diff --git a/vllm/model_executor/guided_decoding/utils.py b/vllm/model_executor/guided_decoding/utils.py
index c3c0378ea952..10981776e768 100644
--- a/vllm/model_executor/guided_decoding/utils.py
+++ b/vllm/model_executor/guided_decoding/utils.py
@@ -33,6 +33,18 @@ def check_object(obj: dict) -> bool:
         ]):
             return True
 
+        # Unsupported keywords for strings
+        if obj.get("type") == "string" and any(
+                key in obj for key in ["minLength", "maxLength", "format"]):
+            return True
+
+        # Unsupported keywords for objects
+        if obj.get("type") == "object" and any(key in obj for key in [
+                "minProperties", "maxProperties", "propertyNames",
+                "patternProperties"
+        ]):
+            return True
+
         # Recursively check all nested objects and arrays
         for value in obj.values():
             if isinstance(value, dict):