mermaid

mermaid is a skill for Claude Code, Codex from bex-co/bex. It costs 37 tokens per session (759 once invoked), scanned A, original, Apache-2.0.

A guide for creating concise Mermaid diagrams of software architecture and dependency flows. Mermaid is a text format that renders diagrams from plain-text definitions.

In plain words
What is it for?
Use it to document services, databases, users, deployment relationships, scheduled jobs, configuration objects, and manual recovery flows.
Why use it?
It helps turn a system description or repository structure into a readable diagram while keeping dependencies and operating environments clear.

Skill for Claude CodeCodex

Written for Claude Code and Codex: allowed-tools in frontmatter, but also agents/openai.yaml present. Also seen: mentions Codex.

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/bex-co/bex/mermaid
Any agent
npx skills add bex-co/bex --skill mermaid
Clone the repo
git clone --depth 1 https://github.com/bex-co/bex

Made for: Claude Code, Codex.

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 mermaid

README.md
[![agentmods](https://agentmods.dev/badge/skills/bex-co/bex/mermaid.svg)](https://agentmods.dev/skills/bex-co/bex/mermaid)
Your own site
<a href="https://agentmods.dev/skills/bex-co/bex/mermaid"><img src="https://agentmods.dev/badge/skills/bex-co/bex/mermaid.svg" alt="Measured on agentmods" height="20"></a>
Per session 37 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 759 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
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.

ModelPer sessionOnce invoked
Fable 5.1 $0.00037 $0.00759
Opus 5 $0.00018 $0.00380
Sonnet 5 $0.00007 $0.00152
Haiku 4.5 $0.00004 $0.00076

Measured 6d ago against content hash 0b9840acc9c8, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-06, from the pricing page.

Security

Grade A, and why

mermaid 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 6d 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.

.claude/skills/mermaid/SKILL.md · 31 lines

How it starts

The opening of the file, as written. The whole thing — 31 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Draw a mermaid architecture diagram in markdown for: $ARGUMENTS

Conventions

  • Boxes are services/components: svc[bex-api]. Use [(...)] for datastores. Humans (user, developer, operator) are triangles: user@{ shape: tri, label: "user" }.
  • A box that is not a long-running service must say so in its label — readers assume boxes are services and ask "where is this running?". Mark scheduled/ephemeral work (cron["backup pod (spawned nightly, exits when done)"]) and inert config objects (secret["Secret foo (k8s object, created once)"]). Draw humans as triangles: operator@{ shape: tri, label: "operator" }. Never draw a manual procedure as a peer box of running infrastructure: give runbook/recovery flows their own subgraph whose title says it's manual and where it runs (subgraph "disaster recovery — manual runbook, any docker host"), with the human actor inside.
  • Arrows are dependency direction: A --> B means A depends on (calls, reads, deploys to) B — never the reverse.
  • Concise but to the point: only load-bearing services and edges. No styling, no colors, no legend. Label an edge (A -->|gRPC| B) only when the relationship isn't obvious. Default to flowchart TB; use LR only if the graph is much wider than deep. Use subgraph only for real boundaries (cluster, node, network, trust zone, automated vs. manual) — subgraphs are how the diagram answers "where does this run?". An edge may target a whole subgraph by id (subgraph cluster["app cluster"]op --> cluster).
  • If $ARGUMENTS refers to this repo, read the relevant docs/code first (docs/ADR002-architecture.md is the map) — don't diagram from guesswork.

Syntax gotchas that break rendering: quote labels containing (, ), [, {, or -->-like text (a["Queue (SQS)"]); never name a node bare end or graph; subgraph titles with spaces need quotes.

Verify (mandatory, before answering)

  1. Write the diagram body (no ```mermaid fence) to a .mmd file in the scratchpad (e.g. /tmp/diagram.mmd or the current workspace).
  2. Run: npx -y @mermaid-js/[email protected] -i <file>.mmd -o <file>.svg — exit 0 means the syntax is valid. (First run downloads a headless browser; that's expected.) The version is pinned deliberately (supply-chain: codex-security #17) — bump it consciously, don't revert to floating.
  3. On failure, read the parse error, fix the diagram, and re-verify. Never output a diagram that hasn't passed.

Read the full file on GitHub · 31 lines

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. 6d ago First seen · 31 lines · 37 tokens per session scan A 0b9840acc9c8

Subscribe to this mod's changes

mermaid is a skill published in the GitHub repository bex-co/bex (420 stars, last pushed today), licensed Apache-2.0. It adds 37 tokens to every session and 759 once invoked, about $0.0002 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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