arXiv AI

Tool-Calling LLM Agents Under Realistic MCP Faults: Scale Does Not Purchase Fault Tolerance

The paper introduces MCP‑Injector, a fault‑injection middleware that simulates realistic failures in the Model Context Protocol used by large‑language‑model agents. Using data from over 57,000 issue and pull‑request threads, the authors calibrate a fault model and run 1,350 experiments across different backbone sizes, agent stacks, and fault conditions. Results show that permanent‑heavy faults drastically reduce task‑completion scores and that larger models (120B) do not gain fault tolerance, highlighting that framework‑level error handling is more critical than model scale.

arXiv AI
Jul 17

MCPEvol-Bench: Benchmarking LLM Agent Performance Across Dynamic Evolutions of MCP Servers

arXiv:2607. 14642v1 Announce Type: new Abstract: As Model Context Protocol (MCP) servers emerge as the core infrastructure for connecting LLMs with external tools, existing benchmarks leverage real-world MCP servers to evaluate LLM agents' tool-using capabilities.

By Huanxi Liu, Kun Hu, Jiaqi Liao, Qiang Wang, Pengfei Qian, YuanZhao Zhai, Dawei Feng, Bo Ding, Huaimin Wang
arXiv AI
Sep 3

How Fast Do Agents Rot? An Empirical Study of Long-Horizon Degradation in LLM Agents for Production Decision-Making

The paper investigates why large language model (LLM) agents fail on long, multi‑step production workflows despite high benchmark success. By testing nine models (1.2 B–671 B parameters) across six task families and multiple horizons, the authors find that task success follows a geometric decay governed by a per‑step reliability that never reaches 1, leading to inevitable collapse for long horizons. The degradation is driven mainly by step count rather than context length, and the study quantifies a significant gap between benchmark and production performance, especially for agentic tool‑use tasks.

By Shubhra Mittal