excalidraw — agent skill

Create and edit Excalidraw diagrams from Claude Code, Codex, or any agent harness — flowcharts, architecture diagrams, sequence diagrams, UML, Gantt charts, mind maps, wireframes, slide decks, roadmaps, personas, brainstorming boards, Lean Canvas, SWOT and competitor analyses, and game-design boards, aligned with the official Excalidraw use cases.

Backed by the official Excalidraw+ MCP server (https://api.excalidraw.com/api/v1/mcp) — scenes are created in your Excalidraw+ workspace, verified by screenshot, and returned as links.

Install

npx skills add NicholasSpisak/excalidraw

Works with the Vercel skills framework; installs for Claude Code, Codex, and other supported agents.

Credentials

You need an Excalidraw+ API key (Excalidraw+ → Settings → API keys). Never commit it. Provide it one of two ways:

# environment variable (works for the bundled CLI and Codex MCP config)
export EXCALIDRAW_API_KEY=sk-...

# or a key file the bundled CLI falls back to
mkdir -p ~/.config/excalidraw
printf '%s\n' 'sk-...' > ~/.config/excalidraw/api_key
chmod 600 ~/.config/excalidraw/api_key

Native MCP setup (optional, recommended)

The skill works out of the box through its bundled CLI. For native MCP tool calling, add the official server config:

Claude Code (~/.claude.json or .mcp.json):

{
  "mcpServers": {
    "excalidraw": {
      "type": "http",
      "url": "https://api.excalidraw.com/api/v1/mcp",
      "headers": {
        "Authorization": "Bearer <API_KEY>"
      }
    }
  }
}

Codex (~/.codex/config.toml):

[mcp_servers.excalidraw]
url = "https://api.excalidraw.com/api/v1/mcp"
env_http_headers = { Authorization = "EXCALIDRAW_API_KEY" }

With env_http_headers, the env var's value is injected verbatim as the header — set EXCALIDRAW_API_KEY="Bearer sk-...". (Codex's bearer_token_env_var alternative takes the raw key and adds Bearer itself. The bundled CLI accepts either form.)

Bundled CLI

node scripts/excal.mjs tools                    # list available tools
node scripts/excal.mjs help create_diagram      # print a tool's input schema
node scripts/excal.mjs call create_diagram --json '{"sceneId":"...","nodes":[...],"edges":[...]}'

Zero dependencies; Node ≥ 18.

What's inside

SKILL.md                 the skill: transport choice, workflow, rules
scripts/excal.mjs        MCP-over-HTTP CLI (auth via env var or key file)
references/use-cases.md  layout playbook per Excalidraw use case
references/api.md        tool catalog notes and sharp edges

License

MIT

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