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

With no annotations provided, the description carries the full burden and does so: it is read-only in effect (only returns a link, never charges), requires human action to complete payment, changes answer shape (kind:'portal') for existing Pro accounts, and specifies the 404 'billing is not enabled' failure mode. This is unusually rich behavioral disclosure.

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?

Front-loaded with the deliverable and price, followed by usage condition and the no-charge/no-open rule. Dense but each sentence earns its place; only the redundant restatement of interval pricing is mildly wasteful.

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 one-parameter tool with no output schema, the description covers trigger, return shape (link vs portal), the human-in-the-loop requirement, and the error case — everything an agent needs to call and interpret it correctly.

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% and the single interval parameter's enum and pricing are already documented in the schema. The description restates the 'year' option at $48, adding marginal value beyond the structured field, so 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 (get a Stripe checkout link), the resource/product (AgentDomains Pro), and the concrete deliverables (100 names, unreachable names retained, priority email support) with pricing. An agent can distinguish this from manage_billing and claim_domain without opening any 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?

Explicitly names the trigger condition ('when a claim is refused because the account is at its name limit and the user wants more') and the already-Pro branch that routes to a portal-style answer. It also states the agent-facing rule: show the URL and price, do not open or pay.

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