diff --git a/packages/svelte/src/toolbar/configure.js b/packages/svelte/src/toolbar/configure.js
index 3b491b502c..7ea6282945 100644
--- a/packages/svelte/src/toolbar/configure.js
+++ b/packages/svelte/src/toolbar/configure.js
@@ -10,15 +10,16 @@ const config = {
  * @param  {Partial<import('./public.d.ts').Config>} options
  */
 export function configure(options) {
-	for (const [key, value] of options) {
+	for (const [key, value] of Object.entries(options)) {
 		if (key === 'tools') {
 			for (let tool of /** @type {import('./public.d.ts').Config.tools[0][]}*/ value) {
 				if(typeof tool === 'function') {
-					tool = tool();
+					tool = tool(); // TODO lazy init?
 				}
+				/** @type {import('./public.d.ts').Tool}*/
 				const existing = config.tools.find((t) => t.name === tool.name);
 				if (existing) {
-					for (const [k, v] of tool) {
+					for (const [k, v] of Object.entries(tool)) {
 						existing[k] = v;
 					}
 				} else {
diff --git a/packages/svelte/src/toolbar/public.d.ts b/packages/svelte/src/toolbar/public.d.ts
index 87a05ba716..aa2d16894e 100644
--- a/packages/svelte/src/toolbar/public.d.ts
+++ b/packages/svelte/src/toolbar/public.d.ts
@@ -3,8 +3,8 @@ export * from './index.js';
 export interface Tool {
 	name: string;
 	icon: string; // url or svg
-	activate();
-	deactivate();
+	activate:()=>void;
+	deactivate:()=>void;
 	keyCombo?: string;
 	disabled?: boolean;
 }