Most CLI tools fail as products not because the logic is wrong, but because the interface is an afterthought. A professional CLI behaves predictably: it parses arguments gracefully, fails loudly on stderr, and returns exit codes a script can rely on.
Arguments are a UX problem
Typer turns type hints into a self-documenting interface: --help text, validation and clear errors come for free. Design commands the way a user thinks about the task, not the way your functions happen to be organized.
import typer
app = typer.App()
@app.command()
def scan(path: str, deep: bool = typer.Option(False, "--deep")):
"""Scan a folder and report what matters."""
...
if __name__ == "__main__":
app()Exit codes and stderr are your API
Scripts chain your tool into pipelines. Keep stdout clean for machine-readable output, send diagnostics to stderr, and return 0 only when the job truly succeeded. A tool that prints stack traces to stdout breaks every pipeline it touches.
Package once, run anywhere
Ship with a requirements.txt pinned to versions you actually tested, and keep the entry point a single main.py. A buyer should go from download to first result in under a minute — that is the standard every PyForge asset is held to.
python -m venv .venv && source .venv/bin/activate
pip install -r requirements.txt
python main.py scan ./logs --deep