diff --git a/README.md b/README.md
index c10cd99..a69425e 100644
--- a/README.md
+++ b/README.md
@@ -31,7 +31,7 @@ Argument    | Type     | Satus    | Default | Description
 `algorithm` | `string` | optional | `HS256` | The algorithm used to sign the payload, possible values: `HS256` or `HS512`
 
 #### `return`
-returns token as a `string`
+Returns token as a `string`.
 
 <hr>
 
diff --git a/index.d.ts b/index.d.ts
index de03419..d42c02d 100644
--- a/index.d.ts
+++ b/index.d.ts
@@ -1,6 +1,38 @@
+/**
+ * JWT
+ *
+ * @class
+ * @constructor
+ * @public
+ */
 declare class JWT {
+
+    /**
+     * Signs a payload and returns the token
+     * 
+     * @param {object} payload The payload object. To use `nbf` (Not Before) and/or `exp` (Expiration Time) add `nbf` and/or `exp` to the payload.
+     * @param {string} secret A string which is used to sign the payload.
+     * @param {'HS256' | 'HS512'} [algorithm=HS256] The algorithm used to sign the payload, possible values: `HS256` or `HS512`
+     * @returns {Promise<string>} Returns token as a `string`.
+     */
     sign(payload: object, secret: string, algorithm?: "HS256" | "HS512"): Promise<string>
+
+    /**
+     * Verifies the integrity of the token and returns a boolean value.
+     * 
+     * @param {string} token The token string generated by `jwt.sign()`.
+     * @param {string} secret The string which was used to sign the payload.
+     * @param {'HS256' | 'HS512'} [algorithm=HS256] The algorithm used to sign the payload, possible values: `HS256` or `HS512`
+     * @returns {Promise<boolean>} Returns `true` if signature, `nbf` (if set) and `exp` (if set) are valid, otherwise returns `false`. 
+     */
     verify(token: string, secret: string, algorithm?: "HS256" | "HS512"): Promise<boolean>
+
+    /**
+     * Returns the payload **without** verifying the integrity of the token. Please use `jwt.verify()` first to keep your application secure!
+     * 
+     * @param {string} token The token string generated by `jwt.sign()`.
+     * @returns {object | null} Returns payload `object`.
+     */
     decode(token: string): object | null
 }
 declare const _exports: JWT