Feature request: tool_choice='none' - for sending tool results, but ensuring another tool call does not occur

[imclerran]

Currently, when sending tool results, the tool definitions must be included in the result. However, sometimes when sending tool results, a user may want to restrict the model not to call another tool. But since tool choice may not be set to "none" and the tool definitions are still present, there is no way to restrict Claude from calling any additional tools when sending tool results.

"message": "Requests which include `tool_use` or `tool_result` blocks must define tools."

[imclerran]

Either an empty tool list should be permitted when sending tool results, or tool_choice should be able to be set to none.