The selected option specifically B states “Add retries with exponential backoff and set request timeouts”, which matches the operational requirement rather than a superficial wording match. The decisive point is failure isolation: Option B keeps the agent’s decision path observable instead of burying behavior inside one prompt or one service. The implementation detail that matters is tool contracts that can be versioned, tested, and observed independently from the reasoning loop. Slow APIs require timeouts and bounded retries with backoff. Caching can help cost, but it does not solve live workflow robustness. That is why the other options are traps: manual tool wiring scales poorly as the catalog grows and usually fails silently when a vendor updates parameters or response fields. The stack-level anchor is clear: NeMo Agent Toolkit treats agents, tools, and workflows as composable functions, so tool-calling agents can choose from names, descriptions, and schemas rather than guessed endpoints. That is the difference between an agent that works in a notebook and an agent that remains reliable in production.