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

With no annotations, the description carries the full behavioral disclosure burden, and it delivers: it reveals asynchronous provisioning ('queue SES provisioning'), idempotency ('asking twice does not provision twice'), and the crucial post-step behavior of returning DKIM records and requiring a follow-up `verify` call. This is meaningful behavioral context beyond what the schema provides.

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 sentences, front-loaded with the primary purpose, with no filler. Each sentence earns its place: purpose, idempotency safeguard, and actionable next step are all packed efficiently.

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 two-parameter tool with no output schema, the description tells the agent everything required to call it correctly: what it does, that it is safely idempotent, that it returns DKIM records, and that `verify` must follow. Nothing needed to invoke the tool successfully is missing.

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%, so the schema already documents both parameters. The description does not add parameter-level detail beyond labeling the operation as registering the organization's 'exact' sending domain, which is a marginal clarification rather than new semantic meaning.

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 states a specific action ('Register... sending domain') and a distinct resource ('domain'), and it clearly distinguishes itself from sibling domain tools by framing this as the provisioning step followed by `domain_verify`. It also adds a key scope qualifier ('exact'), so an agent knows precisely what this tool is for.

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 description provides clear operational context: call this to register/set up the sending domain, then publish DKIM records and call `verify` to observe state. It does not explicitly contrast with alternatives like `tracking_domain_create`, but the sequential workflow instruction effectively guides usage away from raw verification calls until after this step.

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