schema-markup

schema-markup is a skill for Claude Code, Codex from tmj-90/gaffer. It costs 91 tokens per session (1,028 once invoked), scanned A, original, Apache-2.0.

A guide for adding structured data—machine-readable information about a page—to a website using Schema.org and JSON-LD.

In plain words
What is it for?
Use it to implement, audit, or validate Organization, Article, Product, FAQ, breadcrumb, and other schema types.
Why use it?
It helps search engines understand pages and can support enhanced search-result displays such as product or FAQ details.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Good fit Use it to implement, audit, or validate Organization, Article, Product, FAQ, breadcrumb, and other schema types.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/tmj-90/gaffer/schema-markup
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 tmj-90/gaffer --skill schema-markup
Clone the repo
git clone --depth 1 https://github.com/tmj-90/gaffer

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 schema-markup

README.md
[![agentmods](https://agentmods.dev/badge/skills/tmj-90/gaffer/schema-markup/github.svg)](https://agentmods.dev/skills/tmj-90/gaffer/schema-markup)
Your own site
<a href="https://agentmods.dev/skills/tmj-90/gaffer/schema-markup"><img src="https://agentmods.dev/badge/skills/tmj-90/gaffer/schema-markup/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 schema-markup

Your own site · 80×15
<a href="https://agentmods.dev/skills/tmj-90/gaffer/schema-markup"><img src="https://agentmods.dev/badge/skills/tmj-90/gaffer/schema-markup.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 91 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,028 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 $0.00091 $0.01028
Opus 5 $0.00046 $0.00514
Sonnet 5 $0.00018 $0.00206
Haiku 4.5 $0.00009 $0.00103

Measured 6d ago against content hash 712e5beabfbf, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-10, from the pricing page.

Security

Grade A, and why

schema-markup 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 6d 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.

runner/skills/schema-markup/SKILL.md · 79 lines

How it starts

The opening of the file, as written. The whole thing — 79 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Implement structured data that earns rich results

JSON-LD is the recommended format (Google's preference). Schema.org types are the vocabulary. Rich results in Google and citations in AI search engines are the outcomes.

High-value schema types (implement these first)

Type Rich result earned Required fields
Organization Knowledge panel, sitelinks search name, url, logo
WebSite Sitelinks search box url, potentialAction (SearchAction)
FAQPage FAQ dropdowns in SERP mainEntityQuestionacceptedAnswer
Article Top stories, rich snippet headline, author, datePublished, image
Product Product snippet with price/rating name, offers, aggregateRating
HowTo How-to steps in SERP name, step array
BreadcrumbList Breadcrumb in SERP URL itemListElement array
LocalBusiness Local pack, knowledge panel name, address, telephone

JSON-LD placement

Prefer <head> as a <script type="application/ld+json"> block. Google also supports JSON-LD placed in the <body> (including markup injected by JavaScript), so in-body placement is valid when <head> injection isn't practical — <head> is simply the cleaner default. One <script> block per schema type per page (or a @graph array for multiple types).

<script type="application/ld+json">
{
  "@context": "https://schema.org",
  "@type": "FAQPage",
  "mainEntity": [
    {
      "@type": "Question",
      "name": "What is your refund policy?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "We offer a 30-day full refund, no questions asked."
      }
    }
  ]
}
</script>

Common mistakes that block rich results

  • Content mismatch — schema claims a price or rating that doesn't appear on the page. Google requires visible content to match.
  • Missing required fields — check Google's required/recommended fields per type at developers.google.com/search/docs/appearance.
  • Incorrect datePublished format — must be ISO 8601 (2026-06-17T09:00:00+00:00).
  • Markup on 404/noindex pages — Google won't process structured data on non-indexable pages.
  • Multiple conflicting types — use @graph array to combine without conflict.

Read the full file on GitHub · 79 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. 6d ago First seen · 79 lines · 91 tokens per session scan A 712e5beabfbf

Subscribe to this mod's changes

schema-markup is a skill published in the GitHub repository tmj-90/gaffer (2 stars, last pushed 2d ago), licensed Apache-2.0. It adds 91 tokens to every session and 1,028 once invoked, about $0.0005 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 2026-09-03.

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