-def _request(self, method, url, body=None) -> dict:
+def _request(self, method: str, url: str, body: Optional[str] = None) -> dict:
     """Send an HTTP request to the remote server.
 
     Args:
-        method: A string for the HTTP method to send the request with.
-        url: A string for the URL to send the request to.
-        body: A string for request body. Ignored unless method is POST or PUT.
+        method: HTTP method to send the request with (e.g., 'GET', 'POST', 'PUT', 'DELETE').
+        url: Absolute URL to send the request to.
+        body: Request body as a JSON string. Ignored unless method is POST or PUT.
 
     Returns:
         A dictionary with the server's parsed JSON response.
     """
+    if not isinstance(method, str) or method.upper() not in {"GET", "POST", "PUT", "DELETE"}:
+        raise ValueError(f"Unsupported HTTP method: {method!r}")
+    if not isinstance(url, str) or not url:
+        raise ValueError("URL must be a non-empty string")
+
+    method = method.upper()
     parsed_url = parse.urlparse(url)
     headers = self.get_remote_connection_headers(parsed_url, self._client_config.keep_alive)
     auth_header = self._client_config.get_auth_header()

 def _trim_large_entries(self, input_dict, max_length=100) -> dict:
     """Truncate string values in a dictionary if they exceed max_length.
 
     Args:
         input_dict: Dictionary with potentially large values
         max_length: Maximum allowed length of string values
 
     Returns:
         Dictionary with truncated string values
     """
     output_dictionary = {}
     for key, value in input_dict.items():
         if isinstance(value, dict):
             output_dictionary[key] = self._trim_large_entries(value, max_length)
+        elif isinstance(value, list):
+            output_dictionary[key] = [
+                self._trim_large_entries(item, max_length) if isinstance(item, dict) else item for item in value
+            ]
         elif isinstance(value, str) and len(value) > max_length:
             output_dictionary[key] = value[:max_length] + "..."
         else:
             output_dictionary[key] = value
 
     return output_dictionary