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

Annotations already declare readOnlyHint=false, destructiveHint=false and openWorldHint=true, so the description's only added signal is that the external interaction is a DNS lookup rather than a registry mutation. It says nothing about what a failed verification means, whether the call is asynchronous, whether results are polled or returned inline, or what state changes on success.

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?

Six words, front-loaded and free of filler, so it is maximally concise. The terseness is also under-specification: no sentence earns extra weight because none of the operational context an agent needs is present.

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 non-read-only, open-world operation with no output schema and a partially documented schema, the description is too thin. It lacks the prerequisites, the meaning of a success/failure result, and any indication of propagation or retry behavior that an agent would need to use it correctly.

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 only 50%: project_id is documented in the schema (including the use_project session alternative) but domain_id is a bare string with no description. The description does not compensate by explaining that domain_id is the identifier of an already-added custom domain or where to obtain it (e.g., list_domains).

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 pairs a specific verb ("Verify") with a specific resource ("DNS for a custom domain"), which is enough for an agent to distinguish this from add_domain, remove_domain, list_domains or set_primary_domain among the siblings. It stops short of saying what verification produces, but the core action is unambiguous.

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?

There is no guidance on when this should be invoked: no prerequisite that the domain must first exist via add_domain, no mention that DNS records must be configured and propagated, and no alternative or exclusion. The agent must infer the entire workflow from the sibling names.

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