valid-frontmatter

valid-frontmatter is a skill for Claude Code, Codex from itaywol/adeptability. It costs 7 tokens per session (40 once invoked), scanned A, original, MIT.

A skill whose instructions are defined with frontmatter, a metadata section at the start of a file.

In plain words
What is it for?
Use it as a minimal reference when creating or checking skill metadata.
Why use it?
It provides an example of a skill with valid frontmatter and a separate body.

Skill for Claude CodeCodex

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.

agentmods
npx agentmods add skills/itaywol/adeptability/valid-frontmatter
Any agent
npx skills add itaywol/adeptability --skill valid-frontmatter
Clone the repo
git clone --depth 1 https://github.com/itaywol/adeptability

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 valid-frontmatter

README.md
[![agentmods](https://agentmods.dev/badge/skills/itaywol/adeptability/valid-frontmatter.svg)](https://agentmods.dev/skills/itaywol/adeptability/valid-frontmatter)
Your own site
<a href="https://agentmods.dev/skills/itaywol/adeptability/valid-frontmatter"><img src="https://agentmods.dev/badge/skills/itaywol/adeptability/valid-frontmatter.svg" alt="Measured on agentmods" height="20"></a>
Per session 7 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 40 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
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 $0.00007 $0.00040
Opus 5 $0.00003 $0.00020
Sonnet 5 $0.00001 $0.00008
Haiku 4.5 $0.00001 $0.00004

Measured 4d ago against content hash 106d21777241, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

valid-frontmatter 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 4d 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.

internal/canonical/testdata/valid-frontmatter/SKILL.md · 11 lines

What it actually says

Frontmatter Skill

Body lives here.

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. 4d ago First seen · 11 lines · 7 tokens per session scan A 106d21777241

Subscribe to this mod's changes

valid-frontmatter is a skill published in the GitHub repository itaywol/adeptability (9 stars, last pushed 1mo ago), licensed MIT. It adds 7 tokens to every session and 40 once invoked, about $0.0000 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.