Reward shaping for orchestrator-driven agent swarms requires at least three distinct reward signals — instantiation, finish, and outcome — specifically to prevent two degenerate behaviors: serial collapse (the orchestrator does everything itself) and spurious parallelism (spawning agents that contribute nothing).
Multi-agent speedups are not automatic; without explicit rewards for when to spawn and when to terminate sub-agents, the orchestrator degenerates into either a single serial agent or wasteful fan-out. This tells builders that the decomposition policy itself is a learned, reward-shaped artifact rather than a static planner rule, and that harnesses need per-behavior reward instrumentation, not just a final task-success signal.
Any orchestrator/worker architecture (including non-RL planners) needs explicit incentives or heuristics for spawn justification and termination, otherwise fan-out cost is paid without parallelism benefit.
Reinforcement learning for agent swarms requires instantiation, finish, and outcome rewards to prevent serial collapse and spurious parallelism.
Agent swarms save significant execution time on complex tasks compared to single agents.