when ur in the ministry u get posted into one of the several dept...there are diff dept within FSP like protocol/desks associated with diff regions of d world eg SA desk or Middle east desk/cypher dept/administrative /audit...
as the name applies each has desk has peculiar type of responsibilities ..

when ur abroad ur responsibilities are diff as you are there to facilitate ur ambassador in whatever way possible...like coordinating his visits/providing him up to date info reg various issues that might be an issue of discussion etc

overall every FSP officer must have command over his writing/reading/speaking skills.....as a third sec/Asst Dir your major responsibility would be writing briefs/summaries/reports on issues of daily concerns ...as u move up the ladder your interaction with envoys of other countries in d form of meetings increases and hence ur set of responsbilities also become diff...