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 Kastalien-Research/thoughtbox --skill writing-cli-skillsgit clone --depth 1 https://github.com/Kastalien-Research/thoughtboxWrote 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/kastalien-research/thoughtbox/writing-cli-skills)<a href="https://agentmods.dev/skills/kastalien-research/thoughtbox/writing-cli-skills"><img src="https://agentmods.dev/badge/skills/kastalien-research/thoughtbox/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/kastalien-research/thoughtbox/writing-cli-skills"><img src="https://agentmods.dev/badge/skills/kastalien-research/thoughtbox/writing-cli-skills.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector warn
SkillSpector: 1 finding, up to medium
These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →
- medium Rogue Agent · line 8 Skill establishes unauthorized persistence across sessions via cron jobs, startup scripts, or state files. Session persistence allows an attacker to maintain access beyond the current interaction.Fix: Remove any persistence mechanisms (cron jobs, startup scripts, state files). Skills should not maintain state across sessions without explicit user consent.
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 | $0.00031 | $0.00931 |
| Opus 5 | $0.00015 | $0.00465 |
| Sonnet 5 | $0.00006 | $0.00186 |
| Haiku 4.5 | $0.00003 | $0.00093 |
Grade A, and why
writing-cli-skills scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 6d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
Copies of this mod
1 near-identical copy found in the catalogue:
- writing-cli-skills — 91% identical, 2 lines differ
How it starts
The opening of the file, as written. The whole thing — 141 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Writing CLI Skills
How to write an agent skill for a command-line tool.
Quick Start
- Install the tool and play with it — don't just read docs. If the tool is unavailable, use WebFetch on official docs + man pages, but note this in your skill as "not hands-on verified"
- Run
--helpon every subcommand - Try the common operations yourself
- Note what surprises you or isn't obvious
- Copy
references/template.mdto your new skill directory - Fill in sections based on your hands-on experience
- Delete sections that don't apply
# First: actually use the tool
my-tool --help
my-tool subcommand --help
my-tool do-something # try it!
# Then: create the skill
# This will depend on the tool
# Claude Code
ln -s "$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.
- 6d ago First seen · 141 lines · 31 tokens per session scan A 3de6c4650c18
writing-cli-skills is a skill published in the GitHub repository Kastalien-Research/thoughtbox (64 stars, last pushed 1mo ago), licensed MIT. It adds 31 tokens to every session and 931 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 2026-09-03.
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