Hill-Climbing Agent Quality with Agents CLI Evaluation

A walkthrough of the Agents CLI eval loop using the LangChain template in Agents CLI v1.8.0, covering a baseline run (mean 4.0), a system-prompt regression that dropped the mean to 2.75, per-case diffs via eval compare, and a gemini-3.8-flash to gemini-2.5-flash swap whose mean drop traced to a single off-topic case. It also shows scheduling eval runs with cron or Cloud Scheduler, a script that exits non-zero when scores fall past a threshold, and eval optimize for automated prompt hill-climbing on ADK projects.