diff --git a/extensions/notebook/src/book/bookTreeItem.ts b/extensions/notebook/src/book/bookTreeItem.ts
index 86fb760a3c..29d9592f16 100644
--- a/extensions/notebook/src/book/bookTreeItem.ts
+++ b/extensions/notebook/src/book/bookTreeItem.ts
@@ -119,4 +119,13 @@ export class BookTreeItem extends vscode.TreeItem {
 	public get nextUri(): string {
 		return this._nextUri;
 	}
+
+	get tooltip(): string {
+		if (this.book.type === BookTreeItemType.ExternalLink) {
+			return `${this._uri}`;
+		}
+		else {
+			return undefined;
+		}
+	}
 }
\ No newline at end of file