An entity-relationship diagram writing skill for showing data entities, their attributes, and their relationships. An entity-relationship diagram is commonly used to plan or explain a database design.

Use it to describe entities, fields, and one-to-one or one-to-many relationships, then render the result as an image or PDF.

It makes connections such as one person having many orders easier to understand than a list of tables alone. The diagram can be validated and rendered through uml-mcp.

erd — 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 erd

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/erd/github.svg)](https://agentmods.dev/skills/antoinebou12/uml-mcp/erd)

Your own site

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

Per session 49 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 386 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	$0.00049	$0.00386
Opus 5.5	$0.00020	$0.00154
Sonnet 5.5	$0.00010	$0.00077
Haiku 4.5	$0.00005	$0.00039

Measured 14d ago against content hash 806233689104, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

erd 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/erd/SKILL.md · 61 lines

What it actually says

erd diagram (uml-mcp)

diagram_type: erd
Backend: erd
Output formats: png, svg, jpeg, pdf

Entity-relationship 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

Entity titles and attribute lists are the main visual cues; keep names short.
No MCP theme param — layout clarity beats color.

Starter template

[Person]
*name
height
weight

[Order]
*id
date

Person 1--* Order

Example

[Person]
*name
height
weight

[Order]
*id
date

Person 1--* Order

Render with uml-mcp

Set diagram_type to erd exactly.
Call validate_uml when the source is untrusted (prefer strict: true for Mermaid sequence).
Call generate_uml, generate_uml_image (chat PNG), or generate_uml_batch.
Pass theme when this skill's Themes section lists supported values.
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.

14d ago First seen · 61 lines · 49 tokens per session scan A 806233689104

Subscribe to this mod's changes

erd is a skill published in the GitHub repository antoinebou12/uml-mcp (109 stars, last pushed yesterday), licensed MIT. It adds 49 tokens to every session and 386 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.

Databases mcp uml

erd next to 6 skills from other repositories
Mod	Type	Stars	Last push	Licence	Scan	Tokens	Works with
erdantoinebou12/uml-mcp	Skill	109	yesterday	MIT	A	49	Claude Code, Codex
detailed-designpan94u/forge	Skill	40	5d ago	none	A	27	Claude Code
create-prprisma/orm	Skill	48k	yesterday	Apache-2.0	A	48	Claude Code, Codex
schema-explorationlangchain-ai/deepagents	Skill	31k	yesterday	MIT	A	57	Claude Code, Codex
atlas-mssqlariga/atlas	Skill	8.8k	yesterday	Apache-2.0	A	163	Claude Code
ha-data-storesshiwenwen/hope-agent	Skill	1.9k	yesterday	MIT	A	115	Claude Code, Codex
nornicdb-cypher-queriesorneryd/NornicDB	Skill	923	yesterday	MIT	A	79	Claude Code, Codex