verify

verify is a skill for Claude Code, Codex from alessiomarcone/agent-fieldbook. It costs 67 tokens per session (544 once invoked), scanned A, original, MIT.

A skill for checking AI answers or written artifacts against available evidence. It makes uncertainty visible and looks for unsupported claims, hallucinations, and agreement without sufficient scrutiny.

In plain words
What is it for?
It helps fact-check claims, assess evidence, review technical or customer-facing material, and state when a verdict cannot be reached because no source was provided.
Why use it?
It helps prevent incorrect facts or overconfident conclusions from being accepted or published.

Skill for Claude CodeCodex

Written for Claude Code and Codex: shipped in a Claude Code plugin, but also agents/openai.yaml present.

Part of the knowledge-pack plugin — 10 skills shipped together

Good fit It helps fact-check claims, assess evidence, review technical or customer-facing material, and state when a verdict cannot be reached because no source was provided.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/alessiomarcone/agent-fieldbook/verify
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 alessiomarcone/agent-fieldbook --skill verify
Clone the repo
git clone --depth 1 https://github.com/alessiomarcone/agent-fieldbook

Made for: Claude Code, Codex.

Or install knowledge-pack, the plugin that ships this one along with the rest of its 10 skills.

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 verify

README.md
[![agentmods](https://agentmods.dev/badge/skills/alessiomarcone/agent-fieldbook/verify/github.svg)](https://agentmods.dev/skills/alessiomarcone/agent-fieldbook/verify)
Your own site
<a href="https://agentmods.dev/skills/alessiomarcone/agent-fieldbook/verify"><img src="https://agentmods.dev/badge/skills/alessiomarcone/agent-fieldbook/verify/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 verify

Your own site · 80×15
<a href="https://agentmods.dev/skills/alessiomarcone/agent-fieldbook/verify"><img src="https://agentmods.dev/badge/skills/alessiomarcone/agent-fieldbook/verify.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 67 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 544 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 $0.00067 $0.00544
Opus 5 $0.00034 $0.00272
Sonnet 5 $0.00013 $0.00109
Haiku 4.5 $0.00007 $0.00054

Measured 9d ago against content hash 3d0f5153f4c3, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade A, and why

verify 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 9d 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/knowledge-pack/skills/verify/SKILL.md · 47 lines

How it starts

The opening of the file, as written. The whole thing — 47 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Verify

Apply verification in proportion to risk and make uncertainty explicit.

Evidence gate

Run this before factual analysis. Count sources supplied by the user or actually retrieved in this task. If the count is zero, do not assess, compare, correct, or quote facts from pretrained knowledge. Label every claim ⚠️ Unverified — no evidence available, name the exact authoritative retrieval step, report that a verdict is not yet possible, and stop.

References

  • Read references/ai-literacy.md for knowledge gaps, sycophancy, and hallucination patterns.
  • Read references/regole-distillate.md for cross-cutting verification rules.

Procedure

  1. After passing the evidence gate, classify risk. Use a quick check for reversible internal work and a source-backed check for consequential work.
  2. Extract substantive claims, especially names, dates, figures, quotes, citations, recent changes, and niche facts.
  3. Verify each claim against a source that actually supports it. A claim cannot receive ✅ or ❌ without a supplied or retrieved citation. Prefer current primary sources for product, legal, medical, financial, and technical claims.
  4. Check for sycophancy: neutralize the user's framing, seek counterevidence, and distinguish agreement from support.
  5. Inspect the process: undeclared assumptions, circular reasoning, missing cases, inconsistent calculations, or skipped acceptance criteria.
  6. Perform an independent final pass and state what would make the verdict wrong.

Claim labels

  • Verified — directly supported by cited evidence.
  • ⚠️ Plausible, not verified — include the exact verification step.
  • Contradicted or fabricated — directly contradicted by cited evidence; provide a supported correction.

Close with an overall verdict and What would make this output wrong?

Boundaries

  • Absence of evidence is not evidence of absence.
  • If retrieval tools or supplied sources are unavailable, every factual claim remains ⚠️. Do not provide remembered figures, dates, product history, or corrections; give only the exact authoritative source or retrieval step needed.
  • If most claims remain unverified, recommend retrieval from authoritative sources.
  • Never treat the model's confidence as evidence.
  • Answer in the user's language.

Read the full file on GitHub · 47 lines

Files

What ships with it

3 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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. 9d ago First seen · 47 lines · 67 tokens per session scan A 3d0f5153f4c3

Subscribe to this mod's changes

verify is a skill published in the GitHub repository alessiomarcone/agent-fieldbook (5 stars, last pushed yesterday), licensed MIT. It adds 67 tokens to every session and 544 once invoked, about $0.0003 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 2026-08-31.

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