diff --git a/README.md b/README.md
index faec365..d71b8fe 100644
--- a/README.md
+++ b/README.md
@@ -48,7 +48,7 @@ $ export OBJC_DISABLE_INITIALIZE_FORK_SAFETY=YES
 ```
 
 ```
-usage: synthtiger [-h] [-o PATH] [-c INTEGER] [-w INTEGER] [-v] SCRIPT NAME [CONFIG]
+usage: synthtiger [-h] [-o DIR] [-c NUM] [-w NUM] [-v] SCRIPT NAME [CONFIG]
 
 positional arguments:
   SCRIPT                Script file path.
@@ -57,12 +57,9 @@ positional arguments:
 
 optional arguments:
   -h, --help            show this help message and exit
-  -o PATH, --output PATH
-                        Directory path to save data.
-  -c INTEGER, --count INTEGER
-                        Number of data. [default: 100]
-  -w INTEGER, --worker INTEGER
-                        Number of workers. If 0, It generates data in the main process. [default: 0]
+  -o DIR, --output DIR  Directory path to save data.
+  -c NUM, --count NUM   Number of data. [default: 100]
+  -w NUM, --worker NUM  Number of workers. If 0, It generates data in the main process. [default: 0]
   -v, --verbose         Print error messages while generating data.
 ```
 
diff --git a/synthtiger/main.py b/synthtiger/main.py
index f7cbd45..f8b439b 100644
--- a/synthtiger/main.py
+++ b/synthtiger/main.py
@@ -39,14 +39,14 @@ def parse_args():
     parser.add_argument(
         "-o",
         "--output",
-        metavar="PATH",
+        metavar="DIR",
         type=str,
         help="Directory path to save data.",
     )
     parser.add_argument(
         "-c",
         "--count",
-        metavar="INTEGER",
+        metavar="NUM",
         type=int,
         default=100,
         help="Number of data. [default: 100]",
@@ -54,7 +54,7 @@ def parse_args():
     parser.add_argument(
         "-w",
         "--worker",
-        metavar="INTEGER",
+        metavar="NUM",
         type=int,
         default=0,
         help="Number of workers. If 0, It generates data in the main process. [default: 0]",
diff --git a/tools/create_colormap.py b/tools/create_colormap.py
index 29f2a4c..21277f3 100644
--- a/tools/create_colormap.py
+++ b/tools/create_colormap.py
@@ -111,7 +111,7 @@ def parse_args():
     )
     parser.add_argument(
         "--max_k",
-        metavar="INTEGER",
+        metavar="NUM",
         type=int,
         default=3,
         help="Maximum number of colors. [default: 3]",
@@ -119,7 +119,7 @@ def parse_args():
     parser.add_argument(
         "-w",
         "--worker",
-        metavar="INTEGER",
+        metavar="NUM",
         type=int,
         default=1,
         help="Number of workers. [default: 1]",
diff --git a/tools/extract_font_charset.py b/tools/extract_font_charset.py
index 28897c1..59862d3 100644
--- a/tools/extract_font_charset.py
+++ b/tools/extract_font_charset.py
@@ -138,7 +138,7 @@ def parse_args():
     parser.add_argument(
         "-w",
         "--worker",
-        metavar="INTEGER",
+        metavar="NUM",
         type=int,
         default=1,
         help="Number of workers. [default: 1]",