diff --git a/docs/app-directory/spec.md b/docs/app-directory/spec.md
index 6ba765788..3457e633c 100644
--- a/docs/app-directory/spec.md
+++ b/docs/app-directory/spec.md
@@ -17,3 +17,5 @@ View the [full specification](/schemas/next/app-directory) in [OpenAPI v3.0](htt
  `/v1/apps`         | POST   | (deprecated v1 API version) Create a new application definition
  `/v1/apps/{appId}` | GET    | (deprecated v1 API version) Retrieve an application defintion
  `/v1/apps/search`  | GET    | (deprecated v1 API version) Retrieve a list of applications
+
+App Directory implementations MAY extend the list of endpoints to provide other necessary functionality. However, FDC3 Desktop Agent implementations MUST support connection to app directories that only provide the minimum endpoints listed here.