Permanently deletes a subscriber and all list subscriptions; this cannot be undone. To stop mail while keeping the record, set the subscriber status to blocklisted instead.
Permanently delete a subscriber and all their list subscriptions. This cannot be undone. To stop mailing someone but keep their record, use change_subscriber_status with 'blocklisted' instead.
| Name | Required | Description | Default |
|---|---|---|---|
| subscriber_id | Yes | Subscriber ID |
Changes observed during successful MCP inspections.
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already flag destructiveHint=true and idempotentHint=true, but the description adds the key detail annotations cannot convey: the delete cascades to all list subscriptions, not just the record. Irreversibility is stated outright, though permission requirements and any confirmation step are not mentioned.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
Three sentences, zero waste: the action and its irreversibility come first, then the cascade consequence, then the redirect to the safer sibling. Nothing is buried.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
For a one-parameter mutation with no output schema, the description covers what is destroyed, that it is irreversible, and what to do instead. Nothing an agent needs before calling is missing.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Single required parameter with 100% schema coverage, so the schema already documents subscriber_id fully. The description adds no format, range, or lookup hints beyond that, making the baseline 3 correct.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
Specific verb (permanently delete) plus resource (subscriber) and the cascade scope (all their list subscriptions). It also implicitly distinguishes itself from sibling delete_mailing_list/delete_media_file by naming the subscriber domain and from soft-suppression alternatives.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
Explicitly names an alternative tool (change_subscriber_status with 'blocklisted') and the exact condition that should route an agent there instead. This is textbook when-to-use/when-not-to-use guidance.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.