writing-skills

writing-skills is a skill for Claude Code, Codex from KalarisLabs/Skill-Doctor. It costs 20 tokens per session (2,289 once invoked), scanned A, original, Apache-2.0.

A guide for creating, editing, and checking agent skills, which are instruction documents that shape how a coding agent works.

In plain words
What is it for?
Use it to write skill documents, create pressure scenarios that test agent behavior, check compliance, and revise the instructions.
Why use it?
It applies the test-first idea to instructions, helping reveal when an agent ignores or misinterprets a skill before it is deployed.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one. Also seen: reads .claude/ paths; mentions subagents; mentions Claude Code.

Good fit Use it to write skill documents, create pressure scenarios that test agent behavior, check compliance, and revise the instructions.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/kalarislabs/skill-doctor/writing-skills
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 KalarisLabs/Skill-Doctor --skill writing-skills
Clone the repo
git clone --depth 1 https://github.com/KalarisLabs/Skill-Doctor

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 writing-skills

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

Your own site · 80×15
<a href="https://agentmods.dev/skills/kalarislabs/skill-doctor/writing-skills"><img src="https://agentmods.dev/badge/skills/kalarislabs/skill-doctor/writing-skills.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 20 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,289 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 $0.00020 $0.02289
Opus 5.5 $0.00008 $0.00916
Sonnet 5.5 $0.00004 $0.00458
Haiku 4.5 $0.00002 $0.00229

Measured 1mo ago against content hash a63c43b26870, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

writing-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 1mo 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.

skills/writing-skills/SKILL.md · 274 lines

How it starts

The opening of the file, as written. The whole thing — 274 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Writing Skills

Overview

Writing skills IS Test-Driven Development applied to process documentation.

Personal skills live in your runtime's skills directory (~/.claude/skills/ on Claude Code) — see codex-tools.md or gemini-tools.md for the path on those runtimes. Codex, Copilot CLI, and Gemini CLI all also recognize ~/.agents/skills/ as a cross-runtime alias.

You write test cases (pressure scenarios with subagents), watch them fail (baseline behavior), write the skill (documentation), watch tests pass (agents comply), and refactor (close loopholes).

Core principle: If you didn't watch an agent fail without the skill, you don't know if the skill teaches the right thing.

REQUIRED BACKGROUND: You MUST understand superpowers:test-driven-development before using this skill. That skill defines the fundamental RED-GREEN-REFACTOR cycle. This skill adapts TDD to documentation.

Official guidance: For Anthropic's official skill authoring best practices, see anthropic-best-practices.md. This document provides additional patterns and guidelines that complement the TDD-focused approach in this skill.

What is a Skill?

A skill is a reference guide for proven techniques, patterns, or tools. Skills help future agents find and apply effective approaches.

Skills are: Reusable techniques, patterns, tools, reference guides

Skills are NOT: Narratives about how you solved a problem once

TDD Mapping for Skills

TDD Concept Skill Creation
Test case Pressure scenario with subagent
Production code Skill document (SKILL.md)
Test fails (RED) Agent violates rule without skill (baseline)
Test passes (GREEN) Agent complies with skill present
Refactor Close loopholes while maintaining compliance
Write test first Run baseline scenario BEFORE writing skill
Watch it fail Document exact rationalizations agent uses
Minimal code Write skill addressing those specific violations
Watch it pass Verify agent now complies
Refactor cycle Find new rationalizations -> plug -> re-verify

Read the full file on GitHub · 274 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. 1mo ago First seen · 274 lines · 20 tokens per session scan A a63c43b26870

Subscribe to this mod's changes

writing-skills is a skill published in the GitHub repository KalarisLabs/Skill-Doctor (13 stars, last pushed yesterday), licensed Apache-2.0. It adds 20 tokens to every session and 2,289 once invoked, about $0.0001 per session on Opus 5.5. 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 2026-09-11.