diff --git a/src/commands/spec.ts b/src/commands/spec.ts
index c89d467..30644b5 100644
--- a/src/commands/spec.ts
+++ b/src/commands/spec.ts
@@ -1,6 +1,17 @@
 import { optFlag, optSwitch, undefList } from "./common";
 
 export interface RunCPUOptions {
+    /**
+     * Most runcpu commands perform an action on a set of benchmarks.
+     *
+     * The default action is validate.
+     *
+     * 'build'
+     */
+    action?: 'build'
+    | 'buildstep'
+    | 'validate'
+    | 'runsetup';
     /**
      * Config file, used for compiling flags, compiler versions, etc.
      */