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.
npx skills add joshuadavidthomas/agent-skills --skill writing-cli-skillsgit clone --depth 1 https://github.com/joshuadavidthomas/agent-skillsWrote 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/joshuadavidthomas/agent-skills/writing-cli-skills)<a href="https://agentmods.dev/skills/joshuadavidthomas/agent-skills/writing-cli-skills"><img src="https://agentmods.dev/badge/skills/joshuadavidthomas/agent-skills/writing-cli-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.
<a href="https://agentmods.dev/skills/joshuadavidthomas/agent-skills/writing-cli-skills"><img src="https://agentmods.dev/badge/skills/joshuadavidthomas/agent-skills/writing-cli-skills.svg" alt="Reviewed on agentmods" width="80" height="20"></a>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 | $0.00080 | $0.00980 |
| Opus 5 | $0.00040 | $0.00490 |
| Sonnet 5 | $0.00016 | $0.00196 |
| Haiku 4.5 | $0.00008 | $0.00098 |
Grade A, and why
writing-cli-skills scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 12d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
This is a copy
91% identical to writing-cli-skills — 2 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.
How it starts
The opening of the file, as written. The whole thing — 141 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Writing CLI Skills
How to write an agent skill for a command-line tool.
Quick Start
- Install the tool and play with it — don't just read docs. If the tool is unavailable, use WebFetch on official docs + man pages, but note this in your skill as "not hands-on verified"
- Run
--helpon every subcommand - Try the common operations yourself
- Note what surprises you or isn't obvious
- Copy
references/template.mdto your new skill directory - Fill in sections based on your hands-on experience
- Delete sections that don't apply
# First: actually use the tool
my-tool --help
my-tool subcommand --help
my-tool do-something # try it!
# Then: create the skill
# This will depend on the tool
# Claude Code
ln -s "$PWD/skills/my-tool" ~/.claude/skills/my-tool
# OpenCode
ln -s "$PWD/skills/my-tool" ~/.config/opencode/skills/my-tool
# Clawdbot
ln -s "$PWD/skills/my-tool" ~/clawd/skills/my-tool
Reading docs is no substitute for hands-on use. You'll discover defaults, gotchas, and real behavior that docs don't mention.
What NOT to Do
- Do not dump
--helpoutput verbatim — summarize the useful parts - Do not document every flag — focus on the 80% use cases
- Do not include commands you haven't tested
- Do not exceed 500 lines — this bloats agent context windows
Sections
Required
Every CLI skill needs at minimum:
| Section | Purpose |
|---|---|
| Frontmatter | name, description (with trigger phrases) |
| Installation | How to get the binary |
| Usage | The 80% use cases |
Recommended
| Section | When to Include |
|---|---|
| Requirements | Tool needs accounts, API keys, or dependencies |
| Quick Start | Tool has a simple "happy path" |
| Output Formats | Tool can output JSON or custom formats |
| Tips & Gotchas | Tool has some edge cases or things an agentic LLM should not use |
| Troubleshooting | Tool has debug modes or common failure modes |
| Configuration | Tool has config files or env vars |
| Uninstall | Tool leaves config/data behind |
| References | When there are useful docs or content that contains more details |
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.
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.
- 12d ago First seen · 141 lines · 80 tokens per session scan A c2a6b4450e17
writing-cli-skills is a skill published in the GitHub repository joshuadavidthomas/agent-skills (49 stars, last pushed 1mo ago), licensed MIT. It adds 80 tokens to every session and 980 once invoked, about $0.0004 per session on Opus 5. A static security scan graded it A with 0 findings. It is 91% identical to writing-cli-skills, differing in 2 lines, and is treated as a copy.
Other skills, from other repositories
systematic-debugging
Use when encountering any bug, test failure, or unexpected behavior, before proposing fixes.
local-ai-agents
Build local-first AI agents that run entirely on a developer workstation with Microsoft Foundry Local and Qwen function-calling models. Covers Small Language Models (SLMs), the OpenAI-compatible local endpoint, sandboxed local tools, local RAG with Chroma, local MCP servers, hybrid cloud/local routing, and the…
next-cache-components-adoption
Turn on Cache Components in a Next.js app and resolve the blocking routes it surfaces. Use when the user wants to enable, adopt, or migrate to Cache Components, flip the cacheComponents flag, work through a flood of blocking-prerender / instant validation errors, run the cache-components-instant-false codemod, or…
chat-pet-sprite-creation
Use when creating or changing VS Code chat pet sprite art, sprite sheets, state animations, eye treatments, Stable/Insiders variants, or pet transitions under src/vs/workbench/contrib/chat/browser/widget/media/chatPet.
cpu-profile-analysis
Analyze V8/Chrome CPU profiles (.cpuprofile) and DevTools trace files (Trace-.json). Use when: profiling performance, investigating slow functions, comparing code paths, finding bottlenecks, analyzing timeToRequest, understanding call trees from sampling profiler data, analyzing layout/paint/rendering, investigating…
insight-error-page
Write or audit an insight-kind error page for the Next.js dev overlay. Use when creating a new errors/ .mdx page, auditing an existing one, or checking that a page matches the framework fix cards. Covers page structure, title alignment, FixCard cards with Copy prompt button, code snippets, terminology verification…