What is excalidraw-mcp GEMINI.md?

Repository instructions for an Excalidraw integration that lets AI agents create and change diagrams on a shared Excalidraw canvas. Excalidraw is a web drawing tool, while MCP is a way for AI assistants to call external tools.

Use them when building, running, or modifying the Excalidraw MCP server, canvas API, real-time updates, or frontend.

They give the coding agent the project structure, technologies, and operating requirements needed to work across its Python server, TypeScript canvas server, and React interface.

How lesleslie/excalidraw-mcp configures Gemini CLI

Reuse

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.

Copy the file

curl -O https://raw.githubusercontent.com/lesleslie/excalidraw-mcp/main/GEMINI.md

Clone the repo

git clone --depth 1 https://github.com/lesleslie/excalidraw-mcp

Made for: Gemini CLI.

Wrote 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.

README.md

[![agentmods](https://agentmods.dev/badge/instructions/lesleslie/excalidraw-mcp/gemini-md/github.svg)](https://agentmods.dev/instructions/lesleslie/excalidraw-mcp/gemini-md)

Your own site

<a href="https://agentmods.dev/instructions/lesleslie/excalidraw-mcp/gemini-md"><img src="https://agentmods.dev/badge/instructions/lesleslie/excalidraw-mcp/gemini-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.

Your own site · 80×15

<a href="https://agentmods.dev/instructions/lesleslie/excalidraw-mcp/gemini-md"><img src="https://agentmods.dev/badge/instructions/lesleslie/excalidraw-mcp/gemini-md.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 696 This file is loaded in full into every session.

When invoked 696 The same file — it is already loaded in full.

Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.

Origin original No closer match found in the catalogue.

Token cost

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	$0.00696	$0.00696
Opus 5.5	$0.00278	$0.00278
Sonnet 5.5	$0.00139	$0.00139
Haiku 4.5	$0.00070	$0.00070

Measured 2mo ago against content hash ddd4c728867b, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

excalidraw-mcp GEMINI.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 2mo 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.

GEMINI.md · 90 lines

How it starts

The opening of the file, as written. The whole thing — 90 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Gemini Code Assistant Context

This document provides context for the Gemini Code Assistant to understand the excalidraw-mcp project.

Project Overview

excalidraw-mcp is a dual-language system that enables AI agents to create and manipulate Excalidraw diagrams in real-time. It consists of two main components:

Python MCP Server: A Python-based server using the Model Context Protocol (MCP) that exposes tools for AI agents to interact with the Excalidraw canvas. It's built with fastmcp and manages the lifecycle of the canvas server.
TypeScript Canvas Server: A Node.js server built with Express.js and WebSockets that manages the Excalidraw canvas. It provides a REST API for element management and uses WebSockets to synchronize the canvas state with connected clients in real-time. The frontend is a React application that displays the Excalidraw canvas.

The Python MCP server receives commands from an AI agent, translates them into API calls to the TypeScript canvas server, which then updates the canvas and broadcasts the changes to all connected web clients.

Key Technologies

Backend (MCP Server): Python, fastmcp, httpx, pydantic
Backend (Canvas Server): Node.js, TypeScript, Express.js, WebSockets (ws), zod
Frontend: React, TypeScript, Vite
Package Management: uv for Python, npm for Node.js
Testing: pytest for Python, jest for TypeScript

Building and Running

Prerequisites

Python 3.13+
Node.js 16+
uv (for Python package management)

Installation

Clone the repository:

git clone https://github.com/lesleslie/excalidraw-mcp.git
cd excalidraw-mcp

Install Python dependencies:
```
uv sync
```
Install Node.js dependencies:
```
npm install
```

Running the System

The Python MCP server is the main entry point and will automatically start the TypeScript canvas server.

uv run python excalidraw_mcp/server.py

Read the full file on GitHub · 90 lines

Changes

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.

2mo ago First seen · 90 lines · 696 tokens per session scan A ddd4c728867b

Subscribe to this mod's changes

excalidraw-mcp GEMINI.md is an instructions file published in the GitHub repository lesleslie/excalidraw-mcp (15 stars, last pushed 1mo ago), licensed BSD-3-Clause. It adds 696 tokens to every session, about $0.0028 per session on Opus 5.5. 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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excalidraw-mcp: Instructions file for Gemini CLI