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

Defined in: [src/models/streaming.ts:374](https://github.com/strands-agents/harness-sdk/blob/4b38b7443afa906bd2b3be1a7d7ce0cb44f39684/strands-ts/src/models/streaming.ts#L374)

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