Defined in: [src/models/streaming.ts:51](https://github.com/strands-agents/harness-sdk/blob/e4284b561624d906e361535ef1f1adcd5ce3461b/strands-ts/src/models/streaming.ts#L51)

Data for a message start event.

## Properties

### type

```ts
type: "modelMessageStartEvent";
```

Defined in: [src/models/streaming.ts:55](https://github.com/strands-agents/harness-sdk/blob/e4284b561624d906e361535ef1f1adcd5ce3461b/strands-ts/src/models/streaming.ts#L55)

Discriminator for message start events.

---

### role

```ts
role: Role;
```

Defined in: [src/models/streaming.ts:60](https://github.com/strands-agents/harness-sdk/blob/e4284b561624d906e361535ef1f1adcd5ce3461b/strands-ts/src/models/streaming.ts#L60)

The role of the message being started.