Introduction

webmcpui is a framework-agnostic, WebMCP-native web component library. Phase 1 ships form primitives — shared behavior (form association, validation, WebMCP exposure, theming) lives in a WmcpFormControl base class, and each element is a thin subclass that supplies its control and specifics.

Shipped so far: <wmcp-input>, <wmcp-textarea>, <wmcp-select>, <wmcp-checkbox>, <wmcp-radio> / <wmcp-radio-group>.

Why it exists

The same form a person fills in by typing, an agent should be able to fill by calling a tool. webmcpui's elements are proper, accessible, form-associated controls first — and, when you opt in, they also register imperative WebMCP tools an agent can discover and call.

It's all additive and feature-detected: with no agent present (the common case today), the WebMCP layer is a complete no-op, so your inputs are always good form controls.

One source of truth, two channels

Vanilla custom elements built with Lit, distributed two ways:

• an ESM package for build tools (@webmcpui/core), and
• a single-file CDN bundle for no-build environments (Webflow, WordPress, plain HTML).

Next steps

• Installation — add it to your project, with or without a build step.
• Validation — bring any Standard Schema validator.
• WebMCP exposure — how elements become agent tools.
• Testing — exercise exposure with the fake agent.