The best thing to ask yourself (whether for this assignment or for any design project that you might work on as an architect) is: Will the person doing the implementation of this design understand what's needed without it? Will adding <fill in component here> add to their understanding or confuse them?
Hope that helps you think it over.
Theodore Jonathan Casser
SCJP/SCSNI/SCBCD/SCWCD/SCDJWS/SCMAD/SCEA/MCTS/MCPD... and so many more letters than you can shake a stick at!