diff --git a/tests/test_litellm/litellm_core_utils/llm_cost_calc/test_tool_call_cost_tracking_dict_safety.py b/tests/test_litellm/litellm_core_utils/llm_cost_calc/test_tool_call_cost_tracking_dict_safety.py
new file mode 100644
index 00000000000..4eee6b59d34
--- /dev/null
+++ b/tests/test_litellm/litellm_core_utils/llm_cost_calc/test_tool_call_cost_tracking_dict_safety.py
@@ -0,0 +1,88 @@
+"""
+Tests that the cost-tracking call sites tolerate ``server_tool_use`` being
+either a ``dict`` or a ``ServerToolUse`` pydantic instance.
+
+See https://github.com/BerriAI/litellm/issues/26153.
+"""
+
+import os
+import sys
+
+import pytest
+
+sys.path.insert(0, os.path.abspath("../../../.."))
+
+from litellm.litellm_core_utils.llm_cost_calc.tool_call_cost_tracking import (
+    StandardBuiltInToolCostTracking,
+    _get_web_search_requests,
+)
+from litellm.types.utils import ModelResponse, ServerToolUse, Usage
+
+
+class _UsageWithDictServerToolUse:
+    """
+    Tiny stand-in that mimics the broken streaming-rebuild shape:
+    ``server_tool_use`` is a plain dict.
+    """
+
+    def __init__(self, server_tool_use):
+        self.server_tool_use = server_tool_use
+        self.prompt_tokens_details = None
+
+
+def test_get_web_search_requests_handles_none():
+    assert _get_web_search_requests(None) is None
+
+
+def test_get_web_search_requests_handles_dict():
+    assert _get_web_search_requests({"web_search_requests": 5}) == 5
+
+
+def test_get_web_search_requests_handles_dict_missing_key():
+    assert _get_web_search_requests({}) is None
+
+
+def test_get_web_search_requests_handles_pydantic():
+    stu = ServerToolUse(web_search_requests=7)
+    assert _get_web_search_requests(stu) == 7
+
+
+def test_get_web_search_requests_handles_pydantic_with_none_value():
+    stu = ServerToolUse()
+    assert _get_web_search_requests(stu) is None
+
+
+def test_response_object_includes_web_search_call_with_dict_server_tool_use():
+    """
+    The exact bug: ``usage.server_tool_use`` is a dict and the check in
+    ``response_object_includes_web_search_call`` used to crash with
+    ``AttributeError``.
+    """
+    response = ModelResponse()
+    usage = _UsageWithDictServerToolUse({"web_search_requests": 2})
+
+    # Must not raise — and must correctly detect the web search call.
+    result = StandardBuiltInToolCostTracking.response_object_includes_web_search_call(
+        response_object=response, usage=usage  # type: ignore[arg-type]
+    )
+    assert result is True
+
+
+def test_response_object_includes_web_search_call_with_pydantic_server_tool_use():
+    response = ModelResponse()
+    usage = _UsageWithDictServerToolUse(ServerToolUse(web_search_requests=2))
+
+    result = StandardBuiltInToolCostTracking.response_object_includes_web_search_call(
+        response_object=response, usage=usage  # type: ignore[arg-type]
+    )
+    assert result is True
+
+
+def test_response_object_includes_web_search_call_with_none_server_tool_use():
+    response = ModelResponse()
+    usage = _UsageWithDictServerToolUse(None)
+
+    result = StandardBuiltInToolCostTracking.response_object_includes_web_search_call(
+        response_object=response, usage=usage  # type: ignore[arg-type]
+    )
+    assert result is False