# Does tool_error count a tool's output as failed just because it mentions the word error?

No. tool_error only counts a call as failed on structural evidence: an error status on the span, a recorded exception, or a result payload that itself declares an error. The word `error` showing up somewhere in the output text never counts on its own.

That distinction matters because plenty of normal tool output talks about errors without being one: a support tool returning a list of a user's past error tickets, an agent narrating that it already recovered from a problem, a log line the tool echoes back. Scoring on prose would flag all of that as a failure.

It also catches a case text matching would miss: a tool that catches its own exception, hands back something like `{"error": ...}` in a clean response, and closes the span without raising anything. That's a real failure with no exception recorded, and structural evidence is written to catch it anyway.

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Source: https://tessary.ai/answers/tessary-tool-error/does-mentioning-error-in-output-trigger-tool-error
More on Tessary tool error: https://tessary.ai/answers/tessary-tool-error
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