diff --git a/src/fastcs/controller.py b/src/fastcs/controller.py
index fe6863e4..95c64d31 100755
--- a/src/fastcs/controller.py
+++ b/src/fastcs/controller.py
@@ -1,7 +1,6 @@
 from __future__ import annotations
 
 from copy import copy
-from typing import Any
 
 from .attributes import Attribute
 
diff --git a/src/fastcs/exceptions.py b/src/fastcs/exceptions.py
index 5e1f375f..64964cbf 100644
--- a/src/fastcs/exceptions.py
+++ b/src/fastcs/exceptions.py
@@ -1,2 +1,6 @@
 class FastCSException(Exception):
     pass
+
+
+class LaunchError(FastCSException):
+    pass
diff --git a/src/fastcs/main.py b/src/fastcs/main.py
index 42efff05..70589a07 100644
--- a/src/fastcs/main.py
+++ b/src/fastcs/main.py
@@ -1,7 +1,7 @@
+import inspect
 import json
-from inspect import signature
 from pathlib import Path
-from typing import Annotated, Any, get_type_hints
+from typing import Annotated, get_type_hints
 
 import typer
 from pydantic import create_model
@@ -9,6 +9,7 @@
 
 from .backend import Backend
 from .controller import Controller
+from .exceptions import LaunchError
 from .transport.adapter import TransportAdapter
 from .transport.epics.options import EpicsOptions
 from .transport.tango.options import TangoOptions
@@ -51,10 +52,6 @@ def run(self) -> None:
         self._transport.run()
 
 
-class LaunchError(Exception):
-    pass
-
-
 def launch(controller_class: type[Controller]) -> None:
     """
     Serves as an entry point for starting FastCS applications.
@@ -79,24 +76,29 @@ def __init__(self, my_arg: MyControllerOptions) -> None:
         if __name__ == "__main__":
             launch(MyController)
     """
-    args_len = controller_class.__init__.__code__.co_argcount
-    sig = signature(controller_class.__init__)
-    if args_len == 1:
+    _launch(controller_class)()
+
+
+def _launch(controller_class: type[Controller]) -> typer.Typer:
+    # args_len = controller_class.__init__.__code__.co_argcount
+    sig = inspect.signature(controller_class.__init__)
+    args = inspect.getfullargspec(controller_class.__init__)[0]
+    if len(args) == 1:
         fastcs_options = create_model(
             f"{controller_class.__name__}",
             transport=(EpicsOptions | TangoOptions, ...),
             __config__={"extra": "forbid"},
         )
-    elif args_len == 2:
+    elif len(args) == 2:
         hints = get_type_hints(controller_class.__init__)
-        if "self" in hints:
-            del hints["self"]
+        # if "self" in hints:
+        #     del hints["self"]
         if hints:
             options_type = list(hints.values())[-1]
         else:
             raise LaunchError(
-                f"Expected typehinting in {controller_class.__name__}"
-                f".__init__ but received {sig}"
+                f"Expected typehinting in '{controller_class.__name__}"
+                f".__init__' but received {sig}. Add a typehint for `{args[-1]}`."
             )
         fastcs_options = create_model(
             f"{controller_class.__name__}",
@@ -106,32 +108,30 @@ def __init__(self, my_arg: MyControllerOptions) -> None:
         )
     else:
         raise LaunchError(
-            f"Expected up to 2 arguments for {controller_class.__name__}.__init__ "
-            f"but received {args_len} {sig}"
+            f"Expected no more than 2 arguments for '{controller_class.__name__}"
+            f".__init__' but received {len(args)} as `{sig}`"
         )
 
-    _launch_typer = typer.Typer()
+    launch_typer = typer.Typer()
 
     class _LaunchContext:
         def __init__(self, controller_class, fastcs_options):
             self.controller_class = controller_class
             self.fastcs_options = fastcs_options
 
-    @_launch_typer.callback()
+    @launch_typer.callback()
     def create_context(ctx: typer.Context):
         ctx.obj = _LaunchContext(
             controller_class,
             fastcs_options,
         )
 
-    @_launch_typer.command(
-        help=f"Produce json schema for a {controller_class.__name__}"
-    )
+    @launch_typer.command(help=f"Produce json schema for a {controller_class.__name__}")
     def schema(ctx: typer.Context):
         system_schema = ctx.obj.fastcs_options.model_json_schema()
         print(json.dumps(system_schema, indent=2))
 
-    @_launch_typer.command(help=f"Start up a {controller_class.__name__}")
+    @launch_typer.command(help=f"Start up a {controller_class.__name__}")
     def run(
         ctx: typer.Context,
         config: Annotated[
@@ -167,4 +167,4 @@ def run(
             instance.create_docs()
         instance.run()
 
-    _launch_typer()
+    return launch_typer
diff --git a/tests/test_main.py b/tests/test_main.py
new file mode 100644
index 00000000..7c3387c3
--- /dev/null
+++ b/tests/test_main.py
@@ -0,0 +1,80 @@
+import json
+from dataclasses import dataclass
+
+import pytest
+from pydantic import create_model
+from typer.testing import CliRunner
+
+from fastcs.controller import Controller
+from fastcs.exceptions import LaunchError
+from fastcs.main import _launch, launch
+from fastcs.transport.epics.options import EpicsOptions
+from fastcs.transport.tango.options import TangoOptions
+
+
+@dataclass
+class SomeConfig:
+    name: str
+
+
+class SingleArg(Controller):
+    def __init__(self):
+        super().__init__()
+
+
+class NotHinted(Controller):
+    def __init__(self, arg):
+        super().__init__()
+
+
+class IsHinted(Controller):
+    def __init__(self, arg: SomeConfig):
+        super().__init__()
+
+
+class ManyArgs(Controller):
+    def __init__(self, arg: SomeConfig, too_many):
+        super().__init__()
+
+
+runner = CliRunner()
+
+
+def test_is_hinted_schema():
+    target_model = create_model(
+        "IsHinted",
+        controller=(SomeConfig, ...),
+        transport=(EpicsOptions | TangoOptions, ...),
+        __config__={"extra": "forbid"},
+    )
+    target_dict = target_model.model_json_schema()
+
+    app = _launch(IsHinted)
+    result = runner.invoke(app, ["schema"])
+    assert result.exit_code == 0
+    result_dict = json.loads(result.stdout)
+
+    assert result_dict == target_dict
+
+
+def test_not_hinted_schema():
+    error = (
+        "Expected typehinting in 'NotHinted.__init__' but received "
+        "(self, arg). Add a typehint for `arg`."
+    )
+
+    with pytest.raises(LaunchError) as exc_info:
+        launch(NotHinted)
+    assert str(exc_info.value) == error
+
+
+def test_over_defined_schema():
+    error = (
+        ""
+        "Expected no more than 2 arguments for 'ManyArgs.__init__' "
+        "but received 3 as `(self, arg: test_main.SomeConfig, too_many)`"
+    )
+
+    with pytest.raises(LaunchError) as exc_info:
+        launch(ManyArgs)
+    assert str(exc_info.value) == error