write-a-skill

write-a-skill is a skill for Claude Code, Codex from vahidkaargar/it-department-skills. It costs 37 tokens per session (757 once invoked), scanned A, original, MIT.

A guide for creating new skills for coding agents, including their instructions, supporting files, and utility scripts.

In plain words
What is it for?
Use it to gather requirements, draft a SKILL.md, add reference materials or scripts, and review the result with the user.
Why use it?
It helps turn a loosely defined idea into a consistently structured skill without overlooking requirements, references, or review.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one. Also seen: reads .claude/ paths.

Good fit Use it to gather requirements, draft a SKILL.md, add reference materials or scripts, and review the result with the user.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/vahidkaargar/it-department-skills/write-a-skill
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.

Any agent
npx skills add vahidkaargar/it-department-skills --skill write-a-skill
Clone the repo
git clone --depth 1 https://github.com/vahidkaargar/it-department-skills

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 write-a-skill

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

Your own site · 80×15
<a href="https://agentmods.dev/skills/vahidkaargar/it-department-skills/write-a-skill"><img src="https://agentmods.dev/badge/skills/vahidkaargar/it-department-skills/write-a-skill.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 37 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 757 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.
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 $0.00037 $0.00757
Opus 5 $0.00018 $0.00378
Sonnet 5 $0.00007 $0.00151
Haiku 4.5 $0.00004 $0.00076

Measured 11d ago against content hash 6a75b8fb61e9, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-11, from the pricing page.

Security

Grade A, and why

write-a-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 11d ago.

The scan reads SKILL.md. This mod also ships 3 executable files (scripts/skill_description_validator.py, scripts/skill_review_checklist_runner.py, scripts/skill_structure_validator.py), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

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.

skills/write-a-skill/SKILL.md · 90 lines

How it starts

The opening of the file, as written. The whole thing — 90 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Writing Skills

Derived from Matt Pocock's write-a-skill (MIT). Matt's voice and 3-phase workflow preserved verbatim. Additions: validation tools + references + cs-* wrapper (see Tooling + Companions below).

Process

  1. Gather requirements - ask user about:

    • What task/domain does the skill cover?
    • What specific use cases should it handle?
    • Does it need executable scripts or just instructions?
    • Any reference materials to include?
  2. Draft the skill - create:

    • SKILL.md with concise instructions
    • Additional reference files if content exceeds 100 lines
    • Utility scripts if deterministic operations needed
  3. Review with user - present draft and ask:

    • Does this cover your use cases?
    • Anything missing or unclear?
    • Should any section be more/less detailed?

Skill Structure

skill-name/
├── SKILL.md           # Main instructions (required)
├── REFERENCE.md       # Detailed docs (if needed)
├── EXAMPLES.md        # Usage examples (if needed)
└── scripts/           # Utility scripts (if needed)
    └── helper.js

SKILL.md Template

Copy-paste starting point: references/skill_md_template.md.

Description Requirements

The description is the only thing your agent sees when deciding which skill to load — see references/description_design_patterns.md for the four format rules and good/bad examples.

When to Add Scripts

Add utility scripts when:

  • Operation is deterministic (validation, formatting)
  • Same code would be generated repeatedly
  • Errors need explicit handling

Scripts save tokens and improve reliability vs generated code.

When to Split Files

See references/progressive_disclosure_principles.md for the 100-line ceiling, the one-level-deep rule, and anti-patterns to avoid.

Read the full file on GitHub · 90 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 · 90 lines · 37 tokens per session scan A 6a75b8fb61e9

Subscribe to this mod's changes

write-a-skill is a skill published in the GitHub repository vahidkaargar/it-department-skills (2 stars, last pushed 1mo ago), licensed MIT. It adds 37 tokens to every session and 757 once invoked, about $0.0002 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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