Borrowing it
Nothing to install: this file belongs to stevesolun/ctx. 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/stevesolun/ctx/main/.agents/skills/writing-great-skills/SKILL.mdgit clone --depth 1 https://github.com/stevesolun/ctxWrote 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/stevesolun/ctx/writing-great-skills)<a href="https://agentmods.dev/skills/stevesolun/ctx/writing-great-skills"><img src="https://agentmods.dev/badge/skills/stevesolun/ctx/writing-great-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/stevesolun/ctx/writing-great-skills"><img src="https://agentmods.dev/badge/skills/stevesolun/ctx/writing-great-skills.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 | $0.00025 | $0.00330 |
| Opus 5 | $0.00013 | $0.00165 |
| Sonnet 5 | $0.00005 | $0.00066 |
| Haiku 4.5 | $0.00003 | $0.00033 |
Grade A, and why
writing-great-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 11d 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.
What it actually says
Write an effective skill
- Define the job, realistic trigger prompts, non-trigger prompts, expected output, and material failure modes.
- Choose the degree of freedom:
- Use judgment-based guidance when context admits several good approaches.
- Use parameters or pseudocode when a preferred pattern still needs adaptation.
- Use deterministic scripts or hard gates only when reliability, safety, or repeatability justifies the constraint.
- Keep metadata concise and discriminative. Put trigger conditions in the description; put execution guidance in the body.
- Assume the model already understands general software work. Preserve only domain knowledge, workflow choices, tool interfaces, and opinions that materially change behavior.
- Keep the entrypoint legible. Move branch-specific detail, catalogues, templates, and examples to direct references; avoid deep reference chains.
- Prefer positive target behavior and surrounding-context judgment over blanket prohibitions. State exact constraints where mistakes would be costly or hard to recover.
- Validate syntax and links, then test both triggering and output quality with fresh, realistic prompts. Compare against a no-skill baseline when the skill's value is uncertain.
- Prune repetition, stale material, and instructions that do not change model behavior.
Read GLOSSARY.md when shared vocabulary helps discuss invocation, information hierarchy, steering, or pruning.
What ships with it
2 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.
- 11d ago First seen · 34 lines · 25 tokens per session scan A 4a3d098a9f59
writing-great-skills is a skill published in the GitHub repository stevesolun/ctx (585 stars, last pushed 11d ago), licensed MIT. It adds 25 tokens to every session and 330 once invoked, about $0.0001 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 2026-08-30.
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