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 sergei-aronsen/claude-code-toolkit --skill databasegit clone --depth 1 https://github.com/sergei-aronsen/claude-code-toolkitWrote 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/sergei-aronsen/claude-code-toolkit/database)<a href="https://agentmods.dev/skills/sergei-aronsen/claude-code-toolkit/database"><img src="https://agentmods.dev/badge/skills/sergei-aronsen/claude-code-toolkit/database/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/sergei-aronsen/claude-code-toolkit/database"><img src="https://agentmods.dev/badge/skills/sergei-aronsen/claude-code-toolkit/database.svg" alt="Reviewed on agentmods" width="80" 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 5.1 | $0.00029 | $0.01857 |
| Opus 5.5 | $0.00012 | $0.00743 |
| Sonnet 5.5 | $0.00006 | $0.00371 |
| Haiku 4.5 | $0.00003 | $0.00186 |
Grade A, and why
Database 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 — 368 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Database Skill
Load this skill when working with databases, migrations, queries, or data modeling.
Rule
DATABASE CHANGES MUST BE SAFE AND REVERSIBLE!
- Always test migrations on staging
- Never delete data without backup
- Index queries, not tables
Migration Best Practices
Safe Migration Checklist
- Migration is reversible (has
downmethod) - No data loss
- No long locks on production tables
- Tested on copy of production data
- Backward compatible with current code
Dangerous Operations
| Operation | Risk | Safe Alternative |
|---|---|---|
| Drop column | Data loss | Add new column, migrate, then drop |
| Rename column | Breaks code | Add alias, dual-write, then rename |
| Add NOT NULL | Fails on existing nulls | Add nullable, backfill, then add constraint |
| Change type | Data corruption | Add new column, migrate data |
Migration Patterns
Adding Column Safely
-- Step 1: Add nullable column
ALTER TABLE users ADD COLUMN phone VARCHAR(20);
-- Step 2: Backfill data (in batches)
UPDATE users SET phone = 'unknown' WHERE phone IS NULL LIMIT 1000;
-- Step 3: Add NOT NULL constraint (after all data filled)
ALTER TABLE users ALTER COLUMN phone SET NOT NULL;
Zero-Downtime Column Rename
-- Step 1: Add new column
ALTER TABLE users ADD COLUMN full_name VARCHAR(255);
-- Step 2: Dual-write in application (write to both columns)
-- Step 3: Backfill existing data
UPDATE users SET full_name = name WHERE full_name IS NULL;
-- Step 4: Switch reads to new column
-- Step 5: Stop writing to old column
-- Step 6: Drop old column (separate migration, later)
ALTER TABLE users DROP COLUMN name;
Index Strategies
When to Add Index
| Query Pattern | Index Type |
|---|---|
WHERE status = ? |
Single column |
WHERE user_id = ? AND status = ? |
Composite (user_id, status) |
WHERE email LIKE 'john%' |
Single column (prefix only) |
ORDER BY created_at DESC |
Single column DESC |
WHERE status = ? ORDER BY created_at |
Composite (status, created_at) |
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 First seen · 368 lines · 29 tokens per session scan A 543f45e91488
Database is a skill published in the GitHub repository sergei-aronsen/claude-code-toolkit (5 stars, last pushed 2mo ago), licensed MIT. It adds 29 tokens to every session and 1,857 once invoked, about $0.0001 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 2026-08-31.
Other skills, from other repositories
create-pr
Creates a GitHub PR with a Linear-ticket-prefixed title and a decision-led, narrative description for Prisma 8. Use when the user wants to create a pull request, open a PR, or submit changes for review.
schema-exploration
Lists tables, describes columns and data types, identifies foreign key relationships, and maps entity relationships in a database. Use when the user asks about database schema, table structure, column types, what tables exist, ERD, foreign keys, or how entities relate.
atlas-mssql
SQL Server specifics for Atlas (also Azure SQL and MSSQL): login, dev database and URL scope (mode=schema vs mode=database, the database query parameter), compatibility level and collation, system-generated constraint names, clustered index defaults and datetime2 precision in HCL, GO batches and the delimiter…
ha-data-stores
Map of Hope Agent's local data stores and safe read-only query workflow. Use when the user asks where Hope Agent stores data, wants to inspect sessions/messages/memory/logs/background jobs/knowledge indexes/settings, asks the model to query local app data, or debugging requires checking persisted state. Trigger…
nornicdb-cypher-queries
Pick fast, predictable Cypher query shapes in NornicDB — point lookups, batch retrieval, pagination, search, traversal, batched UNWIND/MERGE writes, cleanup, multi-tenant isolation. Use when writing or reviewing Cypher whose latency or throughput matters; maps user intent to the executor's hot-path query templates.
volcengine-rds-postgresql
A tool for operating PostgreSQL databases hosted by Volcano Engine's managed database service. PostgreSQL is a relational database used to store structured application data.