Verified Tool Calls Improve LLM Agent Reliability Under Non-Atomic Failures

2026-07-31

AI Summary

This work addresses the vulnerability of large language model (LLM) agents to non-atomic failures—such as timeouts, delayed visibility, and partial state updates—in real-world systems when executing multi-step tasks via external tools, which often leads to redundant operations or task failure. To enhance robustness without modifying the underlying LLM, the authors propose a lightweight, verification-aware tool-wrapping mechanism that uniquely integrates post-condition validation with idempotency keys and introduces pre-retry verification logic. Experimental results demonstrate that this approach significantly reduces redundant tool invocations across diverse task templates while maintaining success rates comparable to baseline methods, thereby substantially improving the reliability of LLM agents operating in environments prone to non-atomic failures.

Abstract

Large Language Model (LLM) agents rely on external tools to perform multistage tasks. Existing agent frameworks typically assume that tool calls are atomic and return binary success or failure signals. However, real-world systems exhibit non-atomic behaviors such as timeouts after dispatch, delayed visibility, and partial state updates. These mismatches lead to reliability issues including duplicate actions, task success, and unnecessary tool executions. A lightweight, verification-aware tool wrapper is introduced that augments tool calls with postcondition verification, verify-before-retry logic, and idempotency keys. The approach is evaluated in a controlled simulated environment with injected non-atomic failures across multiple task templates. The results demonstrate that the proposed method significantly reduces duplicate actions, while maintaining comparable task success rates. Overall, the findings suggest that strengthening tool interaction semantics is a promising direction for improving LLM agent reliability without requiring modifications to the underlying language model.

Problem

• LLM agents
• tool calls
• non-atomic failures
• reliability
• external tools

Innovation

• verified tool calls
• non-atomic failures
• postcondition verification
• idempotency keys
• LLM agent reliability