Update src/google/adk/tools/_gemini_schema_util.py

Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>

Author: nickvander

src/google/adk/tools/_gemini_schema_util.py

@@ -89,15 +89,16 @@ def _sanitize_schema_type(schema: dict[str, Any]) -> dict[str, Any]:
         non_null_type = t
     if not non_null_type:
       non_null_type = "object"
-    if non_null_type == "array" and "items" not in schema:
-      schema["items"] = {"type": "string"}
     if nullable:
       schema["type"] = [non_null_type, "null"]
     else:
       schema["type"] = non_null_type
   elif schema.get("type") == "null":
     schema["type"] = ["object", "null"]
-  elif schema.get("type") == "array" and "items" not in schema:
+
+  type_val = schema.get("type")
+  main_type = type_val[0] if isinstance(type_val, list) else type_val
+  if main_type == "array" and "items" not in schema:
     schema["items"] = {"type": "string"}
 
   return schema