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

readOnlyHint=true already establishes the safety profile, so the bar is lower. The description does add meaningful state context by indicating it surfaces the still-pending DNS records, which is real behavioral value. It stops short of saying what happens when no domain is connected (empty result, null, or error) or whether verification status is included.

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?

One short sentence with no filler, and the resource is front-loaded. It is a grammatical fragment lacking a verb, which slightly weakens scannability but wastes no space.

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?

As a read-only getter with no output schema, the description carries the burden of describing the return value, and it does so only minimally (domain + pending DNS records). Missing are the shape of the response, verification status fields, and the no-domain-connected case, which an agent needs to interpret results.

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?

Single parameter with 100% schema description coverage; the schema already explains that organizationId is a gym id sourced from list_my_organizations. The description adds no additional meaning about the parameter, which is acceptable at this coverage level but not above baseline.

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?

Names a specific resource (the gym's custom domain) and hints at the return payload (domain plus pending DNS records), but it is a noun phrase with no verb and never states that it retrieves/reads state. Against siblings like connect_gym_custom_domain, refresh_gym_custom_domain, and remove_gym_custom_domain, a reader must infer the read-only distinction from the name alone.

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 when-to-use statement, no prerequisite, and no reference to the connect/refresh/remove siblings that an agent could easily confuse this with. The only steer is indirect, via the schema note that organizationId comes from list_my_organizations.

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