diff --git a/src/meridian/suites/loader.py b/src/meridian/suites/loader.py
index 4655f7c..33cd4e3 100644
--- a/src/meridian/suites/loader.py
+++ b/src/meridian/suites/loader.py
@@ -23,6 +23,16 @@
 
 SUITE_FILE = "suite.yaml"
 TASKS_DIR = "tasks"
+HARBOR_TASK_FILE = "task.toml"
+
+
+def _looks_like_harbor_tasks(root: Path) -> bool:
+    """Harbor keeps task.toml at the dataset root, one level down, or two."""
+    return any(
+        candidate.is_file()
+        for pattern in (HARBOR_TASK_FILE, f"*/{HARBOR_TASK_FILE}", f"*/*/{HARBOR_TASK_FILE}")
+        for candidate in root.glob(pattern)
+    )
 
 
 def _read_yaml(
@@ -73,12 +83,15 @@ def load_suite(path: str | Path) -> Suite:
 
     suite_file = root / SUITE_FILE
     if not suite_file.is_file():
+        message = f"no {SUITE_FILE} in {root}"
+        if _looks_like_harbor_tasks(root):
+            message += "; this looks like Harbor tasks — run `meridian import-harbor` first"
         raise SuiteValidationError(
             [
                 ValidationIssue(
                     code="missing_suite_file",
                     file=SUITE_FILE,
-                    message=f"no {SUITE_FILE} in {root}",
+                    message=message,
                 )
             ]
         )
diff --git a/tests/unit/test_suite_validation.py b/tests/unit/test_suite_validation.py
index f9dd90f..3c8ba8f 100644
--- a/tests/unit/test_suite_validation.py
+++ b/tests/unit/test_suite_validation.py
@@ -79,6 +79,26 @@ def test_missing_suite_file_is_its_own_code(tmp_path: Path) -> None:
     assert excinfo.value.codes() == ["missing_suite_file"]
 
 
+@pytest.mark.unit
+def test_a_harbor_dataset_suggests_importing_it_first(tmp_path: Path) -> None:
+    """Pointing `run` at a Harbor dataset should name the command that converts it."""
+    task = tmp_path / "some-harbor-task"
+    task.mkdir()
+    (task / "task.toml").write_text("", encoding="utf-8")
+    with pytest.raises(SuiteValidationError) as excinfo:
+        load_suite(tmp_path)
+    assert excinfo.value.codes() == ["missing_suite_file"]
+    assert "import-harbor" in str(excinfo.value)
+
+
+@pytest.mark.unit
+def test_a_plain_directory_gets_no_harbor_hint(tmp_path: Path) -> None:
+    (tmp_path / "tasks").mkdir()
+    with pytest.raises(SuiteValidationError) as excinfo:
+        load_suite(tmp_path)
+    assert "import-harbor" not in str(excinfo.value)
+
+
 @pytest.mark.unit
 def test_malformed_yaml_is_reported_as_such(tmp_path: Path) -> None:
     shutil.copytree(FIXTURES / "_valid-control", tmp_path / "suite")