excalidraw

excalidraw is a skill for Claude Code, Codex from johnlarkin1/claude-code-extensions. It costs 95 tokens per session (1,285 once invoked), scanned A, original, no licence file.

A coding skill for generating Excalidraw files, which are hand-drawn-style diagrams used for whiteboarding and visual documentation.

In plain words
What is it for?
Use it to create flowcharts, architecture and sequence diagrams, mind maps, wireframes, and organisation charts.
Why use it?
It helps turn system designs and processes into editable diagrams rather than leaving them as prose.

Skill for Claude CodeCodex

Part of the diagram-code plugin — 3 skills, 1 agent shipped together

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/johnlarkin1/claude-code-extensions/excalidraw
Any agent
npx skills add johnlarkin1/claude-code-extensions --skill excalidraw
Clone the repo
git clone --depth 1 https://github.com/johnlarkin1/claude-code-extensions

Made for: Claude Code, Codex.

Or install diagram-code, the plugin that ships this one along with the rest of its 3 skills, 1 agent.

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.

agentmods badge for excalidraw

README.md
[![agentmods](https://agentmods.dev/badge/skills/johnlarkin1/claude-code-extensions/excalidraw.svg)](https://agentmods.dev/skills/johnlarkin1/claude-code-extensions/excalidraw)
Your own site
<a href="https://agentmods.dev/skills/johnlarkin1/claude-code-extensions/excalidraw"><img src="https://agentmods.dev/badge/skills/johnlarkin1/claude-code-extensions/excalidraw.svg" alt="Measured on agentmods" height="20"></a>
Per session 95 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,285 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin unknown 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.

ModelPer sessionOnce invoked
Fable 5 $0.00095 $0.01285
Opus 5 $0.00048 $0.00642
Sonnet 5 $0.00019 $0.00257
Haiku 4.5 $0.00010 $0.00128

Measured 4d ago against content hash 35913521d4d9, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

excalidraw 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 4d 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.

plugins/diagram-code/skills/excalidraw/SKILL.md · 150 lines

The source is not reproduced here

No licence file

A repository with no LICENSE is all rights reserved by default, so the body is not copied here. The metadata, the measurements and the link are.

Read it on GitHub

Files

What ships with it

1 file beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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.

  1. 4d ago First seen · 150 lines · 95 tokens per session scan A 35913521d4d9

Subscribe to this mod's changes

excalidraw is a skill published in the GitHub repository johnlarkin1/claude-code-extensions (21 stars, last pushed 1mo ago), with no licence file. It adds 95 tokens to every session and 1,285 once invoked, about $0.0005 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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