diff --git a/jambo/parser/_type_parser.py b/jambo/parser/_type_parser.py
index e64ae77..024fed3 100644
--- a/jambo/parser/_type_parser.py
+++ b/jambo/parser/_type_parser.py
@@ -1,32 +1,36 @@
-from pydantic import Field
-from typing_extensions import Self
+from pydantic import Field, TypeAdapter
+from typing_extensions import Annotated, Self
 
 from abc import ABC, abstractmethod
-from typing import Generic, TypeVar
+from typing import Generic, Type, TypeVar
 
 
 T = TypeVar("T")
 
 
 class GenericTypeParser(ABC, Generic[T]):
-    @property
-    @abstractmethod
-    def mapped_type(self) -> type[T]: ...
+    mapped_type: Type[T] = None
 
-    @property
-    @abstractmethod
-    def json_schema_type(self) -> str: ...
+    json_schema_type: str = None
 
     @staticmethod
     @abstractmethod
     def from_properties(
-        name: str, properties: dict[str, any]
-    ) -> tuple[type[T], Field]: ...
+        name: str, properties: dict[str, any], required: bool = False
+    ) -> tuple[T, dict]: ...
 
     @classmethod
     def get_impl(cls, type_name: str) -> Self:
         for subcls in cls.__subclasses__():
+            if subcls.json_schema_type is None:
+                raise RuntimeError(f"Unknown type: {type_name}")
+
             if subcls.json_schema_type == type_name:
-                return subcls
+                return subcls()
 
         raise ValueError(f"Unknown type: {type_name}")
+
+    @staticmethod
+    def validate_default(field_type: type, field_prop: dict, value):
+        field = Annotated[field_type, Field(**field_prop)]
+        TypeAdapter(field).validate_python(value)
diff --git a/jambo/parser/allof_type_parser.py b/jambo/parser/allof_type_parser.py
index 6f23236..7a65b49 100644
--- a/jambo/parser/allof_type_parser.py
+++ b/jambo/parser/allof_type_parser.py
@@ -7,7 +7,7 @@ class AllOfTypeParser(GenericTypeParser):
     json_schema_type = "allOf"
 
     @staticmethod
-    def from_properties(name, properties):
+    def from_properties(name, properties, required=False):
         subProperties = properties.get("allOf")
         if not subProperties:
             raise ValueError("Invalid JSON Schema: 'allOf' is not specified.")
diff --git a/jambo/parser/anyof_type_parser.py b/jambo/parser/anyof_type_parser.py
index 8ee5543..49408be 100644
--- a/jambo/parser/anyof_type_parser.py
+++ b/jambo/parser/anyof_type_parser.py
@@ -1,5 +1,8 @@
 from jambo.parser._type_parser import GenericTypeParser
 
+from pydantic import Field
+from typing_extensions import Annotated
+
 from typing import Union
 
 
@@ -9,20 +12,47 @@ class AnyOfTypeParser(GenericTypeParser):
     json_schema_type = "anyOf"
 
     @staticmethod
-    def from_properties(name, properties):
+    def from_properties(name, properties, required=False):
         if "anyOf" not in properties:
             raise ValueError(f"Invalid JSON Schema: {properties}")
 
         if not isinstance(properties["anyOf"], list):
             raise ValueError(f"Invalid JSON Schema: {properties['anyOf']}")
 
+        mapped_properties = dict()
+
         subProperties = properties["anyOf"]
 
-        types = [
+        sub_types = [
             GenericTypeParser.get_impl(subProperty["type"]).from_properties(
                 name, subProperty
             )
             for subProperty in subProperties
         ]
 
-        return Union[*(t for t, v in types)], {}
+        default_value = properties.get("default")
+        if default_value is not None:
+            for sub_type, sub_property in sub_types:
+                try:
+                    GenericTypeParser.validate_default(
+                        sub_type, sub_property, default_value
+                    )
+                    break
+                except ValueError:
+                    continue
+            else:
+                raise ValueError(
+                    f"Invalid default value {default_value} for anyOf types: {sub_types}"
+                )
+
+            mapped_properties["default"] = default_value
+
+        if not required:
+            mapped_properties["default"] = mapped_properties.get("default")
+
+        # By defining the type as Union, we can use the Field validator to enforce
+        # the constraints on the union type.
+        # We use Annotated to attach the Field validators to the type.
+        field_types = [Annotated[t, Field(**v)] if v else t for t, v in sub_types]
+
+        return Union[(*field_types,)], mapped_properties
diff --git a/jambo/parser/array_type_parser.py b/jambo/parser/array_type_parser.py
index 20a6125..d2d6e30 100644
--- a/jambo/parser/array_type_parser.py
+++ b/jambo/parser/array_type_parser.py
@@ -15,11 +15,11 @@ class ArrayTypeParser(GenericTypeParser):
 
     json_schema_type = "array"
 
-    @classmethod
-    def from_properties(cls, name, properties):
+    @staticmethod
+    def from_properties(name, properties, required=False):
         _item_type, _item_args = GenericTypeParser.get_impl(
             properties["items"]["type"]
-        ).from_properties(name, properties["items"])
+        ).from_properties(name, properties["items"], required=True)
 
         _mappings = {
             "maxItems": "max_length",
@@ -29,11 +29,14 @@ class ArrayTypeParser(GenericTypeParser):
         wrapper_type = set if properties.get("uniqueItems", False) else list
 
         mapped_properties = mappings_properties_builder(
-            properties, _mappings, {"description": "description"}
+            properties,
+            _mappings,
+            required=required,
+            default_mappings={"description": "description"},
         )
 
-        if "default" in properties:
-            default_list = properties["default"]
+        default_list = properties.get("default")
+        if default_list is not None:
             if not isinstance(default_list, list):
                 raise ValueError(
                     f"Default value must be a list, got {type(default_list).__name__}"
@@ -63,4 +66,7 @@ class ArrayTypeParser(GenericTypeParser):
                     default_list
                 )
 
+        if "default_factory" in mapped_properties and "default" in mapped_properties:
+            del mapped_properties["default"]
+
         return wrapper_type[_item_type], mapped_properties
diff --git a/jambo/parser/boolean_type_parser.py b/jambo/parser/boolean_type_parser.py
index 1dec65d..4b21cf8 100644
--- a/jambo/parser/boolean_type_parser.py
+++ b/jambo/parser/boolean_type_parser.py
@@ -10,7 +10,7 @@ class BooleanTypeParser(GenericTypeParser):
     json_schema_type = "boolean"
 
     @staticmethod
-    def from_properties(name, properties):
+    def from_properties(name, properties, required=False):
         _mappings = {
             "default": "default",
         }
diff --git a/jambo/parser/float_type_parser.py b/jambo/parser/float_type_parser.py
index a6dcdd5..5326c08 100644
--- a/jambo/parser/float_type_parser.py
+++ b/jambo/parser/float_type_parser.py
@@ -10,5 +10,5 @@ class FloatTypeParser(GenericTypeParser):
     json_schema_type = "number"
 
     @staticmethod
-    def from_properties(name, properties):
-        return float, numeric_properties_builder(properties)
+    def from_properties(name, properties, required=False):
+        return float, numeric_properties_builder(properties, required)
diff --git a/jambo/parser/int_type_parser.py b/jambo/parser/int_type_parser.py
index 1ef907b..82bbfb9 100644
--- a/jambo/parser/int_type_parser.py
+++ b/jambo/parser/int_type_parser.py
@@ -10,5 +10,5 @@ class IntTypeParser(GenericTypeParser):
     json_schema_type = "integer"
 
     @staticmethod
-    def from_properties(name, properties):
-        return int, numeric_properties_builder(properties)
+    def from_properties(name, properties, required=False):
+        return int, numeric_properties_builder(properties, required)
diff --git a/jambo/parser/object_type_parser.py b/jambo/parser/object_type_parser.py
index 7c0c363..f7c9f6a 100644
--- a/jambo/parser/object_type_parser.py
+++ b/jambo/parser/object_type_parser.py
@@ -7,7 +7,7 @@ class ObjectTypeParser(GenericTypeParser):
     json_schema_type = "object"
 
     @staticmethod
-    def from_properties(name, properties):
+    def from_properties(name, properties, required=False):
         from jambo.schema_converter import SchemaConverter
 
         type_parsing = SchemaConverter.build_object(name, properties)
diff --git a/jambo/parser/string_type_parser.py b/jambo/parser/string_type_parser.py
index dc44ca4..7b77c75 100644
--- a/jambo/parser/string_type_parser.py
+++ b/jambo/parser/string_type_parser.py
@@ -10,31 +10,17 @@ class StringTypeParser(GenericTypeParser):
     json_schema_type = "string"
 
     @staticmethod
-    def from_properties(name, properties):
+    def from_properties(name, properties, required=False):
         _mappings = {
             "maxLength": "max_length",
             "minLength": "min_length",
             "pattern": "pattern",
         }
 
-        mapped_properties = mappings_properties_builder(properties, _mappings)
+        mapped_properties = mappings_properties_builder(properties, _mappings, required)
 
-        if "default" in properties:
-            default_value = properties["default"]
-            if not isinstance(default_value, str):
-                raise ValueError(
-                    f"Default value for {name} must be a string, "
-                    f"but got <{type(properties['default']).__name__}>."
-                )
-
-            if len(default_value) > properties.get("maxLength", float("inf")):
-                raise ValueError(
-                    f"Default value for {name} exceeds maxLength limit of {properties.get('maxLength')}"
-                )
-
-            if len(default_value) < properties.get("minLength", 0):
-                raise ValueError(
-                    f"Default value for {name} is below minLength limit of {properties.get('minLength')}"
-                )
+        default_value = properties.get("default")
+        if default_value is not None:
+            StringTypeParser.validate_default(str, mapped_properties, default_value)
 
         return str, mapped_properties
diff --git a/jambo/schema_converter.py b/jambo/schema_converter.py
index 8dadb7e..39a5848 100644
--- a/jambo/schema_converter.py
+++ b/jambo/schema_converter.py
@@ -71,14 +71,13 @@ class SchemaConverter:
 
         fields = {}
         for name, prop in properties.items():
-            fields[name] = SchemaConverter._build_field(name, prop, required_keys)
+            is_required = name in required_keys
+            fields[name] = SchemaConverter._build_field(name, prop, is_required)
 
         return fields
 
     @staticmethod
-    def _build_field(
-        name, properties: dict, required_keys: list[str]
-    ) -> tuple[type, dict]:
+    def _build_field(name, properties: dict, required=False) -> tuple[type, dict]:
         match properties:
             case {"anyOf": _}:
                 _field_type = "anyOf"
@@ -91,17 +90,6 @@ class SchemaConverter:
 
         _field_type, _field_args = GenericTypeParser.get_impl(
             _field_type
-        ).from_properties(name, properties)
-
-        _field_args = _field_args or {}
-
-        if description := properties.get("description"):
-            _field_args["description"] = description
-
-        if name not in required_keys:
-            _field_args["default"] = properties.get("default", None)
-
-        if "default_factory" in _field_args and "default" in _field_args:
-            del _field_args["default"]
+        ).from_properties(name, properties, required)
 
         return _field_type, Field(**_field_args)
diff --git a/jambo/utils/properties_builder/mappings_properties_builder.py b/jambo/utils/properties_builder/mappings_properties_builder.py
index f743891..e78fc8e 100644
--- a/jambo/utils/properties_builder/mappings_properties_builder.py
+++ b/jambo/utils/properties_builder/mappings_properties_builder.py
@@ -1,4 +1,9 @@
-def mappings_properties_builder(properties, mappings, default_mappings=None):
+def mappings_properties_builder(
+    properties, mappings, required=False, default_mappings=None
+):
+    if not required:
+        properties["default"] = properties.get("default", None)
+
     default_mappings = default_mappings or {
         "default": "default",
         "description": "description",
diff --git a/jambo/utils/properties_builder/numeric_properties_builder.py b/jambo/utils/properties_builder/numeric_properties_builder.py
index f38dea1..343ef4c 100644
--- a/jambo/utils/properties_builder/numeric_properties_builder.py
+++ b/jambo/utils/properties_builder/numeric_properties_builder.py
@@ -3,7 +3,7 @@ from jambo.utils.properties_builder.mappings_properties_builder import (
 )
 
 
-def numeric_properties_builder(properties):
+def numeric_properties_builder(properties, required=False):
     _mappings = {
         "minimum": "ge",
         "exclusiveMinimum": "gt",
@@ -13,9 +13,10 @@ def numeric_properties_builder(properties):
         "default": "default",
     }
 
-    mapped_properties = mappings_properties_builder(properties, _mappings)
+    mapped_properties = mappings_properties_builder(properties, _mappings, required)
 
-    if "default" in properties:
+    default_value = properties.get("default")
+    if default_value is not None:
         default_value = properties["default"]
         if not isinstance(default_value, (int, float)):
             raise ValueError(
diff --git a/tests/parser/test_anyof_type_parser.py b/tests/parser/test_anyof_type_parser.py
index cb97e1b..896b394 100644
--- a/tests/parser/test_anyof_type_parser.py
+++ b/tests/parser/test_anyof_type_parser.py
@@ -1,5 +1,7 @@
 from jambo.parser.anyof_type_parser import AnyOfTypeParser
 
+from typing_extensions import Annotated
+
 from typing import Union, get_args, get_origin
 from unittest import TestCase
 
@@ -21,5 +23,41 @@ class TestAnyOfTypeParser(TestCase):
 
         # check union type has string and int
         self.assertEqual(get_origin(type_parsing), Union)
-        self.assertIn(str, get_args(type_parsing))
-        self.assertIn(int, get_args(type_parsing))
+
+        type_1, type_2 = get_args(type_parsing)
+
+        self.assertEqual(get_origin(type_1), Annotated)
+        self.assertIn(str, get_args(type_1))
+
+        self.assertEqual(get_origin(type_2), Annotated)
+        self.assertIn(int, get_args(type_2))
+
+    def test_any_of_string_or_int_with_default(self):
+        """
+        Tests the AnyOfTypeParser with a string or int type and a default value.
+        """
+
+        properties = {
+            "anyOf": [
+                {"type": "string"},
+                {"type": "integer"},
+            ],
+            "default": 42,
+        }
+
+        type_parsing, type_validator = AnyOfTypeParser.from_properties(
+            "placeholder", properties
+        )
+
+        # check union type has string and int
+        self.assertEqual(get_origin(type_parsing), Union)
+
+        type_1, type_2 = get_args(type_parsing)
+
+        self.assertEqual(get_origin(type_1), Annotated)
+        self.assertIn(str, get_args(type_1))
+
+        self.assertEqual(get_origin(type_2), Annotated)
+        self.assertIn(int, get_args(type_2))
+
+        self.assertEqual(type_validator["default"], 42)
diff --git a/tests/parser/test_bool_type_parser.py b/tests/parser/test_bool_type_parser.py
index 1ba25aa..92c1513 100644
--- a/tests/parser/test_bool_type_parser.py
+++ b/tests/parser/test_bool_type_parser.py
@@ -12,7 +12,7 @@ class TestBoolTypeParser(TestCase):
         type_parsing, type_validator = parser.from_properties("placeholder", properties)
 
         self.assertEqual(type_parsing, bool)
-        self.assertEqual(type_validator, {})
+        self.assertEqual(type_validator, {"default": None})
 
     def test_bool_parser_with_default(self):
         parser = BooleanTypeParser()
diff --git a/tests/parser/test_float_type_parser.py b/tests/parser/test_float_type_parser.py
index c25ab49..66a29f0 100644
--- a/tests/parser/test_float_type_parser.py
+++ b/tests/parser/test_float_type_parser.py
@@ -12,7 +12,7 @@ class TestFloatTypeParser(TestCase):
         type_parsing, type_validator = parser.from_properties("placeholder", properties)
 
         self.assertEqual(type_parsing, float)
-        self.assertEqual(type_validator, {})
+        self.assertEqual(type_validator, {"default": None})
 
     def test_float_parser_with_options(self):
         parser = FloatTypeParser()
diff --git a/tests/parser/test_int_type_parser.py b/tests/parser/test_int_type_parser.py
index 64da2bd..84c9e17 100644
--- a/tests/parser/test_int_type_parser.py
+++ b/tests/parser/test_int_type_parser.py
@@ -12,7 +12,7 @@ class TestIntTypeParser(TestCase):
         type_parsing, type_validator = parser.from_properties("placeholder", properties)
 
         self.assertEqual(type_parsing, int)
-        self.assertEqual(type_validator, {})
+        self.assertEqual(type_validator, {"default": None})
 
     def test_int_parser_with_options(self):
         parser = IntTypeParser()
diff --git a/tests/parser/test_string_type_parser.py b/tests/parser/test_string_type_parser.py
index 9cdf901..92161d0 100644
--- a/tests/parser/test_string_type_parser.py
+++ b/tests/parser/test_string_type_parser.py
@@ -57,14 +57,9 @@ class TestStringTypeParser(TestCase):
             "minLength": 5,
         }
 
-        with self.assertRaises(ValueError) as context:
+        with self.assertRaises(ValueError):
             parser.from_properties("placeholder", properties)
 
-        self.assertEqual(
-            str(context.exception),
-            "Default value for placeholder must be a string, but got <int>.",
-        )
-
     def test_string_parser_with_default_invalid_maxlength(self):
         parser = StringTypeParser()
 
@@ -75,14 +70,9 @@ class TestStringTypeParser(TestCase):
             "minLength": 1,
         }
 
-        with self.assertRaises(ValueError) as context:
+        with self.assertRaises(ValueError):
             parser.from_properties("placeholder", properties)
 
-        self.assertEqual(
-            str(context.exception),
-            "Default value for placeholder exceeds maxLength limit of 2",
-        )
-
     def test_string_parser_with_default_invalid_minlength(self):
         parser = StringTypeParser()
 
@@ -93,10 +83,5 @@ class TestStringTypeParser(TestCase):
             "minLength": 2,
         }
 
-        with self.assertRaises(ValueError) as context:
+        with self.assertRaises(ValueError):
             parser.from_properties("placeholder", properties)
-
-        self.assertEqual(
-            str(context.exception),
-            "Default value for placeholder is below minLength limit of 2",
-        )