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

Annotations already declare readOnly, idempotent, non-destructive, closed-world behavior, so the bar is lower, yet the description still adds real value: the not_found outcome for a missing order, the confidentiality constraint on the key (no URLs or third-party logs), and the warning that paid report evidence is untrusted website data. It does not describe result shape, which is acceptable given an output schema exists.

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?

Four compact sentences, front-loaded with purpose and followed by scope exclusions, failure behavior, and security constraints. Each sentence carries distinct information; the phrasing is dense but no sentence is filler.

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 full annotation coverage and an output schema, the description supplies everything an agent needs: what it reads, what it will not do, where the key comes from, the not_found failure mode, and how to treat returned evidence.

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 coverage is 100%, so the baseline would be 3, but the description adds provenance the schema cannot convey: the key must be the 'high-entropy private idempotency key from the original order' and must be retained confidentially. That tells the agent where the value comes from, not just its format.

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 opens with a precise verb and resource: 'Read the state of an EXISTING buyer-owned Website Check and retrieve its private result if complete.' The word EXISTING plus the explicit negative scope ('No new order, scan, payment or payment authorization') cleanly separates it from the sibling website_check that would create such an order.

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 states the condition that selects this tool (reuse the key from an original order) and enumerates what it must not be used for (new orders, scans, payments, authorizations). It stops short of naming the sibling tool to use instead, so the agent must infer that from names, but the when/when-not framing is otherwise clear.

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