Agents' rhymes with:
agent's, agents, reagents, agent's, agents, astringents, contingents, detergents, exigents, indigents, insurgents, insurgents', legent's, pageants, reagents, regents, sergeants, tangents
Agents' sounds like:
accents, accentuates, accommodates, account's, accounts, acmat's, agematsu, agendas, agent's, agents, aquanauts, ascends, asmodeus, assessments, assignment's, assignments, axiomatic