What is cfn-template-compare?

A comparison workflow for AWS CloudFormation templates, which describe cloud infrastructure. It compares a deployed stack with a locally generated AWS CDK template to find differences.

It is for reviewing CDK changes, comparing resources and properties, and checking infrastructure or IAM differences before deployment.

It helps detect infrastructure drift, meaning the deployed setup no longer matches the code, before changes are deployed.

cfn-template-compare — Skill for Claude Code and Codex by pantheon-org

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.

Any agent

npx skills add pantheon-org/tekhne --skill template-compare

Clone the repo

git clone --depth 1 https://github.com/pantheon-org/tekhne

Made for: Claude Code, Codex.

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.

README.md

[![agentmods](https://agentmods.dev/badge/skills/pantheon-org/tekhne/template-compare/github.svg)](https://agentmods.dev/skills/pantheon-org/tekhne/template-compare)

Your own site

<a href="https://agentmods.dev/skills/pantheon-org/tekhne/template-compare"><img src="https://agentmods.dev/badge/skills/pantheon-org/tekhne/template-compare/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

Your own site · 80×15

<a href="https://agentmods.dev/skills/pantheon-org/tekhne/template-compare"><img src="https://agentmods.dev/badge/skills/pantheon-org/tekhne/template-compare.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 124 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 2,188 The whole file, excluding the scripts and references it only reads on demand.

Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe. Third-party audits

NVIDIA SkillSpector warn 7 Sept 2026

SkillSpector: 2 findings, up to medium

These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →

medium Excessive Agency · line 106
Skill enables autonomous high-impact decisions without human-in-the-loop verification. Critical operations (destructive commands, financial transactions, data deletion) should require explicit user confirmation.

Fix: Add human-in-the-loop confirmation for destructive, irreversible, or high-impact operations. Never auto-execute commands that modify files, send data, or alter system state.
medium Excessive Agency · line 168
Skill enables autonomous high-impact decisions without human-in-the-loop verification. Critical operations (destructive commands, financial transactions, data deletion) should require explicit user confirmation.

Fix: Add human-in-the-loop confirmation for destructive, irreversible, or high-impact operations. Never auto-execute commands that modify files, send data, or alter system state.

How audits are shown

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.

Model	Per session	Once invoked
Fable 5.1	$0.00124	$0.02188
Opus 5	$0.00062	$0.01094
Sonnet 5	$0.00025	$0.00438
Haiku 4.5	$0.00012	$0.00219

Measured 9d ago against content hash 111f91365668, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-12, from the pricing page.

Security

Grade A, and why

cfn-template-compare 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 9d ago.

The scan reads SKILL.md. This mod also ships 1 executable file (scripts/compare-cfn-templates.sh), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

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.

skills/infrastructure/cfn/template-compare/SKILL.md · 227 lines

How it starts

The opening of the file, as written. The whole thing — 227 lines — stays where its author put it; the contents beside it link to each section on GitHub.

CloudFormation Template Comparison Skill

Quick Start

# 1. Retrieve the deployed template
aws cloudformation get-template \
  --stack-name <stack-name> \
  --region <region> \
  --profile <profile> \
  --query TemplateBody \
  --output json > deployed.json

# 2. Synthesize the local CDK template
make synth
cp cdk.out/<stack-name>.template.json local.json

# 3. Compare structure
jq 'keys' deployed.json
jq 'keys' local.json

# 4. Compare resource counts
jq '.Resources | length' deployed.json
jq '.Resources | length' local.json

# 5. Find added/removed resource IDs
diff <(jq -r '.Resources | keys[]' deployed.json | sort) \
     <(jq -r '.Resources | keys[]' local.json | sort)

# 6. Deep diff of a specific resource
diff <(jq '.Resources.<ResourceId>' deployed.json) \
     <(jq '.Resources.<ResourceId>' local.json)

Expected Workflow

Step 1: Preparation — verify prerequisites

# Check AWS credentials
aws sts get-caller-identity --profile <profile>
# → If this fails: verify AWS_PROFILE or --profile value before proceeding

# Confirm stack exists
aws cloudformation describe-stacks \
  --stack-name <stack-name> --region <region> --profile <profile> \
  --query 'Stacks[0].StackStatus'
# → If StackNotFoundException: check stack name and region

# Confirm CDK project synthesises cleanly
make synth
# → If synth fails: fix missing env vars in env-local.mk / env.mk before proceeding

Step 2: Retrieval

# Deployed template
aws cloudformation get-template \
  --stack-name <stack-name> --region <region> --profile <profile> \
  --query TemplateBody --output json > deployed.json
# → Validate: jq '.' deployed.json >/dev/null || echo "ERROR: invalid JSON"

# Local template
cp cdk.out/<stack-name>.template.json local.json
# → Validate: jq '.' local.json >/dev/null || echo "ERROR: invalid JSON"

Step 3: Hierarchical Analysis

# 1. Structure (top-level keys)
diff <(jq 'keys' deployed.json) <(jq 'keys' local.json)

# 2. Resource count
echo "Deployed: $(jq '.Resources | length' deployed.json)"
echo "Local:    $(jq '.Resources | length' local.json)"

# 3. Added / removed resources
comm -3 \
  <(jq -r '.Resources | keys[]' deployed.json | sort) \
  <(jq -r '.Resources | keys[]' local.json | sort)

# 4. Security — CDK Nag suppressions
diff \
  <(jq '[.Resources[].Metadata."cdk_nag" // empty]' deployed.json) \
  <(jq '[.Resources[].Metadata."cdk_nag" // empty]' local.json)

# 5. IAM roles and policies
diff \
  <(jq '[.Resources | to_entries[] | select(.value.Type | startswith("AWS::IAM"))]' deployed.json) \
  <(jq '[.Resources | to_entries[] | select(.value.Type | startswith("AWS::IAM"))]' local.json)

Read the full file on GitHub · 227 lines

Files

What ships with it

23 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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.

9d ago First seen · 227 lines · 124 tokens per session scan A 111f91365668

Subscribe to this mod's changes

cfn-template-compare is a skill published in the GitHub repository pantheon-org/tekhne (10 stars, last pushed yesterday), licensed MIT. It adds 124 tokens to every session and 2,188 once invoked, about $0.0006 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 2026-09-03.

DevOps and cloud agent-skills skills tessl

claude-md-improver

Audit and improve CLAUDE.md files in repositories. Use when user asks to check, audit, update, improve, or fix CLAUDE.md files. Scans for all CLAUDE.md files, evaluates quality against templates, outputs quality report, then makes targeted updates. Also use when the user mentions "CLAUDE.md maintenance" or "project…

anthropics/claude-plugins-official · 82 tokens

gke-reliability

Improves GKE workload reliability, using PDBs, health probes, and topology spread constraints. Use when configuring GKE workload reliability, setting up PDBs, or configuring GKE health probes (liveness, readiness, startup). Don't use for disaster recovery setup or full cluster backups (use gke-backup-dr instead).

google/skills · 73 tokens

gke-workload-security

Audits, configures, and hardens workload-level security controls for Google Kubernetes Engine (GKE) applications and namespaces. Covers running cluster security audits (auditcluster.sh), configuring Workload Identity Federation (impersonation, KSA/GSA binding, and pod setup), enforcing Network Policies (default-deny…

google/skills · 181 tokens

cfn-template-compare