Claude tool calls with no arguments now replay on other models

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 "{}".

# 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 in the documentation.