schema-designer

schema-designer is a skill for Claude Code from clidey/whodb. It costs 34 tokens per session (1,339 once invoked), scanned A, original, Apache-2.0.

A guide for planning database tables and the relationships between them. A database schema is the organised design of the data, including tables, columns, types, keys, and links between records.

In plain words
What is it for?
Use it to design schemas, create tables, add columns, model relationships, choose data types, and produce SQL statements for PostgreSQL, MySQL, or SQLite.
Why use it?
It helps turn a description of the data into a structure that fits the project and avoids unnecessary duplication. It also checks related tables before suggesting changes.

Skill for Claude Code

Written for Claude Code: shipped in a Claude Code plugin.

Part of the whodb plugin — 2 skills shipped together

Good fit Use it to design schemas, create tables, add columns, model relationships, choose data types, and produce SQL statements for PostgreSQL, MySQL, or SQLite.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/clidey/whodb/schema-designer
About the project

WhoDB is a self-hosted workspace for exploring and managing databases through a browser, desktop app, or terminal interface. Developers and data teams use it to browse and edit data, run queries, inspect table relationships, move data, and optionally ask questions through an AI provider. The catalogue includes add-ons for operating WhoDB and working with its database tools.

clidey/whodb · 5,019 stars · on GitHub · whodb.com

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 clidey/whodb --skill schema-designer
Clone the repo
git clone --depth 1 https://github.com/clidey/whodb

Made for: Claude Code.

Or install whodb, the plugin that ships this one along with the rest of its 2 skills.

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 schema-designer

README.md
[![agentmods](https://agentmods.dev/badge/skills/clidey/whodb/schema-designer.svg)](https://agentmods.dev/skills/clidey/whodb/schema-designer)
Your own site
<a href="https://agentmods.dev/skills/clidey/whodb/schema-designer"><img src="https://agentmods.dev/badge/skills/clidey/whodb/schema-designer.svg" alt="Measured on agentmods" height="20"></a>
Per session 34 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,339 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. Third-party audits
  • NVIDIA SkillSpector pass 7 Sept 2026
How audits are shown
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 $0.00034 $0.01339
Opus 5 $0.00017 $0.00669
Sonnet 5 $0.00007 $0.00268
Haiku 4.5 $0.00003 $0.00134

Measured 8d ago against content hash 92b601743b75, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-07, from the pricing page.

Security

Grade A, and why

schema-designer 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 8d 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.

cli/external-plugin/whodb/skills/schema-designer/SKILL.md · 191 lines

How it starts

The opening of the file, as written. The whole thing — 191 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Schema Designer

Help users design database schemas, create tables, and model data relationships.

When to Use

Activate when user asks:

  • "Create a table for storing orders"
  • "Design a schema for a blog"
  • "Add a column to track user preferences"
  • "How should I model this relationship?"

Workflow

1. Understand Requirements

Ask clarifying questions:

  • What data needs to be stored?
  • What are the relationships between entities?
  • What queries will be common?
  • What's the expected data volume?

2. Check Existing Schema

whodb_tables() → See what already exists
whodb_columns(table="related_table") → Understand existing structure

3. Design the Schema

Follow database design principles:

  • Normalize to reduce redundancy
  • Use appropriate data types
  • Define primary keys
  • Establish foreign key relationships
  • Add indexes for common queries

4. Generate DDL

Provide CREATE TABLE statements with explanations.

Data Type Guidelines

Identifiers

Use Case PostgreSQL MySQL SQLite
Auto-increment ID SERIAL / BIGSERIAL INT AUTO_INCREMENT INTEGER PRIMARY KEY
UUID UUID CHAR(36) TEXT

Text

Use Case PostgreSQL MySQL SQLite
Short text (<255) VARCHAR(n) VARCHAR(n) TEXT
Long text TEXT TEXT TEXT
Fixed length CHAR(n) CHAR(n) TEXT

Numbers

Use Case PostgreSQL MySQL SQLite
Integer INTEGER INT INTEGER
Big integer BIGINT BIGINT INTEGER
Decimal (money) NUMERIC(10,2) DECIMAL(10,2) REAL
Float REAL FLOAT REAL

Dates

Use Case PostgreSQL MySQL SQLite
Date only DATE DATE TEXT
Timestamp TIMESTAMP DATETIME TEXT
With timezone TIMESTAMPTZ TIMESTAMP TEXT

Read the full file on GitHub · 191 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.

  1. 8d ago First seen · 191 lines · 34 tokens per session scan A 92b601743b75

Subscribe to this mod's changes

schema-designer is a skill published in the GitHub repository clidey/whodb (5,019 stars, last pushed yesterday), licensed Apache-2.0. It adds 34 tokens to every session and 1,339 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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