Agent Ready HTML

Accept header

In short

The request header that lists media types a client will take, with optional q weights. Example: Claude Code v2.1.38 sent Accept: text/markdown, text/html, */* in Checkly's February 2026 test. Related terms: Content negotiation, Markdown negotiation, Markdown twin, Vary: Accept, AFDocs.

Source of the example

The example in the summary above is from checklyhq.com, read 4 November 2026.

Where it shows up on this site

Neighbouring terms

  • Content negotiation: The HTTP mechanism where the client states preferred formats in the Accept header and the server picks a representation for the same URL.
  • Markdown negotiation: Content negotiation where Accept: text/markdown returns the page as markdown with Content-Type text/markdown.
  • Markdown twin: A markdown copy of a page at a predictable URL, such as page.md or page.html.md.
  • Vary: Accept: A response header telling caches that the body depends on the Accept header, so HTML and markdown are stored separately.
  • AFDocs: The Agent-Friendly Documentation spec and its open-source checker, used by Mintlify, ReadMe and GitBook docs scores.

Sources

  1. checklyhq.com https://www.checklyhq.com/blog/state-of-ai-agent-content-negotation/, read 4 November 2026

Last reviewed 4 November 2026