World's Fair 2025
Turning Fails into Features: Zapier’s Hard-Won Eval Lessons — Rafal Willinski, Vitor Balocco, Zapier
Rafal Willinski , Vitor Balocco , Zapier
Overview
Building effective AI agents and the platforms that enable non-technical users to create them is a complex challenge due to the inherent nondeterminism of AI and unpredictable user behavior. The process requires a shift from traditional software development to building a data flywheel that continuously collects feedback, understands usage patterns, and identifies failures to improve the product iteratively. This involves robust instrumentation, strategic feedback collection, and a tiered approach to evaluation.
Who should watch
- AI Engineers
- Product Managers
- Builders of AI-powered products
- Teams struggling with AI agent reliability
- Those looking to improve their AI evaluation strategies
Key takeaways
- Instrument code thoroughly to log not just completion calls but also tool calls, errors, and pre/postprocessing steps for easier debugging and repeatable evaluation runs.
- Actively solicit user feedback in context, such as immediately after an agent run, to increase submission rates.
- Mine user interactions for implicit feedback signals like agent activation, copying responses, or conversational cues indicating dissatisfaction.
- Employ a hierarchical evaluation strategy, starting with unit-test-like evals for specific failure modes, progressing to trajectory evals for multi-turn interactions, and culminating in A/B testing for real-world validation.
- Leverage LLMs as judges or for rubric-based scoring to benchmark system capabilities and compare model performance, but be mindful of potential biases and the need for careful setup.
- Avoid overfitting unit tests to specific models or paths; trajectory evals are better for assessing end-to-end performance and tool usage.
- Remember that the ultimate goal is user satisfaction, making A/B testing with real user traffic the most reliable method for verifying product improvements.
Notable quotes
*Building good AI agents is hard and building good platform to enable nontechnical people to build AI agents is even harder.*
*The ultimate judge are your users. You shouldn't be optimizing for the biggest scores for the evos and completely disregard the vibes.*
Unofficial community note. Prefer the recording for nuance.