Update tool_config.json

tool_config.json

@@ -1,5 +1,7 @@
 {
   "description": "This is a tool that downloads a file from a `url`. It takes the `url` as input, and returns the text contained in the file.",
   "name": "text_downloader",
-  "tool_class": "text_download.TextDownloadTool"
-}
+  "tool_class": "text_download.TextDownloadTool",
+  "inputs": {"url": "str"},
+  "output_type": "str"
+}