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

The description goes far beyond the annotations: it discloses the re-run of the authoritative gate, the non-purchase confirm_url, quote expiry, premium pricing behavior, and the absence of any purchase-completing tool. This is rich behavioral context that annotations alone could not provide, and nothing contradicts the readOnlyHint.

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 front-loaded with the purpose but becomes verbose and repetitive. Phrases like 'It is NOT a purchase and you cannot make one', 'THE CONFIRM URL IS NOT A PURCHASE', and 'There is deliberately no tool to complete an order' repeat the same idea. Several sentences could be merged or removed without losing meaning.

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 single-parameter read-only tool with no output schema, the description is thorough. It lists the return fields (total_cents, renewal_cents, expiry, confirm_url), explains edge cases (premium, expired quotes, registered names), and even clarifies the role of budget context. Nothing critical for correct invocation or expectation-setting 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?

With schema description coverage at 0%, the description must carry parameter meaning. It partially does by explaining the domain must be an unregistered name and quoting is gated. However, it also references a 'project_id' parameter that does not exist in the input schema, which is misleading and reduces reliability for agents constructing calls.

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?

Description states a specific verb and resource: get the real price for a domain name the user has chosen. It explicitly distinguishes from purchase by saying 'It is NOT a purchase' and from other read tools by focusing on price quoting. The purpose is unambiguous and immediately actionable.

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 says 'Use this when the user has chosen a name and wants the real price' and clearly states the tool cannot purchase. It also includes when-not conditions, e.g., registered names are never quoted. However, it does not name alternative sibling tools, so it misses the full 'alternatives' component of a 5.

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