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

Annotations already declare readOnlyHint=true, destructiveHint=false, and openWorldHint=true, so safety is largely covered. The description still adds real context by disclosing what the read returns and explicitly reassuring that `check` makes no changes, which reinforces rather than contradicts the annotations.

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 tight sentences: the primary read behavior and its output are front-loaded, and the secondary `check` mode follows. No filler or restated title text.

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?

With no output schema, the description carries the burden of describing return content and does so by listing the domain facets returned. Combined with the annotation-covered safety profile, an agent has enough to call it correctly; only the sibling relationship to check_domain remains unaddressed.

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 100%, so both parameters are documented in the schema (id = site id, check = candidate domain). The description slightly enriches `check` by framing it as a non-mutating preflight, but adds no format or constraint detail beyond that, matching the baseline for fully-covered schemas.

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 a specific verb (Read) and resource (the site's custom domain) and enumerates the returned facets: redirect mode, apex/www Vercel state, and required DNS records. It does not, however, name the very similar sibling check_domain, leaving the agent to disambiguate 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?

It explains the `check` mode as a change-free preflight, which is genuine usage guidance for that parameter. But it never states when to call this instead of check_domain, set_domain, or set_domain_redirect_mode, so the selection logic against alternatives is only implied.

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