AI Engineering Judgment/When (Not) to Use AI
Intermediate11 min

Classification & Routing

Intent classification is the backbone of most real AI systems. Learn to build query routers that send different types of inputs to specialized handlers — with confidence thresholds, fallback strategies, and hybrid fast-path/LLM architectures.

Quick Reference

  • Intent classification is the first step in nearly every production AI system — get it right and everything downstream improves
  • Use structured output (JSON mode or function calling) for reliable classification labels
  • Set confidence thresholds: high confidence → auto-route, medium → fast model, low → human review
  • Hybrid routing: keyword/regex for common intents, LLM for ambiguous or novel queries
  • Always log classification decisions with confidence scores for later analysis and fine-tuning
  • Multi-label classification (query can have multiple intents) is common in production — plan for it

Why Classification Is the Foundation

Most production AI systems are not a single monolithic LLM call. They are a routing layer that classifies the input and sends it to the right handler. A customer support bot routes billing questions to the billing agent, technical questions to the troubleshooting agent, and sales questions to the sales flow. A coding assistant classifies whether the user wants to edit code, explain code, generate tests, or fix a bug — each handler has different context, tools, and prompts.

Classification Accuracy Is a Multiplier

If your classifier is 90% accurate, every downstream handler starts with a 10% handicap — it receives queries it was not designed for. Improving classification accuracy from 90% to 98% often has a bigger impact on overall system quality than improving any individual handler.

  • Routing reduces latency: specialized handlers use shorter prompts and smaller context windows
  • Routing reduces cost: simple queries go to cheap models, complex queries go to expensive ones
  • Routing improves quality: each handler is optimized for its specific task
  • Routing enables specialization: different tools, different system prompts, different few-shot examples per intent