Borrowing it
Nothing to install: this file belongs to vchelaru/FlatRedBall2. 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/vchelaru/FlatRedBall2/main/.claude/skills/skills-writer/SKILL.mdgit clone --depth 1 https://github.com/vchelaru/FlatRedBall2Wrote 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/vchelaru/flatredball2/skills-writer)<a href="https://agentmods.dev/skills/vchelaru/flatredball2/skills-writer"><img src="https://agentmods.dev/badge/skills/vchelaru/flatredball2/skills-writer/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/vchelaru/flatredball2/skills-writer"><img src="https://agentmods.dev/badge/skills/vchelaru/flatredball2/skills-writer.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 Agent Snooping · line 16 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 Rogue Agent · line 16 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 73 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.
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 | $0.00036 | $0.02780 |
| Opus 5.5 | $0.00014 | $0.01112 |
| Sonnet 5.5 | $0.00007 | $0.00556 |
| Haiku 4.5 | $0.00004 | $0.00278 |
Grade A, and why
skills-writer 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 16d 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 — 161 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Skills Writer
Mental Model
A skill is a map and a list of landmines, not an encyclopedia. It points an agent at the right code and docs and warns about what isn't obvious from reading them. If a fact already lives in source or docs/, link, don't restate.
A good skill answers three things and stops: where the relevant code/docs live, what gotchas aren't obvious from reading them, and what patterns recur. Default to prose-free pointers and tables; include code only when the snippet is a pattern that can't be conveyed by pointing at a file. Every line is re-read into context on every load, so a skill that says less but points accurately beats a thorough one.
Where Skills Live
All skills for this repo live under .claude/skills/<skill-name>/SKILL.md. Never write skill files outside this repo — not into ~/.claude/skills/, not into a sibling repo, not into the plugin marketplace. The folder name must match the name in frontmatter.
Growing a Skill — Damped Response
A skill is rarely written whole; it grows as pulls act on it — and a pull is any change: a question to answer, a request to create the skill from scratch, or an edit to extend it. Don't satisfy a pull 100% inside the skill — this holds for a brand-new skill as much as for an edit. A new skill's first draft is its signpost-sized core, not a full treatise. Treat demand as an elastic pull and the skill as an object resting in sand: a pull moves toward a fuller answer, the skill responds damped (moves part-way, not all the way), and retains its new position — the sand means it doesn't snap back.
Default: a 100% pull moves ~20% — including the pull that creates the skill. When a pull could be answered in full inside the skill, add only its broad orienting fifth — a concrete signpost plus a one-sentence shape of the answer — not the whole walkthrough. The first draft of a brand-new skill is subject to this too: start at the signpost, not the encyclopedia. A genuinely recurring topic reaches full coverage in a few pulls; a one-off never bloats the skill past its signpost.
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.
- 16d ago Changed · +1 lines · +36 tokens per session 2d89b03a502d
- 1mo ago Changed · +1 lines f6fa0375a206
- 1mo ago First seen · 159 lines · 0 tokens per session scan A 87964055fecf
skills-writer is a skill published in the GitHub repository vchelaru/FlatRedBall2 (15 stars, last pushed today), licensed MIT. It adds 36 tokens to every session and 2,780 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 2026-09-04.
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