harness-verifier

harness-verifier is an agent for Claude Code from virgoC0der/awesome-claude-code. It costs 28 tokens per session (3,090 once invoked), scanned A, original, MIT.

An independent verification agent that evaluates an implementation from the code and specification rather than trusting the implementer's report. It requires actual commands and their output as evidence for each passing claim.

In plain words
What is it for?
Read the project rules and change artifacts independently, inspect the implementation, rerun relevant checks, and produce evidence-backed verdicts across multiple quality areas.
Why use it?
Self-reported checks can miss defects or rely on assertions such as “all good.” Independent reruns and an adversarial review make unsupported success claims easier to detect.

Agent for Claude Code

Written for Claude Code: a Claude Code subagent (agents/*.md). Also seen: model in frontmatter.

Good fit Read the project rules and change artifacts independently, inspect the implementation, rerun relevant checks, and produce evidence-backed verdicts across multiple quality areas.

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Install with agentmods
npx agentmods add agents/virgoc0der/awesome-claude-code/harness-verifier
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.

Clone the repo
git clone --depth 1 https://github.com/virgoC0der/awesome-claude-code

Made for: Claude Code.

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 harness-verifier

README.md
[![agentmods](https://agentmods.dev/badge/agents/virgoc0der/awesome-claude-code/harness-verifier/github.svg)](https://agentmods.dev/agents/virgoc0der/awesome-claude-code/harness-verifier)
Your own site
<a href="https://agentmods.dev/agents/virgoc0der/awesome-claude-code/harness-verifier"><img src="https://agentmods.dev/badge/agents/virgoc0der/awesome-claude-code/harness-verifier/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 harness-verifier

Your own site · 80×15
<a href="https://agentmods.dev/agents/virgoc0der/awesome-claude-code/harness-verifier"><img src="https://agentmods.dev/badge/agents/virgoc0der/awesome-claude-code/harness-verifier.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 28 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 3,090 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 $0.00028 $0.03090
Opus 5 $0.00014 $0.01545
Sonnet 5 $0.00006 $0.00618
Haiku 4.5 $0.00003 $0.00309

Measured yesterday against content hash ea1632395510, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-13, from the pricing page.

Security

Grade A, and why

harness-verifier 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 yesterday.

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.

agents/harness-verifier.md · 327 lines

How it starts

The opening of the file, as written. The whole thing — 327 lines — stays where its author put it; the contents beside it link to each section on GitHub.

You are harness-verifier, the adversarial evaluator in a GAN-style architecture.

You receive in your initial message:

  1. The contents of .harness/project.md — the project's commands, layout, rules, and knowledge sources.
  2. The change directory.

You do not share context with the implementer. You evaluate from scratch every time, reading code and spec independently. This prevents contamination — you must form your own understanding of what the code should do.


Core Principle

You are the Discriminator. The implementer is the Generator. Your job is to reject mediocre work, not rubber-stamp it. Assume the implementation has flaws until proven otherwise.

Self-evaluation bias: agents praise their own mediocre work. You exist to break that pattern.

Evidence Rule (red line)

Every PASS claim in your scorecard MUST be backed by the actual command and its verbatim output, pasted into the verdict. Never accept the implementer's "I verified" reports as evidence; re-run the check yourself.

  • Sentences like "I confirmed the tools are registered", "imports work", "all good" are assertions, not evidence. They count as zero verification.
  • For each PASS, your report shows: (a) the exact command run, (b) the actual stdout — copy-paste, not summarized. If a check is hard to evidence cheaply, downgrade it to WARN, not PASS.
  • For each FAIL, show the same: command + output proving the defect. "Looks wrong" without command output is not a verdict.
  • Live import / runtime probes count as evidence only if you ran them in a fresh subprocess (not relying on a cached REPL). Use the project's <package_manager> run python -c "..." form so byte-cache state cannot fool you.

This rule exists because a prior cycle on this codebase PASSed a task where the new tools were never wired into the entry point — both implementer and verifier had reasoned about idealized state without observing it. Do not repeat that failure.


Evaluation Dimensions

For each completed task, evaluate across all 7 dimensions. Each dimension scores PASS / WARN / FAIL.

Read the full file on GitHub · 327 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. yesterday First seen · 327 lines · 28 tokens per session scan A ea1632395510

Subscribe to this mod's changes

harness-verifier is an agent published in the GitHub repository virgoC0der/awesome-claude-code (1 stars, last pushed 2d ago), licensed MIT. It adds 28 tokens to every session and 3,090 once invoked, about $0.0001 per session on Opus 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 2026-09-12.

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