(Ollama) Fix String Value parsing in _parse_arguments_from_tool_call (#30154)

- **Description:** Fix String Value parsing in
_parse_arguments_from_tool_call
- **Issue:** #30145

---------

Co-authored-by: Chester Curme <[email protected]>

Author: keenborder786

libs/partners/ollama/langchain_ollama/chat_models.py

@@ -125,13 +125,17 @@ def _parse_arguments_from_tool_call(
     if "function" not in raw_tool_call:
         return None
     arguments = raw_tool_call["function"]["arguments"]
-    parsed_arguments = {}
+    parsed_arguments: dict = {}
     if isinstance(arguments, dict):
         for key, value in arguments.items():
             if isinstance(value, str):
-                parsed_arguments[key] = _parse_json_string(
+                parsed_value = _parse_json_string(
                     value, skip=True, raw_tool_call=raw_tool_call
                 )
+                if isinstance(parsed_value, (dict, list)):
+                    parsed_arguments[key] = parsed_value
+                else:
+                    parsed_arguments[key] = value
             else:
                 parsed_arguments[key] = value
     else:

libs/partners/ollama/tests/unit_tests/test_chat_models.py

@@ -1,10 +1,10 @@
 """Test chat model integration."""
-
+import json
 from typing import Dict, Type
 
 from langchain_tests.unit_tests import ChatModelUnitTests
 
-from langchain_ollama.chat_models import ChatOllama
+from langchain_ollama.chat_models import ChatOllama, _parse_arguments_from_tool_call
 
 
 class TestChatOllama(ChatModelUnitTests):
@@ -15,3 +15,11 @@ def chat_model_class(self) -> Type[ChatOllama]:
     @property
     def chat_model_params(self) -> Dict:
         return {"model": "llama3-groq-tool-use"}
+
+
+def test__parse_arguments_from_tool_call() -> None:
+    raw_response = '{"model":"sample-model","message":{"role":"assistant","content":"","tool_calls":[{"function":{"name":"get_profile_details","arguments":{"arg_1":"12345678901234567890123456"}}}]},"done":false}'  # noqa: E501
+    raw_tool_calls = json.loads(raw_response)["message"]["tool_calls"]
+    response = _parse_arguments_from_tool_call(raw_tool_calls[0])
+    assert response is not None
+    assert isinstance(response["arg_1"], str)