agentmods.dev

blockdiag

blockdiag is a skill for Claude Code, Codex from antoinebou12/uml-mcp. It costs 51 tokens per session (417 once invoked), scanned A, original, MIT.

A writing guide for blockdiag diagrams, simple diagrams made from named boxes and arrows. The source can be rendered as PNG, SVG, or PDF.

In plain words
What is it for?
It is for showing straightforward connections such as user-to-system-to-database flows.
Why use it?
It helps the agent express relationships and simple flows in valid blockdiag syntax. It also supports basic node labels, shapes, sizes, and colours.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

not rated 109repo +1 yesterday A scan 51 tokens original MIT

Good fit It is for showing straightforward connections such as user-to-system-to-database flows.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/antoinebou12/uml-mcp/blockdiag
View source ↗ antoinebou12/uml-mcp antoinebou12.github.io
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.

Any agent
npx skills add antoinebou12/uml-mcp --skill blockdiag
Clone the repo
git clone --depth 1 https://github.com/antoinebou12/uml-mcp

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 blockdiag

README.md
[![agentmods](https://agentmods.dev/badge/skills/antoinebou12/uml-mcp/blockdiag/github.svg)](https://agentmods.dev/skills/antoinebou12/uml-mcp/blockdiag)
Your own site
<a href="https://agentmods.dev/skills/antoinebou12/uml-mcp/blockdiag"><img src="https://agentmods.dev/badge/skills/antoinebou12/uml-mcp/blockdiag/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.

agentmods 80×15 button for blockdiag

Your own site · 80×15
<a href="https://agentmods.dev/skills/antoinebou12/uml-mcp/blockdiag"><img src="https://agentmods.dev/badge/skills/antoinebou12/uml-mcp/blockdiag.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 51 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 417 The whole file, excluding the scripts and references it only reads on demand.
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.

ModelPer sessionOnce invoked
Fable 5.1 $0.00051 $0.00417
Opus 5.5 $0.00020 $0.00167
Sonnet 5.5 $0.00010 $0.00083
Haiku 4.5 $0.00005 $0.00042

Measured 14d ago against content hash d8d2fb3203e3, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

blockdiag 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 14d 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.

.skill/skills/blockdiag/SKILL.md · 52 lines

What it actually says

blockdiag diagram (uml-mcp)

diagram_type: blockdiag
Backend: blockdiag
Output formats: png, svg, pdf

Simple block diagram images

Load the workflow skill uml-mcp-diagrams for URL-first replies, progressive discovery, and which MCP tool to call. This file is notation only; it does not add an MCP tool.

Styling

  • Optional default_shape, node_width, colors via color = "…" on nodes.
  • Keep to one row/column flow for chat thumbnails.

Starter template

blockdiag {
  User -> System -> Database;
  System -> User;
}

Example

blockdiag {
  Kroki -> generates -> "Block diagrams";
  Kroki -> is -> "very easy!";
  Kroki [color = "greenyellow"];
  "Block diagrams" [color = "pink"];
  "very easy!" [color = "orange"];
}

Render with uml-mcp

  1. Set diagram_type to blockdiag exactly.
  2. Call validate_uml when the source is untrusted (prefer strict: true for Mermaid sequence).
  3. Call generate_uml, generate_uml_image (chat PNG), or generate_uml_batch.
  4. Pass theme when this skill's Themes section lists supported values.
  5. Surface the returned url / playground (see the workflow skill).

Confirm formats with uml://formats or list_diagram_types when unsure.

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. 14d ago First seen · 52 lines · 51 tokens per session scan A d8d2fb3203e3

Subscribe to this mod's changes

blockdiag is a skill published in the GitHub repository antoinebou12/uml-mcp (109 stars, last pushed yesterday), licensed MIT. It adds 51 tokens to every session and 417 once invoked, about $0.0002 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 2026-10-24.

Design and UXmcpuml
Related

blockdiag compared with skills from other repositories

blockdiag next to 6 skills from other repositories
ModTypeStarsLast pushLicenceScanTokensWorks with
blockdiagantoinebou12/uml-mcpSkill109yesterdayMITA51Claude Code, Codex
detailed-designpan94u/forgeSkill405d agononeA27Claude Code
architecture-diagram-creatorbookforge-ai/bookforge-skillsSkill426mo agoCC-BY-SA-4.0A128Claude Code
webgl-holographic-foilnexu-io/open-designSkill106kyesterdayApache-2.0A41Claude Code, Codex
html-ppt-hermes-cyber-terminalnexu-io/open-designSkill106kyesterdayApache-2.0A53Claude Code, Codex
html-ppt-taste-brutalistnexu-io/open-designSkill106kyesterdayApache-2.0A78Claude Code, Codex
visual-ralphYeachan-Heo/oh-my-codexSkill34k3d agoMITA52Codex