diff --git a/snakemake_interface_executor_plugins/jobs.py b/snakemake_interface_executor_plugins/jobs.py
index 8af4b2c..3809d34 100644
--- a/snakemake_interface_executor_plugins/jobs.py
+++ b/snakemake_interface_executor_plugins/jobs.py
@@ -101,18 +101,18 @@ def benchmark(self) -> Optional[str]: ...
 
     @property
     @abstractmethod
-    def message(self): ...
+    def message(self) -> Optional[str]: ...
 
 
 class GroupJobExecutorInterface(ABC):
     @property
     @abstractmethod
-    def jobs(self): ...
+    def jobs(self) -> Iterable[SingleJobExecutorInterface]: ...
 
     @property
     @abstractmethod
-    def groupid(self): ...
+    def groupid(self) -> str: ...
 
     @property
     @abstractmethod
-    def toposorted(self): ...
+    def toposorted(self) -> Sequence[Sequence[SingleJobExecutorInterface]]: ...