diff --git a/build/toolbase/doc.go b/build/toolbase/doc.go
new file mode 100644
index 0000000..8bf9e25
--- /dev/null
+++ b/build/toolbase/doc.go
@@ -0,0 +1,3 @@
+// toolbase implements common functionality for tools operating on a Monogon
+// workspace, notably CI and developer tools.
+package toolbase