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

Annotations already declare the mutation (readOnlyHint=false), idempotency, and open-world DNS access. The description adds genuinely non-obvious behavior beyond that: verification does not throw when records haven't propagated, it returns the current status instead — important for retry logic. It does not say what permissions or domain states are required.

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 with the action front-loaded and the non-failure caveat second. Every clause carries information; only the slightly redundant 'current domain status' phrasing could be trimmed.

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 does well to explain the fallback return (status instead of error), which is what an agent most needs to branch on. Gaps remain around the success-path return and whether repeated calls are safe across domain states, but the critical behavior is covered.

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?

There is one required parameter with 0% schema description coverage; the schema only supplies type uuid. The description never explains that customDomainId identifies the domain record or where to obtain it (e.g., from connect_custom_domain or the domain status tool), so it adds no meaning over the 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?

States a specific verb chain (check DNS, activate) on a specific resource (pending/stale custom domain), which an agent can distinguish from connect_custom_domain and get_custom_domain_status. It stops short of explicitly naming those siblings as alternatives.

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?

The phrase 'pending or stale custom domain' implies the precondition for use, but the description never explicitly says when to use this instead of get_custom_domain_status (read-only status check) or connect_custom_domain (initial setup). Routing is left to inference.

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