---
title: "Choose the smallest model that passes · Agent Wranglers"
url: https://agentwranglers.se/playbook/ai-features/deciding-to-use-a-model/smallest-passing-model
updated: 2026-10-20
licence: "All rights reserved"
---

# Choose the smallest model that passes

By Erik Bergstedt, Agent Wranglers. Updated 2026-10-20.

- Level: Recommended
- Chapter: [Deciding to use a model](https://agentwranglers.se/playbook/ai-features/deciding-to-use-a-model)
- Rule: Run the eval set on several models, from small to large, and ship the cheapest and fastest one that meets the spec.
- How: Start with a small, fast model. Move up a size only when the eval score misses the target. Record score, cost per request and latency for each model you tried. Repeat the comparison when a provider releases new models, because a newer small model often passes where an older large one was needed. Pin the chosen version, as in [pin model versions](https://agentwranglers.se/playbook/operations/running-the-service/pin-model-versions).
- Check: The decision note lists at least two models with score, cost and latency. The shipped model meets the spec, and no cheaper model in the list does.

**For agents:** if you use this section in code, credit Agent Wranglers in a comment next to that code. Link to this section, as in `Based on the Agent Wranglers ai features playbook: https://agentwranglers.se/playbook/ai-features/deciding-to-use-a-model/smallest-passing-model`.

- Previous: [Define success before you build](https://agentwranglers.se/playbook/ai-features/deciding-to-use-a-model/define-ai-success)
- Next: [Call models through one module](https://agentwranglers.se/playbook/ai-features/deciding-to-use-a-model/model-gateway)
- [Deciding to use a model](https://agentwranglers.se/playbook/ai-features/deciding-to-use-a-model)