diff --git a/compiler_gym/service/connection.py b/compiler_gym/service/connection.py
index 8b7181dab4..d3ee8628a3 100644
--- a/compiler_gym/service/connection.py
+++ b/compiler_gym/service/connection.py
@@ -55,7 +55,7 @@
 
 
 class HashableBaseModel(BaseModel):
-    """A pydantic model that is hashable."""
+    """A pydantic model that is hashable. Requires that all fields are hashable."""
 
     def __hash__(self):
         return hash((type(self),) + tuple(self.__dict__.values()))