diff --git a/packages/@vue/cli-service/types/ProjectOptions.d.ts b/packages/@vue/cli-service/types/ProjectOptions.d.ts
index b4c0269e75..0485ba5c0b 100644
--- a/packages/@vue/cli-service/types/ProjectOptions.d.ts
+++ b/packages/@vue/cli-service/types/ProjectOptions.d.ts
@@ -23,37 +23,137 @@ interface ExtractOptions {
 }
 
 interface CSSOptions {
+  /**
+   * Default: `true`
+   *
+   * By default, only files that ends in `*.module.[ext]` are treated as CSS modules
+   */
   requireModuleExtension?: boolean;
+  /**
+   * Default: `true`
+   *
+   * Whether to extract CSS in your components into a standalone CSS files (instead of inlined in JavaScript and injected dynamically)
+   */
   extract?: boolean | ExtractOptions;
+  /**
+   * Default: `false`
+   *
+   * Whether to enable source maps for CSS. Setting this to `true` may affect build performance
+   */
   sourceMap?: boolean;
+  /**
+   * Default: `{}`
+   *
+   * Pass options to CSS-related loaders
+   */
   loaderOptions?: LoaderOptions;
 }
 
 interface ProjectOptions {
+  /**
+   * Default: `'/'`
+   *
+   * The base URL your application bundle will be deployed at
+   */
   publicPath?: string;
+  /**
+   * Default: `'dist'`
+   *
+   * The directory where the production build files will be generated in when running `vue-cli-service build`
+   */
   outputDir?: string;
+  /**
+   * Default: `''`
+   *
+   * A directory (relative to `outputDir`) to nest generated static assets (js, css, img, fonts) under
+   */
   assetsDir?: string;
+  /**
+   * Default: `'index.html'`
+   *
+   * Specify the output path for the generated `index.html` (relative to `outputDir`). Can also be an absolute path
+   */
   indexPath?: string;
+  /**
+   * Default: `true`
+   *
+   * By default, generated static assets contains hashes in their filenames for better caching control
+   */
   filenameHashing?: boolean;
+  /**
+   * Default: `false`
+   *
+   * Whether to use the build of Vue core that includes the runtime compiler
+   */
   runtimeCompiler?: boolean;
+  /**
+   * Default: `[]`
+   *
+   * If you want to explicitly transpile a dependency with Babel, you can list it in this option
+   */
   transpileDependencies?: Array<string | RegExp>;
+  /**
+   * Default: `true`
+   *
+   * Setting this to `false` can speed up production builds if you don't need source maps for production
+   */
   productionSourceMap?: boolean;
+  /**
+   * Default: `require('os').cpus().length > 1`
+   *
+   * Whether to use `thread-loader` for Babel or TypeScript transpilation
+   */
   parallel?: boolean | number;
-  devServer?: object;
+  /**
+   * [All options for `webpack-dev-server`](https://webpack.js.org/configuration/dev-server/) are supported
+   */
+  devServer?: { proxy: string | object, [key: string]: any };
+  /**
+   * Default: `undefined`
+   *
+   * Build the app in multi-page mode
+   */
   pages?: {
     [key: string]: PageEntry | PageConfig;
   };
+  /**
+   * Default: `undefined`
+   *
+   * Configure the `crossorigin` attribute on `<link rel="stylesheet">` and `<script>` tags in generated HTML
+   */
   crossorigin?: '' | 'anonymous' | 'use-credentials';
+  /**
+   * Default: `false`
+   *
+   * Set to `true` to enable [Subresource Integrity](https://developer.mozilla.org/en-US/docs/Web/Security/Subresource_Integrity) (SRI) on `<link rel="stylesheet">` and `<script>` tags in generated HTML
+   */
   integrity?: boolean;
 
   css?: CSSOptions;
 
+  /**
+   * A function that will receive an instance of `ChainableConfig` powered by [webpack-chain](https://github.com/mozilla-neutrino/webpack-chain)
+   */
   chainWebpack?: (config: ChainableWebpackConfig) => void;
+  /**
+   * Set webpack configuration.  If the value is `Object`, will be merged into config.  If value is `Function`, will receive current config as argument
+   */
   configureWebpack?: WebpackOptions | ((config: WebpackOptions) => (WebpackOptions | void));
 
+  /**
+   * Default: `'default'`
+   *
+   * Whether to perform lint-on-save during development using [eslint-loader](https://github.com/webpack-contrib/eslint-loader)
+   */
   lintOnSave?: boolean | 'default' | 'warning' | 'error';
+  /**
+   * Pass options to the [PWA Plugin](https://github.com/vuejs/vue-cli/tree/dev/packages/%40vue/cli-plugin-pwa)
+   */
   pwa?: object;
 
+  /**
+   * This is an object that doesn't go through any schema validation, so it can be used to pass arbitrary options to 3rd party plugins
+   */
   pluginOptions?: object;
 }