Build a Secure C# MCP App with Cross App Access (XAA)

A few years ago, getting a user signed in to an application or multiple applications with Single Sign-On (SSO) was enough; OpenID Connect (OIDC) handled the login, JWTs carried the claims, and Proof Key for Code Exchange (PKCE) made it secure. Today, with evolving AI, agents act on behalf of users and seek multiple accesses across different resources to execute a task. And that is when you’ll hit the gap.