Cross Account Cost Attribution

Cross-Account Cost Attribution

Routing behavior is governed by china-region-multi-account-routing. This skill assumes the agent is already prepared to hit both China MCPs and focuses on how to query cost data and present a comparative view.

When to use

Use this skill whenever the user's intent involves monetary comparison or attribution across the two China accounts. Examples:

• "这个月两个账号各花了多少"
• "哪个账号贵"
• "两个账号的 EC2 花费对比"
• "北京账号上个月比这个月涨了多少"
• "top 5 services by cost in each account"
• "我这两个中国区账号一共 MTD 多少"

Do not use this skill for:

• Single-account cost queries (the user already specifies account → let

the base aws-api-mcp-server handle it)

• AWS global cost (this skill is China-partition only)
• Forecasting / budget alerts (out of scope — different API surface)

China partition cost API note

AWS China has its own Billing/Cost Explorer API surface at bcm-data-exports.cn-northwest-1.amazonaws.com.cn and ce.cn-north-1.amazonaws.com.cn. The CLI commands are the same as global (aws ce get-cost-and-usage), but credentials must be the China-partition AK/SK — which is exactly what each MCP pod already has. Do not use aws-global credentials; they will fail with AuthFailure.

Procedure

Step 1 — Determine the time range

Parse from the user's query. Default if unspecified: month-to-date (MTD) for the current month. Common mappings:

| User phrase | Time range | |---|---| | "这个月" / "this month" / "MTD" | First day of current month → today | | "上个月" / "last month" | First day → last day of previous month | | "过去 30 天" / "last 30 days" | Today − 30 days → today | | "今年" / "YTD" | Jan 1 of current year → today | | "环比" / "month-over-month" | Return both current MTD and previous full month |

Always include the exact date range in the response so the user can verify.

Step 2 — Query Cost Explorer on both endpoints in parallel

Use aws ce get-cost-and-usage with:

• --time-period Start=...,End=...
• --granularity MONTHLY (or DAILY if range ≤ 31 days and user wants

trend)

• --metrics UnblendedCost
• --group-by Type=DIMENSION,Key=SERVICE (for top-services breakdown)

Call on both aws-cn and aws-cn-2 MCPs concurrently.

Step 3 — Aggregate and compare

For each account, compute:

1. Total spend (sum of UnblendedCost.Amount across groups)
2. Top N services (default N=5, sorted by amount desc)
3. Delta vs prior period (if the user asked for month-over-month or

if the default 1-month view makes comparison obvious)

Step 4 — Present

Two-part format. Headline numbers first, then breakdown tables.

Headline:

Date range: 2026-05-01 → 2026-05-11 (MTD, 11 days)

aws-cn   (Ningxia): ¥ 1,234.56  (ΔMoM: +8% vs April)
aws-cn-2 (Beijing): ¥   456.78  (ΔMoM: −3% vs April)
Combined:           ¥ 1,691.34

Top-services table (side-by-side):

| Service | aws-cn | aws-cn-2 | |-----------------|-------:|---------:| | Amazon EC2 | ¥ 800 | ¥ 200 | | Amazon RDS | ¥ 300 | ¥ 150 | | Amazon S3 | ¥ 80 | ¥ 50 | | Data Transfer | ¥ 30 | ¥ 30 | | Other | ¥ 24 | ¥ 26 | | Total | ¥ 1,234.56 | ¥ 456.78 |

Step 5 — Interpret (1–3 sentences)

State one observation: where is the bigger account spending, is the delta normal, is there an outlier service. Do not recommend cost optimization unless asked — that requires deeper data than this skill retrieves.

Things not to do

• Do not convert currencies. China region returns CNY; present as

¥ and do not add a $ equivalent. Exchange rate assumptions cause confusion and you do not have a rate source.

• Do not compare different time ranges across the two accounts. If

one account's data is incomplete (e.g. CE has 24h lag), note the discrepancy explicitly instead of silently aligning.

• Do not use --metrics BlendedCost or AmortizedCost without the

user asking. Default to UnblendedCost — it matches what users see on the billing console.

• Do not claim a spending anomaly unless you have ≥2 prior periods

for comparison. One-month deltas on new accounts are noisy.

• Do not include detailed SKU-level breakdown unless the user asks.

Service-level is the default granularity.

Examples

Input: "这两个账号这个月花了多少"

Action: MTD on both in parallel, service-level breakdown, side-by-side table. Report total per account + combined.

Input: "哪个账号贵，贵在哪"

Action: Current MTD on both, find the higher one, break down its top-3 services, highlight which service drives the difference.

Input: "北京账号 EC2 比上月涨了没"

Action: aws-cn-2 only, current MTD vs previous full month, filter service=Amazon EC2. Report delta in absolute ¥ and percent. Note if the current month is partial (MTD) and adjust interpretation accordingly.

Input: "过去 90 天两个账号哪天花的最多"

Action: Both accounts, daily granularity, past 90 days. Find the peak-spend day per account and report with date + amount + top service that day.

Source & license

This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.

• Author: aws-samples
• Source: aws-samples/sample-skills-for-AWS-Devops-agent
• License: MIT

Install and usage instructions live in the source repository linked above.