mcp-excalidraw-serverCAUTION
MCP server and Claude Code skill for Excalidraw — programmatic canvas toolkit to create, edit, and export diagrams via AI agents with real-time canvas sync.
Overview
From the repository's own README, as read at the audited commit. Badges and raw HTML are left out.
[](https://github.com/yctimlin/mcpexcalidraw/actions/workflows/ci.yml) [](https://github.com/yctimlin/mcpexcalidraw/actions/workflows/docker.yml) [](https://www.npmjs.com/package/mcp-excalidraw-server) [](LICENSE)
mcp-excalidraw-server gives AI agents a live Excalidraw canvas they can draw on, look at, refine, and save into your repo. Your agent creates architecture diagrams and flowcharts programmatically, sees its own work via screenshots, fixes layout problems, and exports .excalidraw files you can commit next to your code.
One canvas, three ways to drive it:
- Agent Skill + CLI — recommended for coding agents (Claude Code, Codex CLI, Cursor, OpenCode):
npx -y mcp-excalidraw-server. Zero config, auto-starts the canvas, composable JSON in/out. - MCP Server — 26 tools over stdio for any Model Context Protocol client (Claude Desktop, Cursor, Codex CLI, Antigravity, ...). Speaks MCP
2026-07-28(server/discover, per-request_metaenvelope, tool calls without a handshake) and stays compatible with 2025-era clients that open withinitialize. - REST API — plain HTTP for LangChain and custom frameworks.
Core drawing runs locally (Node ≥ 20, MIT licensed) — no API keys or accounts. Mermaid conversion runs in the local browser canvas; share is optional and uploads an encrypted scene to excalidraw.com. The canvas page loads Excalidraw's fonts from the esm.sh CDN.
Demo
*AI agent creates a complete architecture diagram from a single prompt (4x speed). [Wa
d405454fc9a3OBSERVED · 2026-10-12Connect
Built from this server's own package name, version and transport as found in its source — not copied from anyone's documentation, so it cannot drift against a page we do not control.
claude mcp add mcp-excalidraw-server -- npx -y [email protected]
{
"mcpServers": {
"mcp-excalidraw-server": {
"command": "npx",
"args": [
"-y",
"[email protected]"
]
}
}
}Exposed tools (26)
16 read · 8 write · 2 destructive. Blast radius: 2 tools can delete or overwrite — an agent that can be talked into calling a tool can be talked into calling this one.
| Tool | Risk | Description |
|---|---|---|
align_elements | read | Align elements to a specific position |
batch_create_elements | write | Create multiple Excalidraw elements at once. For arrows, use startElementId/endElementId to bind arrows to shapes — Excalidraw auto-routes to element edges. Assign custom id to shapes so arrows can reference them. |
clear_canvas | destructive | Clear all elements from the canvas |
create_element | write | Create a new Excalidraw element. For arrows, use startElementId/endElementId to bind to shapes (auto-routes to edges). |
create_from_mermaid | write | Convert a Mermaid diagram to Excalidraw elements and render them on the canvas |
delete_element | destructive | Delete an Excalidraw element |
describe_scene | read | Get an AI-readable description of the current canvas: element types, positions, connections, labels, spatial layout, and bounding box. Use this to understand what is on the canvas before making changes. |
distribute_elements | read | Distribute elements evenly |
duplicate_elements | read | Duplicate elements with a configurable offset |
export_scene | write | Export the current canvas to .excalidraw JSON format. Optionally write to a file; a path ending in .md is written in the Obsidian Excalidraw plugin format (.excalidraw.md). |
export_to_excalidraw_url | read | Export the current canvas to a shareable excalidraw.com URL. The diagram is encrypted and uploaded; anyone with the URL can view it. Returns the shareable link. |
export_to_image | read | Export the current canvas to a PNG or SVG image. Renders headless in the canvas server (no browser tab needed); SVGs embed fonts. Set embedScene: true for a PNG that is also editable in Excalidraw. |
get_canvas_screenshot | read | Render the current canvas to a PNG and return it as an image. Renders headless in the canvas server (no browser tab needed). Use this to visually verify what the diagram looks like. |
get_element | read | Get a single Excalidraw element by ID |
get_resource | read | Get an Excalidraw resource |
group_elements | read | Group multiple elements together |
import_scene | write | Import elements and image files from .excalidraw JSON, Obsidian .excalidraw.md, a PNG with an embedded Excalidraw scene, or raw JSON data |
lock_elements | read | Lock elements to prevent modification |
query_elements | read | Query Excalidraw elements with optional filters |
read_diagram_guide | read | Returns a comprehensive design guide for creating beautiful Excalidraw diagrams: color palette, sizing rules, layout patterns, arrow binding best practices, diagram templates, and anti-patterns. Call this before creating diagrams to produce professional results. |
restore_snapshot | read | Restore the canvas from a previously saved named snapshot |
set_viewport | write | Control the canvas viewport (camera). Auto-fit all elements, zoom-to-fit a subset of elements, center on a specific element, or set zoom/scroll directly. Requires the canvas frontend open in a browser. |
snapshot_scene | write | Save a named snapshot of the current canvas state for later restoration |
ungroup_elements | read | Ungroup a group of elements |
unlock_elements | read | Unlock elements to allow modification |
update_element | write | Update an existing Excalidraw element |
Trust audit
CAUTIONgrade B · trust 89/100 Install with care. The audit found things worth knowing before you trust its output.
| Layer | What it checks | Result |
|---|---|---|
| L0 | Provenance & inventory | PASS |
| L1 | Static analysis of the code | WARN |
| L2 | Instruction surface (what it tells the agent) | PASS |
| L3 | Class-specific surface | WARN |
| L4 | Behavioural (sandbox) | SKIPPED |
What the source does
- Filesystem
- declared (9 observation(s))
- Network
- declared (6 observation(s))
- Shell
- none-observed
- Dependencies
- not all pinned
- Secrets in source
- none-found
Findings (15)
ENV EXPRESS_SERVER_URL=http://127.0.0.1:3000
clear_canvas, delete_element
import { ensureCanvasRunning } from '../../core/spawn.js';} from '../../core/geometry.js';
import { prepareElement, prepareElementUpdate } from '../../core/normalize.js';} from '../../core/canvas-client.js';
import { ensureCanvasRunning } from '../../core/spawn.js';- **Canvas server**: Excalidraw web UI + REST API + WebSocket real-time sync (default `http://127.0.0.1:3000`)
then tell me I can open http://127.0.0.1:3000 to watch you draw (optional).
There is no separate server setup: any drawing command auto-starts the local canvas server on `http://127.0.0.1:3000`.
open http://127.0.0.1:3000 # optional: watch live (only mermaid needs the tab)
const bytes = Uint8Array.from(atob(data), character => character.charCodeAt(0));
@resvg/resvg-js, cors, dotenv, express, jsdom, winston, ws, zod
No API key is required. Core drawing runs locally under MIT license. Outbound traffic is limited to the canvas page loading Excalidraw's fonts from the esm.sh CDN and the optional `share` upload to ex
demo.gif
Gates applied: no_behavioural_pass.
d405454fc9a3full audit observations/trust-audit/mcp-server/yctimlin__mcp_excalidraw.json · Report an issue / request a re-scanAudit history
Every audit this server has had. A grade with a past is a grade somebody is still checking.
| Date | Source | Verdict | Grade | Score | Change |
|---|---|---|---|---|---|
| 2026-10-12 | d405454fc9a3 | CAUTION | B | 89 | first audit |
Questions
What is the mcp-excalidraw-server MCP server?
MCP server and Claude Code skill for Excalidraw — programmatic canvas toolkit to create, edit, and export diagrams via AI agents with real-time canvas sync.
What tools does mcp-excalidraw-server expose?
26 in total: 16 read-only, 8 that write, and 2 that can delete or overwrite (clear_canvas, delete_element). Every one is listed on this page with its risk.
Is mcp-excalidraw-server safe to connect to an agent?
With care. The audit graded it B (89/100) and found 15 things worth knowing before you trust this server, listed below with the exact line each was found on. Separately from the audit: 2 of its tools can destroy data, so scope the token you give it to what you actually need.
What credentials does mcp-excalidraw-server need?
No credential environment variables were found in its source, so it appears to need none.
How current is this page?
The grade is for one exact copy of the source (d405454fc9a3), read on 2026-10-12. The repository is watched and re-audited when it changes.