diff --git a/src/t2iapi/operation/operation_requests.proto b/src/t2iapi/operation/operation_requests.proto
index d49c6f6..446affa 100644
--- a/src/t2iapi/operation/operation_requests.proto
+++ b/src/t2iapi/operation/operation_requests.proto
@@ -20,4 +20,13 @@ Request to change the devices state, which results in setting the requested Oper
 message SetOperatingModeRequest {
     string handle = 1;
     OperatingMode operating_mode = 2;
+}
+
+/*
+Request to modify the devices descriptor, which results in setting the requested the @InvocationEffectiveTimeout for
+the pm:AbstractOperationDescriptor with the given handle.
+*/
+message ModifyInvocationEffectiveTimeoutRequest {
+    string handle = 1;
+    string invocation_effective_timeout = 2;
 }
\ No newline at end of file
diff --git a/src/t2iapi/operation/service.proto b/src/t2iapi/operation/service.proto
index dc412a7..1426986 100644
--- a/src/t2iapi/operation/service.proto
+++ b/src/t2iapi/operation/service.proto
@@ -31,10 +31,10 @@ service OperationService {
         returns (BasicResponse);
 
     /*
-    Modify the @InvocationEffectiveTimeout of the pm:AbstractOperationDescriptor with the given handle.
+    Modify the pm:AbstractOperationDescriptor with the given handle such that the @InvocationEffectiveTimeout is set to
+    the requested value.
     The manipulated descriptor shall be persistent until a next manipulation call or an SDC operation invocation. If
     the device is not able to maintain the static descriptor, it shall return RESULT_NOT_SUPPORTED.
     */
-    rpc ModifyInvocationEffectiveTimeout (BasicHandleRequest) returns (BasicResponse);
-
+    rpc ModifyInvocationEffectiveTimeout (ModifyInvocationEffectiveTimeoutRequest) returns (BasicResponse);
 }