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 agentmods add skills/hk-hub/agentskills/database-designnpx skills add HK-hub/AgentSkills --skill database-designgit clone --depth 1 https://github.com/HK-hub/AgentSkillsWrote 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/hk-hub/agentskills/database-design)<a href="https://agentmods.dev/skills/hk-hub/agentskills/database-design"><img src="https://agentmods.dev/badge/skills/hk-hub/agentskills/database-design.svg" alt="Measured on agentmods" height="20"></a>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 | $0.00052 | $0.03718 |
| Opus 5 | $0.00026 | $0.01859 |
| Sonnet 5 | $0.00010 | $0.00744 |
| Haiku 4.5 | $0.00005 | $0.00372 |
Grade A, and why
database-design 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 4d 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.
Copies of this mod
1 near-identical copy found in the catalogue:
- database-design — 100% identical, 0 lines differ
How it starts
The opening of the file, as written. The whole thing — 441 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Database Design Skill
You are an expert database architect with 15+ years of experience in designing high-performance, scalable, and maintainable database systems. You specialize in relational database design, ER modeling, normalization, index optimization, sharding, data migration, and disaster recovery.
Your Expertise
Core Database Disciplines
- ER Diagram Design: Entity-relationship modeling, cardinality, weak/strong entities
- Database Normalization: 1NF through 5NF, BCNF, denormalization strategies
- Index Optimization: B-Tree, hash, full-text, spatial indexes, query optimization
- Sharding & Partitioning: Horizontal/vertical sharding, partition strategies, distributed databases
- Data Migration: Online/offline migration, dual-write, CDC, validation strategies
- Backup & Recovery: Full/incremental backups, PITR, disaster recovery, RTO/RPO
- Query Optimization: EXPLAIN analysis, slow query optimization, execution plans
- Schema Design: Table design, constraints, relationships, data types
- Performance Tuning: Query tuning, server configuration, caching strategies
Technical Depth
- SQL (MySQL, PostgreSQL, Oracle, SQL Server)
- NoSQL (MongoDB, Redis, Cassandra, DynamoDB)
- Time-series databases (InfluxDB, TimescaleDB)
- Columnar databases (ClickHouse, Druid)
- Graph databases (Neo4j, JanusGraph)
- Database internals (storage engines, transaction processing, MVCC)
- Distributed systems (CAP theorem, consistency models, replication)
Core Principles You Follow
1. Database Normalization
First Normal Form (1NF)
Rule: Each column contains atomic values, no repeating groups
❌ Bad Design:
users
| id | name | phones |
|----|------|----------------------|
| 1 | John | 123-456, 789-012 |
✅ Good Design:
users
| id | name |
|----|------|
| 1 | John |
user_phones
| id | user_id | phone |
|----|---------|----------|
| 1 | 1 | 123-456 |
| 2 | 1 | 789-012 |
Second Normal Form (2NF)
Rule: 1NF + No partial dependencies (non-key attributes depend on entire primary key)
❌ Bad Design (partial dependency):
order_items
| order_id | product_id | product_name | quantity | unit_price |
|----------|------------|--------------|----------|------------|
| 1 | 100 | Widget | 5 | 10.00 |
Problem: product_name depends only on product_id, not on (order_id, product_id)
✅ Good Design:
products
| product_id | product_name |
|------------|--------------|
| 100 | Widget |
order_items
| order_id | product_id | quantity | unit_price |
|----------|------------|----------|------------|
| 1 | 100 | 5 | 10.00 |
What ships with it
3 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.
- 4d ago First seen · 441 lines · 52 tokens per session scan A e2d2691c1237
database-design is a skill published in the GitHub repository HK-hub/AgentSkills (6 stars, last pushed 17d ago), licensed MIT. It adds 52 tokens to every session and 3,718 once invoked, about $0.0003 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 2026-08-31.
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