Excalidraw Toolkit
An AI-powered diagramming toolkit for Claude Code. Say "diagram this repo" and watch your codebase turn into an architecture diagram on a live Excalidraw canvas.
> diagram this repo
I found 6 components and 5 connections:
- Next.js Frontend → API Routes (REST)
- API Routes → Prisma ORM → PostgreSQL (SQL)
- API Routes → NextAuth (auth) + Stripe API (payments)
Does this look right?
> looks good
[Building diagram on live canvas...]
Install
npx excalidraw-toolkit init
npx excalidraw-toolkit start
Two commands. init copies skills to ~/.claude/plugins/ and configures the MCP server. start clones, builds, and launches the canvas server (first run), then opens your browser.
Restart Claude Code and try: "diagram this repo"
Verify setup with:
npx excalidraw-toolkit doctor
Alternative: install via Claude Code plugin marketplace
/plugin marketplace add edwingao28/excalidraw-skill
/plugin install excalidraw@excalidraw-skill
What You Get
Auto-Diagram — Zero-Config Codebase Visualization
Just say "diagram this repo". No description needed.
The auto-diagram skill runs a 6-phase pipeline:
- Detect project type (monorepo, microservices, standard app) and framework (Next.js, Django, Go, Rails, etc.)
- Discover components (frontend, API routes, database, queues, cache, auth, external services)
- Map connections between components (REST, SQL, gRPC, events, imports)
- Verify with you before drawing — presents a summary, asks for confirmation
- Choose layout (vertical flow, horizontal pipeline, hub-and-spoke, or zoned modules)
- Generate the diagram on the live canvas with color-coded components
Works with any language. Context budget prevents blowout on large codebases.
Agentic Self-Critique
Every diagram goes through an automatic quality check before you see it:
- Snapshot the canvas for rollback safety
- Geometric validation via
query_elements— detects overlapping shapes, cramped spacing, broken zones - Visual validation via screenshot — checks arrow labels, text readability, title, centering
- Auto-fix up to 2 rounds. If fixes make things worse, rolls back to the snapshot
You never see a broken diagram. The self-critique loop catches layout issues that would otherwise require manual tweaking.
Described Diagrams
When you know what you want, describe it:
"Draw a microservices architecture with: React frontend, API Gateway,
Auth Service, User Service, Order Service, RabbitMQ, PostgreSQL, Redis"
Or trace data flows:
"Trace how the auth token flows from login to API request to database query"
Or convert from Mermaid:
"Create an excalidraw diagram from this mermaid:
graph TD; A[Frontend] -->|REST| B[API]; B -->|SQL| C[Database]"
Examples
Same prompt, two renderers: Markdown (Mermaid via create_from_mermaid) vs Excalidraw (native canvas via batch_create_elements).
Microservices Architecture
| Markdown | Excalidraw |
|---|---|
 |  |
CI/CD Pipeline
| Markdown | Excalidraw |
|---|---|
 |  |
Event-Driven System
| Markdown | Excalidraw |
|---|---|
 |  |
Data Pipeline
| Markdown | Excalidraw |
|---|---|
 |  |
Architecture
The toolkit has three layers — only the first is bundled:
| Layer | What | Bundled? |
|---|---|---|
| Skills (this package) | Markdown prompts that guide Claude's diagram generation | Yes |
| MCP Server (mcp-excalidraw-server) | Bridge between Claude and the Excalidraw canvas — provides batch_create_elements, get_canvas_screenshot, etc. | No — auto-downloaded via npx -y on first use |
| Canvas Server (mcp_excalidraw-canvas) | Live Excalidraw editor running in your browser at localhost:3000 | No — auto-cloned and built on first npx excalidraw-toolkit start |
How It Works
Two skills, one toolkit:
| Skill | Triggers On | Does |
|---|---|---|
| auto-diagram | "diagram this repo", "visualize the architecture" | Analyzes codebase, discovers components, generates diagram |
| excalidraw | "draw a diagram of X", user provides description/sample | Renders user-specified diagrams with precise layout control |
Both skills use MCP tools to draw on a live Excalidraw canvas: