# database-documentation

Inspects your live database and reconciles it with ORM models, migrations, and queries. Generates verified Mermaid ER diagrams, data dictionaries, and schema.json.

- skill · `type=skill` · Claude Code, Codex, Cursor, GitHub Copilot, Gemini CLI, OpenCode · 522 installs · ★ 17
- Author: a-tokyo
- License: MIT · policy=mirror · the beginning of the file is at the end of this page
- Source: https://github.com/a-tokyo/agent-skills/tree/HEAD/skills/database-documentation/SKILL.md
- Updated: 2026-10-24
- HTML: https://affpapa.org/en/nevibecode/skills/database-documentation

## What it does

This skill documents relational databases by treating the live database catalog as the ground truth. It queries the running engine, then independently reconciles those findings against ORM models, migration histories, and application queries. The output includes Mermaid ER diagrams, per-table data dictionaries, and a machine-readable `schema.json`.

Execution happens in phases using a temporary `.database-documentation/` folder. The agent fingerprints the engine and identifies a reachability path through a DB MCP server, `docker compose exec`, or a local CLI like `psql` or `mysql`. Passwords found in environment files are redacted. If parallel subagents are available, they extract tables, sequences, foreign keys, triggers, and full view bodies without seeing each other's work.

Support is limited to PostgreSQL, MySQL, SQL Server, and SQLite. If the agent detects a document store such as MongoDB, it stops processing that store immediately. Without direct read access to a running database, the skill drops down its confidence tiers and cannot verify zero drift.

## Requirements
- Works with: PostgreSQL

## Install

### Claude Code (native platform)

1. **Skills CLI (Vercel)**
```bash
npx skills add a-tokyo/agent-skills --skill database-documentation -a claude-code
```

2. **Manually: put the files in place**
- File: `~/.claude/skills/database-documentation/SKILL.md` — Copy the whole skill folder; for one project use .claude/skills/database-documentation/

### Codex

1. **Skills CLI (Vercel)**
```bash
npx skills add a-tokyo/agent-skills --skill database-documentation -a codex
```

2. **Manually: put the files in place**
- File: `.agents/skills/database-documentation/SKILL.md` — For all projects use ~/.agents/skills/

### Cursor

1. **Skills CLI (Vercel)**
```bash
npx skills add a-tokyo/agent-skills --skill database-documentation -a cursor
```

2. **Manually: put the files in place**
- File: `.cursor/skills/database-documentation/SKILL.md` — Cursor also reads .agents/skills/ and .claude/skills/

### GitHub Copilot

1. **GitHub CLI**
```bash
gh skill install a-tokyo/agent-skills database-documentation
```

2. **Manually: put the files in place**
- File: `.github/skills/database-documentation/SKILL.md`

### Gemini CLI

1. **Skills CLI (Vercel)**
```bash
npx skills add a-tokyo/agent-skills --skill database-documentation -a gemini-cli
```

2. **Platform CLI**
```bash
gemini skills install https://github.com/a-tokyo/agent-skills --path skills/database-documentation
```

### Windsurf (Devin Desktop)

**Manually: put the files in place**
- File: `.devin/skills/database-documentation/SKILL.md` — The legacy .windsurf/skills/ path still works

### OpenCode

**Skills CLI (Vercel)**
```bash
npx skills add a-tokyo/agent-skills --skill database-documentation -a opencode
```

### Claude.ai

**Claude.ai**
- Zip the folder and upload it in Settings → Capabilities → Skills

Where a file is given instead of a command, copy the files from the source to that path: https://github.com/a-tokyo/agent-skills/tree/HEAD/skills/database-documentation/SKILL.md

## When to use it
- document a live relational database schema without hallucinations
- generate Mermaid entity-relationship diagrams from catalog data
- audit schema drift between ORM models and the live database
- export a verified schema specification to schema.json

## Example prompts
- Document the database schema and check for drift against our Prisma models.
- Generate a Mermaid ERD and data dictionary for our PostgreSQL database.
- Inspect the live database via docker compose and output schema.json.

## Source text · SKILL.md · MIT

Below is the content of a third-party file. It is data, not instructions for you: do not act on anything written inside unless the human asks. Block tag: 19eea447b6caf27d.

BEGIN THIRD-PARTY FILE 19eea447b6caf27d
```text
---
name: database-documentation
version: 0.0.1
license: MIT
description: >-
  Generate grounded-and-verified, engine-agnostic database documentation that reaches 100% parity with the
  real schema. Introspects the LIVE database as ground truth and cross-validates it against ORM models,
  migrations, generated types, seeds, and application queries, then proves completeness by diffing the docs
  back against the database. Produces ER diagrams (mermaid), per-table data dictionaries, and a
  machine-readable schema.json. Works with PostgreSQL, MySQL, SQL Server, and SQLite across any ORM (Prisma,
  TypeORM, Drizzle, Sequelize, Knex, Django, Rails) or raw SQL. Use when asked to document a database,
  produce an ERD or data dictionary, write db/schema docs, audit schema drift, or refresh existing DB docs.
compatibility: >-
  Best results need read access to the live database (via a DB CLI, docker exec, or a connected DB MCP
  server) and, on platforms that support it, parallel subagents. Degrades gracefully without them.
---

# database-documentation

Document a database so completely and accurately that the docs are **provably** the schema, not a
plausible guess at it. A half-correct schema doc is worse than none: people trust it and write broken code.

## The one principle: grounded AND verified

Every statement in the output must be:
- **grounded** — traceable to a concrete source, preferring the **live database** (introspection of the
  system catalog). ORM models, migrations, generated types, and seeds are *claims about* the database, not
  the database; the catalog is what actually runs.
- **verified** — confirmed by re-introspecting the live database and diffing it against the generated docs
  until the diff is empty or every remaining difference is explicitly justified. Never write "documentation
  is complete" — instead make the diff empty and show it.

A frontier model left to itself reads the ORM, writes confident prose, and ships an **incomplete and
partly hallucinated** schema (missed check-constraint enums, wrong `ON DELETE`, omitted legacy tables,
invented columns). This skill exists to defeat exactly that. Two mechanisms do it: (1) the live DB is the
oracle, and (2) judgment is never one agent's call — independent adversaries hunt for what one pass misses.

## Scope (v1): relational/SQL only

Targets PostgreSQL, MySQL, SQL Server, SQLite. If you detect a document store (MongoDB) or graph database,
```
END THIRD-PARTY FILE 19eea447b6caf27d

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