```ts
type ContentBlockStart = ToolUseStart;
```

Defined in: [src/models/streaming.ts:374](https://github.com/strands-agents/harness-sdk/blob/57d070582e9bd93afb549b4d2f976ce0dbaf03b6/strands-ts/src/models/streaming.ts#L374)

Information about a content block that is starting. Currently only represents tool use starts.