Fix sampling validation test expectations

Author: Epochex

tests/interaction/lowlevel/test_sampling.py

@@ -395,9 +395,7 @@ async def sampling_callback(
 
     assert result == snapshot(
         CallToolResult(
-            content=[
-                TextContent(text="ValueError: The last message must contain only tool_result content if any is present")
-            ]
+            content=[TextContent(text="ValueError: A message must contain only tool_result content if any is present")]
         )
     )
 

tests/server/test_session.py

@@ -161,9 +161,7 @@ async def test_send_request_skips_the_surface_gate_when_method_absent_at_version
 @pytest.mark.anyio
 async def test_create_message_tool_result_validation():
     """Test tool_use/tool_result validation in create_message."""
-    dispatcher = StubDispatcher(
-        result={"role": "assistant", "content": [{"type": "text", "text": "ok"}], "model": "m"}
-    )
+    dispatcher = StubDispatcher(result={"role": "assistant", "content": [{"type": "text", "text": "ok"}], "model": "m"})
     session = _make_session(
         dispatcher, capabilities=ClientCapabilities(sampling=SamplingCapability(tools=SamplingToolsCapability()))
     )