Freshness update: web-api-help-pages-using-swagger.md (#36787)

* Initial plan

* Freshness update: web-api-help-pages-using-swagger.md

Co-authored-by: wadepickett <10985336+wadepickett@users.noreply.github.com>

* Revise Swagger documentation for .NET 9 changes

Updated the article to reflect changes in .NET 9 regarding OpenAPI support and the status of Swashbuckle.

* Convert NOTE callout to introduction paragraphs

Co-authored-by: wadepickett <10985336+wadepickett@users.noreply.github.com>

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: wadepickett <10985336+wadepickett@users.noreply.github.com>
Co-authored-by: Wade Pickett <wpickett@microsoft.com>

Author: Copilot

aspnetcore/tutorials/web-api-help-pages-using-swagger.md

@@ -1,11 +1,12 @@
 ---
 title: ASP.NET Core web API documentation with Swagger / OpenAPI
+ai-usage: ai-assisted
 author: RicoSuter
 description: This tutorial provides a walkthrough of adding Swagger to generate documentation and help pages for a web API app.
 ms.author: wpickett
 ms.custom: mvc
 monikerRange: ">= aspnetcore-3.1 <= aspnetcore-8.0"
-ms.date: 4/25/2024
+ms.date: 02/23/2026
 uid: tutorials/web-api-help-pages-using-swagger
 ---
 # ASP.NET Core web API documentation with Swagger / OpenAPI
@@ -14,6 +15,15 @@ uid: tutorials/web-api-help-pages-using-swagger
 
 By [Rico Suter](https://blog.rsuter.com/)
 
+This article covers using **Swagger** tooling — provided by the [Swashbuckle.AspNetCore](https://github.com/domaindrivendev/Swashbuckle.AspNetCore) and [NSwag](https://github.com/RicoSuter/NSwag) packages — to generate OpenAPI documentation and interactive help pages for ASP.NET Core web APIs.
+
+In .NET 9 and later, ASP.NET Core includes built-in OpenAPI support that replaces Swashbuckle as the default. Swashbuckle is no longer included in project templates, but it remains available as a community package you can add manually.
+
+* To understand the built‑in OpenAPI features, see <xref:fundamentals/openapi/overview?view=aspnetcore-9.0&preserve-view=true>.
+* To add Swagger UI for interactive exploration or local ad‑hoc testing alongside the built-in OpenAPI support, see <xref:fundamentals/openapi/using-openapi-documents#use-swagger-ui-for-local-ad-hoc-testing>.
+
+The following instructions apply to projects using Swashbuckle or NSwag with ASP.NET Core 8.0 and earlier.
+
 [Swagger](https://swagger.io/) ([OpenAPI](https://www.openapis.org/)) is a language-agnostic specification for describing REST APIs. It allows both computers and humans to understand the capabilities of a REST API without direct access to the source code. Its main goals are to:
 
 * Minimize the amount of work needed to connect decoupled services.
@@ -147,12 +157,14 @@ In the preceding code, the `/weatherforecast` endpoint doesn't need authorizatio
 The following Curl passes a JWT token to test the Swagger UI endpoint:
 
 ```bash
-curl -i -H "Authorization: Bearer {token}" https://localhost:{port}/swagger/v1/swagger.json
+curl -i -H "Authorization: Bearer {TOKEN}" https://localhost:{PORT}/swagger/v1/swagger.json
 ```
 
+where the `{TOKEN}` placeholder is the JWT bearer token and the `{PORT}` placeholder is the port number.
+
 For more information on testing with JWT tokens, see <xref:security/authentication/jwt>.
 
-## Generate an XML documentation file at compile time.
+## Generate an XML documentation file at compile time
 
 See [GenerateDocumentationFile](/dotnet/core/project-sdk/msbuild-props#generatedocumentationfile) for more information.