diff --git a/docs/CHANGELOG.md b/docs/CHANGELOG.md
index ed8afb2..6f044de 100644
--- a/docs/CHANGELOG.md
+++ b/docs/CHANGELOG.md
@@ -21,6 +21,8 @@
   reducing duplicate command knowledge in `src/exec.c`.
 - Replaced hard-coded `chat.m1ng.space` examples with `chat.example.com` so
   public documentation does not imply a specific production host.
+- Moved SSH exec usage text and argument-shape checks into `exec_catalog`, so
+  `src/exec.c` no longer duplicates `--json` and required-message validation.
 - Renamed the internal language state from help-oriented names to
   UI-language names (`ui_lang_t`, `client->ui_lang`, and
   `i18n_*_ui_lang`) so future i18n work has a correctly named seam.
diff --git a/include/exec_catalog.h b/include/exec_catalog.h
index 816dbb1..69ae5ac 100644
--- a/include/exec_catalog.h
+++ b/include/exec_catalog.h
@@ -15,7 +15,10 @@ typedef enum {
 
 bool exec_catalog_match(const char *line, tnt_exec_command_id_t *id,
                         const char **args);
+bool exec_catalog_args_valid(tnt_exec_command_id_t id, const char *args);
 void exec_catalog_append_help(char *buffer, size_t buf_size, size_t *pos,
                               ui_lang_t lang);
+void exec_catalog_append_usage(char *buffer, size_t buf_size, size_t *pos,
+                               tnt_exec_command_id_t id, ui_lang_t lang);
 
 #endif /* EXEC_CATALOG_H */
diff --git a/include/i18n.h b/include/i18n.h
index b7ee83d..c54fdcc 100644
--- a/include/i18n.h
+++ b/include/i18n.h
@@ -53,10 +53,6 @@ typedef enum {
     I18N_UNKNOWN_COMMAND_FORMAT,
     I18N_DID_YOU_MEAN_FORMAT,
     I18N_UNKNOWN_GUIDANCE,
-    I18N_EXEC_USERS_USAGE,
-    I18N_EXEC_STATS_USAGE,
-    I18N_EXEC_TAIL_USAGE,
-    I18N_EXEC_POST_USAGE,
     I18N_EXEC_POST_EMPTY,
     I18N_EXEC_POST_INVALID_UTF8,
     I18N_EXEC_UNKNOWN_COMMAND_FORMAT,
diff --git a/src/exec.c b/src/exec.c
index ae3feb0..0824510 100644
--- a/src/exec.c
+++ b/src/exec.c
@@ -126,6 +126,17 @@ static int exec_command_help(client_t *client) {
     return client_send(client, help_text, pos) == 0 ? 0 : 1;
 }
 
+static int exec_command_usage(client_t *client, tnt_exec_command_id_t id) {
+    char usage[128];
+    size_t pos = 0;
+
+    usage[0] = '\0';
+    exec_catalog_append_usage(usage, sizeof(usage), &pos, id,
+                              client->ui_lang);
+    client_printf(client, "%s", usage);
+    return 64;
+}
+
 static int exec_command_health(client_t *client) {
     static const char ok[] = "ok\n";
     return client_send(client, ok, sizeof(ok) - 1) == 0 ? 0 : 1;
@@ -289,9 +300,7 @@ static int exec_command_tail(client_t *client, const char *args) {
     int rc;
 
     if (parse_tail_count(args, &requested) < 0) {
-        client_printf(client, "%s",
-                      i18n_text(client->ui_lang, I18N_EXEC_TAIL_USAGE));
-        return 64;
+        return exec_command_usage(client, TNT_EXEC_COMMAND_TAIL);
     }
 
     pthread_rwlock_rdlock(&g_room->lock);
@@ -343,9 +352,7 @@ static int exec_command_post(client_t *client, const char *args) {
     };
 
     if (!args || args[0] == '\0') {
-        client_printf(client, "%s",
-                      i18n_text(client->ui_lang, I18N_EXEC_POST_USAGE));
-        return 64;
+        return exec_command_usage(client, TNT_EXEC_COMMAND_POST);
     }
 
     strncpy(content, args, sizeof(content) - 1);
@@ -409,26 +416,18 @@ int exec_dispatch(client_t *client) {
     }
 
     if (exec_catalog_match(command_copy, &command_id, &args)) {
+        if (!exec_catalog_args_valid(command_id, args)) {
+            return exec_command_usage(client, command_id);
+        }
+
         switch (command_id) {
             case TNT_EXEC_COMMAND_HELP:
                 return exec_command_help(client);
             case TNT_EXEC_COMMAND_HEALTH:
                 return exec_command_health(client);
             case TNT_EXEC_COMMAND_USERS:
-                if (args && strcmp(args, "--json") != 0) {
-                    client_printf(client, "%s",
-                                  i18n_text(client->ui_lang,
-                                            I18N_EXEC_USERS_USAGE));
-                    return 64;
-                }
                 return exec_command_users(client, args != NULL);
             case TNT_EXEC_COMMAND_STATS:
-                if (args && strcmp(args, "--json") != 0) {
-                    client_printf(client, "%s",
-                                  i18n_text(client->ui_lang,
-                                            I18N_EXEC_STATS_USAGE));
-                    return 64;
-                }
                 return exec_command_stats(client, args != NULL);
             case TNT_EXEC_COMMAND_TAIL:
                 return exec_command_tail(client, args);
diff --git a/src/exec_catalog.c b/src/exec_catalog.c
index 5665e8e..2970fe7 100644
--- a/src/exec_catalog.c
+++ b/src/exec_catalog.c
@@ -5,31 +5,52 @@ typedef struct {
     const char *name;
     const char *alias;
     const char *usage;
+    const char *usage_syntax;
     const char *summary_en;
     const char *summary_zh;
+    bool no_args;
+    bool optional_json;
+    bool requires_args;
 } exec_catalog_entry_t;
 
 static const exec_catalog_entry_t entries[] = {
     {TNT_EXEC_COMMAND_HELP, "help", "--help",
-     "help", "Show this help", "显示此帮助"},
+     "help", "help", "Show this help", "显示此帮助", true, false, false},
     {TNT_EXEC_COMMAND_HEALTH, "health", NULL,
-     "health", "Print service health", "输出服务健康状态"},
+     "health", "health", "Print service health", "输出服务健康状态",
+     true, false, false},
     {TNT_EXEC_COMMAND_USERS, "users", NULL,
-     "users [--json]", "List online users", "列出在线用户"},
+     "users [--json]", "users [--json]",
+     "List online users", "列出在线用户", false, true, false},
     {TNT_EXEC_COMMAND_STATS, "stats", NULL,
-     "stats [--json]", "Print room statistics", "输出房间统计"},
+     "stats [--json]", "stats [--json]",
+     "Print room statistics", "输出房间统计", false, true, false},
     {TNT_EXEC_COMMAND_TAIL, "tail", NULL,
-     "tail [N]", "Print recent messages", "输出最近消息"},
+     "tail [N]", "tail [N] | tail -n N",
+     "Print recent messages", "输出最近消息", false, false, false},
     {TNT_EXEC_COMMAND_TAIL, "tail", NULL,
-     "tail -n N", "Print recent messages", "输出最近消息"},
+     "tail -n N", "tail [N] | tail -n N",
+     "Print recent messages", "输出最近消息", false, false, false},
     {TNT_EXEC_COMMAND_POST, "post", NULL,
-     "post MESSAGE", "Post a message non-interactively", "非交互发送消息"},
+     "post MESSAGE", "post MESSAGE",
+     "Post a message non-interactively", "非交互发送消息",
+     false, false, true},
     {TNT_EXEC_COMMAND_POST, "post", NULL,
-     "post \"/me act\"", "Post an action message", "发送动作消息"},
+     "post \"/me act\"", "post MESSAGE",
+     "Post an action message", "发送动作消息", false, false, true},
     {TNT_EXEC_COMMAND_EXIT, "exit", NULL,
-     "exit", "Exit successfully", "成功退出"}
+     "exit", "exit", "Exit successfully", "成功退出", true, false, false}
 };
 
+static const exec_catalog_entry_t *entry_for_id(tnt_exec_command_id_t id) {
+    for (size_t i = 0; i < sizeof(entries) / sizeof(entries[0]); i++) {
+        if (entries[i].id == id) {
+            return &entries[i];
+        }
+    }
+    return NULL;
+}
+
 static const char *skip_spaces(const char *value) {
     while (value && *value && (*value == ' ' || *value == '\t')) {
         value++;
@@ -84,6 +105,24 @@ bool exec_catalog_match(const char *line, tnt_exec_command_id_t *id,
     return false;
 }
 
+bool exec_catalog_args_valid(tnt_exec_command_id_t id, const char *args) {
+    const exec_catalog_entry_t *entry = entry_for_id(id);
+
+    if (!entry) {
+        return false;
+    }
+    if (entry->no_args) {
+        return !args || args[0] == '\0';
+    }
+    if (entry->optional_json) {
+        return !args || strcmp(args, "--json") == 0;
+    }
+    if (entry->requires_args) {
+        return args && args[0] != '\0';
+    }
+    return true;
+}
+
 void exec_catalog_append_help(char *buffer, size_t buf_size, size_t *pos,
                               ui_lang_t lang) {
     if (lang == UI_LANG_ZH) {
@@ -99,3 +138,19 @@ void exec_catalog_append_help(char *buffer, size_t buf_size, size_t *pos,
                        entries[i].usage, summary);
     }
 }
+
+void exec_catalog_append_usage(char *buffer, size_t buf_size, size_t *pos,
+                               tnt_exec_command_id_t id, ui_lang_t lang) {
+    const exec_catalog_entry_t *entry = entry_for_id(id);
+
+    if (!entry) {
+        return;
+    }
+    if (lang == UI_LANG_ZH) {
+        buffer_appendf(buffer, buf_size, pos, "%s: 用法: %s\n",
+                       entry->name, entry->usage_syntax);
+        return;
+    }
+    buffer_appendf(buffer, buf_size, pos, "%s: usage: %s\n",
+                   entry->name, entry->usage_syntax);
+}
diff --git a/src/i18n_text.c b/src/i18n_text.c
index 7c51be5..31ff12a 100644
--- a/src/i18n_text.c
+++ b/src/i18n_text.c
@@ -208,22 +208,6 @@ static const i18n_text_entry_t text_catalog[I18N_TEXT_COUNT] = {
         "Type :help for help\n",
         "输入 :help 查看帮助\n"
     },
-    [I18N_EXEC_USERS_USAGE] = {
-        "users: usage: users [--json]\n",
-        "users: 用法: users [--json]\n"
-    },
-    [I18N_EXEC_STATS_USAGE] = {
-        "stats: usage: stats [--json]\n",
-        "stats: 用法: stats [--json]\n"
-    },
-    [I18N_EXEC_TAIL_USAGE] = {
-        "tail: usage: tail [N] | tail -n N\n",
-        "tail: 用法: tail [N] | tail -n N\n"
-    },
-    [I18N_EXEC_POST_USAGE] = {
-        "post: usage: post MESSAGE\n",
-        "post: 用法: post MESSAGE\n"
-    },
     [I18N_EXEC_POST_EMPTY] = {
         "post: message cannot be empty\n",
         "post: 消息不能为空\n"
diff --git a/tests/test_exec_mode.sh b/tests/test_exec_mode.sh
index 5578b8e..8b0e26a 100755
--- a/tests/test_exec_mode.sh
+++ b/tests/test_exec_mode.sh
@@ -51,6 +51,17 @@ else
     FAIL=$((FAIL + 1))
 fi
 
+HEALTH_USAGE=$(ssh $SSH_OPTS localhost health extra 2>/dev/null || true)
+printf '%s\n' "$HEALTH_USAGE" | grep -q '^health: 用法: health$'
+if [ $? -eq 0 ]; then
+    echo "✓ no-arg exec usage follows TNT_LANG"
+    PASS=$((PASS + 1))
+else
+    echo "✗ no-arg exec usage output unexpected"
+    printf '%s\n' "$HEALTH_USAGE"
+    FAIL=$((FAIL + 1))
+fi
+
 STATS_OUTPUT=$(ssh $SSH_OPTS localhost stats 2>/dev/null || true)
 printf '%s\n' "$STATS_OUTPUT" | grep -q '^status ok$' &&
 printf '%s\n' "$STATS_OUTPUT" | grep -q '^online_users 0$'
@@ -109,6 +120,17 @@ else
     FAIL=$((FAIL + 1))
 fi
 
+USERS_USAGE=$(ssh $SSH_OPTS localhost users --xml 2>/dev/null || true)
+printf '%s\n' "$USERS_USAGE" | grep -q '^users: 用法: users \[--json\]$'
+if [ $? -eq 0 ]; then
+    echo "✓ users usage follows TNT_LANG"
+    PASS=$((PASS + 1))
+else
+    echo "✗ users usage output unexpected"
+    printf '%s\n' "$USERS_USAGE"
+    FAIL=$((FAIL + 1))
+fi
+
 POST_OUTPUT=$(ssh $SSH_OPTS execposter@localhost post "hello from exec" 2>/dev/null || true)
 if [ "$POST_OUTPUT" = "posted" ]; then
     echo "✓ post publishes a message"
diff --git a/tests/unit/test_exec_catalog.c b/tests/unit/test_exec_catalog.c
index 7d2d35d..ac387d0 100644
--- a/tests/unit/test_exec_catalog.c
+++ b/tests/unit/test_exec_catalog.c
@@ -71,11 +71,45 @@ TEST(matches_exec_commands_and_args) {
     assert(!exec_catalog_match("nope", &id, &args));
 }
 
+TEST(validates_argument_shapes) {
+    assert(exec_catalog_args_valid(TNT_EXEC_COMMAND_HELP, NULL));
+    assert(!exec_catalog_args_valid(TNT_EXEC_COMMAND_HELP, "now"));
+    assert(exec_catalog_args_valid(TNT_EXEC_COMMAND_HEALTH, NULL));
+    assert(!exec_catalog_args_valid(TNT_EXEC_COMMAND_HEALTH, "now"));
+
+    assert(exec_catalog_args_valid(TNT_EXEC_COMMAND_USERS, NULL));
+    assert(exec_catalog_args_valid(TNT_EXEC_COMMAND_USERS, "--json"));
+    assert(!exec_catalog_args_valid(TNT_EXEC_COMMAND_USERS, "--xml"));
+
+    assert(exec_catalog_args_valid(TNT_EXEC_COMMAND_TAIL, NULL));
+    assert(exec_catalog_args_valid(TNT_EXEC_COMMAND_TAIL, "-n 20"));
+
+    assert(!exec_catalog_args_valid(TNT_EXEC_COMMAND_POST, NULL));
+    assert(exec_catalog_args_valid(TNT_EXEC_COMMAND_POST, "hello"));
+}
+
+TEST(generates_localized_usage) {
+    char en[256] = {0};
+    char zh[256] = {0};
+    size_t en_pos = 0;
+    size_t zh_pos = 0;
+
+    exec_catalog_append_usage(en, sizeof(en), &en_pos,
+                              TNT_EXEC_COMMAND_TAIL, UI_LANG_EN);
+    exec_catalog_append_usage(zh, sizeof(zh), &zh_pos,
+                              TNT_EXEC_COMMAND_POST, UI_LANG_ZH);
+
+    assert(strcmp(en, "tail: usage: tail [N] | tail -n N\n") == 0);
+    assert(strcmp(zh, "post: 用法: post MESSAGE\n") == 0);
+}
+
 int main(void) {
     printf("Running exec catalog unit tests...\n\n");
 
     RUN_TEST(generates_localized_exec_help);
     RUN_TEST(matches_exec_commands_and_args);
+    RUN_TEST(validates_argument_shapes);
+    RUN_TEST(generates_localized_usage);
 
     printf("\n✓ All %d tests passed!\n", tests_passed);
     return 0;