excalidraw-diagram

A tool that creates Excalidraw JSON files for diagrams that explain workflows, system designs, and other relationships visually. Excalidraw is a drawing format and app for making editable hand-drawn-style diagrams.

In plain words
What is it for?
Use it to create diagrams of processes, software architectures, and concepts for documentation or discussion.
Why use it?
It helps turn a complex explanation into a visual argument showing how parts connect or what causes what.

Skill for Claude CodeCodex

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/shellydeng08/codebase-slideshow/excalidraw
Any agent
npx skills add ShellyDeng08/codebase-slideshow --skill excalidraw
Clone the repo
git clone --depth 1 https://github.com/ShellyDeng08/codebase-slideshow

Made for: Claude Code, Codex.

Per session 34 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 5,460 The whole file, excluding the scripts and references it only reads on demand.
Security scan B 1 finding. Scan, not verified.
Origin 91% copy Near-identical to another mod 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 $0.00034 $0.05460
Opus 5 $0.00017 $0.02730
Sonnet 5 $0.00007 $0.01092
Haiku 4.5 $0.00003 $0.00546

Measured yesterday against content hash febfa71b6147, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade B, and why

excalidraw-diagram scanned grade B with 1 finding 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 yesterday.

The scan reads SKILL.md. This mod also ships 1 executable file (render_excalidraw.py), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

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.

Subtle steeringmediumPrompt injection

Instructions that bias recommendations or shape behaviour without the user noticing.

- **Don't write a Python generator script.** The templating and coordinate math seem helpful but introduce a layer of indirection that makes debugging harder. Hand-crafted JSON with descriptive IDs is more maintainable.
Origin

This is a copy

91% identical to excalidraw-diagram — 324 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

excalidraw/SKILL.md · 553 lines

How it starts

The opening of the file, as written. The whole thing — 553 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Excalidraw Diagram Creator

Generate .excalidraw JSON files that argue visually, not just display information.

Setup: If the user asks you to set up this skill (renderer, dependencies, etc.), see README.md for instructions.

Customization

All colors and brand-specific styles live in one file: references/color-palette.md. Read it before generating any diagram and use it as the single source of truth for all color choices — shape fills, strokes, text colors, evidence artifact backgrounds, everything.

To make this skill produce diagrams in your own brand style, edit color-palette.md. Everything else in this file is universal design methodology and Excalidraw best practices.


Core Philosophy

Diagrams should ARGUE, not DISPLAY.

A diagram isn't formatted text. It's a visual argument that shows relationships, causality, and flow that words alone can't express. The shape should BE the meaning.

The Isomorphism Test: If you removed all text, would the structure alone communicate the concept? If not, redesign.

The Education Test: Could someone learn something concrete from this diagram, or does it just label boxes? A good diagram teaches—it shows actual formats, real event names, concrete examples.


Depth Assessment (Do This First)

Before designing, determine what level of detail this diagram needs:

Simple/Conceptual Diagrams

Use abstract shapes when:

  • Explaining a mental model or philosophy
  • The audience doesn't need technical specifics
  • The concept IS the abstraction (e.g., "separation of concerns")

Comprehensive/Technical Diagrams

Use concrete examples when:

  • Diagramming a real system, protocol, or architecture
  • The diagram will be used to teach or explain (e.g., YouTube video)
  • The audience needs to understand what things actually look like
  • You're showing how multiple technologies integrate

For technical diagrams, you MUST include evidence artifacts (see below).


Research Mandate (For Technical Diagrams)

Read the full file on GitHub · 553 lines

Files

What ships with it

6 files 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. yesterday First seen · 553 lines · 34 tokens per session scan B febfa71b6147

Subscribe to this mod's changes

excalidraw-diagram is a skill published in the GitHub repository ShellyDeng08/codebase-slideshow (2 stars, last pushed 5mo ago), licensed MIT. It adds 34 tokens to every session and 5,460 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it B with 1 finding (subtle steering). It is 91% identical to excalidraw-diagram, differing in 324 lines, and is treated as a copy.

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