Best practice L1 · Basic prompts informational

Match the Claude Model to the Task, Not the Hype

What it is

A habit of choosing the Claude model by what the task actually demands — a smaller, faster model for simple high-volume work, the most capable model for hard reasoning — rather than defaulting to the biggest one for everything or the cheapest one to save money.

task complexity →↑ need for depthFast modelhigh-volume, simple,latency-sensitiveFrontier modelhard reasoning, architecture,ambiguityFast modelclassification, extraction,formattingBalanced modelmost day-to-day coding andwriting
Reach for the smallest model that clears the task's bar.

Why it works

Model choice is a trade between depth, speed, and cost. Using the frontier model for classification wastes latency and money; using a small model for genuinely hard architecture wastes your time on a weak answer you have to redo. Matching the model to the task gets you the best answer per second and per dollar, and it clarifies your own thinking about how hard the task really is.

When to use it

Whenever you have a choice of model — in the app, the API, or a coding tool. Especially for anything you'll run at volume, where the wrong choice multiplies.

When not to use it

One-off questions where the cost and latency difference is negligible; just use a capable default and move on. Don't agonise over model choice for a single prompt.

Prompt

I'm about to <describe the task and roughly how often I'll run it>. Given a fast/cheap model, a balanced one, and a frontier one, which fits — and what would I lose by dropping to the next one down? Recommend the smallest model that reliably clears this bar.

Example

For tagging 10,000 support tickets by topic, a fast model does it well at a fraction of the cost and latency; you save the frontier model for the weekly 'analyse the themes and draft a strategy memo' task where its extra reasoning actually shows.

Advanced version

Build a two-tier pipeline: a fast model does first-pass extraction or triage at volume, and escalates only the ambiguous cases to the frontier model. You get frontier-quality on the hard 10% at fast-model cost on the easy 90%.

Common mistakes

  • Defaulting to the biggest model for trivial work and eating needless latency and cost.
  • Using a small model for genuinely hard reasoning and then blaming 'AI' for the weak answer.
  • Never re-checking — task mixes change, and last quarter's right default may be wrong now.

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