Mount an end-effector (parallel-jaw gripper, dexterous hand, suction tool, etc.) on a robot arm by attaching its MJCF to the arm's `attachment_site` via MuJoCo's MjSpec API. Use when combining an arm MJCF and an end-effector MJCF into a single combined model. Handles known gotchas the underlying script doesn't: mesh collisions, wrong mount poses, empty-prefix failures, skipped meshes, and tendon-driven hands.
Use when bringing a URDF robot, hand, or CAD-generated model into MuJoCo MJCF and no hand-tuned upstream MJCF exists.
Convert an MJCF (MuJoCo's XML format) to URDF for downstream consumers that don't speak MJCF (RViz, pinocchio, ROS-based motion planning, etc.). The conversion is lossy — `<equality>` constraints, position actuators, contact excludes, and keyframes are all dropped. Use this skill ONLY when a URDF-only consumer needs the kinematic tree; do not use the converted URDF for dynamics.