diff --git a/mpt_api_client/models/model.py b/mpt_api_client/models/model.py
index 321a63c0..c87c67d0 100644
--- a/mpt_api_client/models/model.py
+++ b/mpt_api_client/models/model.py
@@ -15,8 +15,7 @@ class MptBox(Box):
     """python-box that preserves camelCase keys when converted to json."""
 
     def __init__(self, *args, attribute_mapping: dict[str, str] | None = None, **_):  # type: ignore[no-untyped-def]
-        attribute_mapping = attribute_mapping or {}
-        self._attribute_mapping = attribute_mapping
+        self._attribute_mapping = (attribute_mapping or {}).copy()
         super().__init__(
             *args,
             camel_killer_box=False,
@@ -34,7 +33,8 @@ def __setattr__(self, item: str, value: Any) -> None:
         if item in _box_safe_attributes:
             return object.__setattr__(self, item, value)
 
-        super().__setattr__(item, value)  # type: ignore[no-untyped-call]
+        mapped_key = self._prep_key(item)
+        super().__setattr__(mapped_key, value)  # type: ignore[no-untyped-call]
         return None
 
     @override
@@ -50,7 +50,7 @@ def to_dict(self) -> dict[str, Any]:  # noqa: WPS210
         }
         out_dict = {}
         for parsed_key, item_value in super().to_dict().items():
-            original_key = reverse_mapping[parsed_key]
+            original_key = reverse_mapping.get(parsed_key, parsed_key)
             out_dict[original_key] = item_value
         return out_dict
 
@@ -58,8 +58,12 @@ def _prep_key(self, key: str) -> str:
         try:
             return self._attribute_mapping[key]
         except KeyError:
-            self._attribute_mapping[key] = _camel_killer(key)
-            return self._attribute_mapping[key]
+            # Check if key is already a value in the mapping (it's already the API key)
+            if key in self._attribute_mapping.values():
+                return key
+            mapped_key = _camel_killer(key)
+            self._attribute_mapping[key] = mapped_key
+            return mapped_key  # type: ignore[no-any-return]
 
 
 class Model:  # noqa: WPS214
@@ -96,6 +100,12 @@ def __setattr__(self, attribute: str, attribute_value: Any) -> None:
             object.__setattr__(self, attribute, attribute_value)
             return
 
+        # Respect descriptors (e.g., @property setters) defined on the class
+        cls_attr = getattr(self.__class__, attribute, None)
+        if isinstance(cls_attr, property) and cls_attr.fset is not None:
+            cls_attr.fset(self, attribute_value)
+            return
+
         self._box.__setattr__(attribute, attribute_value)
 
     @classmethod
diff --git a/mpt_api_client/resources/catalog/products_parameters.py b/mpt_api_client/resources/catalog/products_parameters.py
index 6205801e..57a19587 100644
--- a/mpt_api_client/resources/catalog/products_parameters.py
+++ b/mpt_api_client/resources/catalog/products_parameters.py
@@ -1,3 +1,5 @@
+from typing import Any, ClassVar
+
 from mpt_api_client.http import AsyncService, Service
 from mpt_api_client.http.mixins import (
     AsyncCollectionMixin,
@@ -11,6 +13,108 @@
 class Parameter(Model):
     """Parameter resource."""
 
+    _attribute_mapping: ClassVar[dict[str, str]] = {"externalId": "external_id"}
+
+    @property
+    def type_(self) -> str:
+        """Returns the parameter type."""
+        return str(self._box.get("type", ""))  # type: ignore[no-untyped-call]
+
+    @type_.setter
+    def type_(self, value: str) -> None:
+        """Sets the parameter type."""
+        self._box.type = value
+
+    @property
+    def scope(self) -> str:
+        """Returns the parameter scope."""
+        return str(self._box.get("scope", ""))  # type: ignore[no-untyped-call]
+
+    @scope.setter
+    def scope(self, value: str) -> None:
+        """Sets the parameter scope."""
+        self._box.scope = value
+
+    @property
+    def phase(self) -> str:
+        """Returns the parameter phase."""
+        return str(self._box.get("phase", ""))  # type: ignore[no-untyped-call]
+
+    @phase.setter
+    def phase(self, value: str) -> None:
+        """Sets the parameter phase."""
+        self._box.phase = value
+
+    @property
+    def context(self) -> str:
+        """Returns the parameter context."""
+        return str(self._box.get("context", ""))  # type: ignore[no-untyped-call]
+
+    @context.setter
+    def context(self, value: str) -> None:
+        """Sets the parameter context."""
+        self._box.context = value
+
+    @property
+    def options(self) -> dict[str, Any]:
+        """Returns the parameter options."""
+        return self._box.get("options", {})  # type: ignore[no-any-return, no-untyped-call]
+
+    @options.setter
+    def options(self, value: dict[str, Any]) -> None:
+        """Sets the parameter options."""
+        self._box.options = value
+
+    @property
+    def multiple(self) -> bool:
+        """Returns whether the parameter allows multiple values."""
+        return bool(self._box.get("multiple", False))  # type: ignore[no-untyped-call]
+
+    @multiple.setter
+    def multiple(self, value: bool) -> None:
+        """Sets whether the parameter allows multiple values."""
+        self._box.multiple = value
+
+    @property
+    def constraints(self) -> dict[str, Any]:
+        """Returns the parameter constraints."""
+        return self._box.get("constraints", {})  # type: ignore[no-any-return, no-untyped-call]
+
+    @constraints.setter
+    def constraints(self, value: dict[str, Any]) -> None:
+        """Sets the parameter constraints."""
+        self._box.constraints = value
+
+    @property
+    def group(self) -> dict[str, Any]:
+        """Returns the parameter group."""
+        return self._box.get("group", {})  # type: ignore[no-any-return,no-untyped-call]
+
+    @group.setter
+    def group(self, value: dict[str, Any]) -> None:
+        """Sets the parameter group."""
+        self._box.group = value
+
+    @property
+    def external_id(self) -> str:
+        """Returns the parameter external ID."""
+        return str(self._box.get("external_id", ""))  # type: ignore[no-untyped-call]
+
+    @external_id.setter
+    def external_id(self, value: str) -> None:
+        """Sets the parameter external ID."""
+        self._box.external_id = value
+
+    @property
+    def status(self) -> str:
+        """Returns the parameter status."""
+        return str(self._box.get("status", ""))  # type: ignore[no-untyped-call]
+
+    @status.setter
+    def status(self, value: str) -> None:
+        """Sets the parameter status."""
+        self._box.status = value
+
 
 class ParametersServiceConfig:
     """Parameters service configuration."""
diff --git a/tests/unit/resources/catalog/test_parameter_properties.py b/tests/unit/resources/catalog/test_parameter_properties.py
new file mode 100644
index 00000000..05efad40
--- /dev/null
+++ b/tests/unit/resources/catalog/test_parameter_properties.py
@@ -0,0 +1,76 @@
+from mpt_api_client.resources.catalog.products_parameters import Parameter
+
+
+def test_parameter_properties_getters():  # noqa: WPS218
+    parameter_data = {
+        "id": "PAR-1",
+        "scope": "Order",
+        "phase": "Order",
+        "context": "Purchase",
+        "options": {"label": "Email"},
+        "multiple": True,
+        "constraints": {"required": True},
+        "group": {"id": "GRP-1"},
+        "externalId": "ext-1",
+        "status": "Active",
+    }
+
+    result = Parameter(parameter_data)
+
+    assert result.id == "PAR-1"
+    assert result.scope == "Order"
+    assert result.phase == "Order"
+    assert result.context == "Purchase"
+    assert result.options == {"label": "Email"}
+    assert result.multiple is True
+    assert result.constraints == {"required": True}
+    assert result.group == {"id": "GRP-1"}
+    assert result.external_id == "ext-1"
+    assert result.status == "Active"
+
+
+def test_parameter_properties_setters():  # noqa: WPS218
+    parameter = Parameter()
+    parameter.scope = "Agreement"
+    parameter.phase = "Configuration"
+    parameter.context = "None"
+    parameter.type_ = "Text"
+    parameter.options = {"label": "Name"}
+    parameter.multiple = False
+    parameter.constraints = {"required": False}
+    parameter.group = {"id": "GRP-2"}
+    parameter.external_id = "ext-2"
+    parameter.status = "Inactive"
+
+    result = parameter
+
+    assert result.scope == "Agreement"
+    assert result.phase == "Configuration"
+    assert result.context == "None"
+    assert result.type_ == "Text"
+    assert result.options == {"label": "Name"}
+    assert result.multiple is False
+    assert result.constraints == {"required": False}
+    assert result.group == {"id": "GRP-2"}
+    assert result.external_id == "ext-2"
+    assert result.status == "Inactive"
+    result_dict = result.to_dict()
+    assert result_dict["scope"] == "Agreement"
+    assert result_dict["externalId"] == "ext-2"
+    assert result_dict["scope"] == "Agreement"
+    assert result_dict["externalId"] == "ext-2"
+
+
+def test_parameter_default_values():  # noqa: WPS218
+    result = Parameter()
+
+    assert not result.id
+    assert not result.scope
+    assert not result.phase
+    assert not result.context
+    assert result.options == {}
+    assert result.multiple is False
+    assert result.constraints == {}
+    assert result.group == {}
+    assert not result.external_id
+    assert not result.status