Your organization's dedicated outbound addresses, for allow-lists. list: The organization's reserved addresses. reserve(family?): Every sandbox of the organization then sends from its own address; family 4 (default) or 6. Needs credit on the account. release(addressId): Give one back by addressId; sandboxes send from the shared addresses again at once.
| Name | Required | Description | Default |
|---|---|---|---|
| action | Yes | ||
| family | No | ||
| addressId | No |
Changes observed during successful MCP inspections.
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already flag the mutating/destructive profile (readOnlyHint=false, destructiveHint=true), and the description adds real context beyond them: reserve requires credit on the account, and release immediately causes all sandboxes to send from shared addresses again. This discloses side effects and prerequisites not present in the structured fields.
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?
Purpose is front-loaded, then each action is covered in a compact clause with no filler. Slightly dense run-on phrasing and the redundant 'list: The organization's reserved addresses' restatement cost it the top score.
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 three-action mutation tool with no output schema and no parameter descriptions, the description covers operations, prerequisites, and side effects well. It does not describe what list returns, but with no output schema that is a minor gap.
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?
Schema coverage is 0%, so the description must carry the meaning: it explains family values (4 default, 6), the addressId role (give one back by addressId), and the three action values. It meaningfully compensates for the missing schema descriptions, though it omits format details like the UUID nature of addressId.
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?
States a specific resource (the organization's dedicated outbound addresses) and then names all three actions with concrete verbs and effects. An agent can tell what each action does without opening the schema, and the tool is clearly distinct from all siblings.
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?
Each action is given a clear context for selection (list = reserved addresses, reserve = per-sandbox addresses, release = return to shared), and the credit prerequisite for reserve is disclosed. There are no named exclusions or alternatives, but none exist among the siblings, so the guidance is effectively complete.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
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