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

The description adds substantial behavioral context beyond the readOnlyHint, idempotentHint, and destructiveHint annotations: it is AI-operated, does not take payment, does not start a read, and only returns a link a person must open and pay at. It also discloses what the eventual read includes: DKIM, SPF, and DMARC.

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 description is longer than average but dense and well-organized: it front-loads price, terms, and output, then explains the read scope, then gives routing guidance, and ends with a critical behavioral warning in caps. Minor redundancy exists around payment and cancellation terms, but each sentence earns its place.

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 quote-and-checkout-link tool, the description is complete: it covers price, payment terms, what is read, what is not done, when to use it, and when to prefer the free siblings. Since an output schema exists, the description does not need to detail the return shape.

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?

The schema already documents main_domain as optional with an example, and schema coverage is 100%. The description adds useful clarification by explicitly stating the parameter is only echoed back for convenience and that the domains actually read are supplied after checkout, which prevents a caller from assuming this parameter controls the scan.

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 explicitly states a specific verb and resource: it returns the price, terms, and checkout link for a paid ROSTER read of up to 25 domains. It also distinguishes itself from the free sibling tools by naming dkim_check and dkim_selector_list and making clear this tool is for bulk-domain checks.

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?

It gives explicit when-to-use guidance: use when a caller asks about checking MANY domains, such as a portfolio or acquired estate, rather than one. It also names alternatives and clarifies that dkim_check and dkim_selector_list remain free and should be used when they answer the caller's question.

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