uv/crates/uv-build/python/uv_build/__main__.py

def main():
    import sys

    # This works both as redirect to use the proper uv package and as smoke test.
    print(
        "uv_build contains only the PEP 517 build backend for uv and can't be used on the CLI. "
        "Use `uv build` or another build frontend instead.",
        file=sys.stderr,
    )
    if "--help" in sys.argv or "-h" in sys.argv:
        sys.exit(0)
    else:
        sys.exit(1)


if __name__ == "__main__":
    main()