diff --git a/src/a2a/compat/v0_3/jsonrpc_adapter.py b/src/a2a/compat/v0_3/jsonrpc_adapter.py
index 073c7854b..d9d698411 100644
--- a/src/a2a/compat/v0_3/jsonrpc_adapter.py
+++ b/src/a2a/compat/v0_3/jsonrpc_adapter.py
@@ -59,7 +59,7 @@ class JSONRPC03Adapter:
         'tasks/pushNotificationConfig/list': types_v03.ListTaskPushNotificationConfigRequest,
         'tasks/pushNotificationConfig/delete': types_v03.DeleteTaskPushNotificationConfigRequest,
         'tasks/resubscribe': types_v03.TaskResubscriptionRequest,
-        'agent/authenticatedExtendedCard': types_v03.GetAuthenticatedExtendedCardRequest,
+        'agent/getAuthenticatedExtendedCard': types_v03.GetAuthenticatedExtendedCardRequest,
     }
 
     def __init__(  # noqa: PLR0913
@@ -225,7 +225,7 @@ async def _process_non_streaming_request(
                     id=request_id, result=None
                 )
             )
-        elif method == 'agent/authenticatedExtendedCard':
+        elif method == 'agent/getAuthenticatedExtendedCard':
             res_card = await self.get_authenticated_extended_card(
                 request_obj, context
             )
@@ -248,7 +248,7 @@ async def get_authenticated_extended_card(
         request: types_v03.GetAuthenticatedExtendedCardRequest,
         context: ServerCallContext,
     ) -> types_v03.AgentCard:
-        """Handles the 'agent/authenticatedExtendedCard' JSON-RPC method."""
+        """Handles the 'agent/getAuthenticatedExtendedCard' JSON-RPC method."""
         if not self.agent_card.capabilities.extended_agent_card:
             raise ExtendedAgentCardNotConfiguredError(
                 message='Authenticated card not supported'
diff --git a/src/a2a/compat/v0_3/jsonrpc_transport.py b/src/a2a/compat/v0_3/jsonrpc_transport.py
index 6153ccfc0..557a63a16 100644
--- a/src/a2a/compat/v0_3/jsonrpc_transport.py
+++ b/src/a2a/compat/v0_3/jsonrpc_transport.py
@@ -376,7 +376,7 @@ async def get_extended_agent_card(
             return card
 
         rpc_request = JSONRPC20Request(
-            method='agent/authenticatedExtendedCard',
+            method='agent/getAuthenticatedExtendedCard',
             params={},
             _id=str(uuid4()),
         )
diff --git a/tests/compat/v0_3/test_jsonrpc_app_compat.py b/tests/compat/v0_3/test_jsonrpc_app_compat.py
index 8120e322f..1417b5dac 100644
--- a/tests/compat/v0_3/test_jsonrpc_app_compat.py
+++ b/tests/compat/v0_3/test_jsonrpc_app_compat.py
@@ -11,6 +11,8 @@
 from a2a.server.request_handlers.request_handler import RequestHandler
 from a2a.types.a2a_pb2 import (
     AgentCard,
+    AgentCapabilities,
+    AgentInterface,
     Message as Message10,
     Part as Part10,
     Role as Role10,
@@ -18,6 +20,7 @@
     TaskStatus as TaskStatus10,
     TaskState as TaskState10,
 )
+
 from a2a.compat.v0_3 import a2a_v0_3_pb2
 
 
@@ -44,15 +47,21 @@ def mock_handler():
 
 @pytest.fixture
 def test_app(mock_handler):
-    mock_agent_card = MagicMock(spec=AgentCard)
-    mock_agent_card.url = 'http://mockurl.com'
-    # Set up capabilities.streaming to avoid validation issues
-    mock_agent_card.capabilities = MagicMock()
-    mock_agent_card.capabilities.streaming = False
-    mock_agent_card.capabilities.push_notifications = True
-    mock_agent_card.capabilities.extended_agent_card = True
+    agent_card = AgentCard(
+        name='TestAgent',
+        description='Test Description',
+        version='1.0.0',
+        capabilities=AgentCapabilities(
+            streaming=False, push_notifications=True, extended_agent_card=True
+        ),
+    )
+    interface = agent_card.supported_interfaces.add()
+    interface.url = 'http://mockurl.com'
+    interface.protocol_binding = 'jsonrpc'
+    interface.protocol_version = '0.3'
+
     jsonrpc_routes = create_jsonrpc_routes(
-        agent_card=mock_agent_card,
+        agent_card=agent_card,
         request_handler=mock_handler,
         enable_v0_3_compat=True,
         rpc_url='/',
@@ -111,3 +120,25 @@ def test_get_task_v03_compat(
     assert 'result' in data
     assert data['result']['id'] == 'test_task_id'
     assert data['result']['status']['state'] == 'completed'
+
+
+def test_get_extended_agent_card_v03_compat(
+    client: TestClient,
+) -> None:
+    """Test that the v0.3 method name 'agent/getAuthenticatedExtendedCard' is correctly routed."""
+    request_payload = {
+        'jsonrpc': '2.0',
+        'id': '3',
+        'method': 'agent/getAuthenticatedExtendedCard',
+        'params': {},
+    }
+
+    response = client.post('/', json=request_payload)
+    assert response.status_code == 200
+    data = response.json()
+
+    assert data['jsonrpc'] == '2.0'
+    assert data['id'] == '3'
+    assert 'result' in data
+    # The result should be a v0.3 AgentCard
+    assert 'supportsAuthenticatedExtendedCard' in data['result']
diff --git a/tests/compat/v0_3/test_jsonrpc_transport.py b/tests/compat/v0_3/test_jsonrpc_transport.py
index 250608014..50b33e162 100644
--- a/tests/compat/v0_3/test_jsonrpc_transport.py
+++ b/tests/compat/v0_3/test_jsonrpc_transport.py
@@ -348,6 +348,39 @@ async def test_compat_jsonrpc_transport_get_extended_agent_card_not_supported(
     assert response == transport.agent_card
 
 
+@pytest.mark.asyncio
+async def test_compat_jsonrpc_transport_get_extended_agent_card_method_name(
+    transport,
+):
+    """Verify the correct v0.3 method name 'agent/getAuthenticatedExtendedCard' is used."""
+    captured_request: dict | None = None
+
+    async def mock_send_request(data, *args, **kwargs):
+        nonlocal captured_request
+        captured_request = data
+        return {
+            'result': {
+                'name': 'ExtendedAgent',
+                'url': 'http://agent',
+                'version': '1.0.0',
+                'description': 'Description',
+                'skills': [],
+                'defaultInputModes': [],
+                'defaultOutputModes': [],
+                'capabilities': {},
+                'supportsAuthenticatedExtendedCard': True,
+            }
+        }
+
+    transport._send_request = mock_send_request
+
+    req = GetExtendedAgentCardRequest()
+    await transport.get_extended_agent_card(req)
+
+    assert captured_request is not None
+    assert captured_request['method'] == 'agent/getAuthenticatedExtendedCard'
+
+
 @pytest.mark.asyncio
 async def test_compat_jsonrpc_transport_close(transport, mock_httpx_client):
     await transport.close()