# Markdown content negotiation (acceptmarkdown.com)

Check id `markdown-negotiation-vary` · Readability · runs in the free CLI · pre-release, in calibration

**What we look for.** Whether the homepage answers Markdown to agents and HTML to browsers, with Vary: Accept on the Markdown response.

**Why it matters.** Without Vary: Accept, a cache can hand your Markdown to a browser or your HTML to an agent.

**How to pass.** Add Vary: Accept to responses that change with the Accept header, at your server or CDN.

Run it: `npx backwatch your-site.com --pillar readability` and find `markdown-negotiation-vary` in the report.