improve-harness

improve-harness is a skill for Claude Code, Codex from KaydenClark/LLM_Workbench. It costs 86 tokens per session (2,643 once invoked), scanned A, original, MIT.

A one-cycle method for improving the environment around a fixed coding agent and job. It compares a baseline, finds the earliest failure in the harness, makes the smallest responsible change, verifies it, reruns the job, and records the result.

In plain words
What is it for?
Use it when an agent job went badly or new harness feedback arrives, to adjust the available context, tools, boundaries, or verification and decide whether to keep the change.
Why use it?
It focuses improvement on the actual cause of a failed run rather than changing many things at once. A harness is the surrounding context, tools, limits, and feedback that shape an agent's work.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one. Also seen: mentions AGENTS.md.

Good fit Use it when an agent job went badly or new harness feedback arrives, to adjust the available context, tools, boundaries, or verification and decide whether to keep the change.

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Install with agentmods
npx agentmods add skills/kaydenclark/llm_workbench/improve-harness
Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add KaydenClark/LLM_Workbench --skill improve-harness
Clone the repo
git clone --depth 1 https://github.com/KaydenClark/LLM_Workbench

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for improve-harness

README.md
[![agentmods](https://agentmods.dev/badge/skills/kaydenclark/llm_workbench/improve-harness/github.svg)](https://agentmods.dev/skills/kaydenclark/llm_workbench/improve-harness)
Your own site
<a href="https://agentmods.dev/skills/kaydenclark/llm_workbench/improve-harness"><img src="https://agentmods.dev/badge/skills/kaydenclark/llm_workbench/improve-harness/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for improve-harness

Your own site · 80×15
<a href="https://agentmods.dev/skills/kaydenclark/llm_workbench/improve-harness"><img src="https://agentmods.dev/badge/skills/kaydenclark/llm_workbench/improve-harness.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 86 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,643 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00086 $0.02643
Opus 5.5 $0.00034 $0.01057
Sonnet 5.5 $0.00017 $0.00529
Haiku 4.5 $0.00009 $0.00264

Measured 12d ago against content hash 39828d70ef23, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

improve-harness scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 12d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

workbench/skills/improve-harness/SKILL.md · 260 lines

How it starts

The opening of the file, as written. The whole thing — 260 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Improve Harness

Harness engineering improves what agents produce by shaping the environment around a fixed model and agent: the context it can reach, the tools it can call, the boundaries it works inside and the feedback that proves its work. This skill is the one procedure for improving that environment around one observed job. It runs one loop:

baseline -> earliest gap -> smallest owning intervention -> native verification -> fresh rerun -> retain, revise or remove

The loop's shape follows Ryan Lopopolo's improve-harness playbook (CC BY 4.0, linked and attributed on the LLM Workbench Wiki's harness engineering lineage page); this skill is written in the Workbench's own words and copies nothing. It replaces a family of review stages with one pass that either closes the job under the observed conditions or names the next missing boundary. Comparative, causal or longitudinal claims need the room's evaluation procedures, not this loop.

Purpose

Take one bounded, representative job that a fixed worker ran in this room, find the earliest point where the harness failed it, make the smallest change at the owner that can shape future runs, prove the change through the room's own checks and a fresh rerun, and then decide whether the change earns its carrying cost. The durable result is a better environment and its evidence, not another harness component.

Method

Read before changing. Every step until the fourth is read-only: the baseline and the gap are established from the room's controls, source, tests, records and the job's trajectory with non-mutating checks only, and a change to Actuality happens only inside the authority the current request and AGENTS.md grant. Read each claim by the Governance Plane it plays in this operation: Canon (the binding current-state rule), Grounding (evidence about whether the work was done correctly), Actuality (the target as it is) and Enduring Context (durable reference). A control that says a thing is not proof the thing happened, and a passing check is not proof the worker was expected to attach it.

Read the full file on GitHub · 260 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 12d ago First seen · 260 lines · 86 tokens per session scan A 39828d70ef23

Subscribe to this mod's changes

improve-harness is a skill published in the GitHub repository KaydenClark/LLM_Workbench (2 stars, last pushed 2d ago), licensed MIT. It adds 86 tokens to every session and 2,643 once invoked, about $0.0003 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-10-07.

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