diff --git a/litellm/proxy/_experimental/mcp_server/caller_sign_in.py b/litellm/proxy/_experimental/mcp_server/caller_sign_in.py
index 13ef8edfb21..b6b5b728924 100644
--- a/litellm/proxy/_experimental/mcp_server/caller_sign_in.py
+++ b/litellm/proxy/_experimental/mcp_server/caller_sign_in.py
@@ -17,9 +17,10 @@ from __future__ import annotations
 import itertools
 from collections.abc import Mapping
 from dataclasses import dataclass
-from typing import TYPE_CHECKING, Final, Protocol, assert_never, cast, runtime_checkable
+from typing import TYPE_CHECKING, Final, Protocol, cast, runtime_checkable
 
 from pydantic import BaseModel, ConfigDict, TypeAdapter, ValidationError
+from typing_extensions import assert_never
 
 import litellm
 from litellm.integrations.custom_guardrail import CustomGuardrail
diff --git a/litellm/proxy/_experimental/mcp_server/server.py b/litellm/proxy/_experimental/mcp_server/server.py
index a4ba9e4d4bb..a42c2b54cec 100644
--- a/litellm/proxy/_experimental/mcp_server/server.py
+++ b/litellm/proxy/_experimental/mcp_server/server.py
@@ -1718,7 +1718,7 @@ if MCP_AVAILABLE:
             # JSON-RPC error and the WWW-Authenticate header is lost. OBO keeps its connect gate;
             # guardrail-only gates fire only on a single-server connect the key's grant admits.
             sign_in = caller_sign_in_for(server, user_api_key_auth) if server is not None else None
-            subject_token: Final = (
+            subject_token = (
                 operations.global_mcp_server_manager._extract_subject_token(  # pyright: ignore[reportPrivateUsage]  # the manager owns the subject/admission filter shared with the preflight
                     oauth2_headers, raw_headers, user_api_key_auth
                 )
@@ -1742,11 +1742,18 @@ if MCP_AVAILABLE:
                 )
 
                 raise_token_exchange_challenge(server, root_path=get_request_root_path(), connected_as=server_name)
+            allowed_single = (
+                await operations._get_allowed_mcp_servers(
+                    user_api_key_auth=user_api_key_auth, mcp_servers=mcp_servers, client_ip=client_ip
+                )
+                if server and len(mcp_servers or []) == 1
+                else []
+            )
             if (
                 server
                 and sign_in is not None
                 and subject_token is not None
-                and await _key_granted_single_server(server, mcp_servers, user_api_key_auth, client_ip)
+                and any(allowed.server_id == server.server_id for allowed in allowed_single)
             ):
                 from litellm.proxy._experimental.mcp_server.caller_sign_in import (  # noqa: PLC0415  # lazy: provider discovery pulls the guardrail registry
                     preflight_caller_sign_in,
@@ -1773,13 +1780,7 @@ if MCP_AVAILABLE:
             if (
                 server
                 and len(mcp_servers or []) == 1
-                and server.server_id
-                in frozenset(
-                    allowed.server_id
-                    for allowed in await operations._get_allowed_mcp_servers(
-                        user_api_key_auth=user_api_key_auth, mcp_servers=mcp_servers, client_ip=client_ip
-                    )
-                )
+                and server.server_id in frozenset(allowed.server_id for allowed in allowed_single)
             ):
                 await operations.global_mcp_server_manager.preflight_token_exchange(
                     server=server,