add_domain

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

No annotations are provided, so the description carries the full burden of behavioral disclosure. It discloses that the tool returns DNS records to add and that verification is automatic after propagation, which is useful. However, it does not mention potential side effects, such as behavior if the domain already exists, or any permissions or rate limits.

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 two sentences, front-loaded with the primary action ('Add a custom sending domain'), and every sentence provides value. There is no wasted text, and the structure is straightforward.

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 simple one-parameter tool without an output schema, the description explains the return value (DNS records) and the follow-up behavior (automatic verification after propagation). It lacks details on input format or error conditions, but it is adequate given the tool's simplicity and the presence of only one parameter.

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?

The schema has one required parameter, hostname, with no description in the schema (0% coverage). The description's phrase 'custom sending domain' implies that hostname is the domain being added, adding meaning beyond the raw string type. This compensates for the lack of schema-level descriptions, though it could be more explicit about the expected format (e.g., should it include a protocol or subdomain?).

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 clearly states the tool adds a custom sending domain, with 'add' as the verb and 'custom sending domain' as the resource. This distinguishes it from siblings, particularly the read-only get_domain tool, by specifying the creation/registration action.

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?

The description implies the tool is used when adding a sending domain, and mentions the follow-up DNS setup and automatic verification. However, it does not explicitly state when not to use it or how it differs from alternatives like get_domain, though the action is clear enough.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.