---
title: "OpenAPI defined | Agent Ready Checklist"
description: "OpenAPI: Machine-readable contract for an HTTP API: paths, parameters, responses, auth. AR-ACT-02 asks for one; agents found it by link 97% of the time."
canonical: https://agentreadychecklist.com/glossary/openapi
site: "Agent Ready Checklist"
last_updated: 2026-11-05
section: "Glossary"
---

# OpenAPI defined | Agent Ready Checklist

> OpenAPI: Machine-readable contract for an HTTP API: paths, parameters, responses, auth. AR-ACT-02 asks for one; agents found it by link 97% of the time.

Source: https://agentreadychecklist.com/glossary/openapi
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)
Access: https://agentreadychecklist.com/auth.md (no key). Pricing: https://agentreadychecklist.com/pricing.md (free).

# OpenAPI

Machine-readable contract for an HTTP API: paths, parameters, responses, auth. AR-ACT-02 asks for one; agents found it by link 97% of the time. Example: curl -s https://example.com/openapi.json | jq -r .openapi. Related rows: AR-FIND-04, AR-READ-06, AR-ACT-01, AR-ACT-02. The Verify Kit check openapi tests OpenAPI.

## Definition

Machine-readable contract for an HTTP API: paths, parameters, responses, auth. AR-ACT-02 asks for one; agents found it by link 97% of the time.

## Example

```bash
curl -s https://example.com/openapi.json | jq -r .openapi
```

## Where it appears on the checklist

-   [AR-FIND-04](https://agentreadychecklist.com/checklist/ar-find-04/)AI Catalog at .well-known: Publish an AI Catalog at /.well-known/ai-catalog.json listing every agent-facing resource (MCP server card, OpenAPI, A2A card, docs, llms.txt, skills), linked with <link rel="ai-catalog"> and an HTTP Link header.
-   [AR-READ-06](https://agentreadychecklist.com/checklist/ar-read-06/)Link the discovery files: Link discovery files (llms.txt, .well-known/\*, openapi.json) from content agents already visit: the footer, <link rel="alternate"> in the head, or a resources section.
-   [AR-ACT-01](https://agentreadychecklist.com/checklist/ar-act-01/)Auth an agent can finish: Make authentication completable by an agent: self-serve keys with documented scopes; for user-delegated access, OAuth 2.0 with metadata under /.well-known.
-   [AR-ACT-02](https://agentreadychecklist.com/checklist/ar-act-02/)OpenAPI contract: Describe the public API with a machine-readable OpenAPI contract.
-   [Guide](https://agentreadychecklist.com/guides/one-day-agent-readiness-sprint/)The one-day agent-readiness sprint
-   [Guide](https://agentreadychecklist.com/guides/ship-llms-txt-and-link-it/)How to ship llms.txt and link it
-   [Guide](https://agentreadychecklist.com/guides/publish-openapi-agents-can-find/)How to publish an OpenAPI file agents can find

## Asked about it

### How do I make an OpenAPI file agents find?

Serve the raw file, link it from docs and the home page, and list it in /.well-known/api-catalog with a service-desc link. On sites that shipped one, 97% of openapi.json fetches came through a link.

### What is the difference between the AI Catalog and the API catalog?

The AI Catalog (AR-FIND-04) at /.well-known/ai-catalog.json lists every agent resource, MCP cards and skills included. The API catalog (RFC 9727) at /.well-known/api-catalog lists APIs with links to OpenAPI and docs.

## Sources

-   [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
-   [isitagentready.com/.well-known/agent-skills/ard/SKILL.md](https://isitagentready.com/.well-known/agent-skills/ard/SKILL.md)read 2026-11-04

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