diff --git a/litellm/llms/anthropic/experimental_pass_through/adapters/transformation.py b/litellm/llms/anthropic/experimental_pass_through/adapters/transformation.py
index de77a74e3f4..091ed4a7190 100644
--- a/litellm/llms/anthropic/experimental_pass_through/adapters/transformation.py
+++ b/litellm/llms/anthropic/experimental_pass_through/adapters/transformation.py
@@ -733,7 +733,9 @@ class LiteLLMAnthropicMessagesAdapter:
                 name=truncated_name,
             )
             if "input_schema" in tool:
-                function_chunk["parameters"] = tool["input_schema"]
+                # Deep-copy so extra kwargs merged below (see #34510) never mutate
+                # the caller's original `input_schema` dict.
+                function_chunk["parameters"] = copy.deepcopy(tool["input_schema"])
             if "description" in tool:
                 function_chunk["description"] = tool["description"]
             if "strict" in tool: