diff --git a/demo-registry/uniswap/eip712-permit2.json b/demo-registry/uniswap/eip712-permit2.json
index 9dcdfbd..bff40f2 100644
--- a/demo-registry/uniswap/eip712-permit2.json
+++ b/demo-registry/uniswap/eip712-permit2.json
@@ -140,13 +140,6 @@
               "params": {
                 "tokenPath": "details.token"
               }
-            },
-            "details.expiration": {
-              "label": "Valid Until",
-              "format": "date",
-              "params": {
-                "encoding": "timestamp"
-              }
             }
           },
           "required": [
diff --git a/src/erc7730/classifier/eip712_classifier.py b/src/erc7730/classifier/eip712_classifier.py
index 5a65e1b..f1d63d0 100644
--- a/src/erc7730/classifier/eip712_classifier.py
+++ b/src/erc7730/classifier/eip712_classifier.py
@@ -8,4 +8,6 @@
 class EIP712Classifier(Classifier[EIP712JsonSchema]):
     @override
     def classify(self, schema: EIP712JsonSchema) -> TxClass | None:
-        pass
+        if "permit" in schema.primaryType.lower():
+            return TxClass.PERMIT
+        return None
diff --git a/src/erc7730/display_format_checker/__init__.py b/src/erc7730/display_format_checker/__init__.py
index ba3cb5f..7d5ea46 100644
--- a/src/erc7730/display_format_checker/__init__.py
+++ b/src/erc7730/display_format_checker/__init__.py
@@ -1,6 +1,16 @@
 from erc7730.classifier import TxClass
 from erc7730.linter import Linter
-from erc7730.model.display import Display
+from erc7730.model.display import Display, Format
+
+
+def _fields_contain(word: str, fields: set[str]) -> bool:
+    """
+    to check if the provided keyword is contained in one of the fields (case insensitive)
+    """
+    for field in fields:
+        if word.lower() in field.lower():
+            return True
+    return False
 
 
 class DisplayFormatChecker:
@@ -8,5 +18,42 @@ def __init__(self, c: TxClass, d: Display):
         self.c = c
         self.d = d
 
+    def _get_all_displayed_fields(self, formats: dict[str, Format]) -> set[str]:
+        fields: set[str] = set()
+        for format in formats.values():
+            if format.fields is not None:
+                for field in format.fields.root.keys():
+                    fields.add(str(field))
+        return fields
+
     def check(self) -> list[Linter.Output]:
-        return []
+        res: list[Linter.Output] = []
+        match self.c:
+            case TxClass.PERMIT:
+                formats = self.d.formats
+                fields = self._get_all_displayed_fields(formats)
+                if not _fields_contain("spender", fields):
+                    res.append(
+                        Linter.Output(
+                            title="Missing spender in displayed fields", message="", level=Linter.Output.Level.ERROR
+                        )
+                    )
+                if not _fields_contain("amount", fields):
+                    res.append(
+                        Linter.Output(
+                            title="Missing amount in displayed fields", message="", level=Linter.Output.Level.ERROR
+                        )
+                    )
+                if (
+                    not _fields_contain("valid until", fields)
+                    and not _fields_contain("expiry", fields)
+                    and not _fields_contain("expiration", fields)
+                ):
+                    res.append(
+                        Linter.Output(
+                            title="Missing expiration date in displayed fields for permit",
+                            message="",
+                            level=Linter.Output.Level.ERROR,
+                        )
+                    )
+        return res
diff --git a/src/erc7730/linter/linter_transaction_type_classifier_ai.py b/src/erc7730/linter/linter_transaction_type_classifier_ai.py
index 796d176..4b209b8 100644
--- a/src/erc7730/linter/linter_transaction_type_classifier_ai.py
+++ b/src/erc7730/linter/linter_transaction_type_classifier_ai.py
@@ -40,7 +40,15 @@ def lint(self, descriptor: ERC7730Descriptor, out: Linter.OutputAdder) -> None:
             return None
         c = determine_tx_class(descriptor)
         if c is None:
+            out(
+                Linter.Output(
+                    title="Transaction type: ",
+                    message="could not determine transaction type",
+                    level=Linter.Output.Level.WARNING,
+                )
+            )
             return None
+        out(Linter.Output(title="Transaction type: ", message=str(c), level=Linter.Output.Level.INFO))
         d: Display | None = descriptor.display
         if d is None:
             return None
diff --git a/src/erc7730/model/display.py b/src/erc7730/model/display.py
index eedd64a..aaabb32 100644
--- a/src/erc7730/model/display.py
+++ b/src/erc7730/model/display.py
@@ -74,7 +74,7 @@ class StructFormats(BaseLibraryModel):
     fields: ForwardRef("Fields")  # type: ignore
 
 
-class Fields(RootModel[dict[str, Union[Reference, Field, StructFormats]]]):
+class Fields(RootModel[dict[str, Union[Reference, FieldDescription, Field, StructFormats]]]):
     """todo use StructFormats instead"""