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 vadimcomanescu/codex-skills --skill senior-prompt-engineergit clone --depth 1 https://github.com/vadimcomanescu/codex-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/vadimcomanescu/codex-skills/senior-prompt-engineer)<a href="https://agentmods.dev/skills/vadimcomanescu/codex-skills/senior-prompt-engineer"><img src="https://agentmods.dev/badge/skills/vadimcomanescu/codex-skills/senior-prompt-engineer/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/vadimcomanescu/codex-skills/senior-prompt-engineer"><img src="https://agentmods.dev/badge/skills/vadimcomanescu/codex-skills/senior-prompt-engineer.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 | $0.00061 | $0.00233 |
| Opus 5 | $0.00030 | $0.00117 |
| Sonnet 5 | $0.00012 | $0.00047 |
| Haiku 4.5 | $0.00006 | $0.00023 |
Grade A, and why
senior-prompt-engineer 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.
What it actually says
Senior Prompt Engineer
Treat prompts like products: versioned, tested, and measurable.
Quick Start
- Define the job: inputs, outputs, and the “definition of done”.
- Write the smallest prompt that:
- states constraints clearly
- defines output format
- includes edge-case handling
- Add examples only when needed (few-shot is expensive).
- Create an eval set: representative cases + adversarial cases.
- Iterate with diffs: change one thing, measure impact.
Optional tool: scaffold a prompt + eval harness
python ~/.codex/skills/senior-prompt-engineer/scripts/scaffold_prompt_eval.py . --out evals/prompt_eval
References
- Prompt review checklist:
references/prompt-review.md
What ships with it
5 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.
- 12d ago First seen · 28 lines · 61 tokens per session scan A f71c044794e6
senior-prompt-engineer is a skill published in the GitHub repository vadimcomanescu/codex-skills (24 stars, last pushed 7mo ago), licensed MIT. It adds 61 tokens to every session and 233 once invoked, about $0.0003 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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