AWS Cost Estimate Skill

Generate accurate AWS cost estimates from architecture documents or descriptions.

Arguments

• doc-path

  : Path to architecture document (markdown, text) or inline description

• --lang

  : Output language.

  ja

  (default) or

  en

• --currency

  :

  usd

  (default) or

  jpy

  . When

  jpy

  , ask the user for the exchange rate to use

Workflow

1. Parse the architecture

Read the provided document. Extract:

• AWS services used and their configuration
• Data flow patterns (for data transfer estimates)
• Scale assumptions (users, queries/day, data volume)

If anything critical is ambiguous, ask using AskUserQuestion. Keep clarification minimal — only ask what materially affects the estimate.

2. Verify pricing — AWS CLI first, web search fallback

CRITICAL: Always verify current prices. Never rely on training data.

1. Silently check if AWS CLI is available and authenticated (see

   references/aws-pricing-api.md

   )
2. If available → use AWS Price List API for exact regional pricing. Read

   references/aws-pricing-api.md

   for service codes, example queries, and JSON parsing
3. If unavailable → fall back to web search:

   "AWS [service] pricing [region] [current year]"

   . Use WebFetch on official pricing pages if results are insufficient

For required permissions, see

references/permissions.md

.

3. Calculate and output the report

Output a clean cost report. No greetings, no sign-offs — just the report.

Structure:

## Assumptions
- Region, scale, availability config
- Exchange rate (if currency is JPY)
- Services using existing infrastructure (noted as $0 with explanation)

## Monthly Cost Breakdown

**[Service name] ([config])**
- Cost: $XX.XX/month
- Calculation: [unit price] × [usage]
- Source: [pricing page URL]

(repeat for each service)

## Monthly Total: $XXX〜$XXX

## Scaling Options
(How cost changes at different tiers, e.g., 1→2→4 OCU)

## Initial Costs
- AWS service fees: none for listed services
- Development effort: [key build tasks]

## Caveats
- Unverified regional prices, assumptions, limitations

Use the user's

--lang

for all section headers and descriptions.

4. Offer AWS Pricing Calculator link (optional)

After outputting the report, ask the user:

"AWS Pricing Calculatorの共有リンクを作成しますか？（Playwrightブラウザ操作が必要です）" (or in English: "Would you like me to generate a shareable AWS Pricing Calculator link? (Requires Playwright browser automation)")

If yes, read

references/calculator-automation.md

for the full Playwright workflow, known limitations, and service-specific tips.

Rules

1. Always verify prices — use AWS Price List API (preferred) or web search. Never use memorized prices
2. Show the math — unit price × usage for each line item
3. Cite sources — pricing page URL for every service
4. No greetings or sign-offs — output is a raw report, not a message
5. Be honest about uncertainty — flag when using US prices with regional estimates
6. Flag cost drivers — clearly call out which service dominates the total
7. Don't editorialize costs — present numbers neutrally, don't say "small" or "large"
8. Include existing infra — if user says a service is already running, show it at $0 with a note

Common pitfalls to verify

• OpenSearch Serverless: min OCU varies (1 without redundancy, 4 with). Actual billing supports 0.5 OCU increments
• S3 endpoints: Gateway Endpoint = FREE, Interface Endpoint = PAID
• Bedrock: separate charges for embedding (Titan) vs generation (Claude) — very different price points
• Transit Gateway: hourly per-attachment + per-GB data processing
• VPC Endpoints: per-AZ pricing — confirm how many AZs
• EC2 Tokyo: typically higher than US East — verify exact regional rate