diff --git a/src/ol/animation.js b/src/ol/animation.js
index 55d4e512ea..4e9833b3fb 100644
--- a/src/ol/animation.js
+++ b/src/ol/animation.js
@@ -24,6 +24,7 @@ ol.animation.bounce = function(options) {
       /**
        * @param {ol.Map} map Map.
        * @param {?olx.FrameState} frameState Frame state.
+       * @return {boolean} Run this function in the next frame.
        */
       function(map, frameState) {
         if (frameState.time < start) {
@@ -62,6 +63,7 @@ ol.animation.pan = function(options) {
       /**
        * @param {ol.Map} map Map.
        * @param {?olx.FrameState} frameState Frame state.
+       * @return {boolean} Run this function in the next frame.
        */
       function(map, frameState) {
         if (frameState.time < start) {
@@ -103,6 +105,7 @@ ol.animation.rotate = function(options) {
       /**
        * @param {ol.Map} map Map.
        * @param {?olx.FrameState} frameState Frame state.
+       * @return {boolean} Run this function in the next frame.
        */
       function(map, frameState) {
         if (frameState.time < start) {
@@ -146,6 +149,7 @@ ol.animation.zoom = function(options) {
       /**
        * @param {ol.Map} map Map.
        * @param {?olx.FrameState} frameState Frame state.
+       * @return {boolean} Run this function in the next frame.
        */
       function(map, frameState) {
         if (frameState.time < start) {