Drive Storage Add-on API Boundaries

The Drive Storage Add-on expands pooled storage for TrekMail accounts. Agents can read add-on status and pricing, but they cannot buy, resize, cancel, or otherwise change the subscription through API or MCP write operations.

This page explains the boundary so automation can be helpful without turning billing decisions into background agent actions.

What agents can read

With drive:addon:read, an integration can read:

• Current Drive Add-on status.
• Capacity and billing period, when an add-on is active.
• Pricing options for supported currencies.
• Cancellation preview information where available.
• Storage usage context that helps explain whether more capacity may be needed.

This is enough for reporting agents, dashboards, storage monitors, and support workflows.

What agents cannot change

The API and MCP server do not expose write operations for:

• Purchasing a Drive Add-on.
• Resizing the add-on up or down.
• Changing billing period or payment method.
• Canceling or reactivating the add-on.
• Triggering card charges or subscription mutations.

There is no drive:addon:write scope. The MCP server has no purchase, resize, or cancel tool.

Why the boundary exists

Storage changes can affect invoices, currency, capacity planning, and data retention. A helpful agent can notice that usage is high and explain options, but the final billing step should happen in the dashboard where a human sees the price and confirms the action.

This also limits damage if an agent is misconfigured. A narrow storage monitor token can report "you are near quota" without being able to spend money or cancel capacity.

Recommended automation pattern

1. Grant drive:addon:read and the relevant Drive read scope.
2. Have the agent check usage and add-on status.
3. If storage is tight, have the agent prepare a short recommendation.
4. Send the user to the dashboard Drive Add-on page for any purchase, resize, or cancel action.

Example agent response:

Your account is using 91% of pooled storage. The current Drive Add-on is active. Based on current growth, consider reviewing add-on size in the dashboard before the next upload batch.

Grace and read-only states

If an add-on is canceled, there may be a grace window where files remain readable while writes are restricted. Agents should treat this as a state to report, not something to fix automatically. The user can decide whether to restore capacity, delete files, or export data.