fix: catch and recover from JSONDecodeError on malformed tool args

2 files changed, 20 insertions, 16 deletions

diff --git a/src/agent.py b/src/agent.py
index 4047b08..a8edb20 100644
--- a/src/agent.py
+++ b/src/agent.py
@@ -248,20 +248,24 @@ class Agent:
                 logger.info(f"LLM requested {len(response_message.tool_calls)} tool execution(s)")
                 for tool_call in response_message.tool_calls:
                     function_name = tool_call.function.name
-                    function_args = json.loads(tool_call.function.arguments)
-
-                    function_to_call = self.available_functions.get(function_name)
-                    if not function_to_call:
-                        error_msg = f"Unknown tool: {function_name}"
+                    try:
+                        function_args = json.loads(tool_call.function.arguments)
+                        logger.info(f"Executing: {function_name}({function_args})")
+
+                        function_to_call = self.available_functions.get(function_name)
+                        if not function_to_call:
+                            error_msg = f"Unknown tool: {function_name}"
+                            logger.warning(error_msg)
+                            function_output = error_msg
+                        else:
+                            try:
+                                function_output = function_to_call(**function_args)
+                            except Exception as e:
+                                function_output = f"Error executing {function_name}: {str(e)}"
+                    except json.JSONDecodeError as e:
+                        error_msg = f"Error parsing tool arguments for {function_name}: {str(e)}. Arguments must be valid JSON."
                         logger.warning(error_msg)
                         function_output = error_msg
-                    else:
-                        try:
-                            function_output = function_to_call(**function_args)
-                        except Exception as e:
-                            function_output = f"Error executing {function_name}: {str(e)}"
-
-                    logger.info(f"Executing: {function_name}({function_args})")
 
                     tool_message = {
                         "tool_call_id": tool_call.id,
diff --git a/tests/test_agent.py b/tests/test_agent.py
index c8164e6..e73b41e 100644
--- a/tests/test_agent.py
+++ b/tests/test_agent.py
@@ -173,10 +173,10 @@ class TestAgentRun:
         )
         agent.client.chat.completions.create.side_effect = [tool_response, final_response]
 
-        # json.loads will raise — this should be caught or propagate clearly
-        # Current code does NOT catch this, so it should raise JSONDecodeError
-        with pytest.raises(json.JSONDecodeError):
-            agent.run("Do something")
+        # json.loads will fail, the agent will catch it, return an error to model,
+        # and on the next turn the model will return "Recovered".
+        result = agent.run("Do something")
+        assert result == "Recovered"
 
     def test_api_error_propagates(self, agent):
         """API errors should propagate, not be silently swallowed."""