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

Annotations declare it is not read-only, is idempotent, and is non-destructive, but the description adds the traits annotations cannot express: the check is asynchronous ('runs a moment after the call'), the result must be retrieved separately via list_site_domains, and it requires the config:write capability. It does not describe failure modes (e.g., what happens if the domain is not registered to the site).

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, front-loaded with the action and its timing advantage, followed by the result-retrieval path and the permission prerequisite. Nothing is redundant with the title or schema.

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 async trigger with no output schema, the description covers everything needed: what it does, when it fires, how to obtain the outcome, and the required capability. No return-value documentation is needed because results are read through another tool.

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% and both parameters are documented in-schema, including the siteId source (list_sites) and a hostname example. The description adds no parameter-level detail beyond the schema, so the baseline 3 applies.

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 verb and resource (check the DNS records of a custom domain) plus the key differentiator: it happens now rather than at the next hourly check. An agent can distinguish this from list_site_domains, which the description explicitly names as the read path.

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?

Gives clear when-to-use context ('now, rather than at the next hourly check') and routes the agent to list_site_domains for reading results, which is the natural companion call. It stops short of explicit exclusions, e.g., that add_site_domain/remove_site_domain are the tools for changing domain configuration rather than triggering a check.

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