mailkite_check_domain_availability

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

The annotation already tells the agent readOnlyHint=true, but the description adds meaningful behavioral context: 'Read-only — no charge' and 'Requires a management session token'. These are material details beyond the structured annotations. It does not disclose the exact return format, but the read‑only nature is well covered.

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 short sentences, each earning their place: the core purpose is front-loaded, followed by the no-charge caveat and the auth requirement. No fluff or irrelevant 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?

With no output schema, the description could clarify what the response will contain beyond 'availability and price', such as whether the price is present only when available or the format of the status. It also doesn't explain error cases or behavior for domains already registered. Still, for a one-parameter, read-only check, the essential trigger is clear enough.

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 description for the single parameter is minimal ('Query parameter `domain`.'), but schema coverage is 100%. The tool description adds no further meaning for the domain parameter — no format, examples, or guidance on accepted values — so the description does not improve on 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 clearly states the verb 'check' and the resource 'domain availability', and adds the outcome 'at what price'. However, it does not explicitly differentiate from the sibling mailkite_check_subdomain; a reader must infer that 'domain' is not 'subdomain'.

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 only guidance offered is 'Requires a management session token', which is a prerequisite rather than a usage scenario. It does not say when to use this tool (e.g., before registering a domain) or when to avoid it and prefer an alternative.

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