diff --git a/packages/svelte/src/internal/client/custom-renderer/index.js b/packages/svelte/src/internal/client/custom-renderer/index.js
index 29f8bb19a6..b7ade121f8 100644
--- a/packages/svelte/src/internal/client/custom-renderer/index.js
+++ b/packages/svelte/src/internal/client/custom-renderer/index.js
@@ -1,9 +1,34 @@
-import { branch, effect_root } from "../reactivity/effects";
-import { push_renderer } from "./state";
+import { branch, effect_root } from '../reactivity/effects';
+import { push_renderer } from './state';
 
 /**
- * @param {*} renderer
- * @returns
+ * @template [TFragment=any]
+ * @template [TElement=any]
+ * @template [TTextNode=any]
+ * @template [TComment=any]
+ * @template [TNode=TElement | TTextNode | TComment | TFragment]
+ * @typedef {Object} Renderer
+ * @property {()=>TFragment} createFragment
+ * @property {(name: string)=>TElement} createElement
+ * @property {(data: string)=>TTextNode} createTextNode
+ * @property {(element: TElement, key: string, value: any)=>void} setAttribute
+ * @property {(node: TNode, text: string)=>void} setText
+ * @property {(data: string)=>TComment} createComment
+ * @property {(element: TNode)=>TNode} getFirstChild
+ * @property {(element: TNode)=>TNode} getLastChild
+ * @property {(element: TNode)=>TNode} getNextSibling
+ * @property {(parent: TNode, element: TNode, anchor: TNode | null)=>void} insert
+ * @property {(node: TNode)=>void} remove
+ * @property {(element: TNode)=>TNode} getParent
+ */
+
+/**
+ * @template [const TFragment=unknown]
+ * @template [const TElement=unknown]
+ * @template [const TTextNode=unknown]
+ * @template [const TComment=unknown]
+ * @param {Renderer<TFragment, TElement, TTextNode, TComment>} renderer
+ * @returns {Renderer<TFragment, TElement, TTextNode, TComment> & { render: (Component: any, options: { target: TNode, props?: any }) => () => void }}
  */
 export function createRenderer(renderer) {
 	return {
@@ -25,4 +50,4 @@ export function createRenderer(renderer) {
 			return unmount;
 		}
 	};
-}
\ No newline at end of file
+}
diff --git a/packages/svelte/src/internal/client/custom-renderer/state.js b/packages/svelte/src/internal/client/custom-renderer/state.js
index c1075ed454..9eee42e14a 100644
--- a/packages/svelte/src/internal/client/custom-renderer/state.js
+++ b/packages/svelte/src/internal/client/custom-renderer/state.js
@@ -1,15 +1,23 @@
 /**
- * @type {any}
+ * @import { Renderer } from ".";
+ */
+
+/**
+ * @type {Renderer | null}
  */
 let renderer = null;
 
+/**
+ *
+ * @returns {Renderer | null}
+ */
 export function get_renderer() {
 	return renderer;
 }
 
 /**
  *
- * @param {any} $renderer
+ * @param {Renderer} $renderer
  */
 export function push_renderer($renderer) {
 	let old_renderer = renderer;
@@ -17,4 +25,4 @@ export function push_renderer($renderer) {
 	return () => {
 		renderer = old_renderer;
 	};
-}
\ No newline at end of file
+}