fix(responses): replay a BM25 tool search under its own name

litellm/responses/litellm_completion_transformation/tool_search_results.py

@@ -32,6 +32,7 @@ _MessageT: Final = TypeVar("_MessageT")
 
 _MAPPING_ADAPTER: Final = TypeAdapter(Mapping[str, object])
 _TOOL_SEARCH_ITEM_TYPES: Final = frozenset({"tool_search_call", "tool_search_output"})
+_BM25_TOOL_SEARCH_TOOL_NAME: Final = "tool_search_tool_bm25"
 
 
 class _ProviderToolResults(LiteLLMBaseModel):
@@ -213,13 +214,26 @@ def _anthropic_tool_search_result(output: _ToolSearchOutputItem) -> Mapping[str,
     return result.model_dump(mode="json")
 
 
+def _search_arguments(arguments: object) -> Mapping[str, object]:
+    try:
+        if isinstance(arguments, str):
+            return _MAPPING_ADAPTER.validate_json(arguments)
+        return _MAPPING_ADAPTER.validate_python(arguments)
+    except ValidationError:
+        return MappingProxyType({})
+
+
+def _search_tool_name(arguments: object) -> str:
+    return _BM25_TOOL_SEARCH_TOOL_NAME if "query" in _search_arguments(arguments) else ANTHROPIC_TOOL_SEARCH_TOOL_NAME
+
+
 def _replayed_item(item: ResponseInputItemParam, replayed_ids: frozenset[str]) -> ResponseInputItemParam | None:
     call: Final = _tool_search_call(item)
     if call is not None and call.call_id in replayed_ids:
         return ResponseFunctionToolCallParam(
             type="function_call",
             call_id=call.call_id,
-            name=ANTHROPIC_TOOL_SEARCH_TOOL_NAME,
+            name=_search_tool_name(call.arguments),
             arguments=serialize_tool_call_arguments(call.arguments, "{}"),
         )
     output: Final = _tool_search_output(item)

tests/unit/responses/litellm_completion_transformation/test_anthropic_responses_bridge.py

@@ -1651,6 +1651,36 @@ def test_responses_over_anthropic_return_the_tool_search_output_and_send_the_sea
     assert _sent_assistant_content(route) == [_SEARCH_USE, search_result, weather_use]
 
 
+
+@pytest.mark.parametrize(
+    ("search_tools", "search_use"),
+    [
+        pytest.param((), _SEARCH_USE, id="regex"),
+        pytest.param(
+            ({"type": "tool_search_tool_bm25_20251119", "name": "tool_search_tool_bm25"},),
+            {**_SEARCH_USE, "name": "tool_search_tool_bm25", "input": {"query": "weather"}},
+            id="bm25",
+        ),
+    ],
+)
+def test_responses_over_anthropic_send_a_search_back_under_the_anthropic_search_tool_that_ran_it(
+    respx_mock: respx.MockRouter, search_tools: tuple[Mapping[str, object], ...], search_use: Mapping[str, object]
+) -> None:
+    tools: Final = [{"type": "tool_search"}, *search_tools, _WEATHER_TOOL]
+    route: Final = respx_mock.post(_ANTHROPIC_MESSAGES_URL).mock(
+        return_value=_anthropic_message(search_use, _SEARCH_RESULT, _WEATHER_USE)
+    )
+
+    first: Final = litellm.responses(model=_MODEL, input=list(_WEATHER_QUESTION), tools=tools, api_key="mock_api_key")
+    litellm.responses(
+        model=_MODEL,
+        input=[*_WEATHER_QUESTION, *(item.model_dump(exclude_none=True) for item in first.output), _WEATHER_ANSWER],
+        tools=tools,
+        api_key="mock_api_key",
+    )
+
+    assert _sent_assistant_content(route) == [search_use, _SEARCH_RESULT, _WEATHER_USE]
+
 def _tool_search_stream(*events: Mapping[str, object]) -> httpx.Response:
     return httpx.Response(
         200,

tests/unit/responses/litellm_completion_transformation/test_litellm_completion_responses.py

@@ -2460,6 +2460,36 @@ class TestToolTransformation:
 
         assert [call["id"] for call in request["messages"][1]["tool_calls"]] == replayed_call_ids
 
+    @pytest.mark.parametrize(
+        ("arguments", "search_tool_name"),
+        [
+            pytest.param({"pattern": "weather"}, "tool_search_tool_regex", id="regex_object"),
+            pytest.param({"query": "weather"}, "tool_search_tool_bm25", id="bm25_object"),
+            pytest.param('{"query": "weather"}', "tool_search_tool_bm25", id="bm25_json"),
+            pytest.param("weather", "tool_search_tool_regex", id="not_json"),
+        ],
+    )
+    def test_stateless_claude_search_is_replayed_under_the_search_tool_its_arguments_belong_to(
+        self, arguments: object, search_tool_name: str
+    ) -> None:
+        items: Final = (
+            {**item, "arguments": arguments} if item["type"] == "tool_search_call" else item
+            for item in _stateless_tool_search_input("srvtoolu_01Search", "completed")
+        )
+        request: Final = LiteLLMCompletionResponsesConfig.transform_responses_api_request_to_chat_completion_request(
+            model="anthropic/claude-sonnet-5-5",
+            input=cast(  # cast-ok: tool search items are not in the SDK's input TypedDicts
+                ResponseInputParam, list(items)
+            ),
+            responses_api_request={"tools": _deferred_tools_with_server_tool_search()},
+            custom_llm_provider="anthropic",
+        )
+
+        assert [(call["id"], call["function"]["name"]) for call in request["messages"][1]["tool_calls"]] == [
+            ("srvtoolu_01Search", search_tool_name),
+            ("toolu_01Weather", "get_weather"),
+        ]
+
     def test_transform_local_shell_tools_dropped(self) -> None:
         (
             result_tools,