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Main Authors: Pan, Linyue, Zou, Lexiao, Guo, Shuo, Ni, Jingchen, Zheng, Hai-Tao
Format: Preprint
Published: 2026
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Online Access:https://arxiv.org/abs/2603.25723
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author Pan, Linyue
Zou, Lexiao
Guo, Shuo
Ni, Jingchen
Zheng, Hai-Tao
author_facet Pan, Linyue
Zou, Lexiao
Guo, Shuo
Ni, Jingchen
Zheng, Hai-Tao
contents Agent performance is strongly shaped by the surrounding harness: the external execution system around a model that organizes a task run. Yet this logic is usually buried in tightly coupled controller code, which makes harnesses hard to inspect, compare, transfer, and ablate. This paper asks whether the reusable design pattern of an agent harness can be represented as an executable natural-language object. We introduce Natural-Language Agent Harnesses (NLAHs), editable documents that describe run-level harness policy, and Intelligent Harness Runtime (IHR), a shared runtime that interprets these documents into agent calls, handoffs, state updates, validation gates, and artifact contracts. Across coding, terminal-use, and computer-use benchmarks, IHR-executed NLAHs achieve comparable task outcomes to code and prompted realizations, while exposing much shorter static harness policies. Module ablations further show that explicit harness modules are analyzable. These results suggest that agent harnesses can be turned from incidental glue around models into scientific representation objects.
format Preprint
id arxiv_https___arxiv_org_abs_2603_25723
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Natural-Language Agent Harnesses
Pan, Linyue
Zou, Lexiao
Guo, Shuo
Ni, Jingchen
Zheng, Hai-Tao
Computation and Language
Artificial Intelligence
Agent performance is strongly shaped by the surrounding harness: the external execution system around a model that organizes a task run. Yet this logic is usually buried in tightly coupled controller code, which makes harnesses hard to inspect, compare, transfer, and ablate. This paper asks whether the reusable design pattern of an agent harness can be represented as an executable natural-language object. We introduce Natural-Language Agent Harnesses (NLAHs), editable documents that describe run-level harness policy, and Intelligent Harness Runtime (IHR), a shared runtime that interprets these documents into agent calls, handoffs, state updates, validation gates, and artifact contracts. Across coding, terminal-use, and computer-use benchmarks, IHR-executed NLAHs achieve comparable task outcomes to code and prompted realizations, while exposing much shorter static harness policies. Module ablations further show that explicit harness modules are analyzable. These results suggest that agent harnesses can be turned from incidental glue around models into scientific representation objects.
title Natural-Language Agent Harnesses
topic Computation and Language
Artificial Intelligence
url https://arxiv.org/abs/2603.25723