diff --git a/openhands/agenthub/codeact_agent/function_calling.py b/openhands/agenthub/codeact_agent/function_calling.py
index bbf291cdf4..040f762f6d 100644
--- a/openhands/agenthub/codeact_agent/function_calling.py
+++ b/openhands/agenthub/codeact_agent/function_calling.py
@@ -76,7 +76,7 @@ def response_to_actions(
             try:
                 arguments = json.loads(tool_call.function.arguments)
             except json.decoder.JSONDecodeError as e:
-                raise RuntimeError(
+                raise FunctionCallValidationError(
                     f'Failed to parse tool call arguments: {tool_call.function.arguments}'
                 ) from e
 
diff --git a/openhands/agenthub/readonly_agent/function_calling.py b/openhands/agenthub/readonly_agent/function_calling.py
index f327ddf0a5..a0b938e8bf 100644
--- a/openhands/agenthub/readonly_agent/function_calling.py
+++ b/openhands/agenthub/readonly_agent/function_calling.py
@@ -127,7 +127,7 @@ def response_to_actions(
             try:
                 arguments = json.loads(tool_call.function.arguments)
             except json.decoder.JSONDecodeError as e:
-                raise RuntimeError(
+                raise FunctionCallValidationError(
                     f'Failed to parse tool call arguments: {tool_call.function.arguments}'
                 ) from e
 
diff --git a/tests/unit/test_function_calling.py b/tests/unit/test_function_calling.py
index 57170bd08f..7f71dde470 100644
--- a/tests/unit/test_function_calling.py
+++ b/tests/unit/test_function_calling.py
@@ -215,6 +215,6 @@ def test_invalid_json_arguments():
             }
         ],
     )
-    with pytest.raises(RuntimeError) as exc_info:
+    with pytest.raises(FunctionCallValidationError) as exc_info:
         response_to_actions(response)
     assert 'Failed to parse tool call arguments' in str(exc_info.value)