Glossary entry model-routerEngines & bots

Model router

The component that decides which LLM (and which retrieval pipeline) handles each query. It's invisible to the user but consequential for AEO.

Filed under: Engines & bots

Definition

A model router is the infrastructure that, given a user query, decides which model handles it: fast/cheap model for simple lookups, frontier model for complex reasoning, search-tool-enabled model for grounded answers. ChatGPT, Claude.ai, Perplexity, and Gemini all use model routers. Different routes = different retrieval pipelines = different citation patterns. Some routes never trigger a web fetch.

Example

ChatGPT may answer 'what's the capital of France' from training data (no citation), but 'what's Stripe's current pricing' from web tool (cited).

How to optimize

Optimize for retrieval-enabled routes. Queries that mention current dates, prices, comparisons, or news typically route to the tool-enabled model. Those are your AEO targets.

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