Reasoning Models

Purpose: Get reliable answers from reasoning models without overspending or stalling on tasks that do not need them.

When to Use This Skill

• Choosing between a reasoning model (o3, GPT-5 thinking, Claude extended thinking, DeepSeek R1, Gemini Thinking) and a fast model
• Setting reasoning_effort (low / medium / high) or thinking-token budgets
• Designing prompts for reasoning models (different from chat models)
• Combining reasoners (planner) with fast models (executor)
• Diagnosing high cost or latency on reasoning calls

When NOT to Use a Reasoning Model

• Routine extraction, summarization, classification -- a fast model is cheaper and faster
• Strict latency budget (<2s end-to-end) -- reasoning models add seconds
• Tool-use-heavy loops where each turn is short -- fast model + scaffolding is usually better