diff --git a/guardrails/run.py b/guardrails/run.py
index f370a53af..883f0ed1c 100644
--- a/guardrails/run.py
+++ b/guardrails/run.py
@@ -308,7 +308,7 @@ def prepare(
                     api, instructions, prompt
                 )
             else:
-                raise ValueError("Prompt or message history must be provided.")
+                raise ValueError("'prompt' or 'msg_history' must be provided.")
 
             action.log(
                 message_type="info",
@@ -367,7 +367,7 @@ def call(
                 except Exception:
                     llm_response = api(prompt.source)
             else:
-                raise ValueError("Prompt or message history must be provided.")
+                raise ValueError("'prompt' or 'msg_history' must be provided.")
 
             action.log(
                 message_type="info",
@@ -695,7 +695,9 @@ async def async_call(
                 except Exception:
                     llm_response = await api(prompt.source)
             else:
-                raise ValueError("Output, prompt or message history must be provided.")
+                raise ValueError(
+                    "'output', 'prompt' or 'msg_history' must be provided."
+                )
 
             action.log(
                 message_type="info",