Start using AI properly: 10 skills that replace an assistant

email-drafter

write the email you have been putting off

How the two work together

Claude thinks it through. Paste the Claude prompt into Claude Code, or drop the folder into your skills folder. Claude does the judgement: what to look for, what is worth doing, what is right.

Codex gets it done. At the hand-off point Claude runs Codex on your machine with one command and passes it the Codex prompt. Codex does the mechanical part and hands the result back. Claude checks it before you see it.

No API key to set up: Claude calls the Codex you already have installed. If Codex is not installed, Claude does that half itself and tells you.

Prompt for Claude

---
name: email-drafter
description: Turns the email you have been avoiding into one sendable draft, five subject lines and two follow-ups, from facts you supply. Use when it is overdue, awkward or stuck in drafts.
---

# Write the email you have been putting off

One sendable email in your own voice, chasers already written.

## Claude does

1. Ask for five things, then wait: who it goes to and what they know, what you want to happen after they read it, the facts you can state, why it has been hard to send, and the signing name.
2. Ask for 3 to 5 emails you have sent that sound like you. Anthropic and Google's whitepaper both settle on 3 to 5, relevant and diverse. Zero is allowed; Claude writes plainly and says the voice is unmatched.
3. Pick the shape. Under 150 words the ask goes in the first two sentences; longer, background first and request last, the order Anthropic measures as worth up to 30 percent better results.
4. Write ONE draft, not a menu of three. Every paragraph opens with an action verb (Ask, Confirm, Send, Decide), the whitepaper's instructions-over-constraints rule.
5. Refuse to guess. Any number, date or promise you did not supply stays as empty [] brackets, listed underneath. A visible hole beats a confident sentence.
6. Name the tone in one word (direct, apologetic, firm, warm) and check it against the examples.

## Then Codex does

Codex takes the approved draft and runs the repetitive passes: the AI-tell scan, five subject lines, two follow-ups. String work over finished text, so bulk not judgement.

Fill {DRAFT_EMAIL}, {SENDER_NAME}, {RECIPIENT_CONTEXT} and {FACT_LIST} into CODEX.md, then run:

```
codex exec --sandbox danger-full-access --skip-git-repo-check -C "<working folder>" - < CODEX.md
```

## Claude checks

1. The scan reports zero hits for delve, tapestry, testament, underscore, pivotal, boasts, nestled, vibrant, showcasing, meticulous.
2. No sentence uses "not just X, but Y" or trails off in a participle such as "highlighting the importance of".
3. Every figure, date and name in all three emails appears in {FACT_LIST}. A follow-up inventing "as discussed on Tuesday" rejects the pack.
4. No em dashes, no bold in a body, and the signature reads {SENDER_NAME}.
5. Subject lines run under 50 characters and none can be answered "no".

Reject and rerun once, quoting the failing lines. Failed twice, Claude does the pass itself and says so.

## Rules

- Public information only.
- Never invent a fact, a number or a quote.
- Anything sent in someone's name says whose name it is.
- Say what the email must do, not what it must avoid.
- Give the reason with the rule; a bare prohibition gets ignored.
- Never send. The pack returns to the person whose name is on it.

## If Codex is not installed

Claude runs the scan, subject lines and follow-ups itself, and says so.

## Built from

- anthropics/skills, https://github.com/anthropics/skills, 174,340 stars from api.github.com; internal-comms, the first-party pattern for writing in a named person's voice.
- anthropics/prompt-eng-interactive-tutorial, https://github.com/anthropics/prompt-eng-interactive-tutorial, 38,070 stars from api.github.com; the 10 slot prompt order.
- Wikipedia:Signs of AI writing, https://en.wikipedia.org/wiki/Wikipedia:Signs_of_AI_writing; the catalogue real editors use to detect AI text; banned words and shapes.
- Google prompt engineering whitepaper, Lee Boonstra, https://www.kaggle.com/whitepaper-prompt-engineering; instructions-over-constraints, 3 to 5 examples.

Prompt for Codex

# Write the email you have been putting off - Codex task

## You are given

- {DRAFT_EMAIL}: a finished, approved email body. Its argument and meaning are settled.
- {SENDER_NAME}: the real person whose name goes at the bottom of every message.
- {RECIPIENT_CONTEXT}: one or two lines on who receives it and what they already know.
- {FACT_LIST}: every fact the sender confirmed. Dates, figures, names, amounts. Nothing outside this list is true.

## Produce

One file, `email-pack.md`, with five sections in this order.

1. `## Approved draft` - {DRAFT_EMAIL} copied in unchanged.
2. `## Scan` - a table with one row per hit: pattern, line number, plain replacement. Scan for the words delve, tapestry, testament, underscore, pivotal, boasts, nestled, vibrant, showcasing, meticulous, landscape; the copula dodges "serves as", "stands as", "represents"; the shape "not just X, but Y"; any sentence ending in a present participle; em dash characters; bold markup inside a body. No hits means write `0 hits` and nothing else.
3. `## Subject lines` - exactly 5, numbered, each under 50 characters, each stating the ask or the fact, none phrased as a yes or no question. Print the character count beside each.
4. `## Follow-up day 3` - under 80 words. Reference the original by its subject line, add no new facts, end with one specific question.
5. `## Follow-up day 7` - under 60 words. Offer a way to close it: a date, a decision, or permission to drop it. No guilt, no new facts.

Sign both follow-ups with {SENDER_NAME}.

## Rules

- Use only {FACT_LIST}. Any date, figure, price or event not in it is forbidden, including "as discussed" and "as promised last week".
- Where a sentence needs a fact you do not have, write empty [] brackets there and record it under a final `## Missing` heading.
- British English throughout. No em dashes anywhere. No headings or bullets inside an email body.
- Do not rewrite, shorten or improve {DRAFT_EMAIL}.
- Do not send anything, open a mail client, or write outside the working folder.

## Return

Print to stdout, in this order:

- the absolute path of `email-pack.md`
- the scan hit count as a single integer
- the 5 subject lines with their character counts
- the word count of each follow-up
- the contents of `## Missing`, or the word NONE

Built from the best public work on this

Sources

  • anthropics/skills, https://github.com/anthropics/skills, 174,340 stars read from api.github.com (20,648 forks, pushed 2026-09-03); its internal-comms skill is the first-party pattern for writing a message in a named person's voice.
  • Anthropic prompt engineering interactive tutorial, https://github.com/anthropics/prompt-eng-interactive-tutorial, 38,070 stars from api.github.com; chapter 09 gives the canonical 10 slot prompt order (role, task context, tone context, rules, examples, input data, immediate task, think step by step, output format, prefill) that the interview in SKILL.md follows.
  • Wikipedia:Signs of AI writing, https://en.wikipedia.org/wiki/Wikipedia:Signs_of_AI_writing; a continuously maintained, community-policed catalogue used by real editors to detect AI text at scale, so it is adversarial rather than a style opinion. Source of the banned vocabulary, the copula dodges, negative parallelism and the trailing participle.
  • Google prompt engineering whitepaper by Lee Boonstra, https://www.kaggle.com/whitepaper-prompt-engineering; 65 pages, extracted in full locally. Source of instructions-over-constraints and of the "at least three to five examples" figure.

Best public prompt we found for this job

https://www.kaggle.com/whitepaper-prompt-engineering

The whitepaper's worked pair is the one line that most improves an email prompt, because it replaces a list of things to avoid with a list of things to do:

DO: "Only discuss the console, the company who made it, the year, and total sales"
DO NOT: "Do not list video game names."

Applied to email: tell the model what the message must contain and what it must achieve, not what tone it should steer clear of. Keep constraints for the two places they earn their keep, safety and a strict output format.

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