diff --git a/graphs/minimum_spanning_tree_kruskal.py b/graphs/minimum_spanning_tree_kruskal.py
index 610baf4b5fe6..a51f970341f7 100644
--- a/graphs/minimum_spanning_tree_kruskal.py
+++ b/graphs/minimum_spanning_tree_kruskal.py
@@ -1,4 +1,18 @@
-def kruskal(num_nodes, num_edges, edges):
+from typing import List, Tuple
+
+
+def kruskal(num_nodes: int, num_edges: int, edges: List[Tuple[int, int, int]]) -> int:
+    """
+    >>> kruskal(4, 3, [(0, 1, 3), (1, 2, 5), (2, 3, 1)])
+    [(2, 3, 1), (0, 1, 3), (1, 2, 5)]
+
+    >>> kruskal(4, 5, [(0, 1, 3), (1, 2, 5), (2, 3, 1), (0, 2, 1), (0, 3, 2)])
+    [(2, 3, 1), (0, 2, 1), (0, 1, 3)]
+
+    >>> kruskal(4, 6, [(0, 1, 3), (1, 2, 5), (2, 3, 1), (0, 2, 1), (0, 3, 2),
+    ... (2, 1, 1)])
+    [(2, 3, 1), (0, 2, 1), (2, 1, 1)]
+    """
     edges = sorted(edges, key=lambda edge: edge[2])
 
     parent = list(range(num_nodes))