Brilliant MCP

Your coding agent designs with you on a real vector canvas. This is the local MCP server for Brilliant, the design tool whose canvas you and your agent both edit: the agent lays out the screen, you drag, retype and restyle it, and the agent sees your changes and keeps going.

@brilliant-hq/mcp is a small local router. It connects any MCP client over stdio to a Brilliant tab in your browser or to the Brilliant desktop app, entirely on 127.0.0.1. Zero bytes of MCP or design data touch Brilliant's servers.

Install

install <client> knows claude-code, cursor, vscode, codex, gemini, antigravity, windsurf, zed, opencode, amp and claude-desktop. Any other MCP client takes the standard stdio entry:

{ "mcpServers": { "brilliant": { "command": "npx", "args": ["-y", "@brilliant-hq/mcp"] } } }

Requires Node 20 or newer. No API key.

Related MCP server: Canvas AIGC

First run

Ask your agent for a design: "design a pricing page for this app". With no Brilliant open, the first tool call opens brilliant.design in your browser (Chrome, Edge or Firefox) and pairs it with your agent session; allow the one-time local network prompt. If the Brilliant desktop app is running, the server connects to it instead and opens nothing. Listing the tools never opens anything.

What your agent can do

The tools are Brilliant's own, served by the tab or the app; this package relays them unchanged. The main doors:

• init: start a session and receive Brilliant's documentation for its tools.

• edit: write designs, as HTML with inline CSS or as Blueprint, Brilliant's plain-text design format. Everything lands as editable vector layers.

• read, get_selection: read canvases, design systems and what you selected.

• export: PNG, JPEG, WebP, SVG, PDF, HTML and React.

• get_knowledge: load design and format guidance on demand.

• generate_image, generate_svg, vectorize_image, remove_background: image and vector generation inside a design.

Every tool carries MCP annotations (a title, read-only and destructive hints), so your client can tell a read from a write before it calls.

How it works

• The server is a relay: MCP JSON-RPC crosses it verbatim. MCP semantics live in the Brilliant tab or desktop app, never here.

• The first instance on a machine becomes the leader (one tab socket, one permission grant); every other MCP client's instance is a follower that forwards over loopback. Leadership reassigns when the leader exits.

• The Brilliant desktop app is detected on 127.0.0.1:3333 to 3335 and covered by the same entry.

The full wire contract is in PROTOCOL.md.

Privacy

This package makes no network calls of its own: no telemetry, no analytics, no update checks. It talks only to a brilliant.design tab you approve or to the Brilliant desktop app on your machine, over 127.0.0.1.

One thing does reach Brilliant's website: when the server opens the pairing tab, the link carries three attribution params, utm_source=mcp-helper, your MCP client's name (utm_medium, for example claude-code) and, if the install snippet set one, a door tag (utm_content, from --src <tag> or BRILLIANT_MCP_SRC). They tell us which install path people use. They say nothing about you, your machine or your designs, and the pairing token stays in the URL fragment, which a browser never sends to a server.

It keeps a small state directory at ~/.config/brilliant/mcp-helper (its ports, the pairings you approved and the last tool list), readable only by you.

Brilliant itself, like any app, has its own data handling: the image tools run on Brilliant's servers when your agent calls them, and a cloud project syncs when you choose one. See the privacy policy.

Security

• Every listener binds the literal 127.0.0.1: never 0.0.0.0, never a scan of private ranges.

• The tab socket validates Origin: https://brilliant.design, a loopback Host (against DNS rebinding), and a pairing token or an association you approved.

• The pairing token is never served from any local endpoint; the state files are mode 0600, and the web side never reads them.

To report a vulnerability, see SECURITY.md.

CLI

npx @brilliant-hq/mcp                              # run the stdio MCP server (default)
npx @brilliant-hq/mcp --src <tag>                  # run it, tagging the pairing link with an install door
npx @brilliant-hq/mcp --version
npx @brilliant-hq/mcp install <client>             # add the server to <client>'s MCP config
npx @brilliant-hq/mcp install <client> --dry-run   # preview the change, write nothing
npx @brilliant-hq/mcp install <client> --remove    # remove it again

install merges into the client's config without touching other servers, keeps JSONC comments, and --remove is its exact inverse.

Development

npm install
npm test

Pricing

Canvas work by your own agents over MCP is unlimited on every Brilliant plan, the free plan included. Generated images and background removal draw on your Brilliant AI usage. Details: https://brilliant.design/pricing

Licence

The code in this repository is licensed under Apache-2.0. The licence covers this local server only: the Brilliant editor, engine and services are not open source, and the Brilliant name and logo are not licensed (see NOTICE).

Docs: https://brilliant.design/docs/agents/overview