ToolCallStartedEvent
Event for a tool call that has begun execution or is waiting for human approval. Check the event name and tool-call status to distinguish these cases; the event context identifies the conversation.
Usage profiles
| Usage | Fields and validation |
|---|---|
| In webhook payloads | View fields |
In webhook payloads
Webhook JSON uses protobuf field names (snake_case).
| Field | Type | Presence | Meaning |
|---|---|---|---|
event_context | EventContext | Optional | Event provenance and routing metadata associated with the emitted event. |
tool_call | ToolCall | Optional | Tool-call snapshot before a result is available, including its identity, name, server and arguments. For llm.tool_call_started the status is EXECUTING; for llm.tool_call_approval_required it is REQUIRES_CONFIRMATION and requires_approval_at is the decision deadline. result_json is unset. |
Where used
| Reference | Relationship |
|---|---|
| llm.tool_call_approval_required | Webhook JSON uses protobuf field names (snake_case). |
| llm.tool_call_started | Webhook JSON uses protobuf field names (snake_case). |
Download the public reference contract.
Document: DOC-API-MODEL-tool-call-started-event.