diff --git a/Mesh_3/include/CGAL/Labeled_mesh_domain_3.h b/Mesh_3/include/CGAL/Labeled_mesh_domain_3.h
index 9a38880f945..6ae4f665ba0 100644
--- a/Mesh_3/include/CGAL/Labeled_mesh_domain_3.h
+++ b/Mesh_3/include/CGAL/Labeled_mesh_domain_3.h
@@ -622,6 +622,11 @@ public:
    * domain to be discretized is the union of voxels that have non-zero
    * values.
    *
+   * \returns either a `Labeled_mesh_domain_3`,
+   *   or a `Mesh_domain_with_polyline_features_3<Labeled_mesh_domain_3>`
+   *   depending on whether one or more of the named parameters
+   *   `detect_features` and `input_features` are provided.
+   *
    * \tparam NamedParameters a sequence of \ref bgl_namedparameters "Named Parameters"
    * \param image_ the input 3D image.
    * \param np an optional sequence of \ref bgl_namedparameters "Named Parameters" among the ones listed below:
@@ -650,11 +655,25 @@ public:
    *   \cgalParamNEnd
    *
    *   \cgalParamNBegin{detect_features}
-   *    \cgalParamDescription{ a functor can be passed to
-   *      `std::function<void(const CGAL::Image_3&, Mesh_domain_with_polyline_features_3<Labeled_mesh_domain_3>&)>`.
+   *    \cgalParamDescription{ a functor that can be passed to
+   *      `std::function<
+   *        std::vector<std::vector<Point_3>>
+   *        (const CGAL::Image_3&, Mesh_domain_with_polyline_features_3<Labeled_mesh_domain_3>&)>`
+   *      and that returns a range of detected polyline features for feature protection.
+   *      Polyline features are added to the domain for further feature protection.
    *      See \ref PkgMesh3FeatureDetection for available functors.}
    *    \cgalParamDefault{CGAL::Null_functor()}
-   *    \cgalParamExtra{The return type of the function depends on whether this parameter is provided or not.}
+   *    \cgalParamExtra{The return type of the function depends on whether this parameter
+                        or `input_features` are provided or not.}
+   *    \cgalParamExtra{If `weights` is provided, this parameter is ignored}
+   *   \cgalParamNEnd
+   *
+   *   \cgalParamNBegin{input_features}
+   *    \cgalParamDescription{ a `Range` of polyline features, represented as `Range`s of `Point_3`.
+   *         Polyline features are added to the domain for further feature protection.}
+   *    \cgalParamDefault{`std::vector<std::vector<Point_3>>()`}
+   *    \cgalParamExtra{The return type of the function depends on whether this parameter
+                        or `input_features` are provided or not.}
    *    \cgalParamExtra{If `weights` is provided, this parameter is ignored}
    *   \cgalParamNEnd
    *
diff --git a/Mesh_3/include/CGAL/Mesh_3/Detect_features_in_image.h b/Mesh_3/include/CGAL/Mesh_3/Detect_features_in_image.h
index 06a3c3a8b82..633d85b9547 100644
--- a/Mesh_3/include/CGAL/Mesh_3/Detect_features_in_image.h
+++ b/Mesh_3/include/CGAL/Mesh_3/Detect_features_in_image.h
@@ -268,6 +268,9 @@ public:
   * \tparam Mesh_domain class model of `MeshDomainWithFeatures_3`
   * \param image the input image
   * \param domain the mesh domain to be enriched with polyline features
+  *
+  * \returns a `std::vector<std::vector<typename Mesh_domain::Point_3>>`
+  * containing the constructed polylines
   */
   template<typename Mesh_domain>
   std::vector<std::vector<typename Mesh_domain::Point_3>>
diff --git a/Mesh_3/include/CGAL/Mesh_3/Detect_features_on_image_bbox.h b/Mesh_3/include/CGAL/Mesh_3/Detect_features_on_image_bbox.h
index 2f8c453b1d1..bc7f0fb5c87 100644
--- a/Mesh_3/include/CGAL/Mesh_3/Detect_features_on_image_bbox.h
+++ b/Mesh_3/include/CGAL/Mesh_3/Detect_features_on_image_bbox.h
@@ -78,6 +78,9 @@ public:
   *
   * \param image the input image
   * \param domain the mesh domain to be enriched with polyline features
+  *
+  * \returns a `std::vector<std::vector<typename Mesh_domain::Point_3>>`
+  * containing the constructed polylines
   */
   template<typename Mesh_domain>
   std::vector<std::vector<typename Mesh_domain::Point_3>>