diff --git a/tests/lib/test_realtime_mcp.py b/tests/lib/test_realtime_mcp.py
new file mode 100644
index 0000000000..de4ffe4bb2
--- /dev/null
+++ b/tests/lib/test_realtime_mcp.py
@@ -0,0 +1,85 @@
+from __future__ import annotations
+
+import os
+import json
+from typing import Protocol, cast
+
+import httpx
+import pytest
+from respx import MockRouter
+
+from openai import OpenAI, AsyncOpenAI
+
+base_url = os.environ.get("TEST_API_BASE_URL", "http://127.0.0.1:4010")
+
+
+class MockRequestCall(Protocol):
+    request: httpx.Request
+
+
+@pytest.mark.respx(base_url=base_url)
+def test_realtime_calls_accept_sends_mcp_tools(client: OpenAI, respx_mock: MockRouter) -> None:
+    respx_mock.post("/realtime/calls/call_123/accept").mock(return_value=httpx.Response(204))
+
+    client.realtime.calls.accept(
+        "call_123",
+        type="realtime",
+        tools=[
+            {
+                "type": "mcp",
+                "server_label": "search",
+                "server_url": "https://example.com/mcp",
+                "allowed_tools": ["lookup"],
+                "headers": {"x-api-key": "test-key"},
+                "require_approval": "never",
+            }
+        ],
+    )
+
+    calls = cast("list[MockRequestCall]", respx_mock.calls)
+    assert json.loads(calls[0].request.content) == {
+        "type": "realtime",
+        "tools": [
+            {
+                "type": "mcp",
+                "server_label": "search",
+                "server_url": "https://example.com/mcp",
+                "allowed_tools": ["lookup"],
+                "headers": {"x-api-key": "test-key"},
+                "require_approval": "never",
+            }
+        ],
+    }
+
+
+@pytest.mark.respx(base_url=base_url)
+async def test_async_realtime_calls_accept_sends_mcp_tools(async_client: AsyncOpenAI, respx_mock: MockRouter) -> None:
+    respx_mock.post("/realtime/calls/call_123/accept").mock(return_value=httpx.Response(204))
+
+    await async_client.realtime.calls.accept(
+        "call_123",
+        type="realtime",
+        tools=[
+            {
+                "type": "mcp",
+                "server_label": "search",
+                "server_url": "https://example.com/mcp",
+                "allowed_tools": {"tool_names": ["lookup"]},
+                "require_approval": {"never": {"tool_names": ["lookup"]}},
+            }
+        ],
+    )
+
+    calls = cast("list[MockRequestCall]", respx_mock.calls)
+    assert json.loads(calls[0].request.content) == {
+        "type": "realtime",
+        "tools": [
+            {
+                "type": "mcp",
+                "server_label": "search",
+                "server_url": "https://example.com/mcp",
+                "allowed_tools": {"tool_names": ["lookup"]},
+                "require_approval": {"never": {"tool_names": ["lookup"]}},
+            }
+        ],
+    }