---
title: "Agent 404: glossary: Agent Ready HTML"
description: "Agent 404 defined: A 404 response written for agents, often markdown, that links the index and similar pages so the agent can recover."
canonical: https://agentreadyhtml.com/glossary/agent-404/
site: "Agent Ready HTML"
last_updated: 2026-11-04
section: "Glossary"
---

# Agent 404: glossary: Agent Ready HTML

> Agent 404 defined: A 404 response written for agents, often markdown, that links the index and similar pages so the agent can recover.

Source: https://agentreadyhtml.com/glossary/agent-404/
Site: Agent Ready HTML
Last reviewed: 2026-11-04

# Agent 404

In short

A 404 response written for agents, often markdown, that links the index and similar pages so the agent can recover. Example: ReadMe returns a markdown 404 with agentTools front matter for missing .md pages. Related terms: Real status code, Soft 404, Agent score (docs), AFDocs.

## Source of the example

The example in the summary above is from [docs.readme.com](https://docs.readme.com/main/docs/llmstxt), read 4 November 2026.

## Where it shows up on this site

-   [Guide: real status codes on a SPA](https://agentreadyhtml.com/guides/real-status-codes-on-a-spa/)

## Neighbouring terms

-   [Real status code](https://agentreadyhtml.com/glossary/real-status-code/): An HTTP status that matches what happened: 200 for a page, 404 for a missing path, 429 for throttling.
-   [Soft 404](https://agentreadyhtml.com/glossary/soft-404/): A missing page that returns 200 with an error message in the body.
-   [Agent score (docs)](https://agentreadyhtml.com/glossary/docs-agent-score/): A docs-specific readiness score computed from AFDocs-style checks, published by docs vendors.
-   [AFDocs](https://agentreadyhtml.com/glossary/afdocs/): The Agent-Friendly Documentation spec and its open-source checker, used by Mintlify, ReadMe and GitBook docs scores.

## Sources

1.  [docs.readme.com](https://docs.readme.com/main/docs/llmstxt) https://docs.readme.com/main/docs/llmstxt, read 4 November 2026

Last reviewed 4 November 2026

Edition

Crawl

2026-11-04

Page updated

2026-11-04

Method

How the viewer reads a page, how a file is graded and how a platform is scored: [the method page](https://agentreadyhtml.com/method/).