cost-estimate

name	cost-estimate
description	Generate a rough monthly cost estimate for a CloudFormation template or proposed architecture

Estimate the monthly AWS cost for the resources in the currently open CloudFormation template or the architecture I describe.

Instructions

1. Identify every resource that has an ongoing cost (ignore free-tier resources in a real production account)
2. Use the default parameter values where provided, or ask for expected values for critical sizing parameters
3. Assume eu-west-1 pricing unless the template specifies a different region
4. Provide estimates for two scenarios: minimum expected (low traffic, minimum instances) and typical production (expected normal load)

Output format

Cost breakdown

Service	Resource	Configuration	Monthly cost (min)	Monthly cost (typical)
Amazon ECS	Fargate tasks	0.5 vCPU, 1GB RAM × 2 tasks	$18	$36
Amazon RDS	PostgreSQL db.t3.medium	Multi-AZ, 100GB storage	$120	$120
Application Load Balancer	1 ALB	~10M requests/month	$20	$35
Amazon S3	3 buckets	Logging, artifacts, backups	$5	$20
Data transfer	Outbound	~50GB/month	$5	$15
Total			$168	$226

Cost drivers

List the top 3 cost items and whether they're fixed or variable:

1. RDS — $120/month fixed (largest item — consider Aurora Serverless for non-prod)
2. ECS Fargate — variable, scales with traffic
3. Data transfer — variable, watch NAT Gateway charges

Cost optimisation opportunities

Based on the template, identify quick wins:

• Is Multi-AZ needed in non-prod? (saves ~50% on RDS)
• Are EC2 instances on On-Demand that could be Savings Plans?
• Any resources that could use Graviton instances (20-40% cheaper)?
• Are S3 lifecycle rules configured for older data?
• Is there a NAT Gateway per AZ when one might suffice for non-prod?

Cost anomaly risks

Flag anything in the template that could cause unexpected cost spikes:

• Auto-scaling with no maximum capacity set
• S3 buckets with no lifecycle rules that store large amounts of data
• DynamoDB with on-demand billing and no estimated read/write unit projections

Compare to actual spend (if cost-explorer MCP is available)

Use the cost-explorer MCP tool to fetch the last month's actual spend for resources tagged with matching tags and compare estimate to actuals.