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

Annotations already declare readOnlyHint, idempotentHint, non-destructive and closed-world, so the safety profile needs no restating. The description earns credit for disclosing the payload shape — setup stage and any still-missing DNS records per domain — which is genuinely useful behavioral context for a tool with no output schema.

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 compact sentence with no filler, and the most useful detail (missing DNS records) is present. It is a sentence fragment lacking a main verb and reads more like a return-value blurb than a lead statement, which slightly weakens front-loading.

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 one-parameter read tool with no output schema, the description covers what is returned (domains plus setup stage and outstanding DNS records) well enough to set expectations. It stops short of saying whether all site domains are returned and whether results are ever empty or paginated.

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 the single site_id parameter is fully documented in the schema, including that it accepts a name or an ID from list_sites. The description adds nothing further about parameters, 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?

The description identifies the resource precisely — custom short-link domains, contrasted with the default go.example.com — but it is a noun phrase with no verb, so the listing action is only implied by the tool name. It does implicitly separate this from list_links and list_sites, though it never names them.

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 guidance, no mention of prerequisites (e.g., needing a site_id first), and no steering toward or away from sibling tools such as list_sites or list_links. Usage must be inferred from the name and the single site_id parameter.

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