# Claude tool calls with no arguments now replay on other models

> Agno now stores a Claude tool call with no arguments as "{}", so a saved history with that call replays through OpenAI models.

- Published: 2026-09-08
- Author: Bas Nijholt
- Categories: Changelog
- Canonical: https://www.agno.com/articles/claude-tool-calls-with-no-arguments-now-replay-on-other-models
- Markdown: https://www.agno.com/articles/claude-tool-calls-with-no-arguments-now-replay-on-other-models.md

When Claude called a zero-argument tool like `get_status`, Agno's Anthropic adapter treated the empty input as nothing and left `function.arguments` out of the stored call. Replaying that history through an OpenAI model then failed, because OpenAI expects the field.

The adapter now serializes every tool input in both streaming and non-streaming responses, so an empty input is kept as `"{}"`.

```python
# Before: a zero-argument call was stored without arguments
{"id": "toolu_01", "type": "function", "function": {"name": "get_status"}}

# Now: the empty input is kept
{"id": "toolu_01", "type": "function", "function": {"name": "get_status", "arguments": "{}"}}
```

Learn more about the [Claude model](https://docs.agno.com/models/providers/native/anthropic/overview) in the documentation.