some comments

README.md

@@ -100,6 +100,7 @@ Add the following to your tsconfig.json
 All decorators accept an object of options that apply to the type being used, for a full list of options please refer to the fastest-validator [documentation](https://www.npmjs.com/package/fastest-validator).
 
 **@Schema(strict=false, messages={})** - Schema decorator. 
+**@Schema({ strict = false, async = false }, messages={})** - Schema decorator. 
 
 **@Field({})** - Generic decorator, no default properties set. Will apply all options to the schema.
 
@@ -143,7 +144,7 @@ All decorators accept an object of options that apply to the type being used, fo
 
 ```ts
 @Custom({
-  check (value: number, errors: {type: string}[]){
+  check (value: number, errors: {type: string, actual: number}[]){
     if (value % 2 !== 0) {
       errors.push({ type: "even", actual : value });
     }

src/index.spec.ts

@@ -841,11 +841,7 @@ describe("Custom async", () => {
       })
         prop!: unknown;
     }
-
-    /**
-     * $$async key is removed for unknown reason from schema object at compile()
-     * https://github.com/icebob/fastest-validator/blob/a746f9311d3ebeda986e4896d39619bfc925ce65/lib/validator.js#L176
-     */
+
     expect(getSchema(Test)).toEqual({
       $$strict: false,
       $$async: true,

src/index.ts

@@ -92,6 +92,8 @@ export function Schema (schemaOptions?: StrictMode | SchemaOptions, messages = {
 
     /**
      * Make a copy of the schema, in order to keep the original from being overriden or deleted by fastest-validator
+     * $$async key is removed from schema object at compile()
+     * https://github.com/icebob/fastest-validator/blob/a746f9311d3ebeda986e4896d39619bfc925ce65/lib/validator.js#L176
      */
     Reflect.defineMetadata(COMPILE_KEY, v.compile({...s}), target);
     return target;
@@ -132,6 +134,7 @@ export function Nested (options: any | any[] = {}): any {
     const props = Object.assign({}, getSchema(t));
     const strict = props.$$strict || false;
     delete props.$$strict;
+    // never $$async in nested
     delete props.$$async;
     updateSchema(target, key, { ...options, props, strict, type: "object" });
   };