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

Annnotations only cover the safety/idempotency profile, so the description adds substantial value: it discloses the auth requirement ('needs account token'), the human-in-the-loop payment flow, and the post-payment consequence ('the domain goes live on that site automatically'). This is exactly the behavioral context an agent needs before invoking a money-spending tool.

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?

The core instruction is front-loaded and useful, but the closing three sentences all restate the same 'don't spend money without asking' rule, which is redundant padding rather than new information.

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 3-parameter tool with no output schema, the description covers the auth prerequisite, the payment flow, and the automatic post-payment state change. Only the shape of the returned link is unaddressed, which is minor given there is no output schema to reference.

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 name, extras, and site_id are already fully documented in the schema. The description adds no syntax, format, or constraint detail about the parameters themselves, 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?

States a specific verb and resource ('Get a payment link for a domain') plus the scope constraint ('on one of your sites', 'Only for sites on the user's account'). It implicitly separates itself from search_domain/point_domain by framing this as the payment step, though it never names a sibling tool explicitly.

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?

Gives explicit when-to-use context and a clear prerequisite/alternative path: 'For an anonymous site, give the human the claim link first.' It also states the hard boundary that the agent itself can never pay and that the human must be asked first, leaving nothing to inference.

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