diff --git a/src/a2a/_base.py b/src/a2a/_base.py
index fc100442..6c50734c 100644
--- a/src/a2a/_base.py
+++ b/src/a2a/_base.py
@@ -1,7 +1,3 @@
-import warnings
-
-from typing import Any, ClassVar
-
 from pydantic import BaseModel, ConfigDict
 from pydantic.alias_generators import to_camel
 
@@ -40,64 +36,3 @@ class A2ABaseModel(BaseModel):
         serialize_by_alias=True,
         alias_generator=to_camel_custom,
     )
-
-    # Cache for the alias -> field_name mapping.
-    # It starts as None and is populated on first access.
-    _alias_to_field_name_map: ClassVar[dict[str, str] | None] = None
-
-    @classmethod
-    def _get_alias_map(cls) -> dict[str, str]:
-        """Lazily builds and returns the alias-to-field-name mapping for the class.
-
-        The map is cached on the class object to avoid re-computation.
-        """
-        if cls._alias_to_field_name_map is None:
-            cls._alias_to_field_name_map = {
-                field.alias: field_name
-                for field_name, field in cls.model_fields.items()
-                if field.alias is not None
-            }
-        return cls._alias_to_field_name_map
-
-    def __setattr__(self, name: str, value: Any) -> None:
-        """Allow setting attributes via their camelCase alias."""
-        # Get the map and find the corresponding snake_case field name.
-        field_name = type(self)._get_alias_map().get(name)  # noqa: SLF001
-
-        if field_name and field_name != name:
-            # An alias was used, issue a warning.
-            warnings.warn(
-                (
-                    f"Setting field '{name}' via its camelCase alias is deprecated and will be removed in version 0.3.0 "
-                    f"Use the snake_case name '{field_name}' instead."
-                ),
-                DeprecationWarning,
-                stacklevel=2,
-            )
-
-        # If an alias was used, field_name will be set; otherwise, use the original name.
-        super().__setattr__(field_name or name, value)
-
-    def __getattr__(self, name: str) -> Any:
-        """Allow getting attributes via their camelCase alias."""
-        # Get the map and find the corresponding snake_case field name.
-        field_name = type(self)._get_alias_map().get(name)  # noqa: SLF001
-
-        if field_name and field_name != name:
-            # An alias was used, issue a warning.
-            warnings.warn(
-                (
-                    f"Accessing field '{name}' via its camelCase alias is deprecated and will be removed in version 0.3.0 "
-                    f"Use the snake_case name '{field_name}' instead."
-                ),
-                DeprecationWarning,
-                stacklevel=2,
-            )
-
-            # If an alias was used, retrieve the actual snake_case attribute.
-            return getattr(self, field_name)
-
-        # If it's not a known alias, it's a genuine missing attribute.
-        raise AttributeError(
-            f"'{type(self).__name__}' object has no attribute '{name}'"
-        )
diff --git a/src/a2a/utils/proto_utils.py b/src/a2a/utils/proto_utils.py
index ddaa4f9e..f4d9e70e 100644
--- a/src/a2a/utils/proto_utils.py
+++ b/src/a2a/utils/proto_utils.py
@@ -363,6 +363,12 @@ def security_scheme(
                     flows=cls.oauth2_flows(scheme.root.flows),
                 )
             )
+        if isinstance(scheme.root, types.MutualTLSSecurityScheme):
+            return a2a_pb2.SecurityScheme(
+                mtls_security_scheme=a2a_pb2.MutualTlsSecurityScheme(
+                    description=scheme.root.description,
+                )
+            )
         return a2a_pb2.SecurityScheme(
             open_id_connect_security_scheme=a2a_pb2.OpenIdConnectSecurityScheme(
                 description=scheme.root.description,
diff --git a/tests/test_types.py b/tests/test_types.py
index c7e4efba..73e6af7b 100644
--- a/tests/test_types.py
+++ b/tests/test_types.py
@@ -1556,7 +1556,11 @@ def test_use_get_task_push_notification_params_for_request() -> None:
     )
 
 
-def test_camelCase() -> None:
+def test_camelCase_access_raises_attribute_error() -> None:
+    """
+    Tests that accessing or setting fields via their camelCase alias
+    raises an AttributeError.
+    """
     skill = AgentSkill(
         id='hello_world',
         name='Returns hello world',
@@ -1565,6 +1569,7 @@ def test_camelCase() -> None:
         examples=['hi', 'hello world'],
     )
 
+    # Initialization with camelCase still works due to Pydantic's populate_by_name config
     agent_card = AgentCard(
         name='Hello World Agent',
         description='Just a hello world agent',
@@ -1577,21 +1582,33 @@ def test_camelCase() -> None:
         supportsAuthenticatedExtendedCard=True,  # type: ignore
     )
 
-    # Test setting an attribute via camelCase alias
-    with pytest.warns(
-        DeprecationWarning,
-        match="Setting field 'supportsAuthenticatedExtendedCard'",
+    # --- Test that using camelCase aliases raises errors ---
+
+    # Test setting an attribute via camelCase alias raises AttributeError
+    with pytest.raises(
+        ValueError,
+        match='"AgentCard" object has no field "supportsAuthenticatedExtendedCard"',
     ):
         agent_card.supportsAuthenticatedExtendedCard = False
 
-    # Test getting an attribute via camelCase alias
-    with pytest.warns(
-        DeprecationWarning, match="Accessing field 'defaultInputModes'"
+    # Test getting an attribute via camelCase alias raises AttributeError
+    with pytest.raises(
+        AttributeError,
+        match="'AgentCard' object has no attribute 'defaultInputModes'",
     ):
-        default_input_modes = agent_card.defaultInputModes
+        _ = agent_card.defaultInputModes
 
-    # Assert the functionality still works as expected
+    # --- Test that using snake_case names works correctly ---
+
+    # The value should be unchanged because the camelCase setattr failed
+    assert agent_card.supports_authenticated_extended_card is True
+
+    # Now, set it correctly using the snake_case name
+    agent_card.supports_authenticated_extended_card = False
     assert agent_card.supports_authenticated_extended_card is False
+
+    # Get the attribute correctly using the snake_case name
+    default_input_modes = agent_card.default_input_modes
     assert default_input_modes == ['text']
     assert agent_card.default_input_modes == ['text']