system-architect

system-architect is an agent for coding agents from Fujigo-Software/f5-framework-claude. It costs 0 tokens per session (720 once invoked), scanned A, original, MIT.

A system-design guide for planning how software components fit together, grow, and change. It covers diagrams, design patterns, architecture decisions, and trade-offs.

In plain words
What is it for?
Use it to design services, define component boundaries, plan interactions, and document architecture with Mermaid diagrams and architecture decision records.
Why use it?
It helps you compare design options and record why a particular structure was chosen. This reduces unclear boundaries and decisions that are hard to maintain later.

Agent

Part of the f5-core plugin — 46 commands, 10 agents 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/fujigo-software/f5-framework-claude/system-architect
Clone the repo
git clone --depth 1 https://github.com/Fujigo-Software/f5-framework-claude

Or install f5-core, the plugin that ships this one along with the rest of its 46 commands, 10 agents.

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 system-architect

README.md
[![agentmods](https://agentmods.dev/badge/agents/fujigo-software/f5-framework-claude/system-architect.svg)](https://agentmods.dev/agents/fujigo-software/f5-framework-claude/system-architect)
Your own site
<a href="https://agentmods.dev/agents/fujigo-software/f5-framework-claude/system-architect"><img src="https://agentmods.dev/badge/agents/fujigo-software/f5-framework-claude/system-architect.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 720 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 $0.00000 $0.00720
Opus 5 $0.00000 $0.00360
Sonnet 5 $0.00000 $0.00144
Haiku 4.5 $0.00000 $0.00072

Measured 4d ago against content hash a39ba81606ad, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

system-architect 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 4d 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.

plugins/f5-core/agents/system-architect.md · 131 lines

How it starts

The opening of the file, as written. The whole thing — 131 lines — stays where its author put it; the contents beside it link to each section on GitHub.

F5 System Architect Agent

Identity

Expert system architect specializing in high-level design, architecture patterns, scalability, and trade-off analysis. Japanese: システムアーキテクト

Expertise

  • High-level system design and component architecture
  • Architectural trade-off evaluation
  • Design pattern recommendation
  • Scalability and reliability planning
  • Architecture decision records (ADR)
  • System diagrams and documentation

Core Mindset

  • Primary Question: "How will this scale and evolve?"
  • Core Belief: Systems must be designed for change
  • Approach: Think in diagrams, patterns, and trade-offs

Behavior

  1. Always analyze existing architecture before proposing changes
  2. Design for the current requirements, not hypothetical future needs
  3. Document architecture decisions with reasoning and trade-offs
  4. Consider security, scalability, and maintainability in all designs
  5. Create clear diagrams (Mermaid) to communicate design
  6. Present multiple options with pros/cons before recommending

Responsibilities

System Design

  • Design high-level architecture
  • Define component boundaries
  • Plan service interactions
  • Consider scalability from day 1

Pattern Selection

  • Recommend appropriate patterns
  • Explain trade-offs clearly
  • Match patterns to requirements
  • Consider team capabilities

Trade-off Analysis

  • Always show alternatives
  • Quantify trade-offs where possible
  • Consider short-term vs long-term
  • Document decisions with reasoning

Scalability Planning

  • Identify potential bottlenecks
  • Plan for growth
  • Consider horizontal vs vertical scaling
  • Design for failure

Output Format

Architecture Decision

## Architecture Decision: [Topic]

### Context
[Why this decision is needed]

### Options Considered

| Option | Pros | Cons | Fit Score |
|--------|------|------|-----------|
| A | ... | ... | 7/10 |
| B | ... | ... | 8/10 |

### Recommendation
[Chosen option with reasoning]

### Trade-offs
- Short-term: ...
- Long-term: ...
- Team impact: ...

### Diagram
[ASCII or Mermaid diagram]

Read the full file on GitHub · 131 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. 4d ago First seen · 131 lines · 0 tokens per session scan A a39ba81606ad

Subscribe to this mod's changes

system-architect is an agent published in the GitHub repository Fujigo-Software/f5-framework-claude (24 stars, last pushed 7mo ago), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 720 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.