Create openapi-spec.md

create openapi spec concept page, waiting for python code sample

Author: lindazqli

articles/ai-services/agents/how-to/tools/openapi-spec.md

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+---
+title: 'How to use Azure AI Agent service with OpenAPI Specified Tools'
+titleSuffix: Azure OpenAI
+description: Learn how to use Azure AI Agents with OpenAPI Specified Tools.
+services: cognitive-services
+manager: nitinme
+ms.service: azure
+ms.topic: how-to
+ms.date: 12/06/2024
+author: aahill
+ms.author: aahi
+zone_pivot_groups: selection-function-calling
+recommendations: false
+---
+# How to use Azure AI Agent service with OpenAPI Specified Tools
+
+::: zone pivot="overview"
+
+You can now connect your Azure AI Agent to an external API using an OpenAPI 3.0 specified tool, 
+allowing for scalable interoperability with various applications. Enable your custom tools 
+to authenticate access and connections with managed identities (Microsoft Entra ID) for 
+added security, making it ideal for integrating with existing infrastructure or web services.
+
+OpenAPI Specified tool improves your function calling experience by providing standardized, 
+automated, and scalable API integrations that enhance the capabilities and efficiency of your agent. 
+[OpenAPI specifications](https://spec.openapis.org/oas/latest.html) provide a formal standard for 
+describing HTTP APIs. This allows people to understand how an API works, how a sequence of APIs 
+work together, generate client code, create tests, apply design standards, and much, much more. 
+
+## Set up
+1. Ensure you've completed the prerequisites and setup steps in the [quickstart](../../quickstart.md).
+
+::: zone-end
+
+::: zone pivot="code-example"
+## Step 1: Create an agent with OpenAPI Spec tool
+
+## Step 2: Enable the OpenAPI Spec tool
+
+## Step 3: Create a thread
+
+## Step 4: Create a run and check the output