A writing guide for bytefield diagrams, which show how bits and bytes are arranged in a binary message or protocol packet. It uses a Lisp-like source format and renders to SVG.

It is for documenting network packets, file formats, and other binary data layouts.

It makes binary layouts easier to describe consistently than a plain text explanation. The diagram can show fields, widths, headers, and payload areas.

bytefield — Skill for Claude Code and Codex by antoinebou12/uml-mcp

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 bytefield

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.

README.md

[![agentmods](https://agentmods.dev/badge/skills/antoinebou12/uml-mcp/bytefield/github.svg)](https://agentmods.dev/skills/antoinebou12/uml-mcp/bytefield)

Your own site

<a href="https://agentmods.dev/skills/antoinebou12/uml-mcp/bytefield"><img src="https://agentmods.dev/badge/skills/antoinebou12/uml-mcp/bytefield/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/skills/antoinebou12/uml-mcp/bytefield"><img src="https://agentmods.dev/badge/skills/antoinebou12/uml-mcp/bytefield.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 53 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 979 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.

Model	Per session	Once invoked
Fable 5.1	$0.00053	$0.00979
Opus 5.5	$0.00021	$0.00392
Sonnet 5.5	$0.00011	$0.00196
Haiku 4.5	$0.00005	$0.00098

Measured 14d ago against content hash 8a9dbcb342da, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

bytefield 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/bytefield/SKILL.md · 94 lines

How it starts

The opening of the file, as written. The whole thing — 94 lines — stays where its author put it; the contents beside it link to each section on GitHub.

bytefield diagram (uml-mcp)

diagram_type: bytefield
Backend: bytefield
Output formats: svg

Binary protocol and byte layout diagrams

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

Use (defattrs … {:fill "#…"}) for row colors.
No MCP theme param.

Starter template

(defattrs :bg-green {:fill "#a0ffa0"})
(defattrs :bg-yellow {:fill "#ffffa0"})
(defattrs :bg-pink {:fill "#ffb0a0"})
(defattrs :bg-cyan {:fill "#a0fafa"})
(defattrs :bg-purple {:fill "#e4b5f7"})

(def row-height 40)
(def row-header-width 50)
(def box-width 30)

(defn draw-packet-header
  []
  (draw-column-headers)
  (draw-box "Version" {:span 8})
  (draw-box "Flags" {:span 8})
  (draw-gap "Payload")
  (draw-bottom))

(draw-packet-header)

Example

(defattrs :bg-green {:fill "#a0ffa0"})
(defattrs :bg-yellow {:fill "#ffffa0"})
(defattrs :bg-pink {:fill "#ffb0a0"})
(defattrs :bg-cyan {:fill "#a0fafa"})
(defattrs :bg-purple {:fill "#e4b5f7"})
(defn draw-group-label-header
  [span label]
  (draw-box (text label [:math {:font-size 12}]) {:span span :borders #{} :height 14}))
(defn draw-remotedb-header
  [kind args]
  (draw-column-headers)
  (draw-group-label-header 5 "start")
  (draw-group-label-header 5 "TxID")
  (draw-group-label-header 3 "type")
  (draw-group-label-header 2 "args")
  (draw-group-label-header 1 "tags")
  (next-row 18)
  (draw-box 0x11 :bg-green)
  (draw-box 0x872349ae [{:span 4} :bg-green])
  (draw-box 0x11 :bg-yellow)
  (draw-box (text "TxID" :math) [{:span 4} :bg-yellow])
  (draw-box 0x10 :bg-pink)
  (draw-box (hex-text kind 4 :bold) [{:span 2} :bg-pink])
  (draw-box 0x0f :bg-cyan)
  (draw-box (hex-text args 2 :bold) :bg-cyan)
  (draw-box 0x14 :bg-purple)
  (draw-box (text "0000000c" :hex [[:plain {:font-weight "light" :font-size 16}] " (12)"]) [{:span 4} :bg-purple])
  (draw-box (hex-text 6 2 :bold) [:box-first :bg-purple])
  (doseq [val [6 6 3 6 6 6 6 3]]
    (draw-box (hex-text val 2 :bold) [:box-related :bg-purple]))
  (doseq [val [0 0]]
    (draw-box val [:box-related :bg-purple]))
  (draw-box 0 [:box-last :bg-purple]))
(draw-remotedb-header 0x4702 9)

Read the full file on GitHub · 94 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.

14d ago First seen · 94 lines · 53 tokens per session scan A 8a9dbcb342da

Subscribe to this mod's changes

bytefield is a skill published in the GitHub repository antoinebou12/uml-mcp (109 stars, last pushed yesterday), licensed MIT. It adds 53 tokens to every session and 979 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.

Hardware and IoT mcp uml

bytefield next to 6 skills from other repositories
Mod	Type	Stars	Last push	Licence	Scan	Tokens	Works with
bytefieldantoinebou12/uml-mcp	Skill	109	yesterday	MIT	A	53	Claude Code, Codex
gke-compute-classesgoogle/skills	Skill	22k	yesterday	Apache-2.0	A	83	Claude Code, Codex
jetson-diagnosticNVIDIA/skills	Skill	3.9k	yesterday	Apache-2.0	A	30	Claude Code, Codex
holoscan-install-wheelNVIDIA/skills	Skill	3.9k	yesterday	Apache-2.0	A	34	Claude Code, Codex
offensive-z-waveSnailSploit/Claude-Red	Skill	10k	25d ago	MIT	A	113	Claude Code, Codex
doca-socket-relayNVIDIA/skills	Skill	3.9k	yesterday	Apache-2.0	A	236	Claude Code, Codex
hsb-flashNVIDIA/skills	Skill	3.9k	yesterday	Apache-2.0	B	94	Claude Code