before getting into the example code of the actual extension. He makes the typical "Hello World" example and shows how, with a simple command line call, you can execute the provider.