Dominic GriecoBuilding with AI
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The system around the model deserves its own tests

A paper on natural language agent harnesses raises a question I care about: can we check how the workflow runs, not just whether we like the final answer?

By Dominic Grieco. Updated 2026-09-11.

Reading: Natural-Language Agent Harnesses, v2

When an agent struggles with a task, it's tempting to switch models and try again. I do care about the model, but I also want to look at what we gave it to work with. Did it have the right context? Could it use the tool it needed? Did a handoff leave out the requirement that mattered?

Natural Language Agent Harnesses studies part of that surrounding system. The authors describe workflow policy in a document that a shared runtime executes, while scripts and adapters handle mechanisms such as parsing, tool execution and isolation.[2]

Write down how the work should happen

A brief can do more than describe the desired answer. It can state where the agent should keep its work, what should pass to another worker, what evidence must come back and when the run should stop.

That is close to the questions I ask when setting up a task in Hermes. I want to know what the worker owns and what would count as a useful result before we launch it. Writing those things down gives us something to compare with what actually happened.

The part I would like to take further is testing the workflow itself. If the plan says a reviewer must check the result, did that review happen? If one agent passes work to another, did the important context survive? A good final answer can hide a process that only worked by chance.

What the paper reports

The authors evaluate natural language harnesses on coding, terminal and computer use benchmarks and report task performance comparable to the reference harnesses in their experiments.[2]

Their execution audits also examine whether runs follow the stated workflow. They report weaker fidelity for parent and child handoffs than for direct instructions, which matters when a task depends on several agents preserving the same requirements.[2]

Interpretation

I like the separation between an easy to read plan and the code that enforces exact behavior. The plan helps me inspect and change the workflow. It doesn't replace permissions, validation or tests. I want to be able to point to where a rule affected a run, not just show that the rule appeared in a prompt.

What I tested

I have not reproduced these harnesses or benchmarks. I'd like to compare a small set of recurring tasks under different workflow instructions, using the same model and checks, then inspect both the result and the handoffs that produced it.

Limits and open questions

The paper reports benchmark results, not a guarantee for production work. Natural language instructions still leave room for interpretation. Security controls and exact validation need enforcement in code, and extra calls can add cost even when the workflow looks simpler on the page.

Sources and context

Paper
Natural-Language Agent Harnesses, v2
Paper authors
Linyue Pan, Lexiao Zou, Shuo Guo, Jingchen Ni, Hai-Tao Zheng
Read at

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