标签：#evals

The evals for my agent skills scored 0% for as long as I had records. Not low. Not noisy. Exactly zero, every skill, every run. And I believed it. For months I thought my skills were bad, because the number said so and the number never wavered. Then one night I actually read the harness. It had fallen back to the wrong auth token. Every call it made came back 401, and it quietly graded each one a failure. The skills never got a chance to fail on their own. I was not measuring them at all. I was reading a broken thermometer. Real weakness is jagged Here is what took me too long to see. When a system is genuinely bad, it scores 40% one week and 60% the next. It passes the easy cases and trips over the hard ones. It has good days. Incompetence has texture, because an incompetent system is still in contact with the world, and the world varies. A flat number has no texture. A flat number means the measurement stopped touching the thing being measured somewhere upstream, and what you are reading is the instrument's resting state. Doctors know this. A heart monitor drawing a perfectly straight line does not mean the patient is calm. Only a broken thermometer writes the same number every time. Key insight: A performance number with no variance is a reading of the instrument, not of the thing being measured. The same bug in three industries I run systems in advertising, in healthcare billing, and in agent operations, and the same shape shows up in all of them. In advertising I found a dashboard figure that had been hardcoded for two years. Nobody questioned it, because it looked right, and it looked right because it never moved. In agent operations, an account-rotation bug in one of my pipelines overwrote every real error with the same generic message, "no active accounts," so for a while every distinct failure in that system looked identical. And in the denial-assessment engine I run for a medical-billing operation, an agreement metric came back at 44.7%, alarmingly low, un

Learning how to add evals to an LLM feature is the difference between shipping a demo and shipping a reliable product. When you embed an LLM into a real feature — a chatbot, a voice agent, a document summarizer — you’re not just calling a model. You’re betting your user’s experience on a non‑deterministic system that can silently break with every prompt tweak, model update, or edge case. That’s why we instrument every LLM feature we build with a purpose‑built eval suite. Here’s how we did it for an outbound AI calling agent and how you can do the same. Why Evals Are Not Optional LLMs are non‑deterministic: give them the same input twice, and you’ll get two different responses. That means unit tests that check for exact string matches are useless. As Pragmatic Engineer notes , you need evals to verify that the solution works well enough — because there’s no guarantee it will. When you’re building a feature that speaks to real customers, like the AI Calling Agent dashboard we built, a regression in tone or missed booking intent can cost revenue immediately. Evals turn that uncertainty into signal. How to Add Evals to an LLM Feature: A 4‑Step Workflow We’ll walk through the exact process we followed, from defining success to automating checks in CI, using the DeepEval framework as an example. You can swap in Evidently AI or build your own, but the pattern is the same. Step 1: Define Success for Your Feature Takeaway: Before you pick a metric, write down the one thing that makes the feature “done” — usually a business outcome, not a technical measure. For the AI Calling Agent, the core feature was an outbound call that books a meeting. The success criterion wasn’t “the LLM replied politely.” It was “the agent scheduled a meeting with the right time and date.” This is a reference‑based evaluation: you compare the output to a known ground truth. Evidently AI’s guide calls this pattern out as essential for regression testing and experimentation. From that criterion, we der