MarginMargin turns your feedback into your AI’s style guide
A Markdown reader for the Mac. Mark a line that sounds like AI, say what’s wrong, and it becomes a rule Claude follows on the next draft.
Select a phrase that sounds like AI, or just watch.
Onboarding is the product
Most teams treat onboarding as a checklist. It’s worth noting that the first session decides whether anyone comes back. This isn’t a design problem. It’s a patience problem. Teams that leverage a short, guided first run keep more of the people who sign up.
Claude’s next draft, in a different post, lands here.
The whole loop in thirty seconds
The same loop in the Mac app, on a sample draft.
- Read the draft. AI writes fluently, and it still doesn’t write like you.
- Mark what’s wrong. Highlight the line and say why in a margin note.
- Feedback becomes a rule. The note turns into a writing rule with a severity and an example.
- Claude checks your rules before it writes. The writing guard catches the pattern and Claude rewrites.
A 30-second film of Margin: an AI draft line uses the pattern “you don’t need to ship, you need to understand”; it is highlighted in Margin with a note on why it sounds like AI; the note becomes a writing rule, one of 356 from Sam’s own corrections; and Claude’s next draft is caught by the writing guard and rewritten.
A reader first, then a memory
If the tool doesn’t feel good to sit in, you won’t annotate. If you don’t annotate, your AI never learns. So Margin is a real Markdown reader before it is anything else.
A page worth sitting in
A 65-character measure and generous line height, with font size, spacing and width you can tune. Tabs, a table of contents from your headings, light and dark, and full-text search across every document.
Highlights that survive edits
Highlight in color and attach a margin note to any highlight. When the file changes, Margin finds each highlight again in four tries.
Praise counts too
Tag a correction as corrective, a pattern to avoid, or positive, writing to emulate. Nine writing types, from email to PRD to cover letter, keep each rule scoped.
“This opening is exactly the right energy: conversational, mid-thought, no preamble.”
“Never use ‘furthermore’. It’s an AI transition tell.”
Claude can’t write what you’ve banned
Switch on the writing guard in Settings and Margin generates a Claude Code hook from your rules. It never touches your Claude or Codex setup unless you do. When Claude tries to write a kill word or an AI-slop pattern into a prose file, the hook rejects the edit before it lands. A bundled MCP server gives Claude your documents, annotations, corrections and rules, and Send to Claude pushes annotations straight in.
The rules come back in the reader too. A reviewed rule underlines its matches in whatever you have open, and the card in the margin offers a one-click replace.
Review AI edits one change at a time
When Claude edits a file you have open, Margin notices. Edits under 5% of the document are accepted quietly. Larger ones show a diff with keep or revert on each change.