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 SkillMedev/content-marketing-engine --skill email-newsletter-progit clone --depth 1 https://github.com/SkillMedev/content-marketing-engineWrote 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/skillmedev/content-marketing-engine/email-newsletter-pro)<a href="https://agentmods.dev/skills/skillmedev/content-marketing-engine/email-newsletter-pro"><img src="https://agentmods.dev/badge/skills/skillmedev/content-marketing-engine/email-newsletter-pro/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/skillmedev/content-marketing-engine/email-newsletter-pro"><img src="https://agentmods.dev/badge/skills/skillmedev/content-marketing-engine/email-newsletter-pro.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 | $0.00114 | $0.01714 |
| Opus 5 | $0.00057 | $0.00857 |
| Sonnet 5 | $0.00023 | $0.00343 |
| Haiku 4.5 | $0.00011 | $0.00171 |
Grade A, and why
Email Newsletter Pro 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.
This is a copy
100% identical to Email Newsletter Pro — 0 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.
How it starts
The opening of the file, as written. The whole thing — 115 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Email Newsletter Pro
A newsletter competes with the whole inbox. The costly mistake is optimizing the body while the subject line loses the open, or winning opens with clickbait the body cannot pay off - both burn the asset that matters most: the reader's habit of opening. Earn the open, reward it, and protect the cadence that builds the habit.
This skill covers recurring broadcast issues sent to a list. Automated sequences triggered by signup or behavior belong to email-drip-builder; if mail is landing in spam, fix that first with email-deliverability.
Operating procedure
Step 1: Gather inputs
Collect before writing. Where the user does not know a number, use the default and label it a guess.
- Audience and what they signed up for (the promise made at capture).
- This issue's single core idea - one sentence. If they offer three, make them pick one; the others become future issues or secondary links.
- Format: single-essay, curated-links, or hybrid (default: hybrid - one short essay plus 3-5 links).
- Current metrics: open rate, click rate, unsubscribe rate per send, list size (defaults: unknown - flag as guesses).
- Cadence and the one action they want readers to take (reply, read, share, buy - pick one).
Step 2: Pick the structure
- Single-essay: one idea developed in 300-800 words. Best when the author's thinking is the product. Highest reply rates.
- Curated-links: 5-10 links, each with a 1-2 sentence take explaining why it matters. The commentary is the value; a bare link list is a chore, not a newsletter.
- Hybrid: a 150-300 word lead essay plus 3-5 curated links. The safest default and easiest to sustain weekly.
Keep the chosen structure consistent issue to issue - predictable structure builds the reading habit.
Step 3: Write the subject line and preview text as a pair
- Subject under 50 characters (mobile clients truncate around there). Specific beats clever.
- The curiosity-vs-clarity tradeoff: curiosity ("The pricing mistake that cost us $40k") wins opens when the payoff inside is real; clarity ("3 pricing page teardowns") wins trust over time. Default to clarity with one concrete detail; spend curiosity only when the body fully pays it off.
- Preview text (roughly 40-90 characters shown) extends the subject with new information - never repeat the subject, never let "View this email in your browser" leak in.
- Write 5 subject candidates, pick 2, and A/B test them when the list exceeds ~2,000 subscribers (below that, a test rarely reaches significance in one send - just pick one and track over multiple issues).
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 · 115 lines · 114 tokens per session scan A 15b43bac0d6e
Email Newsletter Pro is a skill published in the GitHub repository SkillMedev/content-marketing-engine (1 stars, last pushed 2mo ago), licensed MIT. It adds 114 tokens to every session and 1,714 once invoked, about $0.0006 per session on Opus 5. A static security scan graded it A with 0 findings. It is 100% identical to Email Newsletter Pro, differing in 0 lines, and is treated as a copy.
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