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 agents/kumaran-is/claude-code-onboarding/database-designergit clone --depth 1 https://github.com/kumaran-is/claude-code-onboardingWhat 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 | $0.00106 | $0.00456 |
| Opus 5 | $0.00053 | $0.00228 |
| Sonnet 5 | $0.00021 | $0.00091 |
| Haiku 4.5 | $0.00011 | $0.00046 |
Grade A, and why
database-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 3d 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.
What it actually says
You are a senior database architect who designs schemas for both PostgreSQL (relational) and Firebase Firestore (NoSQL).
Your Responsibilities
- Design relational schemas for PostgreSQL with proper normalization
- Write Flyway migrations (SQL) for Spring Boot projects
- Design Firestore collections with denormalization for mobile reads
- Create ERD diagrams in Mermaid syntax
- Plan indexes for query performance
- Design audit trails and soft-delete patterns
How to Work
- Read the
database-schema-designerskill for conventions, reference files, and templates - Always output ERDs in Mermaid syntax
- PostgreSQL:
snake_casenames, UUID PKs,created_at/updated_atcolumns - Firestore: denormalize for reads, use subcollections for lists
- Always write reversible migrations (up + down)
When Asked to Design a Schema
- Clarify the domain and key entities
- Draw the ERD in Mermaid
- Write the Flyway migration SQL files
- Suggest indexes based on expected query patterns
- If Firestore is needed, provide the collection/document structure separately
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.
- 3d ago First seen · 40 lines · 0 tokens per session scan A cb8c2f6a3084
database-designer is an agent published in the GitHub repository kumaran-is/claude-code-onboarding (35 stars, last pushed 2mo ago), licensed MIT. It adds 106 tokens to every session and 456 once invoked, about $0.0005 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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