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

ReadOnlyHint=true is already declared in annotations, so the safety profile is covered. The description adds useful context about what is returned (domain status and DNS records still needed), but it does not disclose behavior when no domain is connected or whether the call fails versus returning empty data.

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?

It is a single, front-loaded sentence with no filler. The noun-phrase fragment is slightly less clear than a complete sentence, but it communicates its content efficiently.

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 read-only, zero-parameter tool with no output schema, the description gives a high-level view of the return content. However, it omits important edge-case behavior, such as what happens if no custom domain exists or if the coach is not on Coach Pro.

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 has zero parameters, so there is no parameter semantics to document; baseline is 4. The description correctly does not spend words re-explaining an empty input 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 identifies the resource: the custom domain tied to the coach's Coach Pro public page, including pending DNS records. It does not use an explicit verb like 'retrieve', but the resource scope is specific and distinguishable from gym or organization domain tools.

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 to use this tool versus alternatives such as connect_my_custom_domain, refresh_my_custom_domain, or remove_my_custom_domain. It also does not state prerequisites, such as whether the coach must already have a Coach Pro plan or a connected domain.

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