Triaging Agent Errors with Phoenix and PXI @arizeai

Uploaded July 2026 | Updated September 2026, 2 weeks ago

Staring at a pile of agent errors? Most of them aren't yours to fix. Here's how to find the ones that are.

Watch this video to learn:

- How to sort agent failures by who actually owns the fix
- Why good eval categories have yes-or-no answers
- How to trace a bug back to the system prompt that caused it

Chapters
00:00 What can we actually fix?
00:21 Filtering to error spans
00:30 Most errors aren't in your control
01:07 Asking PXI to suggest categories
01:28 Root spans → all spans: now there are 17
01:41 Reading PXI's observation journal
02:58 Why categories need yes/no answers
03:38 Pushing back: narrow these down
04:33 Annotating all 17 error spans
05:04 Tip: bypass approvals
06:27 An injection attempt that was a feature
07:19 Purchasing zero items — this one's on us
07:44 Diagnosing the system prompt
09:17 A fix is a hypothesis until you measure it

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Triaging Agent Errors with Phoenix and PXI

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