Case Study: Teresa Torres’s AI Interview Coach

A PM and educator with almost no recent coding experience went from “what’s an eval?” to a production beta in about four months, applying each course lesson to a real product.

AspectWhat she didVault link
ProductGrades customer-interview transcripts on 4 rubric dimensions, with excerpt + tip feedback. Grew from 1 prompt to 5–9 LLM calls–
Traces and first annotation UIAirtable (a known tool, to limit how much was new at once)Annotation Tools and Review Interfaces
AnalysisA Jupyter notebook with ChatGPT/Claude as a tutor, never running code she didn’t understandMinimum Viable Eval Setup
Highest-harm failuresThe coach suggesting leading questions and general questionsError Analysis
Leading questionsLLM judge, iterating on input granularityLLM-as-Judge
General questionsKeyword code assertion, very highly aligned. Spotting that took domain expertiseCode-Based Evals
Context engineeringCached helper functions extract tips and questions, so judges see minimal input and iteration is cheapJudge Context and Context Rot
SurprisesA results grid exposed a helper bug and a case where the eval was more right than her labels, which pushed her to sharpen the rubricCriteria Drift
Big winRepeated excerpts across dimensions went from 81% to 3% through a workflow change (pass used excerpts forward), not a prompt tweak. It needed a new eval just to detect the problem, then an A/B testMulti-Step Workflow Evaluation
Process lessonError-analyze whole traces (what the customer sees) to prioritize. Per-dimension annotation only for targeted evalsError Analysis
NowClaude Code pair-programming, evals separated from the analysis notebook, some evals as production guardrails or sampled monitors, and many small vibe-coded annotation UIsCI Evals vs Production Monitoring

Why it’s a model example (per Hamel): she measured before fixing (81% → 3%), picked cheap evaluators where possible, worked like a data scientist investigating disagreements, and kept the domain expert (herself) at the center.