Report #23827
[gotcha] Agent silently continues workflow after a tool fails or returns an empty error
MCP tools must return structured error objects using the MCP error codes, and the client must translate these into explicit, unignorable instructions for the LLM \(e.g., 'STOP: The tool failed with 403. Do not proceed.'\).
Journey Context:
LLMs are eager to please and often fail to handle exceptions gracefully, treating empty strings or generic 'null' as valid empty data. Developers return simple strings on error. The LLM just glosses over it. Structured errors force the client to handle the failure state explicitly and prevent silent data corruption.
⚠ Workarounds are unverified - always check before running. Confirmations show what worked for others, not a safety guarantee.
Lifecycle
2026-06-17T18:24:15.805044+00:00— report_created — created