DB Cost Diagnosis

Diagnose Alibaba Cloud database costs: "why is my database bill so high", "which billing item dominates this RDS instance's charge", "my DB cost jumped this month — what caused it", "I deleted the instance, why am I still being billed", "which instances are about to expire", "am I paying for idle databases", "what paid feature is charging me".

Core approach: confirm identity and billing scope, then either (1) drill into a single instance's bill detail with billing-item split to locate the dominant cost driver, (2) aggregate the account-level DB cost trend over recent months, detect anomalies, and attribute them to specific products and instances, or (3) run a proactive read-only audit — renewal/expiry risk and order anomalies, idle/low-load detection, or paid-feature attribution for unexplained charges. Conclude with evidence-based findings only; this skill never changes anything.

Absolute Rules

1. ABSOLUTE PROHIBITION (read-only enforcement): Under NO circumstances may you generate, write, or execute any command/script calling a mutating API — e.g. Modify*, Delete*, Create*, Restart*, Release*, Upgrade*, Downgrade*, or any configuration/spec change on database resources. This includes commands "for the user to run manually". If the user asks to downgrade, release, or resize an instance to cut cost, only output the manual guidance and declare this skill is read-only.
2. API WHITELIST: The only permitted OpenAPI actions are the read-only BSS queries DescribeInstanceBill, DescribeSplitItemBill, QueryOrders, and QueryAvailableInstances (bssopenapi, endpoint business.aliyuncs.com, API version 2017-12-14), the read-only CloudMonitor query DescribeMetricList (cms), plus sts:GetCallerIdentity for identity traceability. Any other action is forbidden.
3. ABSOLUTE PROHIBITION (credential handling): Never read, print, or pass AK/SK/STS tokens explicitly. Credentials are resolved automatically by the aliyun CLI default credential chain. Never accept AK/SK from the user or from another script.
4. NO FABRICATION: Every conclusion must be grounded in data actually returned by the billing APIs. If a query fails or returns empty, record it and state the limitation — never invent cost numbers, instance names, or billing items.
5. EXECUTION RULE FOR ERRORS: On any API error, log [WARN] <Code>: <Message> to stderr and continue with the remaining queries — never silently skip or abort the whole diagnosis. The final report is still produced with the data at hand.
6. SCOPE BOUNDARY: This skill answers questions about issued or current bills and cost attribution (which product/instance/billing item produced a charge), and provides READ-ONLY audits of renewal status, order anomalies, idle capacity and paid features. It does NOT execute renewals, unsubscriptions, refunds, or any other mutation, does NOT handle pre-purchase price quotes or unlocking resources after overdue payment — for such requests, state the boundary and point the user to the console purchase/renewal pages.

Execution Principle

All diagnostics MUST be performed by running the scripts under scripts/. The Agent is forbidden from assembling its own aliyun CLI commands or bypassing the scripts to call billing APIs directly — the scripts embed pagination, retry, error degradation, and observability guarantees that ad-hoc commands lack. Read the script output, interpret it, and compose the report; do not re-implement the queries.