diff --git a/packages/frontend/src/account.ts b/packages/frontend/src/account.ts
index 36186ecac1..fb31fef380 100644
--- a/packages/frontend/src/account.ts
+++ b/packages/frontend/src/account.ts
@@ -22,11 +22,35 @@ type Account = Misskey.entities.MeDetailed & { token: string };
 const accountData = miLocalStorage.getItem('account');
 
 // TODO: 外部からはreadonlyに
+/**
+ * Reactive state for the current account. "I" as in "I am logged in".
+ * Initialized from local storage if available, otherwise null.
+ *
+ * @type {Account | null}
+ */
 export const $i = accountData ? reactive(JSON.parse(accountData) as Account) : null;
 
+/**
+ * Whether the current account is a moderator.
+ *
+ * @type {boolean}
+ */
 export const iAmModerator = $i != null && ($i.isAdmin === true || $i.isModerator === true);
+
+/**
+ * Whether the current account is an administrator.
+ *
+ * @type {boolean}
+ */
 export const iAmAdmin = $i != null && $i.isAdmin;
 
+/**
+ * Whether it is necessary to sign in; checks if the current
+ * account is null and throws an error if so.
+ *
+ * @throws {Error} If the current account is null
+ * @returns {Account} The current account
+ */
 export function signinRequired() {
 	if ($i == null) throw new Error('signin required');
 	return $i;