tf-best-practices

tf-best-practices is a skill for Claude Code from awslabs/startups. It costs 107 tokens per session (2,602 once invoked), scanned A, original, Apache-2.0.

A guide and read-only checker for Terraform files that create AWS infrastructure. Terraform is a tool that describes cloud resources in code; the checker reviews the generated files against specified security and configuration rules.

In plain words
What is it for?
Set authoring rules before generating AWS Terraform, then format, initialize, validate, and check the resulting files with a deterministic policy gate.
Why use it?
It gives an infrastructure-generation workflow a defined security baseline and a repeatable way to find policy violations. Because it is read-only, it reports problems without changing the Terraform files.

Skill for Claude Code

Written for Claude Code: shipped in a Claude Code plugin.

Part of the aws-startup-advisor plugin — 9 skills, 6 agents, 1 hook, 4 MCP servers shipped together

About the project

AWS Startups is an official AWS repository containing plugins, skills, tools, and other resources for people building startup products on Amazon Web Services. Its add-ons support startup-focused architecture, migration, and development work on AWS.

awslabs/startups · 17 stars · on GitHub

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 skills/awslabs/startups/tf-best-practices
Any agent
npx skills add awslabs/startups --skill tf-best-practices
Clone the repo
git clone --depth 1 https://github.com/awslabs/startups

Made for: Claude Code.

Or install aws-startup-advisor, the plugin that ships this one along with the rest of its 9 skills, 6 agents, 1 hook, 4 MCP servers.

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 tf-best-practices

README.md
[![agentmods](https://agentmods.dev/badge/skills/awslabs/startups/tf-best-practices.svg)](https://agentmods.dev/skills/awslabs/startups/tf-best-practices)
Your own site
<a href="https://agentmods.dev/skills/awslabs/startups/tf-best-practices"><img src="https://agentmods.dev/badge/skills/awslabs/startups/tf-best-practices.svg" alt="Measured on agentmods" height="20"></a>
Per session 107 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,602 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 5.1 $0.00107 $0.02602
Opus 5 $0.00053 $0.01301
Sonnet 5 $0.00021 $0.00520
Haiku 4.5 $0.00011 $0.00260

Measured 6d ago against content hash 55607f45d3f8, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-06, from the pricing page.

Security

Grade A, and why

tf-best-practices 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 6d ago.

The scan reads SKILL.md. This mod also ships 2 executable files (scripts/test_validate_terraform_policy.py, scripts/validate-terraform-policy.py), 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.

advisor/plugins/aws-startup-advisor/skills/tf-best-practices/SKILL.md · 200 lines

How it starts

The opening of the file, as written. The whole thing — 200 lines — stays where its author put it; the contents beside it link to each section on GitHub.

tf-best-practices — Generated-IaC posture rules + read-only policy gate

A shared authoring guide and verdict producer, not a workflow. It answers two questions for a phase that generates AWS Terraform:

  1. Before writing — "what security posture must the generated terraform/ follow?" (the posture rules + the baseline.tf account-hardening spec)
  2. After writing — "does the generated terraform/ pass policy?" (a deterministic, read-only verdict + a machine-readable report)

Routing — load the part that matches your context

This skill is entered at two touchpoints in the caller's Generate flow, with the caller's own terraform-authoring work in between. The caller states which touchpoint it is at when it loads this skill, and reads the corresponding part:

Caller context Load Why
About to author terraform/ (before writing) Part 1 → references/security-posture-rules.md The "what to emit" AWS authoring rules (gate-enforced + authoring-only + compliance-conditional).
terraform/ written, ready to validate (after writing) Part 2 → references/terraform-validation.md + run the gate script The fmt → init → validate → policy protocol and the read-only verdict.

Everything this skill states is source-cloud-agnostic (pure AWS Terraform). Any GCP/Heroku detection or artifact reading is the caller's job; where a rule needs a caller-known fact (e.g. declared compliance frameworks), the caller passes it as a caller-context signal — see references/security-posture-rules.md § Caller-context signals.

Read the full file on GitHub · 200 lines

Files

What ships with it

28 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.

  1. 6d ago First seen · 200 lines · 107 tokens per session scan A 55607f45d3f8

Subscribe to this mod's changes

tf-best-practices is a skill published in the GitHub repository awslabs/startups (17 stars, last pushed 2d ago), licensed Apache-2.0. It adds 107 tokens to every session and 2,602 once invoked, about $0.0005 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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