---
title: "OpenAPI: plain-language definition | Am I Ready for Agents?"
description: "OpenAPI: A standard file format that describes an API so software, including agents, can read what it does. What it is, a dated example and where it matters."
canonical: https://amireadyforagents.com/glossary/openapi
site: "Am I Ready for Agents?"
last_updated: 2026-11-04
section: "Glossary"
---

# OpenAPI: plain-language definition | Am I Ready for Agents?

> OpenAPI: A standard file format that describes an API so software, including agents, can read what it does. What it is, a dated example and where it matters.

Source: https://amireadyforagents.com/glossary/openapi
Site: Am I Ready for Agents?
Last reviewed: 2026-11-04

# OpenAPI

## In short

OpenAPI is the file that tells an agent what your API does, and agents reach it by link. Whether to publish an API or an MCP server goes into the detail. Ora's lab found 97 percent of openapi.json fetches arrived through a link (October 2026).

## Definition

A standard file format that describes an API so software, including agents, can read what it does.

## A dated example

-   Read 4 Nov 2026
    
    Ora's lab found 97 percent of openapi.json fetches arrived through a link (October 2026).
    
    Vendor claim. [AgentReady.org guide](https://agentready.org/?utm_source=amireadyforagents.com&utm_medium=referral&utm_campaign=glossary), read 4 Nov 2026
    

## Where it matters

It is the file that tells an agent what your API does, and agents reach it by link.

-   [Whether to publish an API or an MCP server](https://amireadyforagents.com/decisions/publish-api-or-mcp)

## Related terms

-   [API](https://amireadyforagents.com/glossary/api)A documented way for software to ask your systems for data or to do something, without using the web pages.
-   [MCP (Model Context Protocol)](https://amireadyforagents.com/glossary/mcp-model-context-protocol)An open standard for offering an AI agent a set of named actions it can call, such as search providers or book an appointment.

## Sources

1.  [AgentReady.org guide](https://agentready.org/?utm_source=amireadyforagents.com&utm_medium=referral&utm_campaign=glossary) (agentready.org), read 4 Nov 2026. Vendor claim.

Last reviewed 4 November 2026

Reviewed 4 November 2026. [1 source](#sources), each with the day it was read.