zinsser

A Claude skill that audits prose against William Zinsser's On Writing Well — scores clarity, simplicity, brevity, and humanity, flags clutter, jargon, passive voice, weak leads and endings, and hands back a tightened rewrite.

Prose only. It is not a code reviewer.

## Zinsser audit — Slack message to the security team

**Reader:** engineers on call · **Job:** know what changed and what to do tonight

| Principle | Score | Note |
|---|---|---|
| Clarity   | 6/10  | The ask is buried in the last sentence. |
| Simplicity| 4/10  | Four -ion nouns in the opening line. |
| Brevity   | 3/10  | 118 words carrying about 50 words of content. |
| Humanity  | 7/10  | Contractions survive; nobody is doing anything, though. |

### Violations (7)
1. [NOUN] "the remediation implementation process" → "the fix" — dead abstraction, no actor
2. [QUAL] "somewhat urgent" → "urgent" — the hedge cancels the word
…

### Rewrite
…

**Cut:** 118 → 61 words (−48%)

Install

Claude Code, every project:

git clone https://github.com/<your-user>/Zinsser.git
bash Zinsser/install.sh

That copies the skill to ~/.claude/skills/zinsser/. To scope it to one project instead, pass the project root:

bash Zinsser/install.sh /path/to/project     # → project/.claude/skills/zinsser

Without cloning — dist/install-zinsser-skill.sh is one self-contained file with no dependencies and no network calls. Download it, run it, done:

bash install-zinsser-skill.sh

Claude.ai / Claude Desktop: upload zinsser.skill (or zip SKILL.md together with references/) through Settings → Capabilities → Skills.

Restart Claude Code or open a new session so it picks up the skill.

Use

/zinsser <paste text>          audit inline text
/zinsser path/to/draft.md      audit a file

Or just hand Claude a draft and say "zinsser this," "tighten this," or "is this well written."

Four modes, inferred from how you ask:

Mode	Say	You get
audit (default)	"zinsser this"	Scorecard, violation report, rewrite
nazi	"just tell me what's wrong"	Violations only, terse, no rewrite
rewrite	"fix it"	The tightened text alone
teach	"why is this bad?"	Audit plus the book's reasoning for each rule

The report scales to the text. A two-line Slack message gets violations and a rewrite, not a scorecard.

Layout

Zinsser/
├── SKILL.md                          the audit workflow (this is what Claude reads first)
├── references/
│   ├── principles.md                 Part I — the transaction, simplicity, clutter, style, words, usage
│   ├── mechanics.md                  Part II — unity, leads and endings, the Bits & Pieces rules
│   ├── clutter-list.md               the grep list: every condemned word and phrase, with fixes
│   ├── business-writing.md           Ch15–16 — technical explanation and institutional prose
│   ├── forms.md                      Ch11–19 — quoting, specificity, cliché disease, metrics, opinion
│   └── voice.md                      Part IV — taste, breeziness, condescension, the rewriting checklist
├── install.sh                        copies the skill out of a clone
├── scripts/build-installer.sh        regenerates dist/ from the files above
└── dist/install-zinsser-skill.sh     generated: one-file installer, never hand-edited

SKILL.md and references/ are the source of truth. Claude loads SKILL.md on every audit and pulls reference files only when the text calls for them — business-writing.md for a memo, forms.md for marketing copy, voice.md for anything signed with your name.

Editing it

Edit SKILL.md or the reference files, then rebuild the standalone installer so it doesn't drift:

bash scripts/build-installer.sh

Two customizations worth making early:

• House style. §4 of SKILL.md defers to a project voice guide on register — formality, openers, closers, emoji — while Zinsser governs the mechanics inside the sentence. Point it at your own style file.
• Your own tells. The clutter list ends each section with an auto-flag block. Add the phrases you keep catching yourself writing.

A note on sources

The reference files distill On Writing Well, 6th ed., by William Zinsser (HarperCollins, 2006) into checkable rules, with short attributed quotations. Buy the book. This repo is a working tool, not a substitute.

License

MIT, for the skill code and the distillation. See LICENSE. The underlying ideas and quoted phrases belong to Zinsser's estate and publisher.