malformed-frontmatter

malformed-frontmatter is a skill for Claude Code, Codex from ghostship25/Skilllint. It costs 18 tokens per session (112 once invoked), scanned A, original, MIT.

An example skill file containing malformed metadata: a stray line that does not follow the required key-and-value format.

In plain words
What is it for?
It demonstrates how the skill checker handles invalid frontmatter and why the file must be repaired by hand.
Why use it?
Its parser reports the problem instead of silently ignoring it, and automatic fixing is refused until the line is corrected manually.

Skill for Claude CodeCodex

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

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/ghostship25/skilllint/malformed-frontmatter
Any agent
npx skills add ghostship25/Skilllint --skill malformed-frontmatter
Clone the repo
git clone --depth 1 https://github.com/ghostship25/Skilllint

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 malformed-frontmatter

README.md
[![agentmods](https://agentmods.dev/badge/skills/ghostship25/skilllint/malformed-frontmatter.svg)](https://agentmods.dev/skills/ghostship25/skilllint/malformed-frontmatter)
Your own site
<a href="https://agentmods.dev/skills/ghostship25/skilllint/malformed-frontmatter"><img src="https://agentmods.dev/badge/skills/ghostship25/skilllint/malformed-frontmatter.svg" alt="Measured on agentmods" height="20"></a>
Per session 18 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 112 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 5.1 $0.00018 $0.00112
Opus 5 $0.00009 $0.00056
Sonnet 5 $0.00004 $0.00022
Haiku 4.5 $0.00002 $0.00011

Measured 6d ago against content hash c0b0da593b03, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-06, from the pricing page.

Security

Grade A, and why

malformed-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 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.

examples/bad/malformed-frontmatter/SKILL.md · 12 lines

What it actually says

This skill exists purely to demonstrate SkillLint's parser-honesty behavior: the stray line above has no recognizable key: value shape, so the parser reports it instead of silently dropping it, and --fix refuses to touch this file until the shape is corrected by hand.

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 · 12 lines · 0 tokens per session scan A c0b0da593b03

Subscribe to this mod's changes

malformed-frontmatter is a skill published in the GitHub repository ghostship25/Skilllint (2 stars, last pushed 20d ago), licensed MIT. It adds 18 tokens to every session and 112 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 2026-08-31.

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