A Model Context Protocol server that lets any AI assistant build a paste-ready embed for the three.ws assistant widget over stdio. Describe how you want the assistant to look and behave and build_assistant_widget returns a ready-to-paste <script> tag, a standalone frame URL for <iframe> embedding, and an equivalent ThreeAssistant.init({...}) JavaScript-API snippet, a floating 3D avatar chatbot that lives in the corner of any site. list_assistant_options enumerates every built-in avatar, background preset, interaction mode, chat lane, and data-* attribute you can set.

Both tools are pure and offline: building an embed is deterministic string logic over local validators. Every field is validated and clamped, so a bad or hostile value falls back to a safe default and the generated HTML is always well-formed. No API key, no signer, no payment, no network call. Point THREE_WS_BASE at a deployment (or leave the default) and go.

Install

npm install @three-ws/assistant-mcp

Or run with npx (no install):

npx -y @three-ws/assistant-mcp

Quick start

Claude Code, one line:

claude mcp add assistant -- npx -y @three-ws/assistant-mcp

Claude Desktop / Cursor (claude_desktop_config.json or mcp.json):

{
	"mcpServers": {
		"assistant": {
			"command": "npx",
			"args": ["-y", "@three-ws/assistant-mcp"]
		}
	}
}

Inspect the surface with the MCP Inspector:

npx -y @modelcontextprotocol/inspector npx @three-ws/assistant-mcp

Tools

| Tool | Type | What it does | | ------------------------ | --------- | -------------------------------------------------------------------------------------------------------------------- | | build_assistant_widget | read-only | A config → a paste-ready <script> embed (non-default settings as data-*), a frame URL, a ThreeAssistant.init() snippet, and the normalized config. | | list_assistant_options | read-only | Enumerate every built-in avatar, background preset and grammar, interaction mode, chat lane, and the full data-* attribute reference. |

build_assistant_widget is a pure function: the same config always yields the same embed, and it never touches the network. The generated <script> tag carries only the settings that differ from their defaults, so a minimal config yields a minimal tag. The frame_url carries every resolved value (including defaults) so the standalone frame renders deterministically when dropped into an <iframe>.

Input parameters

build_assistant_widget, all optional:

| Field | Type / values | Default | | ------------ | ------------------------------------------------------------------------------------------ | ------------- | | avatar | avatar id, /avatars/*.glb path, or GLB URL | mannequin | | agent | a three.ws agent id (alternative to avatar) | (none) | | background | transparent | #hex | ember/ocean/violet/forest/dusk/slate | gradient:#a,#b[,angle] | transparent | | mode | chat | speak | both | both | | name | string (≤ 60) | (none) | | greeting | string (≤ 200) | (none) | | context | string (≤ 500), what the assistant should know about the site | (none) | | accent | #hex | #f97316 | | position | right | left | right | | voice | boolean, start with voice on/off | on | | badge | boolean, show the three.ws attribution badge | on |

Any value that fails validation (a bad hex, an unknown background, an over-long string) falls back to its default rather than being rejected, so you always get a working embed.

list_assistant_options, filter (optional: avatars | backgrounds | modes | chat_lanes | attributes). Omit to get everything.

Example

// build_assistant_widget
> {
    "avatar": "/avatars/selfie-girl.glb",
    "background": "ocean",
    "mode": "both",
    "name": "Aria",
    "greeting": "Hi! Ask me anything about the site.",
    "accent": "#00c2ff",
    "position": "left"
  }
{
  "ok": true,
  "snippet": "<script src=\"https://three.ws/assistant/v1.js\" async data-avatar=\"/avatars/selfie-girl.glb\" data-bg=\"ocean\" data-name=\"Aria\" data-greeting=\"Hi! Ask me anything about the site.\" data-accent=\"#00c2ff\" data-position=\"left\"></script>",
  "frame_url": "https://three.ws/assistant-frame?avatar=%2Favatars%2Fselfie-girl.glb&bg=ocean&mode=both&name=Aria&greeting=Hi%21+Ask+me+anything+about+the+site.&accent=%2300c2ff",
  "js_api": "ThreeAssistant.init({\n  \"bg\": \"ocean\",\n  \"mode\": \"both\",\n  \"accent\": \"#00c2ff\",\n  \"position\": \"left\",\n  \"avatar\": \"/avatars/selfie-girl.glb\",\n  \"name\": \"Aria\",\n  \"greeting\": \"Hi! Ask me anything about the site.\"\n});",
  "builder_url": "https://three.ws/assistant",
  "config": { "bg": "ocean", "mode": "both", "accent": "#00c2ff", "position": "left", "avatar": "/avatars/selfie-girl.glb", "name": "Aria", "greeting": "Hi! Ask me anything about the site." },
  "notes": "Chat runs on the free three.ws LLM chain by default (no key). Visitors can paste their own Groq or OpenRouter key in the widget settings for a private lane; that key stays in their browser."
}

Paste the snippet before </body> on any page, or drop the frame_url into an <iframe>. Design it visually first at three.ws/assistant.

Requirements

• Node.js >= 20.
• No network access needed. THREE_WS_BASE only sets the origin baked into the generated URLs.

Environment variables

| Variable | Required | Default | | --------------- | -------- | ------------------ | | THREE_WS_BASE | no | https://three.ws |

Programmatic use

The package entry point exports TOOLS (every tool definition: name, title, description, inputSchema, annotations, handler) and buildServer(), which returns a fully-registered McpServer with no transport attached. Both tools are pure and offline, so you can call them directly as a widget-builder library with no MCP client involved.

// run from a checkout: node this-file.mjs
import { TOOLS, buildServer } from '@three-ws/assistant-mcp';

const build = TOOLS.find((t) => t.name === 'build_assistant_widget');
const { snippet } = await build.handler({ avatar: '/avatars/michelle.glb', background: 'dusk' });
console.log(snippet);

// Or hand the whole registered server to your own MCP transport.
buildServer();

<script src="https://three.ws/assistant/v1.js" async data-avatar="/avatars/michelle.glb" data-bg="dusk"></script>

Links

• Builder: https://three.ws/assistant
• Docs: https://three.ws/docs/assistant-widget
• Homepage: https://three.ws
• Changelog: https://three.ws/changelog
• Issues: https://github.com/nirholas/three.ws/issues
• License: proprietary, see LICENSE