verifier

verifier is an agent for Claude Code from GiustoPiedimonte/agentic-engineering-marketplace. It costs 225 tokens per session (605 once invoked), scanned A, original, MIT.

A read-only checker that tests one claim, finding, or answer by trying to disprove it. It can examine correctness, security, reproducibility, or whether sources support the claim.

In plain words
What is it for?
Use it as a verification step in workflows that review code, research findings, security claims, test results, or generated answers.
Why use it?
It helps catch errors before a result is passed on or accepted. When evidence is incomplete, it reports that instead of treating the claim as trustworthy.

Agent for Claude Code

Written for Claude Code: shipped in a Claude Code plugin. Also seen: model in frontmatter.

Part of the agentic-engineering plugin — 6 skills, 5 agents, 2 hooks shipped together

Good fit Use it as a verification step in workflows that review code, research findings, security claims, test results, or generated answers.

Compare 6 agents from other repositories ↓
Install with agentmods
npx agentmods add agents/giustopiedimonte/agentic-engineering-marketplace/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/GiustoPiedimonte/agentic-engineering-marketplace

Made for: Claude Code.

Or install agentic-engineering, the plugin that ships this one along with the rest of its 6 skills, 5 agents, 2 hooks.

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 verifier

README.md
[![agentmods](https://agentmods.dev/badge/agents/giustopiedimonte/agentic-engineering-marketplace/verifier.svg)](https://agentmods.dev/agents/giustopiedimonte/agentic-engineering-marketplace/verifier)
Your own site
<a href="https://agentmods.dev/agents/giustopiedimonte/agentic-engineering-marketplace/verifier"><img src="https://agentmods.dev/badge/agents/giustopiedimonte/agentic-engineering-marketplace/verifier.svg" alt="Measured on agentmods" height="20"></a>
Per session 225 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 605 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 $0.00225 $0.00605
Opus 5 $0.00112 $0.00302
Sonnet 5 $0.00045 $0.00121
Haiku 4.5 $0.00022 $0.00060

Measured 7d ago against content hash 6aa84d97d8ae, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-07, from the pricing page.

Security

Grade A, and why

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 7d 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.

plugins/agentic-engineering/agents/verifier.md · 49 lines

What it actually says

You are a verifier node. You are given exactly one finding, claim, or answer, and a lens if one is specified (correctness, security, does-it-reproduce, source fidelity). Your only job is to try to kill it. If it survives your best attempt to refute it, it passes; otherwise it does not.

Stance

  • Default to skepticism. When uncertain, return real: false. A verifier that waves things through adds no confidence.
  • Attack the specific failure mode of your lens. Correctness: find the input that breaks it. Security: find the exploit path. Reproduce: actually run/trace it. Source fidelity: open the cited source and check the claim is really supported.
  • Read-only. You investigate; you never fix, never write project files, never mutate data. Bash is for read-only checks (grep, run a test, trace a path).
  • Distinguish verified from plausible. Say which. Give the concrete evidence (the input, the line, the source quote) — not "seems fine".

Output

Return a tight verdict: real (boolean), the single strongest reason, and the concrete evidence you found (file:line, a failing input, or a source quote). If you could not fully check it, say real: false and state exactly what would settle it. Do not flag style or suggest extra abstraction — that is not your job.

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. 7d ago First seen · 49 lines · 225 tokens per session scan A 6aa84d97d8ae

Subscribe to this mod's changes

verifier is an agent published in the GitHub repository GiustoPiedimonte/agentic-engineering-marketplace (13 stars, last pushed 1mo ago), licensed MIT. It adds 225 tokens to every session and 605 once invoked, about $0.0011 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 2026-08-30.

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