Getting it into your agent
It runs from inside its repository, so the clone comes first — what it calls does not travel with the file alone.
git clone --depth 1 https://github.com/PaulRBerg/agent-skillsnpx agentmods add skills/paulrberg/agent-skills/skill-writingWrote 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/paulrberg/agent-skills/skill-writing)<a href="https://agentmods.dev/skills/paulrberg/agent-skills/skill-writing"><img src="https://agentmods.dev/badge/skills/paulrberg/agent-skills/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/paulrberg/agent-skills/skill-writing"><img src="https://agentmods.dev/badge/skills/paulrberg/agent-skills/skill-writing.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector warn
SkillSpector: 3 findings, 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 41 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.
- medium Agent Snooping · line 263 Skill enumerates or reads other installed skills. Access to other skills' SKILL.md files or the skills directory reveals prompt instructions, capabilities, and secrets that should be invisible to peer skills.Fix: Remove all code or instructions that list or read other skills' files or directories. Skills should operate independently; cross-skill access is a privilege escalation.
- medium Privilege Escalation · line 269 Commands invoke sudo or root privileges. Verify this elevated access is necessary and justified.Fix: Avoid sudo/root unless strictly required. Prefer least-privilege patterns. If elevation is needed, document the justification and scope.
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 | $0.03491 |
| Opus 5 | $0.00017 | $0.01746 |
| Sonnet 5 | $0.00007 | $0.00698 |
| Haiku 4.5 | $0.00003 | $0.00349 |
Grade B, and why
skill-writing scanned grade B with 2 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 2d 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.
Asks for rootmediumPrivilege escalation
A mod that escalates privileges can change anything on the machine, not only the project.
- Patch tooling creates files at mode 0644. Before the first verification run, `chmod 755` every executable under Makes network callslowCapability
Not a fault in itself. Listed so you know the mod talks to something, and to what.
Requires curl and a writable user cache directory; network populates or refreshes the agentskills.io specification. How it starts
The opening of the file, as written. The whole thing — 298 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Skill Writing
Bootstrap a project-local skill with a small observable contract, then symlink it into .claude/skills/ so Claude Code
can discover it. Keep invariant workflow guidance in SKILL.md; move deterministic mechanics and conditional detail
into scripts and references.
Model Optimization
Optimize every new skill and its content for GPT-6 Astra and Claude Fable 5.1. The summaries below are reminders, not substitutes for the live guides. Read both guides before designing or writing a complex, long-running, multi-tool, or orchestration-heavy skill because their recommendations may evolve.
- GPT-6 Astra prompting guidance: Complete authorized work under stated assumptions; make user-instruction precedence over skills explicit; specify writing and delegation preferences; and keep verification proportional to the change.
- Claude Fable 5.1 prompting guidance: Calibrate effort with evals; request progress updates; batch independent tool calls; preserve decisions across compaction; verify changing facts; and finish the requested scope with targeted edits and proportionate tests.
Arguments
- skill-name (required): kebab-case name (e.g.,
my-skill). Stop if missing or invalid.
Reject --global, explicit destination paths, and other scope overrides. The invocation working directory is the only
supported scope.
Repository Catalog Guard
Before resolving project-local paths, read the repository instructions applicable to the invocation working directory.
If they define a source catalog and lifecycle for skill creation, stop this workflow and follow that repository-owned
workflow. Do not create .agents/skills/ or .claude/skills/ paths in that repository.
Resolved Paths
Set <scope> to the working directory where the skill was invoked. Create the source at
<scope>/.agents/skills/<name>/ and the Claude Code symlink at <scope>/.claude/skills/<name>. Do not redirect the
scope to the repository root when invoked from a nested project or workspace. Never create or modify a skill under
~/.agents, ~/.claude, ~/.codex, or another global installation directory.
What ships with it
3 files 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.
- 2d ago Changed · -7 lines 770c5b97e4f6
- 7d ago Changed · -2 lines fb4d626bbd18
- 12d ago First seen · 307 lines · 35 tokens per session scan B ea5bae50fb75
skill-writing is a skill published in the GitHub repository PaulRBerg/agent-skills (70 stars, last pushed yesterday), licensed MIT. It adds 35 tokens to every session and 3,491 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it B with 2 findings (asks for root, makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
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