Thomas does a good job here of defining his research agenda. Notice how it is very concrete and detailed: an exploration of the sense-making debate in Organizational Studies, as well as very broad in its implications: the epistemology of the social sciences.
In job interviews in academia there is always the "summarize your dissertation" question. Then the interviewers will typically ask about the next project beyond the dissertation. That is an opportunity to define your research agenda, because you will be able to make a connection between a specific dissertation topic and the larger agenda of which it forms part. If you can articulate the connection between a narrower topic and a broader agenda, you will be able to be very impressive.