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.
npx agentmods add rules/d-padmanabhan/agent-engineering-handbook/170-cloudformationgit clone --depth 1 https://github.com/d-padmanabhan/agent-engineering-handbookWrote 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.
[](https://agentmods.dev/rules/d-padmanabhan/agent-engineering-handbook/170-cloudformation)<a href="https://agentmods.dev/rules/d-padmanabhan/agent-engineering-handbook/170-cloudformation"><img src="https://agentmods.dev/badge/rules/d-padmanabhan/agent-engineering-handbook/170-cloudformation.svg" alt="Measured on agentmods" height="20"></a>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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5 | $0.00014 | $0.06268 |
| Opus 5 | $0.00007 | $0.03134 |
| Sonnet 5 | $0.00003 | $0.01254 |
| Haiku 4.5 | $0.00001 | $0.00627 |
Grade A, and why
170-cloudformation 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.
How it starts
The opening of the file, as written. The whole thing — 945 lines — stays where its author put it; the contents beside it link to each section on GitHub.
CloudFormation Engineering Ruleset
Audience: engineers writing and reviewing CloudFormation templates Goal: Create secure, maintainable CloudFormation templates following AWS best practices.
CloudFormation Philosophy (Core Principles)
Core Principles:
- "Security by default" - Least privilege IAM, encryption everywhere, no hardcoded secrets
- "Infrastructure as Code" - All resources defined in templates, version controlled, reviewed
- "Parameterization over hardcoding" - Use parameters, mappings, and conditions for flexibility
- "Composition over duplication" - Use nested stacks, modules, and reusable templates
- "Validation before deployment" - Validate templates, test changes, review diffs
- "Idempotency is essential" - Templates should be safe to run multiple times
- "Explicit over implicit" - Clear resource names, documented parameters, explicit dependencies
- "Fail fast, fail clearly" - Use conditions, validations, and clear error messages
Applying CloudFormation Principles:
# BAD: Hardcoded, insecure, monolithic
Resources:
rMyDatabase:
Type: AWS::RDS::DBInstance
Properties:
MasterUsername: admin
MasterUserPassword: Password123!
DBInstanceClass: db.t2.micro
# GOOD: Parameterized, secure, modular
Parameters:
pEnvironment:
Type: String
AllowedValues: [dev, staging, prod]
Description: Deployment environment
pDatabasePassword:
Type: String
NoEcho: true
Description: Database password from Secrets Manager
Resources:
rDatabase:
Type: AWS::RDS::DBInstance
Properties:
MasterUsername: !Ref pDatabaseUsername
MasterUserPassword: !Ref pDatabasePassword
DBInstanceClass: !If [cIsProduction, db.r5.xlarge, db.t3.micro]
StorageEncrypted: true
DeletionProtection: !If [cIsProduction, true, false]
Core Principles
- Security First: Least privilege IAM, encryption at rest and in transit
- Infrastructure as Code: All resources defined in templates
- Parameterization: Use parameters for environment-specific values
- DRY: Use nested stacks and modules for reusable components
- Validation: Validate templates before deployment
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.
- 4d ago First seen · 945 lines · 14 tokens per session scan A 27baa15e2456
170-cloudformation is a cursor rule published in the GitHub repository d-padmanabhan/agent-engineering-handbook (16 stars, last pushed 4d ago), licensed MIT. It adds 14 tokens to every session and 6,268 once invoked, about $0.0001 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.
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