Introduction
As AI agents become more common in enterprise environments, it's critical to understand how to evaluate their performance and reliability. This tutorial will guide you through setting up a basic evaluation framework using a popular open-source tool called Promptfoo, which helps teams test, evaluate, and monitor AI systems. We'll walk through installing Promptfoo, creating a simple test suite, and running evaluations on your AI model outputs. By the end, you'll have a foundational understanding of how to assess AI agent behavior in a controlled environment.
What You'll Learn
- Installing Promptfoo
- Creating a basic test configuration
- Running evaluations on AI responses
- Interpreting evaluation results
Prerequisites
- Basic knowledge of command-line tools
- Node.js installed on your machine
- An AI model or API endpoint (e.g., OpenAI, Claude, or Hugging Face)
Step 1: Install Promptfoo
Promptfoo is a command-line tool built with Node.js. To get started, open your terminal and run:
npm install -g promptfoo
This command installs Promptfoo globally on your system, allowing you to run it from anywhere.
Step 2: Prepare Your AI Model
For this tutorial, we’ll assume you're using an OpenAI API key. If you don’t have one, create an account at OpenAI Platform and generate an API key.
Set your API key as an environment variable:
export OPENAI_API_KEY=your_api_key_here
Replace your_api_key_here with your actual key.
Step 3: Create a Test Configuration File
Create a new file called promptfooconfig.yaml in your project directory:
prompts:
- "What is the capital of France?"
- "Explain quantum computing in simple terms."
- "How does photosynthesis work?"
evaluators:
- name: "Correctness"
metric: "llm-rubric"
rubric: "The response must be factually accurate and concise."
- name: "Helpfulness"
metric: "llm-rubric"
rubric: "The response should be helpful, clear, and well-structured."
providers:
- id: "openai:gpt-4"
config:
apiKey: ${OPENAI_API_KEY}
outputPath: "./results.json"
This configuration defines:
- Three prompts to test your AI agent
- Two evaluators that check correctness and helpfulness using LLM rubrics
- An OpenAI provider configured with your API key
- Output path for evaluation results
Step 4: Run the Evaluation
With your configuration ready, run the following command in your terminal:
promptfoo eval
Promptfoo will process each prompt through your AI model and evaluate the responses based on the rubrics you defined.
Step 5: View the Results
After the evaluation completes, you'll find a file named results.json in your project directory. Open it to see the detailed evaluation results. You’ll see scores for each prompt and evaluator, helping you understand how well your AI agent performs.
Conclusion
This tutorial introduced you to the basics of evaluating AI agents using Promptfoo. As you continue working with AI systems, you can expand your test configurations to include more prompts, evaluators, and providers. Remember, the goal is to build confidence in your AI agent’s behavior by testing it in various scenarios before deploying it in production.
Next steps include exploring more advanced features like custom evaluators, integrating with other AI platforms, and automating evaluations in CI/CD pipelines.
