Question
Short answer
Trace every run end to end, record tool calls and cost on each step, review failures by segment instead of averages, add evaluations for quality, and alert on changes. Start with traces and add the rest as you need it.
In more detail
A trace per run, with a span for each model call and tool call, answers most debugging questions.
Record tokens, cost and time on every step so a slow or expensive run is easy to spot.
Score outputs on a sample of production runs and on a fixed dataset before each release.
Alert on errors and cost spikes, and block a release that scores worse than the last one.
