agent-skills

agent-skills is a skill for Claude Code, Codex from magnus919/agent-skills. It costs 71 tokens per session (2,530 once invoked), scanned A, original, MIT.

A guide to creating, reviewing, and editing Agent Skills, which are folders of instructions and supporting files that give AI agents specialized knowledge or workflows. It also covers how an agent discovers and loads those skills.

In plain words
What is it for?
Use it to create or revise a SKILL.md file, organize references and scripts, define when a skill should load, and add evaluations for new skills.
Why use it?
It helps keep skills consistent, easy to trigger, and compatible with the Agent Skills format. It reduces problems caused by unclear instructions, incorrect metadata, poor folder structure, or loading too much information at once.

Skill for Claude CodeCodex

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

Needs its repository: it runs a file that does not travel with it, so clone the repository first. The line is ruby scripts/validate-skills.rb.

Good fit Use it to create or revise a SKILL.md file, organize references and scripts, define when a skill should load, and add evaluations for new skills.

Compare 6 skills from other repositories ↓
Install

Getting it into your agent

It runs from inside its repository, so the clone comes first — what it calls does not travel with the file alone.

Clone the repo
git clone --depth 1 https://github.com/magnus919/agent-skills
agentmods
npx agentmods add skills/magnus919/agent-skills/agent-skills

Made for: Claude Code, Codex.

Its marketplace also offers this one on its own, as the plugin agent-skills/plugin install agent-skills after adding the marketplace above.

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 agent-skills

README.md
[![agentmods](https://agentmods.dev/badge/skills/magnus919/agent-skills/agent-skills/github.svg)](https://agentmods.dev/skills/magnus919/agent-skills/agent-skills)
Your own site
<a href="https://agentmods.dev/skills/magnus919/agent-skills/agent-skills"><img src="https://agentmods.dev/badge/skills/magnus919/agent-skills/agent-skills/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 agent-skills

Your own site · 80×15
<a href="https://agentmods.dev/skills/magnus919/agent-skills/agent-skills"><img src="https://agentmods.dev/badge/skills/magnus919/agent-skills/agent-skills.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 71 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,530 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. Third-party audits
  • NVIDIA SkillSpector pass 7 Sept 2026
How audits are shown
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 $0.00071 $0.02530
Opus 5 $0.00036 $0.01265
Sonnet 5 $0.00014 $0.00506
Haiku 4.5 $0.00007 $0.00253

Measured 11d ago against content hash fa722681b154, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-11, from the pricing page.

Security

Grade A, and why

agent-skills 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 11d 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.

agent-skills/SKILL.md · 202 lines

How it starts

The opening of the file, as written. The whole thing — 202 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Agent Skills Standard Reference

This skill documents the Agent Skills open format — a standardized way to give AI agents new capabilities and expertise. Follow this workflow when creating or editing skills in this repository.

Authoritative source: agentskills.io/specification. The bundled specification is a working snapshot; check the authoritative source when currentness matters.


Directory Structure

A skill is a directory containing, at minimum, a SKILL.md file:

skill-name/
├── SKILL.md          # Required: metadata + instructions
├── evals/            # Required for new skills in this repository
├── scripts/          # Optional: executable code
├── references/       # Optional: documentation
├── assets/           # Optional: templates, resources
└── ...               # Any additional files or directories

Required Workflow

Create or edit a skill

  1. Read the specification before changing SKILL.md metadata or directory structure.
  2. Ground instructions in real domain knowledge, project artifacts, and observed failure modes. Read best practices when designing or materially revising instructions.
  3. Keep the skill a coherent, triggerable unit. Put only essential instructions in SKILL.md; put conditional detail in focused reference files and state exactly when to read each one.
  4. Use a precise description that says what the skill does, when it applies, and when it does not apply. For skills with meaningful overlap, name the nearest alternative or prerequisite in a ## When not to use section. Test the boundary with at least three should-trigger prompts and two should-not-trigger near-misses; keep these harness-specific trigger checks separate from portable output-quality evals. Read optimizing descriptions for trigger design.
  5. For every new skill, create evals/evals.json with at least five representative output-quality cases. Each case needs a realistic prompt, an expected outcome, and observable assertions. Include edge cases that exercise risky or ambiguous behavior. Read evaluating skills for the eval format and iteration workflow.
  6. When bundling executable code, read using scripts. Document prerequisites and non-interactive invocation in the skill.
  7. Before handoff, run the validation checks in this skill and correct every finding.

Read the full file on GitHub · 202 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. 11d ago First seen · 202 lines · 71 tokens per session scan A fa722681b154

Subscribe to this mod's changes

agent-skills is a skill published in the GitHub repository magnus919/agent-skills (76 stars, last pushed today), licensed MIT. It adds 71 tokens to every session and 2,530 once invoked, about $0.0004 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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