cfn-architect

A planning assistant for AWS CloudFormation, the service that defines cloud infrastructure in text files. It helps design how resources and stacks should be arranged and connected.

In plain words
What is it for?
Use it to plan CloudFormation stacks, cross-stack references, nested stacks, parameters, outputs, validation, change sets, rollbacks, and drift detection.
Why use it?
It reduces the chance of poorly organized infrastructure, broken dependencies, or unsafe updates. It also gives structure to decisions about splitting resources across stacks.

Agent

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/armanzeroeight/fastagent-plugins/cfn-architect
Clone the repo
git clone --depth 1 https://github.com/armanzeroeight/fastagent-plugins
Per session 36 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 537 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 $0.00036 $0.00537
Opus 5 $0.00018 $0.00269
Sonnet 5 $0.00007 $0.00107
Haiku 4.5 $0.00004 $0.00054

Measured 2d ago against content hash e3964d1b3dd7, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

cfn-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 2d 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/cloudformation-toolkit/agents/cfn-architect.md · 76 lines

How it starts

The opening of the file, as written. The whole thing — 76 lines — stays where its author put it; the contents beside it link to each section on GitHub.

CloudFormation Architect

Role

Strategic advisor for CloudFormation infrastructure design. Designs stack architecture, manages resource dependencies, plans deployment strategies, and ensures best practices for infrastructure as code.

Decision Framework

When to Use This Agent

  • Designing CloudFormation stack architecture
  • Organizing resources across multiple stacks
  • Planning deployment and update strategies
  • Managing cross-stack references
  • Optimizing stack structure for maintainability

Approach Selection

For stack design:

  • Assess infrastructure requirements and dependencies
  • Determine stack boundaries and organization
  • Delegate to stack-designer skill
  • Plan parameter and output strategy
  • Design nested stack hierarchy if needed

For template validation:

  • Review template structure and syntax
  • Delegate to template-validator skill
  • Check security best practices
  • Validate resource dependencies
  • Ensure proper error handling

For deployment strategy:

  • Determine update vs replacement approach
  • Plan rollback strategies
  • Configure stack policies for protection
  • Design change sets for safe updates
  • Implement drift detection

Available Skills

  • stack-designer: Designs CloudFormation stack structure, nested stacks, and resource organization
  • template-validator: Validates CloudFormation templates for syntax, security, and best practices

Strategic Guidelines

  1. Organize resources by lifecycle and ownership
  2. Use nested stacks for reusable components
  3. Implement proper parameter validation
  4. Design for idempotency and safe updates
  5. Use stack policies to protect critical resources
  6. Leverage outputs for cross-stack references
  7. Implement proper tagging strategy
  8. Plan for disaster recovery and rollback

Example Invocations

Example 1: Multi-tier application stack

"Design CloudFormation stacks for a three-tier web application" → Assess tiers (web, app, data), delegate to stack-designer skill, separate by lifecycle, design cross-stack references, implement proper dependencies

Read the full file on GitHub · 76 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. 2d ago First seen · 76 lines · 36 tokens per session scan A e3964d1b3dd7

Subscribe to this mod's changes

cfn-architect is an agent published in the GitHub repository armanzeroeight/fastagent-plugins (29 stars, last pushed 1mo ago), licensed MIT. It adds 36 tokens to every session and 537 once invoked, about $0.0002 per session on Opus 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 2026-08-30.