diff --git a/litellm/llms/custom_httpx/llm_http_handler.py b/litellm/llms/custom_httpx/llm_http_handler.py
index 19f0e212902..8158ac66880 100644
--- a/litellm/llms/custom_httpx/llm_http_handler.py
+++ b/litellm/llms/custom_httpx/llm_http_handler.py
@@ -1777,7 +1777,7 @@ class BaseLLMHTTPHandler:
         asearch: bool = False,
         headers: dict[str, object] | None = None,
         provider_config: BaseSearchConfig | None = None,
-        auth_params: dict[str, object] | None = None,
+        auth_params: dict[str, object] | None = None,  # mutable-ok: search signing hooks require a mutable params dict
     ) -> SearchResponse | Coroutine[object, object, SearchResponse]:
         """
         Sync Search handler.
@@ -1823,7 +1823,10 @@ class BaseLLMHTTPHandler:
 
         signed_headers, signed_json_body = provider_config.sign_request(
             headers=headers,
-            optional_params={**optional_params, **(auth_params or {})},
+            optional_params={  # mutable-ok: sign_request requires one merged dict
+                **optional_params,
+                **(auth_params or {}),  # mutable-ok: absent auth params contribute no entries
+            },
             request_data=data,
             api_base=complete_url,
             api_key=api_key,
@@ -1884,7 +1887,7 @@ class BaseLLMHTTPHandler:
         client: HTTPHandler | AsyncHTTPHandler | None = None,
         headers: dict[str, object] | None = None,
         provider_config: BaseSearchConfig | None = None,
-        auth_params: dict[str, object] | None = None,
+        auth_params: dict[str, object] | None = None,  # mutable-ok: search signing hooks require a mutable params dict
     ) -> SearchResponse:
         """
         Async Search handler.
@@ -1918,7 +1921,10 @@ class BaseLLMHTTPHandler:
 
         signed_headers, signed_json_body = provider_config.sign_request(
             headers=headers,
-            optional_params={**optional_params, **(auth_params or {})},
+            optional_params={  # mutable-ok: sign_request requires one merged dict
+                **optional_params,
+                **(auth_params or {}),  # mutable-ok: absent auth params contribute no entries
+            },
             request_data=data,
             api_base=complete_url,
             api_key=api_key,