[This proposal](https://github.com/tc39/proposal-Symbol-description) got stage 4 at the [November 2018 meeting](https://github.com/rwaldron/tc39-notes/blob/be8c2af6d6dcfc9630e00ea15bbabf1a415245cb/es9/2018-11/nov-27.md#conclusionresolution-12), and is not yet implemented in `js-sys`. See [spec text](https://tc39.github.io/ecma262/#sec-symbol.prototype.description) and [MDN docs](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Symbol/description).