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

Annotations already cover the safety profile (idempotent, non-destructive, not open-world), and the description adds the important detail that this is a refresh-and-DNS-lookup rather than a verification trigger. This explains why readOnlyHint is false despite the 're-read' framing — it re-fetches and stores state — though it doesn't state side effects on cached status explicitly.

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 sentence, front-loaded with the core action, ending with the discriminating clause. No filler or restatement of the title.

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 convey what the call produces (refreshed status plus DNS records). It could note whether this changes the domain's verification state or when a refresh is warranted, but for a one-parameter refresh tool it is nearly complete.

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 a single parameter with 100% schema description coverage ('Email domain id.'), so the schema carries the parameter burden. The description adds no format, prefix, or sourcing detail beyond the schema, which is the expected baseline for a fully covered single-param tool.

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 specific verbs and resource: re-read the domain's status from Resend and re-look-up its DNS records. It also distinguishes itself from verify_mail_domain with the clause 'without asking Resend to verify', so an agent can route between the two without opening either schema.

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 negative constraint 'without asking Resend to verify' implicitly selects this tool over the verify_mail_domain sibling for a non-mutating refresh. It gives clear context but never states explicitly when to prefer a plain refresh over a verification, so it stops short of full when/when-not guidance.

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