fix: Add exception checking to AfterToolCall hook

Author: clareliguori

e2e_tests/python/fail_on_tool_error.py

@@ -14,10 +14,13 @@ def register_hooks(self, registry: HookRegistry) -> None:
         registry.add_callback(AfterToolCallEvent, self.check_result)
 
     def check_result(self, event: AfterToolCallEvent) -> None:
-        if event.result.get("isError", False):
+        is_error = event.result.get("isError", False) if event.result else False
+        has_exception = event.exception is not None
+
+        if is_error or has_exception:
             tool_name = event.tool_use["name"]
-            error_content = event.result.get("content", [{}])[0].get("text", "Unknown error")
-            logger.warning(f"Tool {tool_name} failed: {error_content}")
+            error_msg = str(event.exception) if has_exception else event.result.get("content", [{}])[0].get("text", "Unknown error")
+            logger.warning(f"Tool {tool_name} failed: {error_msg}")
 
             for attempt in range(self.max_retries):
                 logger.info(f"Retrying tool {tool_name} (attempt {attempt + 1}/{self.max_retries})")
@@ -27,9 +30,10 @@ def check_result(self, event: AfterToolCallEvent) -> None:
                     if not result.get("isError", False):
                         logger.info(f"Tool {tool_name} succeeded on retry {attempt + 1}")
                         event.result = result
+                        event.exception = None
                         return
                 except Exception as e:
                     logger.warning(f"Retry {attempt + 1} failed: {e}")
                     continue
 
-            raise RuntimeError(f"Tool {tool_name} failed after {self.max_retries} retries: {error_content}")
+            raise RuntimeError(f"Tool {tool_name} failed after {self.max_retries} retries: {error_msg}")