writing-great-skills

writing-great-skills is a skill for Claude Code from sliamh11/Deus. It costs 24 tokens per session (2,008 once invoked), scanned A, a copy of writing-great-skills, MIT.

A reference guide for designing and editing coding-agent skills so they behave predictably.

In plain words
What is it for?
Use it when creating or revising skills, especially their triggers, instructions, and user-facing descriptions.
Why use it?
It explains how invocation rules, descriptions, context size, and clear procedures affect whether a skill is used correctly.

Skill for Claude Code

Written for Claude Code: disable-model-invocation in frontmatter.

Good fit Use it when creating or revising skills, especially their triggers, instructions, and user-facing descriptions.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/sliamh11/deus/writing-great-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 sliamh11/Deus --skill writing-great-skills
Clone the repo
git clone --depth 1 https://github.com/sliamh11/Deus

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 writing-great-skills

README.md
[![agentmods](https://agentmods.dev/badge/skills/sliamh11/deus/writing-great-skills/github.svg)](https://agentmods.dev/skills/sliamh11/deus/writing-great-skills)
Your own site
<a href="https://agentmods.dev/skills/sliamh11/deus/writing-great-skills"><img src="https://agentmods.dev/badge/skills/sliamh11/deus/writing-great-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-great-skills

Your own site · 80×15
<a href="https://agentmods.dev/skills/sliamh11/deus/writing-great-skills"><img src="https://agentmods.dev/badge/skills/sliamh11/deus/writing-great-skills.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 24 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,008 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 100% copy Near-identical to another mod 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 $0.00024 $0.02008
Opus 5 $0.00012 $0.01004
Sonnet 5 $0.00005 $0.00402
Haiku 4.5 $0.00002 $0.00201

Measured 7d ago against content hash 15c4dc32692b, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-11, from the pricing page.

Security

Grade A, and why

writing-great-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 7d 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.

Origin

This is a copy

100% identical to writing-great-skills — 1 line differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

.claude/skills/writing-great-skills/SKILL.md · 84 lines

How it starts

The opening of the file, as written. The whole thing — 84 lines — stays where its author put it; the contents beside it link to each section on GitHub.

A skill exists to wrangle determinism out of a stochastic system. Predictability — the agent taking the same process every run, not producing the same output — is the root virtue; every lever below serves it.

Bold terms are defined in GLOSSARY.md; look them up there for the full meaning.

Invocation

Two choices, trading different costs:

  • A model-invoked skill keeps a description, so the agent can fire it autonomously and other skills can reach it (you can still type its name too). It contributes to context load — the description sits in the window every turn. Mechanics: omit disable-model-invocation, and write a model-facing description with rich trigger phrasing ("Use when the user wants…, mentions…").
  • A user-invoked skill strips the description from the agent's reach: only you, typing its name, can invoke it — and no other skill can. Zero context load, but it spends cognitive load: you are the index that must remember it exists. Mechanics: set disable-model-invocation: true; the description becomes human-facing — a one-line summary, trigger lists stripped.

Pick model-invocation only when the agent must reach the skill on its own, or another skill must. If it only ever fires by hand, make it user-invoked and pay no context load.

When user-invoked skills multiply past what you can remember, that piled-up cognitive load is cured by a router skill: one user-invoked skill that names the others and when to reach for each.

Writing the description

A model-invoked description does two jobs — state what the skill is, and list the branches that should trigger it. Every word increases context load, so a description earns even harder pruning than the body:

  • Front-load the skill's leading word — the description is where it does its invocation work.
  • One trigger per branch. Synonyms that rename a single branch are duplication — "build features using TDD … asks for test-first development" is one branch written twice. Collapse them; keep only genuinely distinct branches.
  • Cut identity that's already in the body. Keep the description to triggers, plus any "when another skill needs…" reach clause.

Read the full file on GitHub · 84 lines

Files

What ships with it

1 file beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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. 7d ago First seen · 84 lines · 24 tokens per session scan A 15c4dc32692b

Subscribe to this mod's changes

writing-great-skills is a skill published in the GitHub repository sliamh11/Deus (51 stars, last pushed yesterday), licensed MIT. It adds 24 tokens to every session and 2,008 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 0 findings. It is 100% identical to writing-great-skills, differing in 1 line, and is treated as a copy.