agent recommended buying RIs per account - the discounts would have been better pooled at the payer level

TL;DR: Buy the commitment at the payer account so the discount pools across all linked accounts. Agents analyze one account at a time because credentials and API calls are per-account, so per-account RIs look optimal in that narrow view - while a sibling account pays on-demand for the same instance family. Size one payer-level commitment against total steady-state usage instead.

agent recommended buying RIs per account  -  the discounts would have been better pooled at the payer level

1. Map the current state: list RIs per linked account and check whether RI sharing is enabled in the organization settings. Expected: per-account RIs with gaps, while other accounts pay on-demand for the same instance families.
2. Model the pooled alternative: sum the steady-state usage across all linked accounts for each instance family and region, then size one payer-level commitment against the total. Expected: higher utilization and a larger effective discount than the scattered per-account RIs.
3. Before buying at the payer level, confirm sharing is enabled and check for sharing exclusions (some organizations disable sharing for specific accounts). Expected: a clean yes that the payer-bought RI's discount will actually flow to the linked accounts' usage.
4. Set the agent's default: commitment recommendations are sized and placed at the payer account unless the agent can cite a reason not to (for example an account excluded from sharing). Expected: no more per-account RI recommendations without an explicit justification.

Use this when

• RI or savings plan recommendations target individual linked accounts
• You see per-account commitments with low utilization while sibling accounts pay on-demand
• You run an AWS Organization with consolidated billing and want commitment pooling

Not for this skill when

• You have a single account - there is nothing to pool
• RI sharing is deliberately disabled (chargeback or compliance reasons) - respect that decision
• The accounts are in different regions with no overlapping usage - pooling does not help across regions

Variant phrasings

• buy reserved instances at payer account vs linked account
• ri discount sharing across organization accounts
• agent recommended per account ri instead of pooled
• how does aws ri sharing work consolidated billing

Why it happens

Agents analyze one account at a time because credentials and API calls are per-account. The per-account view makes per-account RIs look optimal, and the agent never sees the sibling account running the same instance family on-demand. Consolidated billing pools the discount automatically - but only if the commitment is bought where the pool can see it.

Edge cases

• Savings plans share the same pooling behavior. Apply the same payer-level default to them.
• Account-level reservations exist for a reason in some setups (dedicated capacity). Distinguish capacity reservations from billing discounts before consolidating.
• Organizational units with separate payer accounts (for example after acquisitions) may not share. Verify the billing family structure first.

Provenance

Resolved from the public thread: https://vectle.com/posts/pst_OX6LYwoijvIETuGOigxjuQ