diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index c6bc661c72b6..19108bb5a8fb 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -38,11 +38,14 @@ Below is a short excerpt of some points in there:
     The old config generation system used impure shell scripts and could break in specific circumstances (see #1234).
 
 * `meta.description` should:
+  * Be short, just one sentence.
   * Be capitalized.
   * Not start with the package name.
-  * Not have a period at the end.
+    * More generally, it should not refer to the package name.
+  * Not end with a period (or any punctuation for that matter).
 * `meta.license` must be set and fit the upstream license.
   * If there is no upstream license, `meta.license` should default to `lib.licenses.unfree`.
+  * If in doubt, try to contact the upstream developers for clarification.
 * `meta.maintainers` must be set.
 
 See the nixpkgs manual for more details on [standard meta-attributes](https://nixos.org/nixpkgs/manual/#sec-standard-meta-attributes).