diff --git a/build/gulpfile.editor.js b/build/gulpfile.editor.js
index c8308a0d190b7..41dbfe647aefc 100644
--- a/build/gulpfile.editor.js
+++ b/build/gulpfile.editor.js
@@ -235,6 +235,9 @@ const appendJSToESMImportsTask = task.define('append-js-to-esm-imports', () => {
 	}
 });
 
+/**
+ * @param {string} contents
+ */
 function toExternalDTS(contents) {
 	let lines = contents.split(/\r\n|\r|\n/);
 	let killNextCloseCurlyBrace = false;
@@ -278,6 +281,9 @@ function toExternalDTS(contents) {
 	return lines.join('\n').replace(/\n\n\n+/g, '\n\n');
 }
 
+/**
+ * @param {{ (path: string): boolean }} testFunc
+ */
 function filterStream(testFunc) {
 	return es.through(function (data) {
 		if (!testFunc(data.relative)) {
@@ -479,6 +485,8 @@ function createTscCompileTask(watch) {
 			});
 			let errors = [];
 			let reporter = createReporter('monaco');
+
+			/** @type {NodeJS.ReadWriteStream | undefined} */
 			let report;
 			// eslint-disable-next-line no-control-regex
 			let magic = /[\u001b\u009b][[()#;?]*(?:[0-9]{1,4}(?:;[0-9]{0,4})*)?[0-9A-ORZcf-nqry=><]/g; // https://stackoverflow.com/questions/25245716/remove-all-ansi-colors-styles-from-strings
diff --git a/build/gulpfile.extensions.js b/build/gulpfile.extensions.js
index 89517f86fef8e..cdc02cba74b4c 100644
--- a/build/gulpfile.extensions.js
+++ b/build/gulpfile.extensions.js
@@ -239,6 +239,9 @@ const watchWebExtensionsTask = task.define('watch-web', () => buildWebExtensions
 gulp.task(watchWebExtensionsTask);
 exports.watchWebExtensionsTask = watchWebExtensionsTask;
 
+/**
+ * @param {boolean} isWatch
+ */
 async function buildWebExtensions(isWatch) {
 	const webpackConfigLocations = await nodeUtil.promisify(glob)(
 		path.join(extensionsPath, '**', 'extension-browser.webpack.config.js'),
diff --git a/build/gulpfile.hygiene.js b/build/gulpfile.hygiene.js
index 838fc661eb568..a9691fcb0d879 100644
--- a/build/gulpfile.hygiene.js
+++ b/build/gulpfile.hygiene.js
@@ -9,6 +9,9 @@ const path = require('path');
 const task = require('./lib/task');
 const { hygiene } = require('./hygiene');
 
+/**
+ * @param {string} actualPath
+ */
 function checkPackageJSON(actualPath) {
 	const actual = require(path.join(__dirname, '..', actualPath));
 	const rootPackageJSON = require('../package.json');
diff --git a/build/gulpfile.scan.js b/build/gulpfile.scan.js
index cf88b69e0f6b5..4c447641b2ade 100644
--- a/build/gulpfile.scan.js
+++ b/build/gulpfile.scan.js
@@ -29,7 +29,7 @@ const BUILD_TARGETS = [
 ];
 
 BUILD_TARGETS.forEach(buildTarget => {
-	const dashed = (str) => (str ? `-${str}` : ``);
+	const dashed = (/** @type {string | null} */ str) => (str ? `-${str}` : ``);
 	const platform = buildTarget.platform;
 	const arch = buildTarget.arch;
 
diff --git a/build/gulpfile.vscode.linux.js b/build/gulpfile.vscode.linux.js
index 3423e86e8f3e5..47db2af305142 100644
--- a/build/gulpfile.vscode.linux.js
+++ b/build/gulpfile.vscode.linux.js
@@ -103,6 +103,9 @@ function prepareDebPackage(arch) {
 	};
 }
 
+/**
+ * @param {string} arch
+ */
 function buildDebPackage(arch) {
 	const debArch = getDebPackageArch(arch);
 	return shell.task([
@@ -112,14 +115,23 @@ function buildDebPackage(arch) {
 	], { cwd: '.build/linux/deb/' + debArch });
 }
 
+/**
+ * @param {string} rpmArch
+ */
 function getRpmBuildPath(rpmArch) {
 	return '.build/linux/rpm/' + rpmArch + '/rpmbuild';
 }
 
+/**
+ * @param {string} arch
+ */
 function getRpmPackageArch(arch) {
 	return { x64: 'x86_64', armhf: 'armv7hl', arm64: 'aarch64' }[arch];
 }
 
+/**
+ * @param {string} arch
+ */
 function prepareRpmPackage(arch) {
 	const binaryDir = '../VSCode-linux-' + arch;
 	const rpmArch = getRpmPackageArch(arch);
@@ -186,6 +198,9 @@ function prepareRpmPackage(arch) {
 	};
 }
 
+/**
+ * @param {string} arch
+ */
 function buildRpmPackage(arch) {
 	const rpmArch = getRpmPackageArch(arch);
 	const rpmBuildPath = getRpmBuildPath(rpmArch);
@@ -199,10 +214,16 @@ function buildRpmPackage(arch) {
 	]);
 }
 
+/**
+ * @param {string} arch
+ */
 function getSnapBuildPath(arch) {
 	return `.build/linux/snap/${arch}/${product.applicationName}-${arch}`;
 }
 
+/**
+ * @param {string} arch
+ */
 function prepareSnapPackage(arch) {
 	const binaryDir = '../VSCode-linux-' + arch;
 	const destination = getSnapBuildPath(arch);
@@ -247,6 +268,9 @@ function prepareSnapPackage(arch) {
 	};
 }
 
+/**
+ * @param {string} arch
+ */
 function buildSnapPackage(arch) {
 	const snapBuildPath = getSnapBuildPath(arch);
 	// Default target for snapcraft runs: pull, build, stage and prime, and finally assembles the snap.
diff --git a/build/gulpfile.vscode.web.js b/build/gulpfile.vscode.web.js
index e93fbf30008c6..513306c89a93a 100644
--- a/build/gulpfile.vscode.web.js
+++ b/build/gulpfile.vscode.web.js
@@ -235,7 +235,7 @@ const compileWebExtensionsBuildTask = task.define('compile-web-extensions-build'
 ));
 gulp.task(compileWebExtensionsBuildTask);
 
-const dashed = (str) => (str ? `-${str}` : ``);
+const dashed = (/** @type {string} */ str) => (str ? `-${str}` : ``);
 
 ['', 'min'].forEach(minified => {
 	const sourceFolderName = `out-vscode-web${dashed(minified)}`;
diff --git a/build/gulpfile.vscode.win32.js b/build/gulpfile.vscode.win32.js
index 1a73ae9d71bda..81ba509581634 100644
--- a/build/gulpfile.vscode.win32.js
+++ b/build/gulpfile.vscode.win32.js
@@ -20,10 +20,10 @@ const rcedit = require('rcedit');
 const mkdirp = require('mkdirp');
 
 const repoPath = path.dirname(__dirname);
-const buildPath = arch => path.join(path.dirname(repoPath), `VSCode-win32-${arch}`);
-const zipDir = arch => path.join(repoPath, '.build', `win32-${arch}`, 'archive');
-const zipPath = arch => path.join(zipDir(arch), `VSCode-win32-${arch}.zip`);
-const setupDir = (arch, target) => path.join(repoPath, '.build', `win32-${arch}`, `${target}-setup`);
+const buildPath = (/** @type {string} */ arch) => path.join(path.dirname(repoPath), `VSCode-win32-${arch}`);
+const zipDir = (/** @type {string} */ arch) => path.join(repoPath, '.build', `win32-${arch}`, 'archive');
+const zipPath = (/** @type {string} */ arch) => path.join(zipDir(arch), `VSCode-win32-${arch}.zip`);
+const setupDir = (/** @type {string} */ arch, /** @type {string} */ target) => path.join(repoPath, '.build', `win32-${arch}`, `${target}-setup`);
 const issPath = path.join(__dirname, 'win32', 'code.iss');
 const innoSetupPath = path.join(path.dirname(path.dirname(require.resolve('innosetup'))), 'bin', 'ISCC.exe');
 const signWin32Path = path.join(repoPath, 'build', 'azure-pipelines', 'common', 'sign-win32');
@@ -63,6 +63,10 @@ function packageInnoSetup(iss, options, cb) {
 		});
 }
 
+/**
+ * @param {string} arch
+ * @param {string} target
+ */
 function buildWin32Setup(arch, target) {
 	if (target !== 'system' && target !== 'user') {
 		throw new Error('Invalid setup target');
@@ -112,6 +116,10 @@ function buildWin32Setup(arch, target) {
 	};
 }
 
+/**
+ * @param {string} arch
+ * @param {string} target
+ */
 function defineWin32SetupTasks(arch, target) {
 	const cleanTask = util.rimraf(setupDir(arch, target));
 	gulp.task(task.define(`vscode-win32-${arch}-${target}-setup`, task.series(cleanTask, buildWin32Setup(arch, target))));
@@ -124,6 +132,9 @@ defineWin32SetupTasks('ia32', 'user');
 defineWin32SetupTasks('x64', 'user');
 defineWin32SetupTasks('arm64', 'user');
 
+/**
+ * @param {string} arch
+ */
 function archiveWin32Setup(arch) {
 	return cb => {
 		const args = ['a', '-tzip', zipPath(arch), '-x!CodeSignSummary*.md', '.', '-r'];
@@ -138,6 +149,9 @@ gulp.task(task.define('vscode-win32-ia32-archive', task.series(util.rimraf(zipDi
 gulp.task(task.define('vscode-win32-x64-archive', task.series(util.rimraf(zipDir('x64')), archiveWin32Setup('x64'))));
 gulp.task(task.define('vscode-win32-arm64-archive', task.series(util.rimraf(zipDir('arm64')), archiveWin32Setup('arm64'))));
 
+/**
+ * @param {string} arch
+ */
 function copyInnoUpdater(arch) {
 	return () => {
 		return gulp.src('build/win32/{inno_updater.exe,vcruntime140.dll}', { base: 'build/win32' })
@@ -145,6 +159,9 @@ function copyInnoUpdater(arch) {
 	};
 }
 
+/**
+ * @param {string} executablePath
+ */
 function updateIcon(executablePath) {
 	return cb => {
 		const icon = path.join(repoPath, 'resources', 'win32', 'code.ico');