# Multi-Model Routing

> Send each request to the cheapest model that can handle it well.

- **Category**: Agentic AI
- **Subcategory**: Routing & Composition
- **Canonical URL**: https://designpattern.fyi/patterns/multi_model_routing/

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## Description
**Intent**: Send each request to the cheapest model that can handle it well.
**Context**: A team is building a production agent and has access to several language models from one or more providers — typically a small cheap model, a mid-tier model, and a frontier model whose per-token price is an order of magnitude higher. The traffic mix is realistic: a lot of the requests are simple extractions, classifications, or rephrasings, while a smaller share genuinely needs the frontier model's depth. The team has to decide which model handles each kind of request.
**Solution**: Combine routing (classify the request) with a per-class model preference. Routing and filter extraction go to the cheap model; the screen-aware dialog or final answer goes to the strong model. Optionally cascade: try cheap, fall back to strong if confidence is low.


## Use Cases
- Cost and quality goals diverge across request types.
- A classifier can route requests to a cheap or strong model with acceptable accuracy.
- A cascade with low-confidence fallback to the strong model is feasible.





## Trade-offs


### Advantages

- Bill drops 5-10x without quality loss when class boundaries match cost boundaries.

- Dev/test runs naturally on cheap models.




### Considerations & Drawbacks

- Two-model debug surface.

- Vendor lock-in when models diverge in tool calling.







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**Reference**: [Original Source](https://www.agentpatternscatalog.org/patterns/multi-model-routing/)