diff --git a/.gitignore b/.gitignore
index 2bf16d0..99f75a5 100644
--- a/.gitignore
+++ b/.gitignore
@@ -6,3 +6,4 @@ dist/
 wheels/
 *.egg-info
 .venv
+.coverage
diff --git a/scripts/generate_schema.py b/scripts/generate_schema.py
index a96b159..5f686ee 100644
--- a/scripts/generate_schema.py
+++ b/scripts/generate_schema.py
@@ -52,7 +52,8 @@ def generate_node_from_click(ctx, additional_properties=False):
     if param.multiple:
       props[name] = {"type": "array", "items": props[name]}
 
-    props[name]["description"] = param.help
+    if param.help:
+      props[name]["description"] = param.help
 
     default = param.to_info_dict()["default"]
     if default is not None and not param.multiple:
diff --git a/src/dbyaml/cli.py b/src/dbyaml/cli.py
index 02d3a31..d86f18c 100644
--- a/src/dbyaml/cli.py
+++ b/src/dbyaml/cli.py
@@ -33,6 +33,8 @@ else:
 
   import yaml
 
+  from dbyaml.db import dump, load
+
   class FormatType(str, enum.Enum):
     @staticmethod
     def _generate_next_value_(name, start, count, last_values):
@@ -127,6 +129,7 @@ else:
     "format_type",
     help="Format type.",
     type=click.Choice(FormatType, case_sensitive=False),
+    default=FormatType.yaml,
     envvar="DBYAML_FORMAT",  # instead of auto DBYAML_FORMAT_TYPE
     show_envvar=True,
   )
@@ -159,12 +162,12 @@ else:
   @pass_context
   def main(ctx, filename, config, format_type, quiet, verbose, debug):
     """The uncompromising db(yaml) utility."""
-    ctx.obj["DEBUG"] = debug
     if ctx.invoked_subcommand is None:
-      click.echo("I was invoked without subcommand")
-    else:
-      click.echo(f"I am about to invoke {ctx.invoked_subcommand}")
+      ctx.invoke(list)
 
   @main.command
   @pass_context
-  def list(ctx): ...
+  def list(ctx):
+    data = load(ctx.obj["filename"])
+    res = dump(data, format_type=ctx.obj["format_type"])
+    print(res)
diff --git a/src/dbyaml/db.py b/src/dbyaml/db.py
new file mode 100644
index 0000000..2734be1
--- /dev/null
+++ b/src/dbyaml/db.py
@@ -0,0 +1,31 @@
+import json
+import os
+import subprocess
+
+import yaml
+
+
+def load(filename):
+  with open(filename) as f:
+    data_str = f.read()
+  data = yaml.safe_load(data_str)
+  return data
+
+
+def dump(data, format_type="raw"):
+  if format_type == "yaml":
+    res = yaml.dump(data)
+  elif format_type == "json":
+    res = json.dumps(data)
+  else:
+    res = str(data)
+  return res
+
+
+def run_shebang(script):
+  """
+  Run script string as file while honoring the shebang line dynamically.
+  """
+  fd = os.memfd_create("inline_script")
+  os.write(fd, script.encode())
+  subprocess.run([f"/dev/fd/{fd}"], check=False)
diff --git a/src/dbyaml/db.pyi b/src/dbyaml/db.pyi
new file mode 100644
index 0000000..246d53f
--- /dev/null
+++ b/src/dbyaml/db.pyi
@@ -0,0 +1,3 @@
+def load(filename: str) -> list | dict: ...
+def dump(data: list | dict, format_type: str) -> str: ...
+def run_shebang(script: str) -> None: ...
diff --git a/src/dbyaml/resources/dbyaml.schema.json b/src/dbyaml/resources/dbyaml.schema.json
index 98b1e87..f45c2b0 100644
--- a/src/dbyaml/resources/dbyaml.schema.json
+++ b/src/dbyaml/resources/dbyaml.schema.json
@@ -11,7 +11,8 @@
         "yaml",
         "json"
       ],
-      "description": "Format type."
+      "description": "Format type.",
+      "default": "yaml"
     },
     "quiet": {
       "type": "boolean",
@@ -25,7 +26,6 @@
     },
     "debug": {
       "type": "boolean",
-      "description": null,
       "default": false
     },
     "list": {
diff --git a/src/dbyaml/schema.py b/src/dbyaml/schema.py
index f1d4127..2840e4e 100644
--- a/src/dbyaml/schema.py
+++ b/src/dbyaml/schema.py
@@ -2,9 +2,8 @@ import importlib.resources
 import json
 
 
-def get_schema(tool_name="dbyaml"):
+def get_schema():
   """Get the stored complete schema for dbyaml's db files."""
-  assert tool_name == "dbyaml", "Only yamldb is supported."
 
   pkg = "dbyaml.resources"
   fname = "dbyaml.schema.json"
diff --git a/tests/test_schema.py b/tests/test_schema.py
index a585f60..ec591d6 100644
--- a/tests/test_schema.py
+++ b/tests/test_schema.py
@@ -8,8 +8,7 @@ def test_schema_entrypoint() -> None:
 
   dbyaml_fn = dbyaml_ep.load()
   schema = dbyaml_fn()
-  assert schema == dbyaml_fn("dbyaml")
-  print(schema["properties"])
+  assert schema == dbyaml_fn()
   assert schema["type"] == "object"
   assert schema["properties"]["verbose"]["type"] == "boolean"
   assert schema["properties"]["list"]["type"] == "object"