Route AI queries cost‐efficiently with GPT‐4o‐mini, GPT‐4o and confidence scoring

This workflow implements a cost-optimized AI routing system using n8n. It intelligently decides whether a request should be handled by a low-cost model or escalated to a higher-quality model based on response confidence.

The goal is to minimize LLM usage costs while maintaining high answer quality.

A query is first processed by a cheaper model. The response is then evaluated by a confidence-scoring AI agent. If the response quality is insufficient, the workflow automatically escalates the request to a more capable model.

This approach is useful for building scalable AI systems where most queries can be answered cheaply, while complex queries still receive high-quality responses.

How It Works

1. Webhook Trigger

• Receives a user query from an external application.

1. Workflow Configuration

• Defines parameters such as:
• confidence threshold
• cheap model cost
• expensive model cost

1. Cheap Model Response

• The query is first processed using GPT-4o-mini to minimize cost.

1. Confidence Evaluation

• An AI agent analyzes the response quality.
• It evaluates accuracy, completeness, clarity, and relevance.

1. Structured Output Parsing

• The evaluator returns structured data including:
• confidence score
• explanation
• escalation recommendation.

1. Decision Logic

• If the confidence score is below the configured threshold, the workflow escalates the request.

1. Expensive Model Escalation

• The query is reprocessed using GPT-4o for a higher-quality answer.

1. Cost Calculation

• Token usage is analyzed to estimate:
• total cost
• cost difference between models.

1. Final Response Formatting

• The workflow returns:
• AI response
• model used
• confidence score
• escalation status
• estimated cost.

Setup Instructions

1. Create an OpenAI credential in n8n.

2. Configure the following nodes:

• Cheap Model (GPT-4o-mini)
• Expensive Model (GPT-4o)
• OpenAI Chat Model used by the confidence evaluator agent.

1. Adjust configuration values in the Workflow Configuration node:

• confidenceThreshold
• cheapModelCostPer1kTokens
• expensiveModelCostPer1kTokens

1. Deploy the workflow and send requests to the Webhook URL.

Example webhook payload:

{
 "query": "Explain how photosynthesis works."
}