diff --git a/python/scripts/dependencies/add_dependency_to_project.py b/python/scripts/dependencies/add_dependency_to_project.py
index cb389a89ba9..21516fbec41 100644
--- a/python/scripts/dependencies/add_dependency_to_project.py
+++ b/python/scripts/dependencies/add_dependency_to_project.py
@@ -90,7 +90,6 @@ def main() -> None:
         "--package",
         dest="project",
         metavar="PACKAGE",
-        required=True,
         help="Workspace package selector, such as `core`.",
     )
     # Keep the old long flag as a silent alias while downstream automation
@@ -98,6 +97,8 @@ def main() -> None:
     parser.add_argument("--project", dest="project", help=argparse.SUPPRESS)
     parser.add_argument("-D", "--dependency", required=True, help="Dependency specifier to add.")
     args = parser.parse_args()
+    if args.project is None:
+        parser.error("the following arguments are required: -P/--package")
 
     workspace_root = Path(__file__).resolve().parents[2]
     package = _resolve_workspace_package(workspace_root, args.project)
diff --git a/python/scripts/dependencies/tests/test_add_dependency_to_project.py b/python/scripts/dependencies/tests/test_add_dependency_to_project.py
new file mode 100644
index 00000000000..cbcf443107b
--- /dev/null
+++ b/python/scripts/dependencies/tests/test_add_dependency_to_project.py
@@ -0,0 +1,78 @@
+# Copyright (c) Microsoft. All rights reserved.
+
+import sys
+from pathlib import Path
+from subprocess import CompletedProcess
+from unittest.mock import Mock
+
+import pytest
+
+from scripts.dependencies import add_dependency_to_project as add_dependency
+
+
+def _mock_dependency_add(monkeypatch: pytest.MonkeyPatch) -> tuple[Mock, Mock]:
+    package = add_dependency.WorkspacePackage(
+        short_name="core",
+        project_path=Path("packages/core"),
+        distribution_name="agent-framework-core",
+    )
+    resolve = Mock(return_value=package)
+    run = Mock(return_value=CompletedProcess(args=[], returncode=0))
+    monkeypatch.setattr(add_dependency, "_resolve_workspace_package", resolve)
+    monkeypatch.setattr(add_dependency.subprocess, "run", run)
+    return resolve, run
+
+
+@pytest.mark.parametrize(
+    ("selector_args", "expected_selector"),
+    [
+        (["-P", "core"], "core"),
+        (["--package", "core"], "core"),
+        (["--project", "core"], "core"),
+        (["--package", "core", "--project", "openai"], "openai"),
+        (["--project", "core", "--package", "openai"], "openai"),
+    ],
+)
+def test_main_accepts_selector_spellings(
+    monkeypatch: pytest.MonkeyPatch, selector_args: list[str], expected_selector: str
+) -> None:
+    resolve, run = _mock_dependency_add(monkeypatch)
+    monkeypatch.setattr(sys, "argv", ["add_dependency_to_project.py", *selector_args, "--dependency", "httpx"])
+
+    add_dependency.main()
+
+    workspace_root = Path(add_dependency.__file__).resolve().parents[2]
+    resolve.assert_called_once_with(workspace_root, expected_selector)
+    run.assert_called_once_with(
+        ["uv", "add", "--package", "agent-framework-core", "httpx"],
+        cwd=workspace_root,
+        check=False,
+    )
+
+
+@pytest.mark.parametrize("arguments", [["--dependency", "httpx"], ["--package", "core"]])
+def test_main_requires_selector_and_dependency(monkeypatch: pytest.MonkeyPatch, arguments: list[str]) -> None:
+    resolve, run = _mock_dependency_add(monkeypatch)
+    monkeypatch.setattr(sys, "argv", ["add_dependency_to_project.py", *arguments])
+
+    with pytest.raises(SystemExit) as error:
+        add_dependency.main()
+
+    assert error.value.code == 2
+    resolve.assert_not_called()
+    run.assert_not_called()
+
+
+def test_help_keeps_legacy_selector_hidden(monkeypatch: pytest.MonkeyPatch, capsys: pytest.CaptureFixture[str]) -> None:
+    resolve, run = _mock_dependency_add(monkeypatch)
+    monkeypatch.setattr(sys, "argv", ["add_dependency_to_project.py", "--help"])
+
+    with pytest.raises(SystemExit) as error:
+        add_dependency.main()
+
+    assert error.value.code == 0
+    help_text = capsys.readouterr().out
+    assert "--package" in help_text
+    assert "--project" not in help_text
+    resolve.assert_not_called()
+    run.assert_not_called()