fix(messages): honor additional_drop_params for mcp_servers and read the beta map only for hosted MCP tools

litellm/litellm_core_utils/tool_fields.py

@@ -247,6 +247,13 @@ def _is_mcp_toolset(tool: object) -> bool:
             return False
 
 
+def drops_mcp_servers(request_kwargs: Mapping[str, object]) -> bool:
+    additional_drop_params: Final = request_kwargs.get("additional_drop_params")
+    return drops_unsupported_params(request_kwargs.get("drop_params")) or (
+        isinstance(additional_drop_params, list) and "mcp_servers" in additional_drop_params
+    )
+
+
 def tools_without_mcp_servers(
     mcp_servers: object, tools: Sequence[_ToolT], model: str, route: str, drop_params: bool
 ) -> Sequence[_ToolT]:
@@ -270,11 +277,17 @@ _TOOL_SELECTION_PARAMS: Final = frozenset({"tools", "tool_choice", "parallel_too
 _ParamsT: Final = TypeVar("_ParamsT", bound=dict[str, object])
 
 
-def tool_params_without_hosted_mcp(params: _ParamsT, model: str, route: str, drop_params: bool) -> _ParamsT:
+def tool_params_without_hosted_mcp(
+    params: _ParamsT, model: str, route: str, drop_params: bool, runs_hosted_mcp: Callable[[], bool] | None = None
+) -> _ParamsT:
     tools: Final = params.get("tools")
     if not isinstance(tools, list) or not tools:
         return params
     sent_tools: Final = _TOOLS.validate_python(tools)
+    if all(_hosted_mcp_server_label(tool) is None for tool in sent_tools) or (
+        runs_hosted_mcp is not None and runs_hosted_mcp()
+    ):
+        return params
     kept_tools: Final = tools_without_hosted_mcp(tools=sent_tools, model=model, route=route, drop_params=drop_params)
     if len(kept_tools) == len(sent_tools):
         return params

litellm/llms/anthropic/chat/transformation.py

@@ -1828,12 +1828,12 @@ class AnthropicConfig(AnthropicModelInfo, BaseConfig):
         model: str,
         drop_params: bool,
     ) -> dict:
-        request_params: Final = (
-            non_default_params
-            if self.runs_hosted_mcp()
-            else tool_params_without_hosted_mcp(
-                non_default_params, model=model, route=self._resolved_provider, drop_params=drop_params
-            )
+        request_params: Final = tool_params_without_hosted_mcp(
+            non_default_params,
+            model=model,
+            route=self._resolved_provider,
+            drop_params=drop_params,
+            runs_hosted_mcp=self.runs_hosted_mcp,
         )
         is_thinking_enabled: Final = self.is_thinking_enabled(non_default_params=request_params)
 

litellm/llms/anthropic/messages/adapters/handler.py

@@ -15,7 +15,11 @@ from litellm._logging import verbose_logger
 from litellm.litellm_core_utils.asyncify import run_async_function
 from litellm.litellm_core_utils.core_helpers import drops_unsupported_params
 from litellm.litellm_core_utils.litellm_logging import Logging as LiteLLMLoggingObject
-from litellm.litellm_core_utils.tool_fields import ROUTES_WITHOUT_MCP_SERVERS, tools_without_mcp_servers
+from litellm.litellm_core_utils.tool_fields import (
+    ROUTES_WITHOUT_MCP_SERVERS,
+    drops_mcp_servers,
+    tools_without_mcp_servers,
+)
 from litellm.llms.anthropic.messages.adapters.transformation import (
     AnthropicAdapter,
 )
@@ -620,7 +624,7 @@ class LiteLLMMessagesToCompletionTransformationHandler:
                 tools or (),
                 model=model,
                 route=target_provider,
-                drop_params=drop_params,
+                drop_params=drops_mcp_servers(provider_kwargs),
             )
             if strips_mcp_servers
             else tools

litellm/llms/anthropic/messages/responses_adapters/handler.py

@@ -20,7 +20,7 @@ from litellm.litellm_core_utils.prompt_templates.common_utils import (
     prompt_cache_breakpoint_for_wire,
     with_prompt_cache_breakpoint,
 )
-from litellm.litellm_core_utils.tool_fields import tools_without_mcp_servers
+from litellm.litellm_core_utils.tool_fields import drops_mcp_servers, tools_without_mcp_servers
 from litellm.responses.utils import auto_reasoning_summary
 from litellm.types.integrations.custom_logger import CONVERTED_STREAM_KEYS
 from litellm.types.llms.anthropic import (
@@ -169,7 +169,7 @@ def _build_responses_kwargs(
         tools or (),
         model=model,
         route=target_provider if isinstance(target_provider, str) else "this route",
-        drop_params=drops_unsupported_params(forwarded_kwargs.get("drop_params")),
+        drop_params=drops_mcp_servers(forwarded_kwargs),
     )
     block_rewrite: Final = _prompt_cache_block_rewrite(model, forwarded_kwargs)
     request_messages: Final[AnthropicRequestMessages] = (

tests/unit/llms/anthropic/messages/adapters/test_handler_output_config_passthrough.py

@@ -27,6 +27,7 @@ Tests cover (consolidating PRs #23706 and #22727):
 
 import os
 import sys
+from collections.abc import Mapping
 from typing import Final
 from unittest.mock import MagicMock, patch
 
@@ -341,7 +342,14 @@ def test_drop_params_drops_the_mcp_toolset_tools_of_dropped_mcp_servers(
     assert ("tool_choice" in completion_kwargs) == bool(kept_tool_names)
 
 
-@pytest.mark.parametrize("drop_params", ["request", "global"])
+_DROP_FORMS: Final[Mapping[str, Mapping[str, object]]] = {
+    "request": {"drop_params": True},
+    "global": {},
+    "additional_drop_params": {"additional_drop_params": ["mcp_servers"]},
+}
+
+
+@pytest.mark.parametrize("drop_params", list(_DROP_FORMS))
 def test_drop_params_drops_mcp_servers_instead_of_forwarding_them(
     monkeypatch: pytest.MonkeyPatch, drop_params: str
 ) -> None:
@@ -350,7 +358,7 @@ def test_drop_params_drops_mcp_servers_instead_of_forwarding_them(
         extra_kwargs={
             "mcp_servers": [_DEEPWIKI_SERVER],
             "custom_llm_provider": "gemini",
-            **({"drop_params": True} if drop_params == "request" else {}),
+            **_DROP_FORMS[drop_params],
         },
         model="gemini-3.8-flash",
     )

tests/unit/llms/anthropic/messages/responses_adapters/test_responses_adapters_handler.py

@@ -780,11 +780,18 @@ def test_mcp_servers_the_responses_bridge_cannot_run_answer_400(monkeypatch: pyt
     assert "to gpt-5.6 on openai, so the MCP server `deepwiki` would not run" in rejected.value.message
 
 
-def test_drop_params_keeps_mcp_servers_off_the_responses_request(monkeypatch: pytest.MonkeyPatch) -> None:
+@pytest.mark.parametrize(
+    "drop_form",
+    [{"drop_params": True}, {"additional_drop_params": ["mcp_servers"]}],
+    ids=["drop_params", "additional_drop_params"],
+)
+def test_drop_params_keeps_mcp_servers_off_the_responses_request(
+    monkeypatch: pytest.MonkeyPatch, drop_form: Mapping[str, object]
+) -> None:
     monkeypatch.setattr(litellm, "drop_params", False)
     responses_kwargs: Final = _build_responses_kwargs(
         model="gpt-5.6",
-        extra_kwargs={**OPENAI_API, "mcp_servers": [_DEEPWIKI_SERVER], "drop_params": True},
+        extra_kwargs={**OPENAI_API, "mcp_servers": [_DEEPWIKI_SERVER], **drop_form},
         max_tokens=1024,
         messages=MESSAGES,
     )