beta_tool and beta_async_tool accept input_examples as Iterable[dict[str, object]], but BaseFunctionTool retains a supplied iterator directly. The first request consumes it during body serialization. Later requests from the same tool runner still carry that exhausted iterator and send input_examples: [] instead of the configured examples.
examples = ({"city": city} for city in ["Kraków", "London"])
tool = beta_tool(lookup, input_examples=examples)
# In a two-turn tool_runner run, the first request includes both examples;
# the follow-up request sends an empty input_examples list.This silently changes the tool definition during a conversation and loses the examples intended for subsequent model calls. Lists and tuples do not exhibit the problem.
Materialize the iterable once when constructing the function tool, retaining its values for repeated serialization. Empty iterables and omitted examples should keep their respective empty/omitted behavior.
A public-client matrix reproduces the issue across sync/async and JSON/streaming runners, with generator and list-iterator inputs plus list/tuple/empty/omitted controls. Eight cases fail on unchanged main. The change is separate from #1838, which prevents telemetry from consuming the outer messages/tools iterables, and #1953, which concerns ToolError content.
beta_tool and beta_async_tool accept input_examples as Iterable[dict[str, object]], but BaseFunctionTool retains a supplied iterator directly. The first request consumes it during body serialization. Later requests from the same tool runner still carry that exhausted iterator and send input_examples: [] instead of the configured examples.
This silently changes the tool definition during a conversation and loses the examples intended for subsequent model calls. Lists and tuples do not exhibit the problem.
Materialize the iterable once when constructing the function tool, retaining its values for repeated serialization. Empty iterables and omitted examples should keep their respective empty/omitted behavior.
A public-client matrix reproduces the issue across sync/async and JSON/streaming runners, with generator and list-iterator inputs plus list/tuple/empty/omitted controls. Eight cases fail on unchanged main. The change is separate from #1838, which prevents telemetry from consuming the outer messages/tools iterables, and #1953, which concerns ToolError content.