System Architecture Designer

What it does

When your agent uses it

• Designing a new system's high-level architecture
• Deciding between a monolith and microservices for a project
• Writing an ADR for a significant technical decision

Example prompts

• “Design the architecture for a multi-tenant SaaS billing system.”
• “Should this service be a monolith or split into microservices?”
• “Write an ADR comparing Postgres and DynamoDB for this workload.”

Workflow steps

5 steps, taken from the first numbered list in SKILL.md.

1. 1Understand requirements — Gather functional, non-functional, and constraint requirements. Verify full requirements coverage before…
2. 2Identify patterns — Match requirements to architectural patterns (see Reference Guide).
3. 3Design — Create architecture with trade-offs explicitly documented; produce a diagram.
4. 4Document — Write ADRs for all key decisions.
5. 5Review — Validate with stakeholders. If review fails, return to step 3 with recorded feedback.

What it can do on your machine

Read from SKILL.md and the folder at commit 1be15d8. It shows what the files ask for, not the result of running them.

• Tool permissions

  Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.

  From allowed-tools in the SKILL.md frontmatter.

• Runs code

  No scripts in the folder and no shell commands in SKILL.md (its code samples are mermaid and markdown).

  From the folder's file list and the shell code blocks in SKILL.md.

• Network

  Links to these hosts (documentation or services it may open):

  • github.com
  • synergetic.solutions
  • jeffallan.github.io

  From URLs in SKILL.md, links to its own repository left out.

• Credentials

  Names no API keys, tokens, secrets or passwords.

  From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

Context cost

System Architecture Designer loads about 1.2k tokens when it runs, and up to ~5.2k if it reads all its reference files. Until then it costs about 133 tokens; SKILL.md has 280 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it

~133

When it runs · the whole SKILL.md, loaded when a task matches

~1.2k

With references · SKILL.md plus every file in references/, read only if the agent opens them

~5.2k

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from Jeffallan/claude-skills at commit 1be15d8, republished under its MIT licence (© Jeffallan). 280 words, ~1,227 tokens.

name

architecture-designer

description

Use when designing new high-level system architecture, reviewing existing designs, or making architectural decisions. Invoke to create architecture diagrams, write Architecture Decision Records (ADRs), evaluate technology trade-offs, design component interactions, and plan for scalability. Use for system design, architecture review, microservices structuring, ADR authoring, scalability planning, and infrastructure pattern selection — distinct from code-level design patterns or database-only design tasks.

license

MIT

metadata.author

https://github.com/Jeffallan

metadata.company

https://synergetic.solutions

metadata.version

1.1.1

metadata.domain

api-architecture

metadata.triggers

architecture, system design, design pattern, microservices, scalability, ADR, technical design, infrastructure

metadata.role

expert

metadata.scope

design

metadata.output-format

document

metadata.related-skills

fullstack-guardian, devops-engineer, secure-code-guardian, microservices-architect, code-reviewer

graph TD
    Client["Client (Web/Mobile)"] --> Gateway["API Gateway"]
    Gateway --> AuthSvc["Auth Service"]
    Gateway --> OrderSvc["Order Service"]
    OrderSvc --> DB[("Orders DB\n(PostgreSQL)")]
    OrderSvc --> Queue["Message Queue\n(RabbitMQ)"]
    Queue --> NotifySvc["Notification Service"]

# ADR-001: Use PostgreSQL for Order Storage

## Status
Accepted

## Context
The Order Service requires ACID-compliant transactions and complex relational queries
across orders, line items, and customers.

## Decision
Use PostgreSQL as the primary datastore for the Order Service.

## Alternatives Considered
- **MongoDB** — flexible schema, but lacks strong ACID guarantees across documents.
- **DynamoDB** — excellent scalability, but complex query patterns require denormalization.

## Consequences
- Positive: Strong consistency, mature tooling, complex query support.
- Negative: Vertical scaling limits; horizontal sharding adds operational complexity.

## Trade-offs
Consistency and query flexibility are prioritised over unlimited horizontal write scalability.

© Jeffallan, MIT. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

SKILL.md and 5 other files (references) in skills/architecture-designer of Jeffallan/claude-skills.

• SKILL.md
• references/adr-template.md
• references/architecture-patterns.md
• references/database-selection.md
• references/nfr-checklist.md
• references/system-design.md

Open the folder on GitHubat commit 1be15d8