# Can an agent recover from a tool call that returns a wrong value in the right shape?

Sometimes, if something is watching for it. A 2026 study checks each tool result against an "outcome contract," a rule for what that value should look like, mined from the tool's normal runs or taken straight from its schema; a negative inventory count or a cached error page returned as data both break one. When a rule breaks, nothing is blocked or rewritten. The agent gets a note naming the broken rule and the recovery tools available, and decides itself what to do next. Across four models in two model families, that lifted completion on a benchmark of injected tool failures from 10.9% to 28.1%, with a third model family replicating the result, and lifted tau-bench's retail tasks by 12 to 14 points across DeepSeek V4 Flash and Pro. The gain only reaches as far as the contracts do: on failures outside the mined vocabulary, the agent caught less than half of them. [What are the ways a single tool call can fail](/answers/tool-calling/what-are-the-ways-a-tool-call-can-fail) covers the failure itself; this is about whether anything notices once it happens.

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Sources:
- "Outcome Monitors: Recovery Affordances for Silent Tool Failures" (arXiv:2608.19303): https://arxiv.org/abs/2608.19303 (fetched 2026-10-14)

Source: https://tessary.ai/answers/silent-failures/can-an-agent-recover-from-a-tool-call-with-a-wrong-value
More on Silent failures: https://tessary.ai/answers/silent-failures
From Tessary, agent reliability for AI agents in production: https://tessary.ai