[Documentation request] Authentication architecture suggestions

It would be great if the documentation website had a few pointers on authentication architecture choices.

Imagine you have an existing ASP.NET Core API project which already has its own AzureAD authentication + JWT Bearer authentication for development (with dotnet user-jwts). I think this is a common scenario for people wanting to add MCP functionality to their existing solution.

It would be great to read something about setting that up, and about the choices that can be made there:

• one project vs multiple projects:
  • putting both the MCP and normal API endpoints in the same project. This adds some complexity regarding coexistence of authentication schemes. I see for MCP a different scheme is needed.
  • factoring out the business logic into a common project that is referenced by a REST API project and a MCP server project
• one app registration vs multiple app registrations in Entra ID?

Searched:

• https://github.com/modelcontextprotocol/csharp-sdk/discussions?discussions_q=authentication only lists questions from 2025 (before v1.0 was released)
• https://www.google.com/search?q=adding+mcp+server+to+existing+asp.net+core+api+project yields no recent articles that cover coexisting authentication options on v1.0
• https://devblogs.microsoft.com/dotnet/release-v10-of-the-official-mcp-csharp-sdk/ has no info on cover coexisting authentication options
• https://github.com/microsoft/mcp-gateway seems to have a REST API (for management purposes) in parallel to a MCP endpoint, both with Entra ID integration. However, its setup is much more complex than the usecase explained above, which makes it difficult to use as an example to understand how to set it up.
• These two documentation pages might be helpful:
  • https://learn.microsoft.com/en-us/aspnet/core/security/authorization/limitingidentitybyscheme?view=aspnetcore-10.0#use-multiple-authentication-schemes
  • https://learn.microsoft.com/en-us/aspnet/core/security/authentication/policyschemes?view=aspnetcore-10.0#jwt-with-multiple-schemes

Start with the documentation website and the two linked ASP.NET Core authentication pages, then compare the existing API-plus-MCP scenarios described in the issue with the mcp-gateway example. Done means adding guidance that explains project and Entra ID app-registration choices, including how coexisting authentication schemes can be approached.