diff --git a/docs/development/CUSTOM_RULES.md b/docs/development/CUSTOM_RULES.md
index a101dadbd297..345e42c289ec 100644
--- a/docs/development/CUSTOM_RULES.md
+++ b/docs/development/CUSTOM_RULES.md
@@ -46,20 +46,23 @@ export const rule = createRule({
   create(context) {
     return {
       FunctionDeclaration(node) {
-        if (/^[a-z]/.test(node.id.name)) {
-          context.report({
-            messageId: 'uppercase',
-            node: node.id,
-          });
+        if (node.id != null) {
+          if (/^[a-z]/.test(node.id.name)) {
+            context.report({
+              messageId: 'uppercase',
+              node: node.id,
+            });
+          }
         }
       },
     };
   },
+  name: 'uppercase-first-declarations',
   meta: {
     docs: {
-      category: 'Best Practices',
       description:
         'Function declaration names should start with an upper-case letter.',
+      recommended: 'warn',
     },
     messages: {
       uppercase: 'Start this name with an upper-case letter.',
@@ -67,6 +70,7 @@ export const rule = createRule({
     type: 'suggestion',
     schema: [],
   },
+  defaultOptions: [],
 });
 ```