always-verify-numbers-and-links

always-verify-numbers-and-links is a skill for Claude Code from alivirgo/Major-AI-Skills. It costs 29 tokens per session (1,441 once invoked), scanned A, original, MIT.

A set of rules for checking numbers, calculations, and web links before an AI assistant presents them. It uses external checks and tools because language models can produce plausible but incorrect facts and URLs.

In plain words
What is it for?
Use it when an agent reports figures, calculates results, cites websites, or needs to confirm that a URL works.
Why use it?
It reduces invented statistics, broken links, outdated information, and arithmetic errors in generated answers.

Skill for Claude Code

Written for Claude Code: shipped in a Claude Code plugin. Also seen: mentions Codex.

Part of the major-ai-skills plugin — 147 skills, 8 plugins shipped together

Good fit Use it when an agent reports figures, calculates results, cites websites, or needs to confirm that a URL works.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/alivirgo/major-ai-skills/always-verify-numbers-and-links
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 alivirgo/Major-AI-Skills --skill always-verify-numbers-and-links
Clone the repo
git clone --depth 1 https://github.com/alivirgo/Major-AI-Skills

Made for: Claude Code.

Or install major-ai-skills, the plugin that ships this one along with the rest of its 147 skills, 8 plugins.

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 always-verify-numbers-and-links

README.md
[![agentmods](https://agentmods.dev/badge/skills/alivirgo/major-ai-skills/always-verify-numbers-and-links/github.svg)](https://agentmods.dev/skills/alivirgo/major-ai-skills/always-verify-numbers-and-links)
Your own site
<a href="https://agentmods.dev/skills/alivirgo/major-ai-skills/always-verify-numbers-and-links"><img src="https://agentmods.dev/badge/skills/alivirgo/major-ai-skills/always-verify-numbers-and-links/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 always-verify-numbers-and-links

Your own site · 80×15
<a href="https://agentmods.dev/skills/alivirgo/major-ai-skills/always-verify-numbers-and-links"><img src="https://agentmods.dev/badge/skills/alivirgo/major-ai-skills/always-verify-numbers-and-links.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 29 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,441 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 $0.00029 $0.01441
Opus 5 $0.00015 $0.00720
Sonnet 5 $0.00006 $0.00288
Haiku 4.5 $0.00003 $0.00144

Measured yesterday against content hash 1f67198459c9, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-12, from the pricing page.

Security

Grade A, and why

always-verify-numbers-and-links 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.

skills/always-verify-numbers-and-links/SKILL.md · 132 lines

How it starts

The opening of the file, as written. The whole thing — 132 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Overview

Large Language Models (LLMs) do not compute math or maintain an internal web directory in real time - they predict the most probable sequence of tokens. As a result, AI assistants can invent plausible-looking URLs, 404 links, outdated statistics, and subtly incorrect arithmetic with complete grammatical confidence.

This skill outlines the Grounding & Verification Protocol: a strict set of operating rules to validate figures, test web endpoints, and force AI models to ground their claims in verifiable data.


┌─────────────────────────────────────────────────────────────┐
│                    The Hallucination Trap                   │
│                                                             │
│  User Asks: "What is the URL for the IRS form 1099-MISC?"   │
│                                                             │
│  AI Internal Probability:                                   │
│  "https://www.irs.gov/forms-pubs/about-form-1099-misc" (92%)│
│  ↳ Plausible URL structure generated purely from token patterns │
│  ↳ Result in 35% of cases: HTTP 404 (Page Not Found)       │
└─────────────────────────────────────────────────────────────┘
  1. Token Stitching: The model synthesizes domain names, paths, and slugs based on common internet grammar rather than checking live DNS records.
  2. Arithmetic Estimation: Without a dedicated Python execution environment or calculator plugin, multi-step math (especially compound percentages and multi-digit multiplication) is approximated via semantic probability, frequently leading to calculation drift.
  3. Temporal Blind Spots: Outdated dates, pricing tiers, and changed support numbers are confidently cited from stale training weights.

The 4-Point Grounding Audit

Before using any AI-generated figure or URL in production, emails, presentations, or contracts, run through this checklist:

[ ] 1. CLICK-TEST: Did you click the URL directly in an incognito window?
[ ] 2. SOURCE-CHECK: Is the stat attributed to a named primary source (e.g. "BLS 2024 Report") rather than a generic claim ("Studies show...")?
[ ] 3. CALC-RUN: Did you re-run the final math formula through a calculator or Python snippet?
[ ] 4. RECENCY-VERIFY: Does the date match the current quarter or fiscal year?

Read the full file on GitHub · 132 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 Changed · -7 tokens per session 1f67198459c9
  2. 7d ago First seen · 132 lines · 36 tokens per session scan A d306a6ba2dcf

Subscribe to this mod's changes

always-verify-numbers-and-links is a skill published in the GitHub repository alivirgo/Major-AI-Skills (1 stars, last pushed today), licensed MIT. It adds 29 tokens to every session and 1,441 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 2026-09-05.

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