Content Writer Agent
mastra-ai/mastra
Authoring playbook for building agents that draft written content — blog posts, marketing copy, social media posts, newsletters, product descriptions, landing pages, or ad copy.
Email copywriting skill used by the copywriter agent. An agent skill from revfactory/harness-100.
Install Email Copywriting
$ npx skills add revfactory/harness-100 --skill email-copywriting -a claude-codeProject install by default; add -g for ~/.claude/skills/.
$ gh skill install revfactory/harness-100 email-copywriting --agent claude-codeProject scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).
$ git clone --depth 1 https://github.com/revfactory/harness-100.git skills-src && mkdir -p .claude/skills && cp -r skills-src/en/03-newsletter-engine/.claude/skills/email-copywriting .claude/skills/email-copywriting && rm -rf skills-srcUse ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.
Claude Code skills documentation · loads skills from .claude/skills/
Install the "email-copywriting" agent skill from https://github.com/revfactory/harness-100/tree/main/en/03-newsletter-engine/.claude/skills/email-copywriting into .claude/skills/email-copywriting/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "email-copywriting", then confirm the skill loads.Claude Code copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$skill-installer install https://github.com/revfactory/harness-100/tree/main/en/03-newsletter-engine/.claude/skills/email-copywritingType this inside Codex. $skill-installer <name> installs a curated skill from openai/skills. The installer writes to $CODEX_HOME/skills (default ~/.codex/skills). Restart Codex if the skill does not show up.
$ npx skills add revfactory/harness-100 --skill email-copywriting -a codexProject install goes to .agents/skills/; add -g for ~/.codex/skills/.
$ gh skill install revfactory/harness-100 email-copywriting --agent codexProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/revfactory/harness-100.git skills-src && mkdir -p .agents/skills && cp -r skills-src/en/03-newsletter-engine/.claude/skills/email-copywriting .agents/skills/email-copywriting && rm -rf skills-srcUse ~/.agents/skills/ instead of .agents/skills for a personal install.
Codex skills documentation · loads skills from .agents/skills/
Install the "email-copywriting" agent skill from https://github.com/revfactory/harness-100/tree/main/en/03-newsletter-engine/.claude/skills/email-copywriting into .agents/skills/email-copywriting/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "email-copywriting", then confirm the skill loads.Codex copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ npx skills add revfactory/harness-100 --skill email-copywriting -a cursorProject install goes to .agents/skills/; add -g for ~/.cursor/skills/.
$ gh skill install revfactory/harness-100 email-copywriting --agent cursorProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/revfactory/harness-100.git skills-src && mkdir -p .cursor/skills && cp -r skills-src/en/03-newsletter-engine/.claude/skills/email-copywriting .cursor/skills/email-copywriting && rm -rf skills-srcUse ~/.cursor/skills/ instead of .cursor/skills for a personal install.
Cursor skills documentation · loads skills from .cursor/skills/, .agents/skills/, .claude/skills/, .codex/skills/
Install the "email-copywriting" agent skill from https://github.com/revfactory/harness-100/tree/main/en/03-newsletter-engine/.claude/skills/email-copywriting into .cursor/skills/email-copywriting/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "email-copywriting", then confirm the skill loads.Cursor copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ gemini skills install https://github.com/revfactory/harness-100.git --path en/03-newsletter-engine/.claude/skills/email-copywriting--scope user (default) or --scope workspace; --path is the subfolder of the repo that holds the skill; --consent skips the security confirmation prompt.
$ npx skills add revfactory/harness-100 --skill email-copywriting -a gemini-cliProject install goes to .agents/skills/; add -g for ~/.gemini/skills/.
$ gh skill install revfactory/harness-100 email-copywriting --agent gemini-cliProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/revfactory/harness-100.git skills-src && mkdir -p .gemini/skills && cp -r skills-src/en/03-newsletter-engine/.claude/skills/email-copywriting .gemini/skills/email-copywriting && rm -rf skills-srcUse ~/.gemini/skills/ instead of .gemini/skills for a personal install, then run /skills reload.
Gemini CLI skills documentation · loads skills from .gemini/skills/, .agents/skills/
Install the "email-copywriting" agent skill from https://github.com/revfactory/harness-100/tree/main/en/03-newsletter-engine/.claude/skills/email-copywriting into .gemini/skills/email-copywriting/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "email-copywriting", then confirm the skill loads.Gemini CLI copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ gh skill install revfactory/harness-100 email-copywritingInstalls for Copilot at project scope by default; add --scope user for a personal install. Preview a skill first with gh skill preview. Needs GitHub CLI 2.90.0 or later (public preview).
$ npx skills add revfactory/harness-100 --skill email-copywriting -a github-copilotProject install goes to .agents/skills/; add -g for ~/.copilot/skills/.
$ git clone --depth 1 https://github.com/revfactory/harness-100.git skills-src && mkdir -p .github/skills && cp -r skills-src/en/03-newsletter-engine/.claude/skills/email-copywriting .github/skills/email-copywriting && rm -rf skills-srcUse ~/.copilot/skills/ instead of .github/skills for a personal install. Commit .github/skills so cloud agent and code review can use it.
GitHub Copilot skills documentation · loads skills from .github/skills/, .claude/skills/, .agents/skills/
Install the "email-copywriting" agent skill from https://github.com/revfactory/harness-100/tree/main/en/03-newsletter-engine/.claude/skills/email-copywriting into .github/skills/email-copywriting/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "email-copywriting", then confirm the skill loads.GitHub Copilot copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ npx skills add revfactory/harness-100 --skill email-copywriting -a opencodeOpenCode documents no install command of its own. Project install goes to .agents/skills/; add -g for ~/.config/opencode/skills/.
$ gh skill install revfactory/harness-100 email-copywriting --agent opencodeProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/revfactory/harness-100.git skills-src && mkdir -p .opencode/skills && cp -r skills-src/en/03-newsletter-engine/.claude/skills/email-copywriting .opencode/skills/email-copywriting && rm -rf skills-srcUse ~/.config/opencode/skills/ instead of .opencode/skills for a personal install.
OpenCode skills documentation · loads skills from .opencode/skills/, .claude/skills/, .agents/skills/
Install the "email-copywriting" agent skill from https://github.com/revfactory/harness-100/tree/main/en/03-newsletter-engine/.claude/skills/email-copywriting into .opencode/skills/email-copywriting/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "email-copywriting", then confirm the skill loads.OpenCode copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
Facts
- Skill name
email-copywriting- GitHub stars
- 1.3k
- Token cost
- ~1.5k tokens
- SKILL.md length
- 687 words
- Files
- 1
- Skills in repo
- 464
- Repo updated
- First seen
- Licence
- Apache-2.0
At a glance
Email copywriting skill used by the copywriter agent. An agent skill from revfactory/harness-100.
- Works in 5 steps: The first sentence is everything: The… → Inverted pyramid: Most important… → Visual breaks: Insert subheadings,… → …
- Newsletter writing
- SKILL.md covers Why Email Copy Is Different, Subject Line Design: The CURVE…, Preheader (Preview Text)… and Body Structure: F-Pattern Scan…, plus 3 more sections
- Instructions only: no scripts, shell commands, URLs or credentials in SKILL.md
What it does
Email Copywriting is an agent skill from revfactory/harness-100. Email copywriting skill used by the copywriter agent. Provides subject line psychology, preheader optimization, CTA design, and scannable body structure methodologies specific to the email medium. Use for 'email copy,' 'newsletter writing,' 'subject lines,' 'CTA design,' and similar requests.
Its SKILL.md is about 1.5k tokens, which your agent loads only when the skill is triggered. It is a single SKILL.md file with no bundled scripts.
It sits in Writing & Content, covering Copywriting and Newsletters. The licence is Apache-2.0.
When your agent uses it
- Newsletter writing
- Similar requests
Example prompts
- “email copy,”
- “newsletter writing,”
- “subject lines,”
- “/email-copywriting”
Workflow steps
5 steps, taken from the first numbered list in SKILL.md.
- The first sentence is everything: The 1–2 sentences visible on open determine whether the entire email gets read
- Inverted pyramid: Most important information at the top, supplementary info below
- Visual breaks: Insert subheadings, dividers, images, or pull quotes every 3–4 sentences
- One paragraph = one idea: 2–3 sentences per paragraph; never exceed 5
- Link strategy: Place important links in the top 1/3 of the body (drive clicks before scrolling)
What it can do on your machine
Read from SKILL.md and the folder at commit 8e8d35c. It shows what the files ask for, not the result of running them.
Tool permissions
Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.
From allowed-tools in the SKILL.md frontmatter.
Runs code
No scripts in the folder and no shell commands in SKILL.md.
From the folder's file list and the shell code blocks in SKILL.md.
Network
No URLs in SKILL.md.
From URLs in SKILL.md, links to its own repository left out.
Credentials
Names no API keys, tokens, secrets or passwords.
From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.
Context cost
Email Copywriting loads about 1.5k tokens when it runs. Until then it costs about 78 tokens; SKILL.md has 687 words of instructions outside code blocks.
Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.
Safety
Auto-check passed
The automated check found no risky patterns in SKILL.md.
Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.
SKILL.md
The full file from revfactory/harness-100 at commit 8e8d35c, republished under its Apache-2.0 licence (© revfactory). 687 words, ~1,526 tokens.
Download SKILL.mdSave it as
.claude/skills/email-copywriting/SKILL.md (or your agent's skills folder).- name
- email-copywriting
- description
- Email copywriting skill used by the copywriter agent. Provides subject line psychology, preheader optimization, CTA design, and scannable body structure methodologies specific to the email medium. Use for 'email copy,' 'newsletter writing,' 'subject lines,' 'CTA design,' and similar requests.
Email Copywriting — Email Copywriting Methodology
Writing techniques specific to the email medium, used by the copywriter agent when crafting newsletters.
Why Email Copy Is Different
Blog posts are found via search. Social media posts are discovered in feeds. Emails must be opened from the inbox to be read. The battle is won or lost at the subject line, and within 7 seconds of opening, readers decide whether to scroll or close.
Subject Line Design: The CURVE Framework
| Element | Description | Example |
|---|---|---|
| Curiosity | Create an information gap | "The email secret most marketers don't know" |
| Urgency | Create time pressure | "Only until midnight — sharing this strategy" |
| Relevance | Connect to the reader's current interests | "[AI Trends] 3 things you need to know this week" |
| Value | Promise a specific benefit | "3 minutes to read, 3 hours saved" |
| Emotion | Trigger an emotion | "I made this mistake too (and deeply regretted it)" |
12 Subject Line Formulas
| # | Formula | Template |
|---|---|---|
| 1 | Number + Benefit | "[N] ways to achieve [result]" |
| 2 | Question | "Struggling with [reader's pain point]?" |
| 3 | How-to | "How to [desired result] (expert-verified)" |
| 4 | Negative | "If you're making [mistake], stop now" |
| 5 | Social Proof | "The [tool] that [famous person/company] actually uses" |
| 6 | Contrast/Reversal | "You think [conventional wisdom]? It's the opposite" |
| 7 | Personal Story | "One thing I learned from [experience]" |
| 8 | Breaking News | "News just dropped that will reshape [industry]" |
| 9 | Listicle Preview | "In this week's newsletter: [Topic 1], [Topic 2], and..." |
| 10 | Exclusive/Scarcity | "Subscriber-only [content] revealed" |
| 11 | Challenge/Provocation | "If you want [result], drop this [habit]" |
| 12 | Open Loop | "[Situation] happened. The result..." |
Subject Line Optimization Rules
- Length: 28–50 characters (avoids truncation on mobile)
- Personalization: [Name] insertion boosts open rates by an average of 26% (but don't overuse)
- Emojis: 1 is acceptable; 2+ risks spam filter triggers
- Capitalization: No all-caps; sentence case only
- A/B Variable: Always write 2+ subject lines for A/B testing
Preheader (Preview Text) Strategy
The preheader is the subject line's supporting weapon. When the subject line sparks curiosity, the preheader delivers specifics.
| Strategy | Description | Example |
|---|---|---|
| Complementary | Expand on the subject line's info | Subject: "Top 3 AI stories this week" → Preheader: "OpenAI's new model + Google strikes back + startup jackpot" |
| Continuation | Continue the subject line's sentence | Subject: "We cut our marketing budget by 50%..." → Preheader: "and revenue actually went up" |
| CTA | Directly prompt action | Subject: "Free template release" → Preheader: "Download now (48-hour window)" |
| Social Proof | Show others' reactions | Preheader: "127 replies to our last issue" |
- Length: 40–90 characters (varies by email client; Gmail shows up to 90)
- Prohibited: Repeating the subject line verbatim
Show full SKILL.md (275 more words)Show less
Body Structure: F-Pattern Scan Design
Email readers don't read — they scan in an F-shaped pattern.
Newsletter Body Design Principles
- The first sentence is everything: The 1–2 sentences visible on open determine whether the entire email gets read
- Inverted pyramid: Most important information at the top, supplementary info below
- Visual breaks: Insert subheadings, dividers, images, or pull quotes every 3–4 sentences
- One paragraph = one idea: 2–3 sentences per paragraph; never exceed 5
- Link strategy: Place important links in the top 1/3 of the body (drive clicks before scrolling)
Recommended Section Structure
[Intro: 1–2 sentences — this issue's core message]
---
[Main Story: Most important content]
- Subheading
- Body (5–8 sentences)
- CTA button or link
---
[Sub Stories 2–3: Short curations]
- 2–3 sentences each + link
---
[Recommended Resources / Tools / Books]
---
[Closing: Question for reader or preview of next issue]CTA (Call-to-Action) Design
CTA Placement Strategy
| Position | CTA Type | Expected Conversion |
|---|---|---|
| Top (first 200px) | Primary CTA — this issue's main action | Highest |
| Middle (after main story) | Secondary CTA — explore related content | Medium |
| Bottom (closing) | Repeat CTA — same as top or share prompt | Safety net |
CTA Copy Formula
- Start with a verb: "Read the guide," "Download now," "Check it out"
- Include specific benefit: "Read the 5-minute guide" > "Learn more"
- Button design: Buttons get 28% higher CTR than text links
- Add urgency: "48-hour window," "First 100 only"
Tone & Voice Matrix
| Newsletter Type | Recommended Tone | First Person | Reader Address | Emoji Use |
|---|---|---|---|---|
| Business/Industry | Professional + witty | "I/we" | "you" | Minimal (section dividers) |
| Tech/Dev | Casual + practical | "I" | "you" | Freely |
| Lifestyle | Intimate + emotional | "I" | "you" | Generous |
| Curation/News | Objective + concise | "The editorial team" | "readers" | Almost none |
A/B Test Variable Priority
Test in order of impact (one variable at a time):
- Subject line (direct impact on open rate — test first)
- Send time (day + time slot)
- CTA copy/design (click-through rate)
- Body length (long-form vs. short-form)
- Preheader (fine-tuning open rate)
- Sender name (brand name vs. personal name)
© revfactory, Apache-2.0. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file
Files
Just SKILL.md in en/03-newsletter-engine/.claude/skills/email-copywriting of revfactory/harness-100.
Open the folder on GitHubat commit 8e8d35c
Compare with similar skills
Email Copywriting next to the 5 skills that share the most tags, products or categories with it. Stars are the repository's; “used in” counts other GitHub owners with a copy.
| Skill | Stars | Used in | Tokens | Auto-check | Licence | Repo updated |
|---|---|---|---|---|---|---|
| Email Copywriting this skillrevfactory/harness-100 | 1.3k | — | ~1.5k | Automated safety check: Pass | Apache-2.0 | |
| Content Writer Agentmastra-ai/mastra | 29k | — | ~1.3k | Automated safety check: Pass | Custom licence | |
| Natural Chinesegarden-cosmos/natural-chinese-protocol | 143 | — | ~1.4k | Automated safety check: Pass | MIT | |
| End-of-Article CTA Designersamber/cc-skills | 228 | — | ~3.1k | Automated safety check: Pass | MIT | |
| Copywriting Hookssamber/cc-skills | 228 | — | ~6.8k | Automated safety check: Pass | MIT | |
| Press Media Relationsaaron-he-zhu/aaron-marketing-skills | 2.9k | — | ~3.1k | Automated safety check: Pass | Apache-2.0 |
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Categories
Questions about Email Copywriting
What does Email Copywriting do?
Email copywriting skill used by the copywriter agent. An agent skill from revfactory/harness-100. Email Copywriting is an agent skill from revfactory/harness-100. Email copywriting skill used by the copywriter agent.
When should I use Email Copywriting?
Email Copywriting fits situations like: newsletter writing; similar requests.
How do I install Email Copywriting in Claude Code?
Run `npx skills add revfactory/harness-100 --skill email-copywriting -a claude-code`. Or copy the skill folder (en/03-newsletter-engine/.claude/skills/email-copywriting in revfactory/harness-100) into .claude/skills/email-copywriting in your project. Claude Code loads it when a task matches its description.
How do I install Email Copywriting in Codex?
Run `npx skills add revfactory/harness-100 --skill email-copywriting -a codex`. Or copy the skill folder (en/03-newsletter-engine/.claude/skills/email-copywriting in revfactory/harness-100) into .agents/skills/email-copywriting in your project. Codex loads it when a task matches its description.
Can I use Email Copywriting in Cursor, Gemini CLI or GitHub Copilot?
Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add revfactory/harness-100 --skill email-copywriting -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/email-copywriting, .gemini/skills/email-copywriting, .github/skills/email-copywriting and .opencode/skills/email-copywriting in your project.
What does Email Copywriting need to run?
SKILL.md names no scripts, command-line tools or credentials: Email Copywriting is instructions for the agent only.
Does Email Copywriting access the network?
SKILL.md contains no URLs. Any network use would come from the scripts or tools the agent runs. This is read from the text; nothing was executed.
Is Email Copywriting safe to install?
Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. Review the folder before installing.
What licence does Email Copywriting use?
Email Copywriting is published under the Apache-2.0 licence (the repository's licence). It allows redistribution, so the full SKILL.md is shown on this page.
How many tokens does Email Copywriting use?
About 1.5k tokens (SKILL.md is roughly 6.1k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full.
What are the alternatives to Email Copywriting?
Skills that share tags, products or a category with Email Copywriting: Content Writer Agent (mastra-ai/mastra, 29k stars), Natural Chinese (garden-cosmos/natural-chinese-protocol, 143 stars), End-of-Article CTA Designer (samber/cc-skills, 228 stars) and Copywriting Hooks (samber/cc-skills, 228 stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.
Who maintains Email Copywriting?
revfactory (a GitHub user) maintains it in revfactory/harness-100, which has 1,295 GitHub stars. The repository holds 464 skills in this directory. The repository was last updated on March 22, 2026.
Source: revfactory/harness-100 on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.