existing-skill

existing-skill is a skill for Claude Code, Codex from anton-abyzov/vskill. It costs 9 tokens per session (83 once invoked), scanned A, original, MIT.

A checker for Markdown files, which are text files formatted with simple symbols for headings and lists. It looks for passive voice, unclear modifiers, and inconsistent heading capitalization.

In plain words
What is it for?
Use it to review Markdown files for grammar and house-style issues.
Why use it?
It catches common writing and style problems before Markdown documentation is shared.

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/anton-abyzov/vskill/existing-skill
Any agent
npx skills add anton-abyzov/vskill --skill existing-skill
Clone the repo
git clone --depth 1 https://github.com/anton-abyzov/vskill

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 existing-skill

README.md
[![agentmods](https://agentmods.dev/badge/skills/anton-abyzov/vskill/existing-skill.svg)](https://agentmods.dev/skills/anton-abyzov/vskill/existing-skill)
Your own site
<a href="https://agentmods.dev/skills/anton-abyzov/vskill/existing-skill"><img src="https://agentmods.dev/badge/skills/anton-abyzov/vskill/existing-skill.svg" alt="Measured on agentmods" height="20"></a>
Per session 9 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 83 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 $0.00009 $0.00083
Opus 5 $0.00005 $0.00042
Sonnet 5 $0.00002 $0.00017
Haiku 4.5 $0.00001 $0.00008

Measured 5d ago against content hash 1bd3fb14c731, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

existing-skill 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 5d 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.

src/commands/__tests__/fixtures/existing-skill/SKILL.md · 18 lines

What it actually says

/lint-markdown

Lint markdown files following house style. Flag passive voice, dangling modifiers, and inconsistent heading capitalization.

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. 5d ago First seen · 18 lines · 9 tokens per session scan A 1bd3fb14c731

Subscribe to this mod's changes

existing-skill is a skill published in the GitHub repository anton-abyzov/vskill (45 stars, last pushed 2d ago), licensed MIT. It adds 9 tokens to every session and 83 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 2026-08-30.

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