diff --git a/python/mujoco/specs.cc b/python/mujoco/specs.cc
index 783a87b2..872761c7 100644
--- a/python/mujoco/specs.cc
+++ b/python/mujoco/specs.cc
@@ -18,7 +18,7 @@
 #include <memory>
 #include <string>
 #include <string_view>  // IWYU pragma: keep
-#include <vector>  // IWYU pragma: keep
+#include <vector>       // IWYU pragma: keep
 
 #include <Eigen/Core>
 #include <Eigen/Eigen>
@@ -298,202 +298,201 @@ PYBIND11_MODULE(_specs, m) {
     mjs_detachBody(self.ptr, &body);
   });
   mjSpec.def_property_readonly(
-    "actuators",
-    [](MjSpec& self) -> py::list {
-      py::list list;
-      raw::MjsElement* el = mjs_firstElement(self.ptr, mjOBJ_ACTUATOR);
-      while (el) {
-        list.append(mjs_asActuator(el));
-        el = mjs_nextElement(self.ptr, el);
-      }
-      return list;
-    },
-    py::return_value_policy::reference_internal);
+      "actuators",
+      [](MjSpec& self) -> py::list {
+        py::list list;
+        raw::MjsElement* el = mjs_firstElement(self.ptr, mjOBJ_ACTUATOR);
+        while (el) {
+          list.append(mjs_asActuator(el));
+          el = mjs_nextElement(self.ptr, el);
+        }
+        return list;
+      },
+      py::return_value_policy::reference_internal);
   mjSpec.def_property_readonly(
-    "sensors",
-    [](MjSpec& self) -> py::list {
-      py::list list;
-      raw::MjsElement* el = mjs_firstElement(self.ptr, mjOBJ_SENSOR);
-      while (el) {
-        list.append(mjs_asSensor(el));
-        el = mjs_nextElement(self.ptr, el);
-      }
-      return list;
-    },
-    py::return_value_policy::reference_internal);
+      "sensors",
+      [](MjSpec& self) -> py::list {
+        py::list list;
+        raw::MjsElement* el = mjs_firstElement(self.ptr, mjOBJ_SENSOR);
+        while (el) {
+          list.append(mjs_asSensor(el));
+          el = mjs_nextElement(self.ptr, el);
+        }
+        return list;
+      },
+      py::return_value_policy::reference_internal);
   mjSpec.def_property_readonly(
-    "flexes",
-    [](MjSpec& self) -> py::list {
-      py::list list;
-      raw::MjsElement* el = mjs_firstElement(self.ptr, mjOBJ_FLEX);
-      while (el) {
-        list.append(mjs_asFlex(el));
-        el = mjs_nextElement(self.ptr, el);
-      }
-      return list;
-    },
-    py::return_value_policy::reference_internal);
+      "flexes",
+      [](MjSpec& self) -> py::list {
+        py::list list;
+        raw::MjsElement* el = mjs_firstElement(self.ptr, mjOBJ_FLEX);
+        while (el) {
+          list.append(mjs_asFlex(el));
+          el = mjs_nextElement(self.ptr, el);
+        }
+        return list;
+      },
+      py::return_value_policy::reference_internal);
   mjSpec.def_property_readonly(
-    "pairs",
-    [](MjSpec& self) -> py::list {
-      py::list list;
-      raw::MjsElement* el = mjs_firstElement(self.ptr, mjOBJ_PAIR);
-      while (el) {
-        list.append(mjs_asPair(el));
-        el = mjs_nextElement(self.ptr, el);
-      }
-      return list;
-    },
-    py::return_value_policy::reference_internal);
+      "pairs",
+      [](MjSpec& self) -> py::list {
+        py::list list;
+        raw::MjsElement* el = mjs_firstElement(self.ptr, mjOBJ_PAIR);
+        while (el) {
+          list.append(mjs_asPair(el));
+          el = mjs_nextElement(self.ptr, el);
+        }
+        return list;
+      },
+      py::return_value_policy::reference_internal);
   mjSpec.def_property_readonly(
-    "equality",
-    [](MjSpec& self) -> py::list {
-      py::list list;
-      raw::MjsElement* el = mjs_firstElement(self.ptr, mjOBJ_EQUALITY);
-      while (el) {
-        list.append(mjs_asEquality(el));
-        el = mjs_nextElement(self.ptr, el);
-      }
-      return list;
-    },
-    py::return_value_policy::reference_internal);
+      "equality",
+      [](MjSpec& self) -> py::list {
+        py::list list;
+        raw::MjsElement* el = mjs_firstElement(self.ptr, mjOBJ_EQUALITY);
+        while (el) {
+          list.append(mjs_asEquality(el));
+          el = mjs_nextElement(self.ptr, el);
+        }
+        return list;
+      },
+      py::return_value_policy::reference_internal);
   mjSpec.def_property_readonly(
-    "excludes",
-    [](MjSpec& self) -> py::list {
-      py::list list;
-      raw::MjsElement* el = mjs_firstElement(self.ptr, mjOBJ_EXCLUDE);
-      while (el) {
-        list.append(mjs_asExclude(el));
-        el = mjs_nextElement(self.ptr, el);
-      }
-      return list;
-    },
-    py::return_value_policy::reference_internal);
+      "excludes",
+      [](MjSpec& self) -> py::list {
+        py::list list;
+        raw::MjsElement* el = mjs_firstElement(self.ptr, mjOBJ_EXCLUDE);
+        while (el) {
+          list.append(mjs_asExclude(el));
+          el = mjs_nextElement(self.ptr, el);
+        }
+        return list;
+      },
+      py::return_value_policy::reference_internal);
   mjSpec.def_property_readonly(
-    "tendons",
-    [](MjSpec& self) -> py::list {
-      py::list list;
-      raw::MjsElement* el = mjs_firstElement(self.ptr, mjOBJ_TENDON);
-      while (el) {
-        list.append(mjs_asTendon(el));
-        el = mjs_nextElement(self.ptr, el);
-      }
-      return list;
-    },
-    py::return_value_policy::reference_internal);
+      "tendons",
+      [](MjSpec& self) -> py::list {
+        py::list list;
+        raw::MjsElement* el = mjs_firstElement(self.ptr, mjOBJ_TENDON);
+        while (el) {
+          list.append(mjs_asTendon(el));
+          el = mjs_nextElement(self.ptr, el);
+        }
+        return list;
+      },
+      py::return_value_policy::reference_internal);
   mjSpec.def_property_readonly(
-    "numeric",
-    [](MjSpec& self) -> py::list {
-      py::list list;
-      raw::MjsElement* el = mjs_firstElement(self.ptr, mjOBJ_NUMERIC);
-      while (el) {
-        list.append(mjs_asNumeric(el));
-        el = mjs_nextElement(self.ptr, el);
-      }
-      return list;
-    },
-    py::return_value_policy::reference_internal);
+      "numeric",
+      [](MjSpec& self) -> py::list {
+        py::list list;
+        raw::MjsElement* el = mjs_firstElement(self.ptr, mjOBJ_NUMERIC);
+        while (el) {
+          list.append(mjs_asNumeric(el));
+          el = mjs_nextElement(self.ptr, el);
+        }
+        return list;
+      },
+      py::return_value_policy::reference_internal);
   mjSpec.def_property_readonly(
-    "text",
-    [](MjSpec& self) -> py::list {
-      py::list list;
-      raw::MjsElement* el = mjs_firstElement(self.ptr, mjOBJ_TEXT);
-      while (el) {
-        list.append(mjs_asText(el));
-        el = mjs_nextElement(self.ptr, el);
-      }
-      return list;
-    },
-    py::return_value_policy::reference_internal);
+      "text",
+      [](MjSpec& self) -> py::list {
+        py::list list;
+        raw::MjsElement* el = mjs_firstElement(self.ptr, mjOBJ_TEXT);
+        while (el) {
+          list.append(mjs_asText(el));
+          el = mjs_nextElement(self.ptr, el);
+        }
+        return list;
+      },
+      py::return_value_policy::reference_internal);
   mjSpec.def_property_readonly(
-    "tuple",
-    [](MjSpec& self) -> py::list {
-      py::list list;
-      raw::MjsElement* el = mjs_firstElement(self.ptr, mjOBJ_TUPLE);
-      while (el) {
-        list.append(mjs_asTuple(el));
-        el = mjs_nextElement(self.ptr, el);
-      }
-      return list;
-    },
-    py::return_value_policy::reference_internal);
+      "tuple",
+      [](MjSpec& self) -> py::list {
+        py::list list;
+        raw::MjsElement* el = mjs_firstElement(self.ptr, mjOBJ_TUPLE);
+        while (el) {
+          list.append(mjs_asTuple(el));
+          el = mjs_nextElement(self.ptr, el);
+        }
+        return list;
+      },
+      py::return_value_policy::reference_internal);
   mjSpec.def_property_readonly(
-    "key",
-    [](MjSpec& self) -> py::list {
-      py::list list;
-      raw::MjsElement* el = mjs_firstElement(self.ptr, mjOBJ_KEY);
-      while (el) {
-        list.append(mjs_asKey(el));
-        el = mjs_nextElement(self.ptr, el);
-      }
-      return list;
-    },
-    py::return_value_policy::reference_internal);
+      "key",
+      [](MjSpec& self) -> py::list {
+        py::list list;
+        raw::MjsElement* el = mjs_firstElement(self.ptr, mjOBJ_KEY);
+        while (el) {
+          list.append(mjs_asKey(el));
+          el = mjs_nextElement(self.ptr, el);
+        }
+        return list;
+      },
+      py::return_value_policy::reference_internal);
   mjSpec.def_property_readonly(
-    "mesh",
-    [](MjSpec& self) -> py::list {
-      py::list list;
-      raw::MjsElement* el = mjs_firstElement(self.ptr, mjOBJ_MESH);
-      while (el) {
-        list.append(mjs_asMesh(el));
-        el = mjs_nextElement(self.ptr, el);
-      }
-      return list;
-    },
-    py::return_value_policy::reference_internal);
+      "mesh",
+      [](MjSpec& self) -> py::list {
+        py::list list;
+        raw::MjsElement* el = mjs_firstElement(self.ptr, mjOBJ_MESH);
+        while (el) {
+          list.append(mjs_asMesh(el));
+          el = mjs_nextElement(self.ptr, el);
+        }
+        return list;
+      },
+      py::return_value_policy::reference_internal);
   mjSpec.def_property_readonly(
-    "hfield",
-    [](MjSpec& self) -> py::list {
-      py::list list;
-      raw::MjsElement* el = mjs_firstElement(self.ptr, mjOBJ_HFIELD);
-      while (el) {
-        list.append(mjs_asHField(el));
-        el = mjs_nextElement(self.ptr, el);
-      }
-      return list;
-    },
-    py::return_value_policy::reference_internal);
+      "hfield",
+      [](MjSpec& self) -> py::list {
+        py::list list;
+        raw::MjsElement* el = mjs_firstElement(self.ptr, mjOBJ_HFIELD);
+        while (el) {
+          list.append(mjs_asHField(el));
+          el = mjs_nextElement(self.ptr, el);
+        }
+        return list;
+      },
+      py::return_value_policy::reference_internal);
   mjSpec.def_property_readonly(
-    "skin",
-    [](MjSpec& self) -> py::list {
-      py::list list;
-      raw::MjsElement* el = mjs_firstElement(self.ptr, mjOBJ_SKIN);
-      while (el) {
-        list.append(mjs_asSkin(el));
-        el = mjs_nextElement(self.ptr, el);
-      }
-      return list;
-    },
-    py::return_value_policy::reference_internal);
+      "skin",
+      [](MjSpec& self) -> py::list {
+        py::list list;
+        raw::MjsElement* el = mjs_firstElement(self.ptr, mjOBJ_SKIN);
+        while (el) {
+          list.append(mjs_asSkin(el));
+          el = mjs_nextElement(self.ptr, el);
+        }
+        return list;
+      },
+      py::return_value_policy::reference_internal);
   mjSpec.def_property_readonly(
-    "texture",
-    [](MjSpec& self) -> py::list {
-      py::list list;
-      raw::MjsElement* el = mjs_firstElement(self.ptr, mjOBJ_TEXTURE);
-      while (el) {
-        list.append(mjs_asTexture(el));
-        el = mjs_nextElement(self.ptr, el);
-      }
-      return list;
-    },
-    py::return_value_policy::reference_internal);
+      "texture",
+      [](MjSpec& self) -> py::list {
+        py::list list;
+        raw::MjsElement* el = mjs_firstElement(self.ptr, mjOBJ_TEXTURE);
+        while (el) {
+          list.append(mjs_asTexture(el));
+          el = mjs_nextElement(self.ptr, el);
+        }
+        return list;
+      },
+      py::return_value_policy::reference_internal);
   mjSpec.def_property_readonly(
-    "material",
-    [](MjSpec& self) -> py::list {
-      py::list list;
-      raw::MjsElement* el = mjs_firstElement(self.ptr, mjOBJ_MATERIAL);
-      while (el) {
-        list.append(mjs_asMaterial(el));
-        el = mjs_nextElement(self.ptr, el);
-      }
-      return list;
-    },
-    py::return_value_policy::reference_internal);
+      "material",
+      [](MjSpec& self) -> py::list {
+        py::list list;
+        raw::MjsElement* el = mjs_firstElement(self.ptr, mjOBJ_MATERIAL);
+        while (el) {
+          list.append(mjs_asMaterial(el));
+          el = mjs_nextElement(self.ptr, el);
+        }
+        return list;
+      },
+      py::return_value_policy::reference_internal);
 
   // ============================= MJSBODY =====================================
   mjsBody.def_property_readonly(
-      "id", [](raw::MjsBody& self) -> int { return mjs_getId(self.element); },
-      py::return_value_policy::reference_internal);
+      "id", [](raw::MjsBody& self) -> int { return mjs_getId(self.element); });
   mjsBody.def("delete", [](raw::MjsBody& self) { mjs_delete(self.element); });
   mjsBody.def(
       "add_body",
@@ -666,8 +665,7 @@ PYBIND11_MODULE(_specs, m) {
 
   // ============================= MJSFRAME ====================================
   mjsFrame.def_property_readonly(
-      "id", [](raw::MjsFrame& self) -> int { return mjs_getId(self.element); },
-      py::return_value_policy::reference_internal);
+      "id", [](raw::MjsFrame& self) -> int { return mjs_getId(self.element); });
   mjsFrame.def("delete", [](raw::MjsFrame& self) { mjs_delete(self.element); });
   mjsFrame.def("set_frame", [](raw::MjsFrame& self, raw::MjsFrame& frame) {
     mjs_setFrame(self.element, &frame);
@@ -679,8 +677,7 @@ PYBIND11_MODULE(_specs, m) {
 
   // ============================= MJSGEOM =====================================
   mjsGeom.def_property_readonly(
-      "id", [](raw::MjsGeom& self) -> int { return mjs_getId(self.element); },
-      py::return_value_policy::reference_internal);
+      "id", [](raw::MjsGeom& self) -> int { return mjs_getId(self.element); });
   mjsGeom.def("delete", [](raw::MjsGeom& self) { mjs_delete(self.element); });
   mjsGeom.def("set_frame", [](raw::MjsGeom& self, raw::MjsFrame& frame) {
     mjs_setFrame(self.element, &frame);
@@ -697,8 +694,7 @@ PYBIND11_MODULE(_specs, m) {
 
   // ============================= MJSJOINT ====================================
   mjsJoint.def_property_readonly(
-      "id", [](raw::MjsJoint& self) -> int { return mjs_getId(self.element); },
-      py::return_value_policy::reference_internal);
+      "id", [](raw::MjsJoint& self) -> int { return mjs_getId(self.element); });
   mjsJoint.def("delete", [](raw::MjsJoint& self) { mjs_delete(self.element); });
   mjsJoint.def("set_frame", [](raw::MjsJoint& self, raw::MjsFrame& frame) {
     mjs_setFrame(self.element, &frame);
@@ -715,8 +711,7 @@ PYBIND11_MODULE(_specs, m) {
 
   // ============================= MJSSITE =====================================
   mjsSite.def_property_readonly(
-      "id", [](raw::MjsSite& self) -> int { return mjs_getId(self.element); },
-      py::return_value_policy::reference_internal);
+      "id", [](raw::MjsSite& self) -> int { return mjs_getId(self.element); });
   mjsSite.def("delete", [](raw::MjsSite& self) { mjs_delete(self.element); });
   mjsSite.def("set_frame", [](raw::MjsSite& self, raw::MjsFrame& frame) {
     mjs_setFrame(self.element, &frame);
@@ -732,9 +727,9 @@ PYBIND11_MODULE(_specs, m) {
       py::return_value_policy::reference_internal);
 
   // ============================= MJSCAMERA ===================================
-  mjsCamera.def_property_readonly(
-      "id", [](raw::MjsCamera& self) -> int { return mjs_getId(self.element); },
-      py::return_value_policy::reference_internal);
+  mjsCamera.def_property_readonly("id", [](raw::MjsCamera& self) -> int {
+    return mjs_getId(self.element);
+  });
   mjsCamera.def("delete",
                 [](raw::MjsCamera& self) { mjs_delete(self.element); });
   mjsCamera.def("set_frame", [](raw::MjsCamera& self, raw::MjsFrame& frame) {
@@ -752,8 +747,7 @@ PYBIND11_MODULE(_specs, m) {
 
   // ============================= MJSLIGHT ====================================
   mjsLight.def_property_readonly(
-      "id", [](raw::MjsLight& self) -> int { return mjs_getId(self.element); },
-      py::return_value_policy::reference_internal);
+      "id", [](raw::MjsLight& self) -> int { return mjs_getId(self.element); });
   mjsLight.def("delete", [](raw::MjsLight& self) { mjs_delete(self.element); });
   mjsLight.def("set_frame", [](raw::MjsLight& self, raw::MjsFrame& frame) {
     mjs_setFrame(self.element, &frame);
@@ -769,10 +763,9 @@ PYBIND11_MODULE(_specs, m) {
       py::return_value_policy::reference_internal);
 
   // ============================= MJSMATERIAL =================================
-  mjsMaterial.def_property_readonly(
-      "id",
-      [](raw::MjsMaterial& self) -> int { return mjs_getId(self.element); },
-      py::return_value_policy::reference_internal);
+  mjsMaterial.def_property_readonly("id", [](raw::MjsMaterial& self) -> int {
+    return mjs_getId(self.element);
+  });
   mjsMaterial.def("delete",
                   [](raw::MjsMaterial& self) { mjs_delete(self.element); });
   mjsMaterial.def("set_default",
@@ -788,8 +781,7 @@ PYBIND11_MODULE(_specs, m) {
 
   // ============================= MJSMESH =====================================
   mjsMesh.def_property_readonly(
-      "id", [](raw::MjsMesh& self) -> int { return mjs_getId(self.element); },
-      py::return_value_policy::reference_internal);
+      "id", [](raw::MjsMesh& self) -> int { return mjs_getId(self.element); });
   mjsMesh.def("delete", [](raw::MjsMesh& self) { mjs_delete(self.element); });
   mjsMesh.def("set_default", [](raw::MjsMesh& self, raw::MjsDefault& def) {
     mjs_setDefault(self.element, &def);
@@ -803,8 +795,7 @@ PYBIND11_MODULE(_specs, m) {
 
   // ============================= MJSPAIR =====================================
   mjsPair.def_property_readonly(
-      "id", [](raw::MjsPair& self) -> int { return mjs_getId(self.element); },
-      py::return_value_policy::reference_internal);
+      "id", [](raw::MjsPair& self) -> int { return mjs_getId(self.element); });
   mjsPair.def("delete", [](raw::MjsPair& self) { mjs_delete(self.element); });
   mjsPair.def("set_default", [](raw::MjsPair& self, raw::MjsDefault& def) {
     mjs_setDefault(self.element, &def);
@@ -817,10 +808,9 @@ PYBIND11_MODULE(_specs, m) {
       py::return_value_policy::reference_internal);
 
   // ============================= MJSEQUAL ====================================
-  mjsEquality.def_property_readonly(
-      "id",
-      [](raw::MjsEquality& self) -> int { return mjs_getId(self.element); },
-      py::return_value_policy::reference_internal);
+  mjsEquality.def_property_readonly("id", [](raw::MjsEquality& self) -> int {
+    return mjs_getId(self.element);
+  });
   mjsEquality.def("delete",
                   [](raw::MjsEquality& self) { mjs_delete(self.element); });
   mjsEquality.def("set_default",
@@ -835,10 +825,9 @@ PYBIND11_MODULE(_specs, m) {
       py::return_value_policy::reference_internal);
 
   // ============================= MJSACTUATOR =================================
-  mjsActuator.def_property_readonly(
-      "id",
-      [](raw::MjsActuator& self) -> int { return mjs_getId(self.element); },
-      py::return_value_policy::reference_internal);
+  mjsActuator.def_property_readonly("id", [](raw::MjsActuator& self) -> int {
+    return mjs_getId(self.element);
+  });
   mjsActuator.def("delete",
                   [](raw::MjsActuator& self) { mjs_delete(self.element); });
   mjsActuator.def("set_default",
@@ -853,9 +842,9 @@ PYBIND11_MODULE(_specs, m) {
       py::return_value_policy::reference_internal);
 
   // ============================= MJSTENDON ===================================
-  mjsTendon.def_property_readonly(
-      "id", [](raw::MjsTendon& self) -> int { return mjs_getId(self.element); },
-      py::return_value_policy::reference_internal);
+  mjsTendon.def_property_readonly("id", [](raw::MjsTendon& self) -> int {
+    return mjs_getId(self.element);
+  });
   mjsTendon.def("delete",
                 [](raw::MjsTendon& self) { mjs_delete(self.element); });
   mjsTendon.def("set_default", [](raw::MjsTendon& self, raw::MjsDefault& def) {
@@ -893,22 +882,21 @@ PYBIND11_MODULE(_specs, m) {
       py::return_value_policy::reference_internal);
 
   // ============================= MJSSENSOR ===================================
-  mjsSensor.def_property_readonly(
-      "id", [](raw::MjsSensor& self) -> int { return mjs_getId(self.element); },
-      py::return_value_policy::reference_internal);
+  mjsSensor.def_property_readonly("id", [](raw::MjsSensor& self) -> int {
+    return mjs_getId(self.element);
+  });
   mjsSensor.def("delete",
                 [](raw::MjsSensor& self) { mjs_delete(self.element); });
 
   // ============================= MJSFLEX =====================================
   mjsFlex.def_property_readonly(
-      "id", [](raw::MjsFlex& self) -> int { return mjs_getId(self.element); },
-      py::return_value_policy::reference_internal);
+      "id", [](raw::MjsFlex& self) -> int { return mjs_getId(self.element); });
   mjsFlex.def("delete", [](raw::MjsFlex& self) { mjs_delete(self.element); });
 
   // ============================= MJSHFIELD ===================================
-  mjsHField.def_property_readonly(
-      "id", [](raw::MjsHField& self) -> int { return mjs_getId(self.element); },
-      py::return_value_policy::reference_internal);
+  mjsHField.def_property_readonly("id", [](raw::MjsHField& self) -> int {
+    return mjs_getId(self.element);
+  });
   mjsHField.def("delete",
                 [](raw::MjsHField& self) { mjs_delete(self.element); });
 
@@ -919,46 +907,43 @@ PYBIND11_MODULE(_specs, m) {
   mjsSkin.def("delete", [](raw::MjsSkin& self) { mjs_delete(self.element); });
 
   // ============================= MJSTEXTURE ==================================
-  mjsTexture.def_property_readonly(
-      "id",
-      [](raw::MjsTexture& self) -> int { return mjs_getId(self.element); },
-      py::return_value_policy::reference_internal);
+  mjsTexture.def_property_readonly("id", [](raw::MjsTexture& self) -> int {
+    return mjs_getId(self.element);
+  });
   mjsTexture.def("delete",
                  [](raw::MjsTexture& self) { mjs_delete(self.element); });
 
   // ============================= MJSKEY ======================================
-  mjsKey.def("id",
-             [](raw::MjsKey& self) -> int { return mjs_getId(self.element); });
+  mjsKey.def_property_readonly(
+      "id", [](raw::MjsKey& self) -> int { return mjs_getId(self.element); });
   mjsKey.def("delete", [](raw::MjsKey& self) { mjs_delete(self.element); });
 
   // ============================= MJSTEXT =====================================
-  mjsText.def("id", [](raw::MjsText& self) -> int {
-    return mjs_getId(self.element);
-  });
+  mjsText.def_property_readonly(
+      "id", [](raw::MjsText& self) -> int { return mjs_getId(self.element); });
   mjsText.def("delete", [](raw::MjsText& self) { mjs_delete(self.element); });
 
   // ============================= MJSNUMERIC ==================================
-  mjsNumeric.def("id", [](raw::MjsNumeric& self) -> int {
+  mjsNumeric.def_property_readonly("id", [](raw::MjsNumeric& self) -> int {
     return mjs_getId(self.element);
   });
   mjsNumeric.def("delete",
                  [](raw::MjsNumeric& self) { mjs_delete(self.element); });
 
   // ============================= MJSEXCLUDE ==================================
-  mjsExclude.def("id", [](raw::MjsExclude& self) -> int {
+  mjsExclude.def_property_readonly("id", [](raw::MjsExclude& self) -> int {
     return mjs_getId(self.element);
   });
   mjsExclude.def("delete",
                  [](raw::MjsExclude& self) { mjs_delete(self.element); });
 
   // ============================= MJSTUPLE ====================================
-  mjsTuple.def("id", [](raw::MjsTuple& self) -> int {
-    return mjs_getId(self.element);
-  });
+  mjsTuple.def_property_readonly(
+      "id", [](raw::MjsTuple& self) -> int { return mjs_getId(self.element); });
   mjsTuple.def("delete", [](raw::MjsTuple& self) { mjs_delete(self.element); });
 
   // ============================= MJSPLUGIN ===================================
-  mjsPlugin.def("id", [](raw::MjsPlugin& self) -> int {
+  mjsPlugin.def_property_readonly("id", [](raw::MjsPlugin& self) -> int {
     return mjs_getId(self.instance);
   });
   mjsPlugin.def("delete",