Agile is all about doing the right amount of something at any given time and no more. We should author user stories with the detail necessary to get the job done and no more. We should build what we know we need now. We should not build some huge framework we think we may need someday.
This principle will scare teams who are used to waterfall projects. It first glance, it seems crazy to welcome change late in the development process.
Agile Estimating and Planning