Borrowing it
Nothing to install: this file belongs to lesleslie/excalidraw-mcp. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/lesleslie/excalidraw-mcp/main/CLAUDE.mdgit clone --depth 1 https://github.com/lesleslie/excalidraw-mcpWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/instructions/lesleslie/excalidraw-mcp/claude-md)<a href="https://agentmods.dev/instructions/lesleslie/excalidraw-mcp/claude-md"><img src="https://agentmods.dev/badge/instructions/lesleslie/excalidraw-mcp/claude-md/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/instructions/lesleslie/excalidraw-mcp/claude-md"><img src="https://agentmods.dev/badge/instructions/lesleslie/excalidraw-mcp/claude-md.svg" alt="Reviewed on agentmods" width="80" height="20"></a>What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.01192 | $0.01192 |
| Opus 5 | $0.00596 | $0.00596 |
| Sonnet 5 | $0.00238 | $0.00238 |
| Haiku 4.5 | $0.00119 | $0.00119 |
Grade A, and why
excalidraw-mcp CLAUDE.md scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 9d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 133 lines — stays where its author put it; the contents beside it link to each section on GitHub.
CLAUDE.md
This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.
For a shorter, tool-neutral bootstrap document, start with AGENTS.md.
Project Overview
excalidraw-mcp is a dual-language MCP server for manipulating a live Excalidraw canvas.
Core parts:
excalidraw_mcp/: Python FastMCP server and canvas-process supervisionsrc/: TypeScript canvas server, HTTP API, and WebSocket coordinationfrontend/src/: React Excalidraw client
The Python server owns the MCP protocol surface and supervises the TypeScript canvas service.
Key Constraints
- The Python and TypeScript halves must stay in sync on payload shape and element semantics.
- The canvas server is process-managed by the MCP server unless the task explicitly targets standalone canvas work.
- Element storage is in-memory; do not assume persistence unless you are adding it intentionally.
- Environment-driven security settings must remain configuration, not code constants.
Development Commands
Setup
uv sync
npm install
npm run build
Main Workflows
uv run python excalidraw_mcp/server.py
npm run dev
npm run canvas
npm run production
npm run type-check
uv run pytest
Useful Validation
npm run build:frontend
npm run build:server
npm run test:coverage
uv run ruff check --fix
Quality Workflow
Use Crackerjack-aligned Python quality checks for the repo's CI path, and pair them with the TypeScript build, type-check, and test flow whenever a change crosses stacks.
Architecture Notes
The runtime path is:
- MCP tool call in Python
- HTTP call to the TypeScript canvas API
- WebSocket broadcast to connected clients
- canvas update in the React frontend
Keep responsibilities split this way:
- Python: MCP interface, validation, process lifecycle, recovery behavior
- TypeScript server: element state, HTTP API, WebSocket fanout
- React: rendering and client synchronization
If a change crosses layers, update the shared types and confirm the request and response contracts still match.
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 9d ago First seen · 133 lines · 1,192 tokens per session scan A 6e35d16c61f3
excalidraw-mcp CLAUDE.md is an instructions file published in the GitHub repository lesleslie/excalidraw-mcp (14 stars, last pushed 8d ago), licensed BSD-3-Clause. It adds 1,192 tokens to every session, about $0.0060 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
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