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.
npx skills add OneWave-AI/claude-skills --skill database-schema-designergit clone --depth 1 https://github.com/OneWave-AI/claude-skillsWrote 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.
[](https://agentmods.dev/skills/onewave-ai/claude-skills/database-schema-designer)<a href="https://agentmods.dev/skills/onewave-ai/claude-skills/database-schema-designer"><img src="https://agentmods.dev/badge/skills/onewave-ai/claude-skills/database-schema-designer/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.
<a href="https://agentmods.dev/skills/onewave-ai/claude-skills/database-schema-designer"><img src="https://agentmods.dev/badge/skills/onewave-ai/claude-skills/database-schema-designer.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- Socket pass
- Snyk pass
- NVIDIA SkillSpector pass
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 | $0.00141 | $0.01452 |
| Opus 5.5 | $0.00056 | $0.00581 |
| Sonnet 5.5 | $0.00028 | $0.00290 |
| Haiku 4.5 | $0.00014 | $0.00145 |
Grade A, and why
database-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 1mo 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.
How it starts
The opening of the file, as written. The whole thing — 62 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Database Schema Designer
Design a schema that enforces the data's rules in the database and makes the app's real queries fast.
Workflow
-
Collect requirements. Get from the conversation or codebase, and ask only for what blocks the design:
- Engine and version (default: PostgreSQL 18; check
docker-compose.yml, ORM config, or Supabase project if present) - Entities and how they relate, in plain language
- The 5-10 most frequent or most important queries, including filters and sort order
- Volume and growth (rows per table per year), read/write mix
- Tenancy (single app, multi-tenant by organization), retention, audit, and compliance needs (PII, deletion requests)
- ORM or migration tool in use (Prisma, Drizzle, Rails, Django, Alembic, Supabase migrations, plain SQL)
- Engine and version (default: PostgreSQL 18; check
-
Model entities and relationships. List entities, attributes, and cardinality (1:1, 1:N, N:M). Normalize to 3NF by default; denormalize only for a named query that needs it, and say which.
-
Choose keys and types using references/postgres.md (or references/other-engines.md for MySQL, SQLite, MongoDB). Defaults for Postgres:
bigint generated always as identityoruuid DEFAULT uuidv7()primary keys,textovervarchar(n),timestamptzfor every timestamp,numericfor money. -
Encode the rules as constraints.
NOT NULLwherever a value is required,UNIQUEfor natural keys,CHECKfor ranges and allowed values, foreign keys with a deliberateON DELETEchoice for each. Data rules that live only in app code get broken by the next script or admin fix. -
Derive indexes from the queries in step 1, not from a checklist. For each query, name the index that serves it. Index every foreign key column you join or cascade on (Postgres does not do this automatically). Do not add an index a
UNIQUEor primary key already provides. -
Write the deliverable: DDL, ERD, index rationale, and migrations with rollback, using references/schema-templates.md and the layout in references/output-format.md. Match the user's migration tool if they have one.
What ships with it
4 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
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.
- 1mo ago Changed · +21 lines · +87 tokens per session 8807c7f705b4
- 1mo ago First seen · 41 lines · 54 tokens per session scan A a1ca262a1283
database-schema-designer is a skill published in the GitHub repository OneWave-AI/claude-skills (376 stars, last pushed 5d ago), licensed MIT. It adds 141 tokens to every session and 1,452 once invoked, about $0.0006 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 2026-09-03.
Other skills, from other repositories
kysely
Guidelines for developing with Kysely, a type-safe TypeScript SQL query builder with autocompletion support.
postgresql-best-practices
PostgreSQL development best practices for schema design, query optimization, and database administration.
database-expert
Advanced database design and administration for PostgreSQL, MongoDB, and Redis. Use when designing schemas, optimizing queries, managing database performance, or implementing data patterns.
software-database-design
Designs database schemas, migrations, and data models for PostgreSQL, MySQL, MongoDB, and Redis. Use when planning tables, relationships, indexes, or ORM-backed schema changes.
agent-database-expert
Specialist subagent: Expert database architect and engineer for PostgreSQL, MongoDB, Redis, and all major databases. Use when designing schemas, optimizing queries, planning migrations, implementing caching, or troubleshooting database performance.
mongodb-development
MongoDB development guidelines with Payload CMS, Mongoose, aggregation pipelines, and TypeScript best practices.