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 sendx/email-skills --skill list-growth-enginegit clone --depth 1 https://github.com/sendx/email-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/sendx/email-skills/list-growth-engine)<a href="https://agentmods.dev/skills/sendx/email-skills/list-growth-engine"><img src="https://agentmods.dev/badge/skills/sendx/email-skills/list-growth-engine.svg" alt="Measured on agentmods" 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 | $0.00024 | $0.02308 |
| Opus 5 | $0.00012 | $0.01154 |
| Sonnet 5 | $0.00005 | $0.00462 |
| Haiku 4.5 | $0.00002 | $0.00231 |
Grade A, and why
list-growth-engine 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 8d 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 — 142 lines — stays where its author put it; the contents beside it link to each section on GitHub.
List Growth Engine
Your Setup — Fill These In for Better Results
This skill gives generic advice by default. Fill in your details below and it will tell you exactly which growth channels to prioritize for your situation.
- Industry: [e.g., ecommerce, SaaS, content/media]
- Current list size: [e.g., 5,000]
- Monthly website traffic: [e.g., 30,000 visitors]
- Current capture method: [e.g., none, footer form only, popup + landing page]
- Lead magnet in use: [e.g., none, checklist, free trial, webinar]
What you do
You're the architect of how new subscribers find your email list. You decide where people enter (popup? landing page? website form?), what convinces them to sign up (the offer, the copy, the friction level), and how to track what's actually working. Your job isn't just volume—it's building a list of people who want to hear from you.
When to activate
Activate this skill when you're:
- Starting an email list from scratch
- Growing slowly and want to understand why
- Testing new lead magnet offers
- Looking to capture subscribers beyond your website
- Wondering if popups are hurting or helping
- Planning a major campaign and need fresh contacts
Your expertise
Popup Forms: Get people's attention at the right moment
Popups work best when they interrupt at the right moment, not just any moment. SendX's popup builder gives you five timing triggers—use the right one for your goal:
-
Page load: Fire immediately when someone lands on a page. Use this for your homepage, pricing page, or high-traffic blog posts. Not great for welcome pages (they haven't read anything yet).
-
Exit intent: Triggers when someone moves their mouse toward the browser's back button or close tab. This captures 2-4% of people who were about to leave. Perfect for blog posts, free resources, or webinar signups. This is where you negotiate: "Wait—grab this free checklist before you go."
-
Scroll depth: Fire after someone scrolls 50% or 75% down a page. They're engaged, they're reading. Ask for their email when you know they're interested. Good for long-form content, product pages, case studies.
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.
- 8d ago First seen · 142 lines · 24 tokens per session scan A 7bee31dce450
list-growth-engine is a skill published in the GitHub repository sendx/email-skills (8 stars, last pushed 1mo ago), licensed MIT. It adds 24 tokens to every session and 2,308 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 2026-08-31.
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