# Model Routing Is Simple. Until It Isn't.

DevFeed: [Model Routing Is Simple. Until It Isn't.](<https://devfeed.tech/articles/model-routing-is-simple-until-it-isn-t-7268.md>)

Original publisher: [Read original article](<https://huggingface.co/blog/ibm-research/model-routing-is-simple-until-it-isnt>)

Author: Yara Rizk; Eyal Shnarch; Jason Tsay; Merve Unuvar

Published: 2026-07-15T17:27:01Z

Content type: article

Language: en

Sources: [Hugging Face - Blog](<https://devfeed.tech/sources/hugging-face-blog.md>)

Topics: [Model Routing](<https://devfeed.tech/topics/model-routing.md>), [Optimization](<https://devfeed.tech/topics/optimization.md>), [systems](<https://devfeed.tech/topics/systems.md>), [Caching](<https://devfeed.tech/topics/caching.md>), [Claude](<https://devfeed.tech/topics/claude.md>), [anthropic](<https://devfeed.tech/topics/anthropic.md>)

Tags: [agentic](<https://devfeed.tech/tags/agentic.md>), [caching](<https://devfeed.tech/tags/caching.md>), [claude](<https://devfeed.tech/tags/claude.md>), [compliance](<https://devfeed.tech/tags/compliance.md>), [cost](<https://devfeed.tech/tags/cost.md>), [enterprise](<https://devfeed.tech/tags/enterprise.md>), [latency](<https://devfeed.tech/tags/latency.md>), [model-routing](<https://devfeed.tech/tags/model-routing.md>), [optimization](<https://devfeed.tech/tags/optimization.md>), [privacy](<https://devfeed.tech/tags/privacy.md>), [production](<https://devfeed.tech/tags/production.md>), [reasoning](<https://devfeed.tech/tags/reasoning.md>), [systems](<https://devfeed.tech/tags/systems.md>), [tool](<https://devfeed.tech/tags/tool.md>)

## AI overview

Model routing in agentic systems is more than classifying task difficulty or comparing list prices. Effective cost depends on the interaction between the model, workload, and serving infrastructure, including cache-hit rates and cache-read pricing. Production routers must balance cost, quality, latency, specialization, reliability, and enterprise governance constraints such as compliance, data residency, privacy, and approved-model policies.

## Source excerpt

Except it's not. Most routing systems assume that model selection is a classification problem. In our experience building routing into agentic systems, what looks like a model-selection problem quickly becomes a systems optimization problem. Three dimensions made this surprisingly hard for us. We expected GPT-4.1 to be cheaper than Claude Sonnet 4.6. It wasn't.