Index Ai Academy
Phase 1 · Building with LLMs · Prompting

Reasoning models and effort

When models think before answering, and how to control it.

About 25 minutes · Free account required

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Why it matters

Modern models can think before they answer. They work through a problem in private, then write the reply. That's why they can now plan an analysis, fix broken code or weigh the options in a brief. But thinking costs tokens, and tokens cost time and money. You can set how hard the model thinks, one task at a time. That setting is one of the biggest levers you have on quality, speed and cost.

What you'll be able to do

  • Explain what thinking is and why it improves answers to hard problems
  • Set the effort level on a request and choose it for a task
  • Read thinking blocks in a response, and ask for readable summaries
  • Budget max_tokens and cost for requests that think

Inside this lesson

  • 11 short sections
  • 4 code examples you can edit and run
  • a practice exercise that checks your code
  • a 5-question quiz
  • 4 review cards for spaced repetition

What it covers

  1. What thinking is
  2. Adaptive thinking and effort
  3. Reading thinking in a response
  4. Thinking costs tokens
  5. Worked example: what does more effort cost?
  6. Keeping thinking blocks in conversations

A taste of the code

body = {
    "model": "claude-opus-5-5",
    "max_tokens": 8000,
    "output_config": {"effort": "low"},   # low, medium, high, xhigh or max
    "messages": [{"role": "user", "content": "Tag this review: 'Arrived chipped.'"}],
}
In the lesson you can change this and run it in your browser.

Try a quiz question

You run 200,000 review-tagging requests a day on Claude Opus 5.5 and they're slower than you'd like. What should you try first?

  1. Set effort to low
  2. Set effort to max
  3. Add a thinking budget of 100 tokens
  4. Set temperature to 0

Answer it at the end of the lesson to see if you're right, and why.

Before this lesson