Add an extra SMTP domain to a mail zone so incoming mail for that domain is handled by the alias addresses of the main domain.
Add an extra SMTP domain to the mail zone, so mail sent to that domain is caught by the matching addresses on the main domain.
| Name | Required | Description | Default |
|---|---|---|---|
| hostname | Yes | The extra domain, e.g. 'example.com' | |
| domain_name | Yes | The main domain (mail zone) |
Changes observed during successful MCP inspections.
v1.0.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already indicate this is non-read-only, non-idempotent, and non-destructive. The description adds useful behavioral context by explaining the effect on mail routing. However, it does not disclose what happens on duplicate creation, whether domains must already be registered/verified, or other side effects that would matter for a write operation.
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?
The description is a single, front-loaded sentence. It leads with the action, then gives the behavioral rationale. There is no filler, repetition, or unnecessary detail.
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 two-parameter create operation with fully described parameters and no output schema, the description plus schema provides enough to select and invoke the tool correctly. It could be more complete by noting duplicate-handling or domain-verification requirements, but nothing essential for basic invocation 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?
Schema description coverage is 100%, so the baseline is 3; the schema already explains 'extra domain' and 'main domain (mail zone)'. The description reinforces the relationship between the two parameters but does not add meaningful detail beyond the schema.
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?
The description states a specific verb and resource: 'Add an extra SMTP domain to the mail zone.' It also explains the operational purpose: mail to that domain is caught by matching addresses on the main domain. It does not explicitly name or contrast sibling tools like smtp_domains_update/delete, but the 'add/create' semantics and resource type make it reasonably distinguishable.
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?
Usage is implied rather than explicit: an agent can infer this is for adding a new extra SMTP domain to a mail zone. There is no when-to-use/when-not-to-use guidance, no mention of prerequisites, and no direct comparison with alternatives such as aliases or catch-all creation.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.