agent failed to generate anomaly report error failed to fetch monte carlo metrics

TL;DR

Separate the fetch failure from the report failure: test the metrics API call the agent makes on its own, check the returned payload shape against what the report builder expects, and add a cached fallback of the last good metrics so one API outage does not kill the whole report. The agent should report the fetch failure explicitly instead of producing an empty or invented report.

agent failed to generate anomaly report error failed to fetch monte carlo metrics

Use this when

• The check or run fails with this symptom: the agent's anomaly report generation fails at the metrics fetch step.
• You are working on an agent that cannot fetch Monte Carlo metrics for its anomaly report and the failure repeats on the same data or configuration.
• You need the failing rows, rule, or stage isolated before changing thresholds or code.

Not for this skill when

• A report that renders wrongly from successfully fetched metrics, which is a rendering bug instead.
• The error text names a different tool, stage, or root cause. Match the verbatim error first and use that skill.

Steps

1. Replay the agent's metrics request manually with the same parameters and capture the response status and body shape. Verify: the request's real response is captured
2. Compare the response fields with the fields the report builder reads, looking for renamed or nested metric fields. Verify: field differences between API and builder are listed
3. Check the API credential's scope: whether it can read the monitors and tables the report asks for. Verify: the credential scope is verified against the request
4. Fix the request or the builder mapping, and add a fallback that marks the report as using cached metrics with their timestamp when the fetch fails. Verify: the fix is applied and the fallback is explicit
5. Generate the report end to end and confirm every metric in it traces to a fetched value. Verify: the report's metrics all trace to the fetch

Variant phrasings

agent failed generate anomaly report monte carlo metrics fetch

The verbatim report-fetch phrasing.

monte carlo API metrics field changed report builder

The field-change phrasing for API shape drift.

agent anomaly report cached metrics fallback timestamp

The fallback phrasing for explicit cached data.

Compatibility: Agent reporting against Monte Carlo style APIs and warehouse metric stores

Why it happens

Report builders assume the metrics API returns a stable shape with a readable credential, and either assumption breaking produces the same generation failure. Worse, an agent under pressure to produce a report may fill gaps from memory, so the fetch must be verified independently of the report.

Edge cases / pitfalls

• Never let the agent estimate missing metrics. A report with an explicit gap is useful; an invented number is not.
• Pin the API version the builder targets and note it in the report footer.

Provenance

Resolved from the public thread: https://vectle.com/posts/pst_nMHeKVubqkR6Uznfx0vFyw