What do I need to use Entity-Relationship Diagram?

The entities; Relationships; Key attributes; The domain.

Is Entity-Relationship Diagram free to use?

Yes — run it free in the browser playground (no API key needed for the sponsored trial, or bring any provider key), or install it into Claude Code, Cursor, ChatGPT and more via npx pm-claude-skills. MIT-licensed and open source.

Entity-Relationship Diagram

Q: How do I know the Entity-Relationship Diagram output is good?

The skill verifies itself against its own quality checks: Every relationship has explicit, correct cardinality (not just a plain line); Primary and foreign keys are marked (PK/FK); Many-to-many relationships are resolved with a join entity where appropriate; Attribute types are sensible for the domain.

🔵 Stable🕐 updated 2026-10-06 🔷 SkillSpec L3 pm-visuals

Turn a data model into an entity-relationship (ER) diagram. Use when asked to design a schema, model data, show how tables/entities relate, or diagram a database. Produces a ready-to-render Mermaid ER diagram (renders live, exportable as PNG/SVG) plus key attributes, cardinality, and design notes.

▶ Run it free — no key needed 📝 Grade your existing draft ⬇ Add to Claude (works in Duet) 📱 Use as an app View SKILL.md ↗ What changed

🗣 Say this to your agent

“Design a schema.”“Model data.”“Show how tables/entities relate.”“Diagram a database.”

What to give it

▸The entities — the core objects/tables (User, Order, Product…).

▸Relationships — how they relate, and the cardinality (a user *has many* orders, an order *has many* line items).

▸Key attributes — the important fields per entity (especially keys); full column lists aren't required.

▸The domain — what the system does, so the model is realistic.

✅ The bar it holds itself to

Every skill in this library self-verifies — these are this skill's own quality checks, straight from its definition.

✓Every relationship has explicit, correct cardinality (not just a plain line)

✓Primary and foreign keys are marked (PK/FK)

✓Many-to-many relationships are resolved with a join entity where appropriate

✓Attribute types are sensible for the domain

✓The Mermaid block renders without edits

⚠️ What it refuses to do

Do not draw relationships without cardinality — "related" isn't a data model

Do not leave many-to-many unresolved when a join table is the right call

Do not dump every conceivable column — show the keys and the attributes that matter

Do not omit foreign keys — they're how the relationships are actually enforced

Do not break Mermaid with unquoted spaced labels

Install

npx pm-claude-skills add --agent claude   # or codex · cursor · gemini · hermes
# or one-line MCP (every skill, any client):
claude mcp add pm-skills -- npx -y -p pm-claude-skills pm-claude-skills-mcp

Related skills

🔌 Embed this skill

Drop this on your blog, docs, or site — it renders a "Run this skill" card:

<div data-pm-skill="entity-relationship-diagram"></div>
<script src="https://mohitagw15856.github.io/pm-claude-skills/embed.js" async></script>

💬 Discussion

Entity-Relationship Diagram is one of 1326 open-source professional AI agent skills — all SkillSpec L3. Try them all in the browser · ⭐ Star on GitHub · Browse the full catalog