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

Annotations are empty, so the description carries the full burden. It discloses the return shape ('values' object with a data-row array), which is useful, but says nothing about pagination, filtering, date ranges, or permission/authentication requirements for a list-style read.

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 core purpose and otherwise terse, with no filler sentences. The @param/@return tags are compact and each carries information, though the return sentence is slightly clunky in phrasing.

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 simple read tool with no annotations and no output schema, the description does describe the return shape, partially offsetting the missing output schema. It still omits pagination behavior and any filtering context, leaving gaps an agent would want before calling it.

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 0% for the single parameter, so the description must compensate. It does add real value by clarifying that customer_id is 'the customer's database id' rather than an external identifier, but gives no constraints or allowed-range information beyond that.

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 ('Returns the customer's invoices'), which is clearly interpretable. It does not, however, distinguish itself from closely related siblings like paywall__customer_payment_history or paywall__delete_unpaid_invoice, so an agent gets no help disambiguating within the paywall family.

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?

There is no when-to-use guidance, no mention of prerequisites (e.g., a customer must exist), and no routing to alternatives such as customer_payment_history. The agent is left to infer usage entirely.

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