diff --git a/nmcp/src/main/kotlin/nmcp/NmcpExtension.kt b/nmcp/src/main/kotlin/nmcp/NmcpExtension.kt
index e0f0875..89933db 100644
--- a/nmcp/src/main/kotlin/nmcp/NmcpExtension.kt
+++ b/nmcp/src/main/kotlin/nmcp/NmcpExtension.kt
@@ -11,6 +11,7 @@ interface NmcpExtension {
      * - Adds `nmcpPublishAllPublicationsToCentralPortal`
      * - Adds `nmcpPublishAllPublicationsToCentralPortalSnapshots`
      */
+    @Deprecated("This duplicates the com.gradleup.nmcp.aggregation functionality. Either apply com.gradleup.nmcp.aggregation or the settings plugin to publish an aggregation.")
     fun publishAllPublicationsToCentralPortal(action: Action<CentralPortalOptions>)
 
     /**
diff --git a/nmcp/src/main/kotlin/nmcp/internal/DefaultNmcpExtension.kt b/nmcp/src/main/kotlin/nmcp/internal/DefaultNmcpExtension.kt
index cbfb85b..e3de803 100644
--- a/nmcp/src/main/kotlin/nmcp/internal/DefaultNmcpExtension.kt
+++ b/nmcp/src/main/kotlin/nmcp/internal/DefaultNmcpExtension.kt
@@ -83,6 +83,7 @@ internal abstract class DefaultNmcpExtension(private val project: Project): Nmcp
         }
     }
 
+    @Deprecated("This duplicates the com.gradleup.nmcp.aggregation functionality. Either apply com.gradleup.nmcp.aggregation or the settings plugin to publish an aggregation.")
     override fun publishAllPublicationsToCentralPortal(action: Action<CentralPortalOptions>) {
         action.execute(spec)
     }