What linter or formatter does Anthropic use for Markdown files?

[raky291]

What tools does the Anthropic team use to maintain so many consistent Markdown files? Do they use a linter or formatter? I'd like to know so I can use the same tools.

[ryanportfolio]

So there's nothing to copy from this repo tool-wise beyond the template idea, but Prettier + markdownlint-cli2 gets you the "many consistent Markdown files" outcome mechanically.

But this repo there's no markdownlint, Prettier, .editorconfig, etc.

The consistency comes from how the files are written. Every skill is scaffolded from template/SKILL.md, follows a written spec (spec/agent-skills-spec.md), and gets checked by a small script (quick_validate.py) that validates frontmatter structure only. The files are largely written and maintained by Claude following that template and spec, so they come out consistent by construction.

If your goal is keeping a lot of Markdown files consistent in your own project, the setup that actually does that has two parts:

1. A template plus a short written style guide for structure (which sections exist, in what order, how headings are phrased). No tool enforces this part; a template does.

2. A formatter plus a linter for everything mechanical. Prettier normalizes wrapping, list markers, and spacing (set "proseWrap": "always" so prose wraps consistently too), and markdownlint-cli2 enforces style rules like heading hierarchy and consistent list styles:

npm i -D prettier markdownlint-cli2
npx prettier --write "**/*.md"
npx markdownlint-cli2 "**/*.md"

Wire both into pre-commit or CI and drift stops accumulating.