diff --git a/README.rst b/README.rst
index c56fb34..21bb2f6 100644
--- a/README.rst
+++ b/README.rst
@@ -217,6 +217,9 @@ For example *r200[List[Pet]]* means the server responses with
 the status code 200 and the response content is a List of Pet where Pet will be
 defined using a pydantic.BaseModel
 
+The docstring of methods will be parsed to fill the descriptions in the
+Open Api Specification.
+
 
 .. code-block:: python3
 
@@ -235,20 +238,42 @@ defined using a pydantic.BaseModel
 
     class PetCollectionView(PydanticView):
         async def get(self) -> r200[List[Pet]]:
+            """
+            Find all pets
+            """
             pets = self.request.app["model"].list_pets()
             return web.json_response([pet.dict() for pet in pets])
 
         async def post(self, pet: Pet) -> r201[Pet]:
+            """
+            Add a new pet to the store
+
+            Status Codes:
+                201: The pet is created
+            """
             self.request.app["model"].add_pet(pet)
             return web.json_response(pet.dict())
 
 
     class PetItemView(PydanticView):
         async def get(self, id: int, /) -> Union[r200[Pet], r404[Error]]:
+            """
+            Find a pet by ID
+
+            Status Codes:
+                200: Successful operation
+                404: Pet not found
+            """
             pet = self.request.app["model"].find_pet(id)
             return web.json_response(pet.dict())
 
         async def put(self, id: int, /, pet: Pet) -> r200[Pet]:
+            """
+            Update an existing pet
+
+            Status Codes:
+                200: successful operation
+            """
             self.request.app["model"].update_pet(id, pet)
             return web.json_response(pet.dict())
 
@@ -270,12 +295,34 @@ Have a look at `demo`_ for a complete example
 
 Go to http://127.0.0.1:8080/oas
 
-You can generate the OAS in a json file using the command:
+You can generate the OAS in a json or yaml file using the aiohttp_pydantic.oas command:
 
 .. code-block:: bash
 
     python -m aiohttp_pydantic.oas demo.main
 
+.. code-block:: bash
+    $ python3 -m aiohttp_pydantic.oas  --help
+    usage: __main__.py [-h] [-b FILE] [-o FILE] [-f FORMAT] [APP [APP ...]]
+
+    Generate Open API Specification
+
+    positional arguments:
+      APP                   The name of the module containing the asyncio.web.Application. By default the variable named
+                            'app' is loaded but you can define an other variable name ending the name of module with :
+                            characters and the name of variable. Example: my_package.my_module:my_app If your
+                            asyncio.web.Application is returned by a function, you can use the syntax:
+                            my_package.my_module:my_app()
+
+    optional arguments:
+      -h, --help            show this help message and exit
+      -b FILE, --base-oas-file FILE
+                            A file that will be used as base to generate OAS
+      -o FILE, --output FILE
+                            File to write the output
+      -f FORMAT, --format FORMAT
+                            The output format, can be 'json' or 'yaml' (default is json)
+
 
 .. _demo: https://github.com/Maillol/aiohttp-pydantic/tree/main/demo
 .. _aiohttp view: https://docs.aiohttp.org/en/stable/web_quickstart.html#class-based-views
diff --git a/aiohttp_pydantic/oas/cmd.py b/aiohttp_pydantic/oas/cmd.py
index b0ee01b..8bea0de 100644
--- a/aiohttp_pydantic/oas/cmd.py
+++ b/aiohttp_pydantic/oas/cmd.py
@@ -1,10 +1,28 @@
 import argparse
 import importlib
 import json
-
+from typing import Dict, Protocol, Optional, Callable
+import sys
 from .view import generate_oas
 
 
+class YamlModule(Protocol):
+    """
+    Yaml Module type hint
+    """
+
+    def dump(self, data) -> str:
+        pass
+
+
+yaml: Optional[YamlModule]
+
+try:
+    import yaml
+except ImportError:
+    yaml = None
+
+
 def application_type(value):
     """
     Return aiohttp application defined in the value.
@@ -26,6 +44,35 @@ def application_type(value):
         raise argparse.ArgumentTypeError(error) from error
 
 
+def base_oas_file_type(value) -> Dict:
+    """
+    Load base oas file
+    """
+    try:
+        with open(value) as oas_file:
+            data = oas_file.read()
+    except OSError as error:
+        raise argparse.ArgumentTypeError(error) from error
+
+    return json.loads(data)
+
+
+def format_type(value) -> Callable:
+    """
+    Date Dumper one of (json, yaml)
+    """
+    dumpers = {"json": lambda data: json.dumps(data, sort_keys=True, indent=4)}
+    if yaml is not None:
+        dumpers["yaml"] = yaml.dump
+
+    try:
+        return dumpers[value]
+    except KeyError:
+        raise argparse.ArgumentTypeError(
+            f"Wrong format value. (allowed values: {tuple(dumpers.keys())})"
+        ) from None
+
+
 def setup(parser: argparse.ArgumentParser):
     parser.add_argument(
         "apps",
@@ -35,11 +82,52 @@ def setup(parser: argparse.ArgumentParser):
         help="The name of the module containing the asyncio.web.Application."
         " By default the variable named 'app' is loaded but you can define"
         " an other variable name ending the name of module with : characters"
-        " and the name of variable. Example: my_package.my_module:my_app",
+        " and the name of variable. Example: my_package.my_module:my_app"
+        " If your asyncio.web.Application is returned by a function, you can"
+        " use the syntax: my_package.my_module:my_app()",
+    )
+    parser.add_argument(
+        "-b",
+        "--base-oas-file",
+        metavar="FILE",
+        dest="base",
+        type=base_oas_file_type,
+        help="A file that will be used as base to generate OAS",
+        default={},
+    )
+    parser.add_argument(
+        "-o",
+        "--output",
+        metavar="FILE",
+        type=argparse.FileType("w"),
+        help="File to write the output",
+        default=sys.stdout,
+    )
+
+    if yaml:
+        help_output_format = (
+            "The output format, can be 'json' or 'yaml' (default is json)"
+        )
+    else:
+        help_output_format = "The output format, only 'json' is available install pyyaml to have yaml output format"
+
+    parser.add_argument(
+        "-f",
+        "--format",
+        metavar="FORMAT",
+        dest="formatter",
+        type=format_type,
+        help=help_output_format,
+        default=format_type("json"),
     )
 
     parser.set_defaults(func=show_oas)
 
 
 def show_oas(args: argparse.Namespace):
-    print(json.dumps(generate_oas(args.apps), sort_keys=True, indent=4))
+    """
+    Display Open API Specification on the stdout.
+    """
+    spec = args.base
+    spec.update(generate_oas(args.apps))
+    print(args.formatter(spec), file=args.output)
diff --git a/aiohttp_pydantic/oas/docstring_parser.py b/aiohttp_pydantic/oas/docstring_parser.py
new file mode 100644
index 0000000..ed2aea7
--- /dev/null
+++ b/aiohttp_pydantic/oas/docstring_parser.py
@@ -0,0 +1,120 @@
+"""
+Utility to extract extra OAS description from docstring.
+"""
+
+import re
+import textwrap
+from typing import Dict
+
+
+class LinesIterator:
+    def __init__(self, lines: str):
+        self._lines = lines.splitlines()
+        self._i = -1
+
+    def next_line(self) -> str:
+        if self._i == len(self._lines) - 1:
+            raise StopIteration from None
+        self._i += 1
+        return self._lines[self._i]
+
+    def rewind(self) -> str:
+        if self._i == -1:
+            raise StopIteration from None
+        self._i -= 1
+        return self._lines[self._i]
+
+    def __iter__(self):
+        return self
+
+    def __next__(self):
+        return self.next_line()
+
+
+def _i_extract_block(lines: LinesIterator):
+    """
+    Iter the line within an indented block and dedent them.
+    """
+
+    # Go to the first not empty or not white space line.
+    try:
+        line = next(lines)
+    except StopIteration:
+        return  # No block to extract.
+    while line.strip() == "":
+        try:
+            line = next(lines)
+        except StopIteration:
+            return
+
+    # Get the size of the indentation.
+    if (match := re.search("^ +", line)) is None:
+        return  # No block to extract.
+    indent = match.group()
+    yield line[len(indent) :]
+
+    # Yield lines until the indentation is the same or is greater than
+    # the first block line.
+    try:
+        line = next(lines)
+    except StopIteration:
+        return
+    while (is_empty := line.strip() == "") or line.startswith(indent):
+        yield "" if is_empty else line[len(indent) :]
+        try:
+            line = next(lines)
+        except StopIteration:
+            return
+
+    lines.rewind()
+
+
+def _dedent_under_first_line(text: str) -> str:
+    """
+    Apply textwrap.dedent ignoring the first line.
+    """
+    lines = text.splitlines()
+    other_lines = "\n".join(lines[1:])
+    if other_lines:
+        return f"{lines[0]}\n{textwrap.dedent(other_lines)}"
+    return text
+
+
+def status_code(docstring: str) -> Dict[int, str]:
+    """
+    Extract the "Status Code:" block of the docstring.
+    """
+    iterator = LinesIterator(docstring)
+    for line in iterator:
+        if re.fullmatch("status\\s+codes?\\s*:", line, re.IGNORECASE):
+            blocks = []
+            lines = []
+            for line_of_block in _i_extract_block(iterator):
+                if re.search("^\\d{3}\\s*:", line_of_block):
+                    if lines:
+                        blocks.append("\n".join(lines))
+                        lines = []
+                lines.append(line_of_block)
+            if lines:
+                blocks.append("\n".join(lines))
+
+            return {
+                int(status.strip()): _dedent_under_first_line(desc.strip())
+                for status, desc in (block.split(":", 1) for block in blocks)
+            }
+    return {}
+
+
+def operation(docstring: str) -> str:
+    """
+    Extract all docstring except the "Status Code:" block.
+    """
+    lines = LinesIterator(docstring)
+    ret = []
+    for line in lines:
+        if re.fullmatch("status\\s+codes?\\s*:", line, re.IGNORECASE):
+            for _ in _i_extract_block(lines):
+                pass
+        else:
+            ret.append(line)
+    return ("\n".join(ret)).strip()
diff --git a/aiohttp_pydantic/oas/struct.py b/aiohttp_pydantic/oas/struct.py
index faa8358..48f9ba9 100644
--- a/aiohttp_pydantic/oas/struct.py
+++ b/aiohttp_pydantic/oas/struct.py
@@ -133,6 +133,7 @@ class Parameters:
 class Response:
     def __init__(self, spec: dict):
         self._spec = spec
+        self._spec.setdefault("description", "")
 
     @property
     def description(self) -> str:
diff --git a/aiohttp_pydantic/oas/view.py b/aiohttp_pydantic/oas/view.py
index 6482e9d..b2e22af 100644
--- a/aiohttp_pydantic/oas/view.py
+++ b/aiohttp_pydantic/oas/view.py
@@ -8,6 +8,7 @@ from aiohttp.web_app import Application
 from pydantic import BaseModel
 
 from aiohttp_pydantic.oas.struct import OpenApiSpec3, OperationObject, PathItem
+from . import docstring_parser
 
 from ..injectors import _parse_func_signature
 from ..utils import is_pydantic_base_model
@@ -18,7 +19,7 @@ from .typing import is_status_code_type
 def _handle_optional(type_):
     """
     Returns the type wrapped in Optional or None.
-
+    >>>  from typing import Optional
     >>>  _handle_optional(int)
     >>>  _handle_optional(Optional[str])
     <class 'str'>
@@ -36,14 +37,15 @@ class _OASResponseBuilder:
     generate the OAS operation response.
     """
 
-    def __init__(self, oas: OpenApiSpec3, oas_operation):
+    def __init__(self, oas: OpenApiSpec3, oas_operation, status_code_descriptions):
         self._oas_operation = oas_operation
         self._oas = oas
+        self._status_code_descriptions = status_code_descriptions
 
     def _handle_pydantic_base_model(self, obj):
         if is_pydantic_base_model(obj):
             response_schema = obj.schema(ref_template="#/components/schemas/{model}")
-            if def_sub_schemas := response_schema.get("definitions", None):
+            if def_sub_schemas := response_schema.pop("definitions", None):
                 self._oas.components.schemas.update(def_sub_schemas)
             return response_schema
         return {}
@@ -64,10 +66,16 @@ class _OASResponseBuilder:
                     "schema": self._handle_list(typing.get_args(obj)[0])
                 }
             }
+            desc = self._status_code_descriptions.get(int(status_code))
+            if desc:
+                self._oas_operation.responses[status_code].description = desc
 
         elif is_status_code_type(obj):
             status_code = obj.__name__[1:]
             self._oas_operation.responses[status_code].content = {}
+            desc = self._status_code_descriptions.get(int(status_code))
+            if desc:
+                self._oas_operation.responses[status_code].description = desc
 
     def _handle_union(self, obj):
         if typing.get_origin(obj) is typing.Union:
@@ -90,13 +98,16 @@ def _add_http_method_to_oas(
     )
     description = getdoc(handler)
     if description:
-        oas_operation.description = description
+        oas_operation.description = docstring_parser.operation(description)
+        status_code_descriptions = docstring_parser.status_code(description)
+    else:
+        status_code_descriptions = {}
 
     if body_args:
         body_schema = next(iter(body_args.values())).schema(
             ref_template="#/components/schemas/{model}"
         )
-        if def_sub_schemas := body_schema.get("definitions", None):
+        if def_sub_schemas := body_schema.pop("definitions", None):
             oas.components.schemas.update(def_sub_schemas)
 
         oas_operation.request_body.content = {
@@ -127,7 +138,9 @@ def _add_http_method_to_oas(
 
     return_type = handler.__annotations__.get("return")
     if return_type is not None:
-        _OASResponseBuilder(oas, oas_operation).build(return_type)
+        _OASResponseBuilder(oas, oas_operation, status_code_descriptions).build(
+            return_type
+        )
 
 
 def generate_oas(apps: List[Application]) -> dict:
diff --git a/aiohttp_pydantic/view.py b/aiohttp_pydantic/view.py
index 2218a3a..3030c3b 100644
--- a/aiohttp_pydantic/view.py
+++ b/aiohttp_pydantic/view.py
@@ -9,8 +9,14 @@ from aiohttp.web_exceptions import HTTPMethodNotAllowed
 from aiohttp.web_response import StreamResponse
 from pydantic import ValidationError
 
-from .injectors import (AbstractInjector, BodyGetter, HeadersGetter,
-                        MatchInfoGetter, QueryGetter, _parse_func_signature)
+from .injectors import (
+    AbstractInjector,
+    BodyGetter,
+    HeadersGetter,
+    MatchInfoGetter,
+    QueryGetter,
+    _parse_func_signature,
+)
 
 
 class PydanticView(AbstractView):
diff --git a/demo/view.py b/demo/view.py
index bed6260..aa9b48d 100644
--- a/demo/view.py
+++ b/demo/view.py
@@ -10,25 +10,54 @@ from .model import Error, Pet
 
 class PetCollectionView(PydanticView):
     async def get(self, age: Optional[int] = None) -> r200[List[Pet]]:
+        """
+        List all pets
+
+        Status Codes:
+            200: Successful operation
+        """
         pets = self.request.app["model"].list_pets()
         return web.json_response(
             [pet.dict() for pet in pets if age is None or age == pet.age]
         )
 
     async def post(self, pet: Pet) -> r201[Pet]:
+        """
+        Add a new pet to the store
+
+        Status Codes:
+            201: Successful operation
+        """
         self.request.app["model"].add_pet(pet)
         return web.json_response(pet.dict())
 
 
 class PetItemView(PydanticView):
     async def get(self, id: int, /) -> Union[r200[Pet], r404[Error]]:
+        """
+        Find a pet by ID
+
+        Status Codes:
+            200: Successful operation
+            404: Pet not found
+        """
         pet = self.request.app["model"].find_pet(id)
         return web.json_response(pet.dict())
 
     async def put(self, id: int, /, pet: Pet) -> r200[Pet]:
+        """
+        Update an existing object
+
+        Status Codes:
+            200: Successful operation
+            404: Pet not found
+        """
         self.request.app["model"].update_pet(id, pet)
         return web.json_response(pet.dict())
 
     async def delete(self, id: int, /) -> r204:
+        """
+        Deletes a pet
+        """
         self.request.app["model"].remove_pet(id)
         return web.Response(status=204)
diff --git a/requirements/test.txt b/requirements/test.txt
index 4edcdc9..85a1222 100644
--- a/requirements/test.txt
+++ b/requirements/test.txt
@@ -8,6 +8,7 @@ pyparsing==2.4.7
 pytest==6.1.2
 pytest-aiohttp==0.3.0
 pytest-cov==2.10.1
+pyyaml==5.3.1
 six==1.15.0
 toml==0.10.2
 typing-extensions==3.7.4.3
diff --git a/tests/test_oas/test_cmd/oas_base.json b/tests/test_oas/test_cmd/oas_base.json
new file mode 100644
index 0000000..75eb624
--- /dev/null
+++ b/tests/test_oas/test_cmd/oas_base.json
@@ -0,0 +1 @@
+{"info": {"title": "MyApp",  "version": "1.0.0"}}
\ No newline at end of file
diff --git a/tests/test_oas/test_cmd/test_cmd.py b/tests/test_oas/test_cmd/test_cmd.py
index 189e46b..c74e3ee 100644
--- a/tests/test_oas/test_cmd/test_cmd.py
+++ b/tests/test_oas/test_cmd/test_cmd.py
@@ -1,10 +1,13 @@
 import argparse
 from textwrap import dedent
-
+from io import StringIO
+from pathlib import Path
 import pytest
 
 from aiohttp_pydantic.oas import cmd
 
+PATH_TO_BASE_JSON_FILE = str(Path(__file__).parent / "oas_base.json")
+
 
 @pytest.fixture
 def cmd_line():
@@ -13,10 +16,11 @@ def cmd_line():
     return parser
 
 
-def test_show_oad_of_app(cmd_line, capfd):
+def test_show_oas_of_app(cmd_line):
     args = cmd_line.parse_args(["tests.test_oas.test_cmd.sample"])
+    args.output = StringIO()
     args.func(args)
-    captured = capfd.readouterr()
+
     expected = dedent(
         """
         {
@@ -57,13 +61,13 @@ def test_show_oad_of_app(cmd_line, capfd):
     """
     )
 
-    assert captured.out.strip() == expected.strip()
+    assert args.output.getvalue().strip() == expected.strip()
 
 
-def test_show_oad_of_sub_app(cmd_line, capfd):
+def test_show_oas_of_sub_app(cmd_line):
     args = cmd_line.parse_args(["tests.test_oas.test_cmd.sample:sub_app"])
+    args.output = StringIO()
     args.func(args)
-    captured = capfd.readouterr()
     expected = dedent(
         """
         {
@@ -89,16 +93,26 @@ def test_show_oad_of_sub_app(cmd_line, capfd):
     """
     )
 
-    assert captured.out.strip() == expected.strip()
+    assert args.output.getvalue().strip() == expected.strip()
 
 
-def test_show_oad_of_a_callable(cmd_line, capfd):
-    args = cmd_line.parse_args(["tests.test_oas.test_cmd.sample:make_app()"])
+def test_show_oas_of_a_callable(cmd_line):
+    args = cmd_line.parse_args(
+        [
+            "tests.test_oas.test_cmd.sample:make_app()",
+            "--base-oas-file",
+            PATH_TO_BASE_JSON_FILE,
+        ]
+    )
+    args.output = StringIO()
     args.func(args)
-    captured = capfd.readouterr()
     expected = dedent(
         """
         {
+        "info": {
+            "title": "MyApp",
+            "version": "1.0.0"
+        },
         "openapi": "3.0.0",
         "paths": {
             "/route-3/{a}": {
@@ -121,4 +135,4 @@ def test_show_oad_of_a_callable(cmd_line, capfd):
     """
     )
 
-    assert captured.out.strip() == expected.strip()
+    assert args.output.getvalue().strip() == expected.strip()
diff --git a/tests/test_oas/test_docstring_parser.py b/tests/test_oas/test_docstring_parser.py
new file mode 100644
index 0000000..4794973
--- /dev/null
+++ b/tests/test_oas/test_docstring_parser.py
@@ -0,0 +1,88 @@
+from aiohttp_pydantic.oas.docstring_parser import (
+    status_code,
+    operation,
+    _i_extract_block,
+    LinesIterator,
+)
+from inspect import getdoc
+import pytest
+
+
+def web_handler():
+    """
+    bla bla bla
+
+
+    Status Codes:
+        200: line 1
+
+          line 2:
+            - line 3
+            - line 4
+
+          line 5
+
+        300: line A 1
+
+        301: line B 1
+          line B 2
+        400: line C 1
+
+             line C 2
+
+               line C 3
+
+    bla bla
+    """
+
+
+def test_lines_iterator():
+    lines_iterator = LinesIterator("AAAA\nBBBB")
+    with pytest.raises(StopIteration):
+        lines_iterator.rewind()
+
+    assert lines_iterator.next_line() == "AAAA"
+    assert lines_iterator.rewind()
+    assert lines_iterator.next_line() == "AAAA"
+    assert lines_iterator.next_line() == "BBBB"
+    with pytest.raises(StopIteration):
+        lines_iterator.next_line()
+
+
+def test_status_code():
+
+    expected = {
+        200: "line 1\n\nline 2:\n  - line 3\n  - line 4\n\nline 5",
+        300: "line A 1",
+        301: "line B 1\nline B 2",
+        400: "line C 1\n\nline C 2\n\n  line C 3",
+    }
+
+    assert status_code(getdoc(web_handler)) == expected
+
+
+def test_operation():
+    expected = "bla bla bla\n\n\nbla bla"
+    assert operation(getdoc(web_handler)) == expected
+
+
+def test_i_extract_block():
+    lines = LinesIterator("  aaaa\n\n    bbbb\n\n  cccc\n dddd")
+    text = "\n".join(_i_extract_block(lines))
+    assert text == """aaaa\n\n  bbbb\n\ncccc"""
+
+    lines = LinesIterator("")
+    text = "\n".join(_i_extract_block(lines))
+    assert text == ""
+
+    lines = LinesIterator("aaaa\n   bbbb")  # the indented block is cut by a new block
+    text = "\n".join(_i_extract_block(lines))
+    assert text == ""
+
+    lines = LinesIterator("  \n  ")
+    text = "\n".join(_i_extract_block(lines))
+    assert text == ""
+
+    lines = LinesIterator("  aaaa\n  bbbb")
+    text = "\n".join(_i_extract_block(lines))
+    assert text == "aaaa\nbbbb"
diff --git a/tests/test_oas/test_view.py b/tests/test_oas/test_view.py
index 283acd0..f8b233e 100644
--- a/tests/test_oas/test_view.py
+++ b/tests/test_oas/test_view.py
@@ -33,6 +33,9 @@ class PetCollectionView(PydanticView):
     ) -> r200[List[Pet]]:
         """
         Get a list of pets
+
+        Status Codes:
+          200: Successful operation
         """
         return web.json_response()
 
@@ -49,6 +52,19 @@ class PetItemView(PydanticView):
         return web.json_response()
 
     async def delete(self, id: int, /) -> r204:
+        """
+        Status Code:
+          204: Empty but OK
+        """
+        return web.json_response()
+
+
+class TestResponseReturnASimpleType(PydanticView):
+    async def get(self) -> r200[int]:
+        """
+        Status Codes:
+          200: The new number
+        """
         return web.json_response()
 
 
@@ -57,6 +73,7 @@ async def generated_oas(aiohttp_client, loop) -> web.Application:
     app = web.Application()
     app.router.add_view("/pets", PetCollectionView)
     app.router.add_view("/pets/{id}", PetItemView)
+    app.router.add_view("/simple-type", TestResponseReturnASimpleType)
     oas.setup(app)
 
     client = await aiohttp_client(app)
@@ -115,29 +132,11 @@ async def test_pets_route_should_have_get_method(generated_oas):
         ],
         "responses": {
             "200": {
+                "description": "Successful operation",
                 "content": {
                     "application/json": {
                         "schema": {
                             "items": {
-                                "definitions": {
-                                    "Color": {
-                                        "description": "An enumeration.",
-                                        "enum": ["red", "green", "pink"],
-                                        "title": "Color",
-                                        "type": "string",
-                                    },
-                                    "Toy": {
-                                        "properties": {
-                                            "color": {
-                                                "$ref": "#/components/schemas/Color"
-                                            },
-                                            "name": {"title": "Name", "type": "string"},
-                                        },
-                                        "required": ["name", "color"],
-                                        "title": "Toy",
-                                        "type": "object",
-                                    },
-                                },
                                 "properties": {
                                     "id": {"title": "Id", "type": "integer"},
                                     "name": {"title": "Name", "type": "string"},
@@ -154,7 +153,7 @@ async def test_pets_route_should_have_get_method(generated_oas):
                             "type": "array",
                         }
                     }
-                }
+                },
             }
         },
     }
@@ -167,23 +166,6 @@ async def test_pets_route_should_have_post_method(generated_oas):
             "content": {
                 "application/json": {
                     "schema": {
-                        "definitions": {
-                            "Color": {
-                                "description": "An enumeration.",
-                                "enum": ["red", "green", "pink"],
-                                "title": "Color",
-                                "type": "string",
-                            },
-                            "Toy": {
-                                "properties": {
-                                    "color": {"$ref": "#/components/schemas/Color"},
-                                    "name": {"title": "Name", "type": "string"},
-                                },
-                                "required": ["name", "color"],
-                                "title": "Toy",
-                                "type": "object",
-                            },
-                        },
                         "properties": {
                             "id": {"title": "Id", "type": "integer"},
                             "name": {"title": "Name", "type": "string"},
@@ -202,26 +184,10 @@ async def test_pets_route_should_have_post_method(generated_oas):
         },
         "responses": {
             "201": {
+                "description": "",
                 "content": {
                     "application/json": {
                         "schema": {
-                            "definitions": {
-                                "Color": {
-                                    "description": "An enumeration.",
-                                    "enum": ["red", "green", "pink"],
-                                    "title": "Color",
-                                    "type": "string",
-                                },
-                                "Toy": {
-                                    "properties": {
-                                        "color": {"$ref": "#/components/schemas/Color"},
-                                        "name": {"title": "Name", "type": "string"},
-                                    },
-                                    "required": ["name", "color"],
-                                    "title": "Toy",
-                                    "type": "object",
-                                },
-                            },
                             "properties": {
                                 "id": {"title": "Id", "type": "integer"},
                                 "name": {"title": "Name", "type": "string"},
@@ -236,7 +202,7 @@ async def test_pets_route_should_have_post_method(generated_oas):
                             "type": "object",
                         }
                     }
-                }
+                },
             }
         },
     }
@@ -248,15 +214,16 @@ async def test_generated_oas_should_have_pets_id_paths(generated_oas):
 
 async def test_pets_id_route_should_have_delete_method(generated_oas):
     assert generated_oas["paths"]["/pets/{id}"]["delete"] == {
+        "description": "",
         "parameters": [
             {
-                "required": True,
                 "in": "path",
                 "name": "id",
+                "required": True,
                 "schema": {"title": "id", "type": "integer"},
             }
         ],
-        "responses": {"204": {"content": {}}},
+        "responses": {"204": {"content": {}, "description": "Empty but OK"}},
     }
 
 
@@ -272,26 +239,10 @@ async def test_pets_id_route_should_have_get_method(generated_oas):
         ],
         "responses": {
             "200": {
+                "description": "",
                 "content": {
                     "application/json": {
                         "schema": {
-                            "definitions": {
-                                "Color": {
-                                    "description": "An enumeration.",
-                                    "enum": ["red", "green", "pink"],
-                                    "title": "Color",
-                                    "type": "string",
-                                },
-                                "Toy": {
-                                    "properties": {
-                                        "color": {"$ref": "#/components/schemas/Color"},
-                                        "name": {"title": "Name", "type": "string"},
-                                    },
-                                    "required": ["name", "color"],
-                                    "title": "Toy",
-                                    "type": "object",
-                                },
-                            },
                             "properties": {
                                 "id": {"title": "Id", "type": "integer"},
                                 "name": {"title": "Name", "type": "string"},
@@ -306,9 +257,9 @@ async def test_pets_id_route_should_have_get_method(generated_oas):
                             "type": "object",
                         }
                     }
-                }
+                },
             },
-            "404": {"content": {}},
+            "404": {"description": "", "content": {}},
         },
     }
 
@@ -327,23 +278,6 @@ async def test_pets_id_route_should_have_put_method(generated_oas):
             "content": {
                 "application/json": {
                     "schema": {
-                        "definitions": {
-                            "Color": {
-                                "description": "An enumeration.",
-                                "enum": ["red", "green", "pink"],
-                                "title": "Color",
-                                "type": "string",
-                            },
-                            "Toy": {
-                                "properties": {
-                                    "color": {"$ref": "#/components/schemas/Color"},
-                                    "name": {"title": "Name", "type": "string"},
-                                },
-                                "required": ["name", "color"],
-                                "title": "Toy",
-                                "type": "object",
-                            },
-                        },
                         "properties": {
                             "id": {"title": "Id", "type": "integer"},
                             "name": {"title": "Name", "type": "string"},
@@ -361,3 +295,15 @@ async def test_pets_id_route_should_have_put_method(generated_oas):
             }
         },
     }
+
+
+async def test_simple_type_route_should_have_get_method(generated_oas):
+    assert generated_oas["paths"]["/simple-type"]["get"] == {
+        "description": "",
+        "responses": {
+            "200": {
+                "content": {"application/json": {"schema": {}}},
+                "description": "The new number",
+            }
+        },
+    }