diff --git a/tests/test_span_attribute_invariants.py b/tests/test_span_attribute_invariants.py
new file mode 100644
index 0000000000..b54e4d3027
--- /dev/null
+++ b/tests/test_span_attribute_invariants.py
@@ -0,0 +1,17 @@
+import pytest
+
+def validate_span_attribute(key: str, value) -> bool:
+    if not isinstance(key, str) or not key.strip():
+        return False
+    if not isinstance(value, (str, int, float, bool, bytes)):
+        return False
+    return True
+
+def test_valid_span_attributes():
+    assert validate_span_attribute("http.status_code", 200) is True
+    assert validate_span_attribute("db.system", "postgresql") is True
+    assert validate_span_attribute("ai.request.duration_ms", 142.5) is True
+
+def test_invalid_span_attributes():
+    assert validate_span_attribute("", 200) is False
+    assert validate_span_attribute("custom.key", [1, 2, 3]) is False