Borrowing it
Nothing to install: this file belongs to rust-works/succinctly. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/rust-works/succinctly/main/.claude/skills/skill-writing/SKILL.mdgit clone --depth 1 https://github.com/rust-works/succinctlyWrote 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.
[](https://agentmods.dev/skills/rust-works/succinctly/skill-writing)<a href="https://agentmods.dev/skills/rust-works/succinctly/skill-writing"><img src="https://agentmods.dev/badge/skills/rust-works/succinctly/skill-writing/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.
<a href="https://agentmods.dev/skills/rust-works/succinctly/skill-writing"><img src="https://agentmods.dev/badge/skills/rust-works/succinctly/skill-writing.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector pass
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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00035 | $0.01364 |
| Opus 5.5 | $0.00014 | $0.00546 |
| Sonnet 5.5 | $0.00007 | $0.00273 |
| Haiku 4.5 | $0.00003 | $0.00136 |
Grade A, and why
skill-writing 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 3d 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.
How it starts
The opening of the file, as written. The whole thing — 188 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Writing Effective Claude Code Skills
Core Principle: Progressive Disclosure
The most important concept for building skills is progressive disclosure — show just enough information to help Claude decide what to do next, then reveal more details as needed.
- Keep
SKILL.mdunder 500 lines - Move detailed reference material to separate files
- Reference supporting files so Claude knows when to load them
Skill File Structure
Every skill needs a SKILL.md file with two parts:
---
name: my-skill-name
description: What this skill does and when to use it
---
# Skill Title
[Instructions Claude follows when the skill is invoked]
## Examples
## Guidelines
Directory Structure
my-skill/
├── SKILL.md # Main instructions (required)
├── reference.md # Detailed docs (loaded when needed)
├── examples/ # Example outputs
└── scripts/ # Executable scripts
Frontmatter Reference
| Field | Purpose |
|---|---|
name |
Slash command name (lowercase, hyphens, max 64 chars) |
description |
Recommended - helps Claude decide when to use skill |
argument-hint |
Autocomplete hint, e.g., [issue-number] |
disable-model-invocation |
true = only user can invoke (for deploy, commit, etc.) |
user-invocable |
false = hide from / menu (background knowledge) |
allowed-tools |
Tools Claude can use without permission when skill active |
model |
Override model for this skill |
context |
fork = run in isolated subagent |
agent |
Subagent type when context: fork (Explore, Plan) |
Types of Skill Content
Reference Skills (Knowledge)
Add conventions, patterns, or domain knowledge Claude applies to current work:
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.
- 3d ago Changed · +136 lines · +3 tokens per session 0a4f50620674
- 1mo ago Changed · -133 lines · -3 tokens per session a4c189b7731e
- 2mo ago First seen · 185 lines · 35 tokens per session scan A 775def8e7f34
skill-writing is a skill published in the GitHub repository rust-works/succinctly (52 stars, last pushed yesterday), licensed MIT. It adds 35 tokens to every session and 1,364 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 2026-08-30.
skill-writing compared with skills from other repositories
| Mod | Type | Stars | Last push | Licence | Scan | Tokens | Works with |
|---|---|---|---|---|---|---|---|
| skill-writingrust-works/succinctly | Skill | 52 | yesterday | MIT | A | 35 | Claude Code |
| imagegenopenai/codex | Skill | 133k | yesterday | Apache-2.0 | A | 113 | Codex |
| playwright-climicrosoft/playwright | Skill | 99k | yesterday | Apache-2.0 | A | 19 | Claude Code |
| local-ai-agentsmicrosoft/ai-agents-for-beginners | Skill | 79k | 4d ago | MIT | A | 200 | Claude Code, Codex |
| systematic-debuggingobra/superpowers | Skill | 313k | 3d ago | MIT | A | 21 | Claude Code |
| next-cache-components-adoptionvercel/next.js | Skill | 143k | yesterday | MIT | A | 95 | Claude Code |
| next-partial-prefetching-adoptionvercel/next.js | Skill | 143k | yesterday | MIT | A | 103 | Claude Code |