Validation

Every control accepts a Standard Schema validator on its schema property. Bring Zod, Valibot, ArkType, or anything that implements the spec — there's no bespoke schema language to learn.

import { z } from 'zod';

const input = document.querySelector('wmcp-input')!;
input.schema = z.string().email('Enter a valid email');

Validation runs on input and during native form validation. On failure the element:

• sets aria-invalid,
• renders the error message in a live region (announced to assistive tech), and
• propagates the failure to the containing <form> via ElementInternals, so native form submission is blocked just like a built-in control.

Required fields

required is a real constraint, not just a visual marker — an empty required control fails validation and participates in native form validity.

<wmcp-input label="Name" name="name" required></wmcp-input>

A note on tool schemas

Standard Schema validates values but does not emit JSON Schema, so a control's WebMCP tool parameter schema is derived from the element (its type, or its enumerated options for <wmcp-select> / <wmcp-radio-group>) rather than from the validator. Richer tool schemas are a future enhancement.