diff --git a/action.yml b/action.yml
index b20fad3..ef1f492 100644
--- a/action.yml
+++ b/action.yml
@@ -8,10 +8,12 @@ inputs:
     description: Windows SDK number to build for
   spectre:
     description: Enable Specre mitigations
+    default: "false"
   toolset:
     description: VC++ compiler toolset version
   uwp:
     description: Build for Universal Windows Platform
+    default: "false"
   vsversion:
     description: The Visual Studio version to use. This can be the version number (e.g. 16.0 for 2019) or the year (e.g. "2019").
 runs:
diff --git a/lib.d.ts b/lib.d.ts
new file mode 100644
index 0000000..88b4e83
--- /dev/null
+++ b/lib.d.ts
@@ -0,0 +1,46 @@
+/**
+ * Convert the vs version (e.g. 2022) or year (e.g. 17.0) to the version number (e.g. 17.0)
+ * @param {string | undefined} vsversion the year (e.g. 2022) or version number (e.g. 17.0)
+ * @returns {string | undefined} the version number (e.g. 17.0)
+ */
+export function vsversion_to_versionnumber(version: string | undefined): string | undefined
+
+/**
+ * Convert the vs version (e.g. 17.0) or year (e.g. 2022) to the year (e.g. 2022)
+ * @param {string} vsversion the version number (e.g. 17.0) or year (e.g. 2022)
+ * @returns {string} the year (e.g. 2022)
+ */
+export function vsversion_to_year(version: string): string
+
+/**
+ * Find MSVC tools with vswhere
+ * @param {string} pattern the pattern to search for
+ * @param {string} version_pattern the version pattern to search for
+ * @returns {string | null} the path to the found MSVC tools
+ */
+export function findWithVswhere(version: string, version_pattern: string): string | null
+
+/**
+ * Find the vcvarsall.bat file for the given Visual Studio version
+ * @param {string | undefined} vsversion the version of Visual Studio to find (year or version number)
+ * @returns {string} the path to the vcvarsall.bat file
+ */
+export function findVcvarsall(version: string): string
+
+/**
+ * Setup MSVC Developer Command Prompt
+ * @param {string} arch - Target architecture
+ * @param {string | undefined} sdk - Windows SDK number to build for
+ * @param {string | undefined} toolset - VC++ compiler toolset version
+ * @param {boolean | 'true' | 'false' | undefined} uwp - Build for Universal Windows Platform
+ * @param {boolean | 'true' | 'false' | undefined} spectre - Enable Spectre mitigations
+ * @param {string | undefined} vsversion - The Visual Studio version to use. This can be the version number (e.g. 16.0 for 2019) or the year (e.g. "2019").
+ */
+export function setupMSVCDevCmd(
+  arch: string,
+  sdk?: string,
+  toolset?: string,
+  uwp?: boolean | 'true' | 'false',
+  spectre?: boolean | 'true' | 'false',
+  vsversion?: string,
+)
diff --git a/lib.js b/lib.js
index e1774d8..03762e1 100644
--- a/lib.js
+++ b/lib.js
@@ -19,6 +19,11 @@ const VsYearVersion = {
     '2013': '12.0',
 }
 
+/**
+ * Convert the vs version (e.g. 2022) or year (e.g. 17.0) to the version number (e.g. 17.0)
+ * @param {string | undefined} vsversion the year (e.g. 2022) or version number (e.g. 17.0)
+ * @returns {string | undefined} the version number (e.g. 17.0)
+ */
 function vsversion_to_versionnumber(vsversion) {
     if (Object.values(VsYearVersion).includes(vsversion)) {
         return vsversion
@@ -31,6 +36,11 @@ function vsversion_to_versionnumber(vsversion) {
 }
 exports.vsversion_to_versionnumber = vsversion_to_versionnumber
 
+/**
+ * Convert the vs version (e.g. 17.0) or year (e.g. 2022) to the year (e.g. 2022)
+ * @param {string} vsversion the version number (e.g. 17.0) or year (e.g. 2022)
+ * @returns {string} the year (e.g. 2022)
+ */
 function vsversion_to_year(vsversion) {
     if (Object.keys(VsYearVersion).includes(vsversion)) {
         return vsversion
@@ -47,6 +57,12 @@ exports.vsversion_to_year = vsversion_to_year
 
 const VSWHERE_PATH = `${PROGRAM_FILES_X86}\\Microsoft Visual Studio\\Installer`
 
+/**
+ * Find MSVC tools with vswhere
+ * @param {string} pattern the pattern to search for
+ * @param {string} version_pattern the version pattern to search for
+ * @returns {string | null} the path to the found MSVC tools
+ */
 function findWithVswhere(pattern, version_pattern) {
     try {
         let installationPath = child_process.execSync(`vswhere -products * ${version_pattern} -prerelease -property installationPath`).toString().trim()
@@ -58,6 +74,11 @@ function findWithVswhere(pattern, version_pattern) {
 }
 exports.findWithVswhere = findWithVswhere
 
+/**
+ * Find the vcvarsall.bat file for the given Visual Studio version
+ * @param {string | undefined} vsversion the version of Visual Studio to find (year or version number)
+ * @returns {string} the path to the vcvarsall.bat file
+ */
 function findVcvarsall(vsversion) {
     const vsversion_number = vsversion_to_versionnumber(vsversion)
     let version_pattern
@@ -120,7 +141,15 @@ function filterPathValue(path) {
     return paths.filter(unique).join(';')
 }
 
-/** See https://github.com/ilammy/msvc-dev-cmd#inputs */
+/**
+ * Setup MSVC Developer Command Prompt
+ * @param {string} arch - Target architecture
+ * @param {string | undefined} sdk - Windows SDK number to build for
+ * @param {string | undefined} toolset - VC++ compiler toolset version
+ * @param {boolean | 'true' | 'false' | undefined} uwp - Build for Universal Windows Platform
+ * @param {boolean | 'true' | 'false' | undefined} spectre - Enable Spectre mitigations
+ * @param {string | undefined} vsversion - The Visual Studio version to use. This can be the version number (e.g. 16.0 for 2019) or the year (e.g. "2019").
+ */
 function setupMSVCDevCmd(arch, sdk, toolset, uwp, spectre, vsversion) {
     if (process.platform != 'win32') {
         core.info('This is not a Windows virtual environment, bye!')
@@ -147,7 +176,8 @@ function setupMSVCDevCmd(arch, sdk, toolset, uwp, spectre, vsversion) {
     // Call the configuration batch file and then output *all* the environment variables.
 
     var args = [arch]
-    if (uwp == 'true') {
+
+    if (uwp && JSON.parse(uwp) === true) {
         args.push('uwp')
     }
     if (sdk) {
@@ -156,7 +186,7 @@ function setupMSVCDevCmd(arch, sdk, toolset, uwp, spectre, vsversion) {
     if (toolset) {
         args.push(`-vcvars_ver=${toolset}`)
     }
-    if (spectre == 'true') {
+    if (spectre && JSON.parse(spectre) === true) {
         args.push('-vcvars_spectre_libs=spectre')
     }
 
diff --git a/package.json b/package.json
index 1b35f6e..d7028f7 100644
--- a/package.json
+++ b/package.json
@@ -3,6 +3,8 @@
   "version": "1.13.0-dev",
   "description": "GitHub Action to setup Developer Command Prompt for Microsoft Visual C++",
   "main": "index.js",
+  "types": "./lib.d.ts",
+  "type": "commonjs",
   "scripts": {
     "lint": "eslint index.js"
   },