schema-designer

schema-designer is an agent for Claude Code from myrtlepn/gran-maestro. It costs 0 tokens per session (1,005 once invoked), scanned A, original, MIT.

A database planning template for defining data models, table relationships, field rules, indexes, and migration plans. It produces design documents rather than implementation code.

In plain words
What is it for?
Use it to plan a database schema, create a text-based ERD, specify fields and constraints, and prepare backward-compatible migrations.
Why use it?
It exposes data relationships and migration risks before database changes are made, helping protect existing data.

Agent for Claude Code

Written for Claude Code: shipped in a Claude Code plugin. Also seen: mentions Codex.

Part of the mst plugin — 42 skills, 6 agents, 4 hooks shipped together

Install

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.

agentmods
npx agentmods add agents/myrtlepn/gran-maestro/schema-designer
Clone the repo
git clone --depth 1 https://github.com/myrtlepn/gran-maestro

Made for: Claude Code.

Or install mst, the plugin that ships this one along with the rest of its 42 skills, 6 agents, 4 hooks.

Wrote 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.

agentmods badge for schema-designer

README.md
[![agentmods](https://agentmods.dev/badge/agents/myrtlepn/gran-maestro/schema-designer.svg)](https://agentmods.dev/agents/myrtlepn/gran-maestro/schema-designer)
Your own site
<a href="https://agentmods.dev/agents/myrtlepn/gran-maestro/schema-designer"><img src="https://agentmods.dev/badge/agents/myrtlepn/gran-maestro/schema-designer.svg" alt="Measured on agentmods" height="20"></a>
Per session 0 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 1,005 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

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.

ModelPer sessionOnce invoked
Fable 5.1 $0.00000 $0.01005
Opus 5 $0.00000 $0.00502
Sonnet 5 $0.00000 $0.00201
Haiku 4.5 $0.00000 $0.00101

Measured 6d ago against content hash 8a50f967ad60, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-05, from the pricing page.

Security

Grade A, and why

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 6d 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.

agents/schema-designer.md · 114 lines

How it starts

The opening of the file, as written. The whole thing — 114 lines — stays where its author put it; the contents beside it link to each section on GitHub.

DEPRECATED: 이 파일은 스킬로 전환되었습니다. skills/schema-designer/SKILL.md를 참조하세요. 이 파일은 호환성을 위해 유지되며, 향후 버전에서 제거될 예정입니다.

Schema Designer Template (Design Wing)

Analysis Squad의 Design Wing 멤버. DB 스키마, 데이터 모델, ERD, 마이그레이션 계획을 설계합니다. 이 파일은 에이전트가 아닌 템플릿으로, PM Conductor가 변수를 치환하여 /mst:codex로 실행합니다.

<schema_designer> You are the Schema Designer in Gran Maestro's Design Wing. Your mission is to design data models, database schemas, entity relationships, and migration strategies for features that involve data model changes. You produce data model design documents — you NEVER write implementation code.

<success_criteria>

  • Entity-Relationship diagram is clear and complete
  • All fields have explicit types, constraints, and defaults
  • Migration strategy preserves data integrity
  • Indexes are designed for query patterns
  • Backward compatibility is addressed </success_criteria>

Existing Schemas & Data Models

{EXISTING_SCHEMAS}

Architecture Context

{DESIGN_CONTEXT}

<output_format> Write the design document in the following format:

Data Model Design - {REQ_ID}

Entity-Relationship Diagram

[Text-based ERD description]

Entities

{EntityName}

Field Type Constraint Default Description
id UUID PK auto Primary key
... ... ... ... ...

Indexes

Name Fields Type Rationale
... ... ... ...

Relationships

From To Type FK Cascade
... ... 1:N ... ...

Migration Strategy

  1. [Step 1 — non-breaking change]
  2. [Step 2 — data migration]
  3. [Step 3 — cleanup]

Read the full file on GitHub · 114 lines

Changes

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.

  1. 6d ago First seen · 114 lines · 0 tokens per session scan A 8a50f967ad60

Subscribe to this mod's changes

schema-designer is an agent published in the GitHub repository myrtlepn/gran-maestro (24 stars, last pushed 17d ago), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 1,005 tokens. 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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