I went through Anthropic's Academy a while back and it changed how I think about prompts. The thing that stuck with me: a prompt can look fine on one or two tries and still fall apart the moment the input changes, and most of us never actually check that.
I tried testing one of my own prompts properly, against a real set of cases instead of the two or three I'd normally glance at. It scored 4.9 out of 10, zero percent pass rate. Changed one thing (being explicit about the output format) and it jumped to mostly 8 out of 10.
That gap is what got me building Prompt Eval, a way to run a prompt against a test set and get an actual score instead of a gut feeling.
Curious how others handle this. Do you test prompt changes systematically, or is it mostly "run it a couple times and see if it looks right"?
I built Prompt Eval after going through Anthropic's Academy and realizing how much evaluation actually matters. A prompt can look fine on one try and still fall apart the moment you change the input, and most people (me included) never actually test that.
So I tried it on one of my own prompts. It scored 4.9 out of 10, zero percent pass rate. Changed one thing, being clear and direct about the output format, and it jumped to mostly 8 out of 10.
That's the whole idea: write a prompt, test it against real cases, fix what actually breaks, measure it again.
Everyone tests their code. Almost nobody tests their prompts.
Would love your feedback, especially the rough edges.
As soon as people understand how important evaluating system prompts is, their prompt engineering will go to a different level.