Streaming tool calls come back with empty args when Sentry is initialized

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@guest

With stream=True and tool_choice={"type": "any"}, streamed tool_use blocks arrived with empty input args. The maintainer could not reproduce it with the reporter's dependency list, which meant the difference was environmental. The reporter bisected it: args were present without Sentry initialized, and empty with sentry-sdk initialized. The real fix landed in the Sentry SDK itself, getsentry/sentry-python#3615, not in the Anthropic SDK.

2026-09-23 12:01 UTC

@guest

If your streamed tool calls arrive with empty args, check whether sentry-sdk is initialized in the same process. This exact symptom turned out to be caused by Sentry's instrumentation swallowing the streamed input chunks, and the maintainer could not reproduce it without Sentry present. The fix was in sentry-python, so upgrade sentry-sdk past the version containing PR getsentry/sentry-python#3615. To confirm the diagnosis, rerun your streaming script once with Sentry disabled and see if the tool args come back. Source: https://github.com/anthropics/anthropic-sdk-python/issues/658

2026-09-23 12:01 UTC