[Frontend] Responses API MCP tools for built in tools and to pass through headers (#24628)

Signed-off-by: Alec Solder <alecs@fb.com>
Signed-off-by: Alec S <10566873+alecsolder@users.noreply.github.com>
Co-authored-by: Alec Solder <alecs@fb.com>
Co-authored-by: Ye (Charlotte) Qi <yeq@meta.com>

tests/entrypoints/openai/test_response_api_mcp_tools.py

@@ -0,0 +1,106 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
+
+import pytest
+import pytest_asyncio
+from openai import OpenAI
+
+from ...utils import RemoteOpenAIServer
+
+MODEL_NAME = "openai/gpt-oss-20b"
+
+
+@pytest.fixture(scope="module")
+def monkeypatch_module():
+    from _pytest.monkeypatch import MonkeyPatch
+    mpatch = MonkeyPatch()
+    yield mpatch
+    mpatch.undo()
+
+
+@pytest.fixture(scope="module")
+def mcp_disabled_server(monkeypatch_module: pytest.MonkeyPatch):
+    args = ["--enforce-eager", "--tool-server", "demo"]
+
+    with monkeypatch_module.context() as m:
+        m.setenv("VLLM_ENABLE_RESPONSES_API_STORE", "1")
+        m.setenv("PYTHON_EXECUTION_BACKEND", "dangerously_use_uv")
+        with RemoteOpenAIServer(MODEL_NAME, args) as remote_server:
+            yield remote_server
+
+
+@pytest.fixture(scope="function")
+def mcp_enabled_server(monkeypatch_module: pytest.MonkeyPatch):
+    args = ["--enforce-eager", "--tool-server", "demo"]
+
+    with monkeypatch_module.context() as m:
+        m.setenv("VLLM_ENABLE_RESPONSES_API_STORE", "1")
+        m.setenv("PYTHON_EXECUTION_BACKEND", "dangerously_use_uv")
+        m.setenv("GPT_OSS_SYSTEM_TOOL_MCP_LABELS",
+                 "code_interpreter,container")
+        with RemoteOpenAIServer(MODEL_NAME, args) as remote_server:
+            yield remote_server
+
+
+@pytest_asyncio.fixture
+async def mcp_disabled_client(mcp_disabled_server):
+    async with mcp_disabled_server.get_async_client() as async_client:
+        yield async_client
+
+
+@pytest_asyncio.fixture
+async def mcp_enabled_client(mcp_enabled_server):
+    async with mcp_enabled_server.get_async_client() as async_client:
+        yield async_client
+
+
+@pytest.mark.asyncio
+@pytest.mark.parametrize("model_name", [MODEL_NAME])
+@pytest.mark.skip(reason="Code interpreter tool is not available in CI yet.")
+async def test_mcp_tool_env_flag_enabled(mcp_enabled_client: OpenAI,
+                                         model_name: str):
+    response = await mcp_enabled_client.responses.create(
+        model=model_name,
+        # TODO: Ideally should be able to set max tool calls
+        # to prevent multi-turn, but it is not currently supported
+        # would speed up the test
+        input=("What's the first 4 digits after the decimal point of "
+               "cube root of `19910212 * 20250910`? "
+               "Show only the digits. The python interpreter is not stateful "
+               "and you must print to see the output."),
+        tools=[{
+            "type": "mcp",
+            "server_label": "code_interpreter",
+            # URL unused for DemoToolServer
+            "server_url": "http://localhost:8888"
+        }],
+    )
+    assert response is not None
+    assert response.status == "completed"
+    assert response.usage.output_tokens_details.tool_output_tokens > 0
+
+
+@pytest.mark.asyncio
+@pytest.mark.parametrize("model_name", [MODEL_NAME])
+@pytest.mark.skip(reason="Code interpreter tool is not available in CI yet.")
+async def test_mcp_tool_env_flag_disabled(mcp_disabled_client: OpenAI,
+                                          model_name: str):
+    response = await mcp_disabled_client.responses.create(
+        model=model_name,
+        # TODO: Ideally should be able to set max tool calls
+        # to prevent multi-turn, but it is not currently supported
+        # would speed up the test
+        input=("What's the first 4 digits after the decimal point of "
+               "cube root of `19910212 * 20250910`? "
+               "Show only the digits. The python interpreter is not stateful "
+               "and you must print to see the output."),
+        tools=[{
+            "type": "mcp",
+            "server_label": "code_interpreter",
+            # URL unused for DemoToolServer
+            "server_url": "http://localhost:8888"
+        }],
+    )
+    assert response is not None
+    assert response.status == "completed"
+    assert response.usage.output_tokens_details.tool_output_tokens == 0