```ts
type ContentBlock =
  | TextBlock
  | ToolUseBlock
  | ToolResultBlock
  | ReasoningBlock
  | CachePointBlock
  | GuardContentBlock
  | ImageBlock
  | VideoBlock
  | DocumentBlock
  | CitationsBlock;
```

Defined in: [src/types/messages.ts:190](https://github.com/strands-agents/harness-sdk/blob/f23d6cce5a8fae509dc0ad28ee20de4be886e7d9/strands-ts/src/types/messages.ts#L190)