diff --git a/src/index.js b/src/index.js
index 983c56433..37482bacc 100644
--- a/src/index.js
+++ b/src/index.js
@@ -1 +1,4 @@
 export { createHeadlessForm } from './createHeadlessForm';
+
+export { pickXKey } from './internals/helpers';
+export { buildCompleteYupSchema } from './yupSchema';
diff --git a/src/internals/helpers.js b/src/internals/helpers.js
index ff7f6e46a..81111ccf6 100644
--- a/src/internals/helpers.js
+++ b/src/internals/helpers.js
@@ -10,10 +10,12 @@ import isEmpty from 'lodash/isEmpty';
 import isFunction from 'lodash/isFunction';
 
 /**
- * Returns the object from the JSON-schema node using the key.
- *
+ * Shorthand to lookup for keys with `x-jsf-*` preffix.
  * @param {Object} node - JSON-schema node
- * @param {String} key - JSON-schema key name
+ * @param {"presentation"|"errorMessage"} key - JSON-schema key name
+ * @example
+ *  pickKey(properties, 'presentation')
+ *  is the same as properties["x-jsf-presentation"]
  * @returns {Object}
  */
 export function pickXKey(node, key) {
diff --git a/src/yupSchema.js b/src/yupSchema.js
index 6ec2cf84b..362afc9e7 100644
--- a/src/yupSchema.js
+++ b/src/yupSchema.js
@@ -8,6 +8,7 @@ import { convertDiskSizeFromTo } from './utils';
 
 /**
  * @typedef {import('./createHeadlessForm').FieldParameters} FieldParameters
+ * @typedef {import('../createHeadlessForm').JsfConfig} JsfConfig
  */
 
 export const DEFAULT_DATE_FORMAT = 'yyyy-MM-dd';
@@ -297,6 +298,14 @@ function getSchema(fields = [], config) {
   return newSchema;
 }
 
+/**
+ * Returns the Yup schema structure of given fields.
+ * These fields must be the same from
+ * const { fields } = createHeadlessForm()
+ * @param {Fields[]} fields - List of fields
+ * @param {JsfConfig} config - Config
+ * @returns
+ */
 export function buildCompleteYupSchema(fields, config) {
   return object().shape(getSchema(fields, config), getNoSortEdges(fields));
 }