authoring-skills

authoring-skills is a skill for Claude Code from vercel/next.js. It costs 75 tokens per session (913 once invoked), scanned A, original, MIT.

A guide for creating and maintaining agent skills, which are focused instruction packages for coding agents.

In plain words
What is it for?
Use it to create SKILL.md files, write descriptions and frontmatter, choose names, organize supporting files, and decide when a task needs its own skill.
Why use it?
It helps decide which instructions belong in a skill or in the always-loaded AGENTS.md file and keeps skill files consistent.

Skill for Claude Code

Written for Claude Code: user-invocable in frontmatter. Also seen: mentions subagents; installed under .agents/ (shared by several agents); mentions AGENTS.md.

About the project

Next.js is a React framework for building applications that run across the browser and Node.js, including server-rendered applications. It is used by developers building web applications with React components.

vercel/next.js · 142,095 stars · on GitHub · nextjs.org

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/vercel/next.js/authoring-skills
Any agent
npx skills add vercel/next.js --skill authoring-skills
Clone the repo
git clone --depth 1 https://github.com/vercel/next.js

Made for: Claude Code.

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 authoring-skills

README.md
[![agentmods](https://agentmods.dev/badge/skills/vercel/next.js/authoring-skills.svg)](https://agentmods.dev/skills/vercel/next.js/authoring-skills)
Your own site
<a href="https://agentmods.dev/skills/vercel/next.js/authoring-skills"><img src="https://agentmods.dev/badge/skills/vercel/next.js/authoring-skills.svg" alt="Measured on agentmods" height="20"></a>
Per session 75 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 913 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 $0.00075 $0.00913
Opus 5 $0.00037 $0.00456
Sonnet 5 $0.00015 $0.00183
Haiku 4.5 $0.00007 $0.00091

Measured 6d ago against content hash 8ca094a90721, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-05, from the pricing page.

Security

Grade A, and why

authoring-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 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.

.agents/skills/authoring-skills/SKILL.md · 117 lines

How it starts

The opening of the file, as written. The whole thing — 117 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Authoring Skills

Use this skill when creating or modifying agent skills in .agents/skills/.

When to Create a Skill

Create a skill when content is:

  • Too detailed for AGENTS.md (code templates, multi-step workflows, diagnostic procedures)
  • Only relevant for specific tasks (not needed every session)
  • Self-contained enough to load independently

Keep in AGENTS.md instead when:

  • It's a one-liner rule or guardrail every session needs
  • It's a general-purpose gotcha any agent could hit

File Structure

.agents/skills/
└── my-skill/
    ├── SKILL.md          # Required: frontmatter + content
    ├── workflow.md        # Optional: supplementary detail
    └── examples.md        # Optional: referenced from SKILL.md

Supported Frontmatter Fields

---
name: my-skill # Required. Used for $name references and /name commands.
description: > # Required. How Claude decides to auto-load the skill.
  What this covers and when to use it. Include file names and keywords.
argument-hint: '<pr-number>' # Optional. Hint for expected arguments.
user-invocable: false # Optional. Set false to hide from / menu.
disable-model-invocation: true # Optional. Set true to prevent auto-triggering.
allowed-tools: [Bash, Read] # Optional. Tools allowed without permission.
model: opus # Optional. Model override.
context: fork # Optional. Isolated subagent execution.
agent: Explore # Optional. Subagent type (with context: fork).
---

Only use fields from this list. Unknown fields are silently ignored.

Writing Descriptions

The description is the primary matching surface for auto-activation. Include:

  1. What the skill covers (topic)
  2. When to use it (trigger scenario)
  3. Key file names the skill references (e.g. config-shared.ts)
  4. Keywords a user or agent might mention (e.g. "feature flag", "DCE")
# Too vague - won't auto-trigger reliably
description: Helps with flags.

# Good - specific files and concepts for matching
description: >
  How to add or modify Next.js experimental feature flags end-to-end.
  Use when editing config-shared.ts, config-schema.ts, define-env-plugin.ts.

Read the full file on GitHub · 117 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 · 117 lines · 75 tokens per session scan A 8ca094a90721

Subscribe to this mod's changes

authoring-skills is a skill published in the GitHub repository vercel/next.js (142,095 stars, last pushed today), licensed MIT. It adds 75 tokens to every session and 913 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.

Related

Other skills, from other repositories