diff --git a/src/anthropic/lib/tools/_beta_functions.py b/src/anthropic/lib/tools/_beta_functions.py
index fd4540da8..5b2044408 100644
--- a/src/anthropic/lib/tools/_beta_functions.py
+++ b/src/anthropic/lib/tools/_beta_functions.py
@@ -171,7 +171,7 @@ def __init__(
         self._cache_control = cache_control
         self._allowed_callers = allowed_callers
         self._eager_input_streaming = eager_input_streaming
-        self._input_examples = input_examples
+        self._input_examples = list(input_examples) if input_examples is not None else None
         self._strict = strict
 
         self.description = description or self._get_description_from_docstring()
diff --git a/tests/lib/tools/test_functions.py b/tests/lib/tools/test_functions.py
index 1152f5d85..17c334e63 100644
--- a/tests/lib/tools/test_functions.py
+++ b/tests/lib/tools/test_functions.py
@@ -168,6 +168,21 @@ def get_weather(location: str, unit: str = "celsius") -> str:  # noqa: ARG001
             "required": ["location"],
         }
 
+    def test_input_examples_materialized_from_iterable(self) -> None:
+        def lookup(city: str) -> str:
+            return city
+
+        generator_examples = ({"city": c} for c in ["Kraków", "London"])
+        tool = beta_tool(lookup, input_examples=generator_examples)
+
+        # First call to to_dict
+        first_dict = tool.to_dict()
+        assert first_dict["input_examples"] == [{"city": "Kraków"}, {"city": "London"}]
+
+        # Second call to to_dict must still have the examples
+        second_dict = tool.to_dict()
+        assert second_dict["input_examples"] == [{"city": "Kraków"}, {"city": "London"}]
+
     def test_to_dict_method(self) -> None:
         def simple_func(message: str) -> str:
             """A simple function."""