---
title: "Retry-After defined | Agent Ready Checklist"
description: "Retry-After: Response header telling a client how many seconds (or until what date) to wait before retrying. Pair it with 429. Related rows: AR-READ-02."
canonical: https://agentreadychecklist.com/glossary/retry-after
site: "Agent Ready Checklist"
last_updated: 2026-11-05
section: "Glossary"
---

# Retry-After defined | Agent Ready Checklist

> Retry-After: Response header telling a client how many seconds (or until what date) to wait before retrying. Pair it with 429. Related rows: AR-READ-02.

Source: https://agentreadychecklist.com/glossary/retry-after
Site: Agent Ready Checklist
Last reviewed: 2026-11-05
Agent endpoints: https://agentreadychecklist.com/llms.txt (index), https://agentreadychecklist.com/openapi.json (API), https://agentreadychecklist.com/mcp (MCP server), https://agentreadychecklist.com/ask (search)
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# Retry-After

Response header telling a client how many seconds (or until what date) to wait before retrying. Pair it with 429. Example: HTTP/1.1 429 Too Many Requests Retry-After: 120. Related row: AR-READ-02 (Real HTTP status codes). The guide "One-day agent-readiness sprint" covers a row that names Retry-After.

## Definition

Response header telling a client how many seconds (or until what date) to wait before retrying. Pair it with 429.

## Example

```text
HTTP/1.1 429 Too Many Requests
Retry-After: 120
```

## Where it appears on the checklist

-   [AR-READ-02](https://agentreadychecklist.com/checklist/ar-read-02/)Real HTTP status codes: Return accurate HTTP status codes: 404 or a real redirect for missing paths, 429 with Retry-After when throttling; never 200 for a missing page and never a silent challenge page in place of 429.
-   [Guide](https://agentreadychecklist.com/guides/one-day-agent-readiness-sprint/)The one-day agent-readiness sprint
-   [Guide](https://agentreadychecklist.com/guides/read-server-logs-for-agent-user-agents/)How to read your server logs for agent user agents
-   [Guide](https://agentreadychecklist.com/guides/keep-a-site-agent-ready-in-ci/)How to keep a site agent ready in CI

## Asked about it

### What should my rate limiter return to agents?

A 429 Too Many Requests with a Retry-After header, not a CAPTCHA or challenge page. Agents and crawlers treat 429 as a back-off signal and come back; a challenge page looks like content or a block.

## Sources

-   [rfc-editor.org/rfc/rfc6585](https://www.rfc-editor.org/rfc/rfc6585)read 2026-11-04
-   [github.com/agentready-org/standard/blob/main/spec/spec.md](https://github.com/agentready-org/standard/blob/main/spec/spec.md)read 2026-11-04

Last reviewed 2026-11-05. AgentReady v2.0, read 2026-11-04.