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

Annotations already declare readOnlyHint=true, idempotentHint=true and non-destructive behaviour, so the safety profile is covered. The description adds real value by enumerating the lifecycle statuses (pending_dns, verifying, ssl_provisioning, active, error) and noting DNS records are returned, which tells the agent what state information to expect. It stops short of describing return shape or whether results are site-scoped via context.

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?

Two compact sentences with zero filler. The most useful content — the domain statuses — is front-loaded in the first sentence, and the second sentence adds a short boundary note.

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?

There is no output schema, and the description compensates by explaining what the response contains: domain entries, their status enum values, and the required DNS records. For a zero-parameter read tool with annotations covering safety, that is close to complete; only the site-scoping mechanism (how 'the site' is resolved) is left unstated.

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 tool takes zero parameters, so there is nothing for the description to disambiguate. The baseline of 4 applies; the description correctly avoids inventing parameter discussion.

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 names the specific resource (custom domains connected to the site) and what it exposes: status values and the DNS records the owner must set. The listing verb is only implied through the tool name rather than stated, but no sibling tool covers domains, so the resource alone disambiguates it cleanly.

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 only implied — an agent can infer it is for checking domain verification/SSL progress and needed DNS setup. The clause 'The owner adds domains in Cockatoo' is a useful exclusion signalling this tool cannot create domains, but there is no explicit when-to-use or alternative routing.

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