Enum ToolDecision 

#[non_exhaustive]
pub enum ToolDecision {
    Continue,
    Skip {
        reason: String,
    },
    Terminate {
        reason: String,
    },
}

Decision returned from ChatMiddleware::on_before_tool_call to optionally bypass or abort a tool invocation.

Variants (Non-exhaustive)

Non-exhaustive enums could have additional variants added in future. Therefore, when matching against variants of non-exhaustive enums, an extra wildcard arm must be added to account for any future variants.

Continue

Default: execute the tool.

Skip

Skip execution. The engine synthesizes an is_error: true crate::ToolResultContent carrying reason and feeds it back to the model so the loop can continue. Use when a single tool call should be denied (rate limit, policy violation) but the run as a whole should keep going.

Fields

reason: String

Human-readable reason; surfaces in the synthesized error tool_result the model receives.

Terminate

Abort the run before executing this tool. The engine surfaces the reason as crate::FinishReason::Aborted(reason) and fires ChatMiddleware::on_run_finished; partial tool results from earlier tool calls in the same step are preserved in new_messages.

Fields

reason: String

Human-readable reason; threaded through FinishReason::Aborted.