In the theory of structural dissociation what they term 'tendencies' is the equivalent of a 'sense of agency'. In SD they recognize that human beings have normal 'tendencies' towards certain behaviors, such as exploration, attachment, sexual expression, self protection etc etc. And in the theory of structural dissociation there are very particular patterns of alters that can be grouped or understood according to which human tendency they express.
For instance it is common for young 'cute' child like alters to contain and express the tendency for attachment. Likewise there are classifications of alters that hold the tendency for defense (protection). And yes there are classifications of alters that hold the human tendency for expression or experience of intense emotion.

I would guess that 'sense of agency' is another way of meaning 'expression of human tendency'. In relation to DID it just kinda means that an alter deals / carries / feels a particular experience or typical human activity (not necessarily in healthy adaptive ways though).