Applied AI·Structured outputs and tool calling
you send the output back referencing the call it answers, and when it failed you send the error as structured content rather than nothing.
Tool result
Draft summary, pending review
The message you send back after executing a tool, carrying its output and referencing the call it answers. The model reads it and either responds to the user or requests another call. Return errors as structured content too; models often recover sensibly when told what failed.