Should This Endpoint Use Chain-of-Thought?

Your team owns two LLM-backed endpoints:

• /classify-urgency: takes a support message and returns one of low/medium/high urgency, called on every incoming message (millions/day), p95 latency budget of 300ms.
• /plan-migration: takes a description of a database schema change and returns a step-by-step migration plan with rollback steps, called a few hundred times a day by engineers, no hard latency requirement.

A new team member proposes adding "think step by step, then give your final answer" to both prompts because "reasoning models perform better."

1. For each endpoint, say whether you'd add chain-of-thought prompting, and justify it mechanistically rather than by appeal to "reasoning models are better."
2. If you were unsure rather than confident, how would you settle it empirically instead of guessing?
3. For whichever endpoint you do add CoT to, describe the concrete change you'd make to how you capture the reasoning output, and why.