After Missions of Interest groups have been computed (i.e. shown in the Missions of Interest tab), max-level followers display an additional icon in the Followers tab of the Command Table/Garrison Report. Hovering over this icon shows a tooltip listing which MoI missions an individual follower is required for.
Updated follower search:
Prefixing a search term with ! inverts the set of followers it matches; searching for e.g. !Wild Aggression will display followers who cannot presently counter Wild Aggression.
Prefixing a mechanic name with + results in the set of followers whose class/spec has a counter for the mechanic.
Separating search terms with ; results in the intersection of the search terms; searching for e.g. !Wild Aggression;+Wild Aggression will display followers who do not presently counter Wild Aggression, but could counter Wild Aggression if their abilities were re-rolled.
Searching for "Upgradable gear", results in the set of followers whose gear you can presently upgrade.
Searching for "Redundant", after Missions of Interest groups have been computed, results in the set of redundant followers, i.e. those not required by any Mission of Interest.
Searching for "Duplicate counters", results in the set of active followers who share their current mechanic counter combination with at least one other active follower. Searching for "+Duplicate counters" results in the set of followers who share their current mechanic counter combination with at least one other follower.
Separating search terms with / results in the union of the search terms. Note that the above extensions cannot be used with /-containing queries.