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

The annotations already declare readOnlyHint=true, and the description adds useful behavioral context beyond that: the exact API endpoint, the newest-first ordering, and the pagination wrapper shape. It does not cover rate limits, authentication, or the internal structure of the returned credit-note items, but for a read-only list operation this is reasonably transparent.

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 three short clauses, each serving a clear purpose: identifying the resource, giving the API endpoint, and describing the response envelope. The main verb and object are front-loaded, and there is no redundant or filler content.

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 read-only list operation with six fully documented optional parameters and no output schema, the description gives the essential invocation context: endpoint, default ordering, and pagination format. It does not enumerate the fields inside the returned credit-note objects, but that is a minor gap given that the tool's purpose is to list known entities and the schema fully documents the request parameters.

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 input schema has 100% description coverage, documenting all six parameters including q, date, contact, pagination cursors, and per_page. The description adds no parameter-level information beyond what the schema already provides, so the baseline score of 3 is appropriate.

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 clearly states the verb 'List' and the resource 'credit notes,' clarifies that they are refund documents, and specifies the default ordering (newest first). It is distinct from sibling tools like list_invoices and get_credit_note by naming the exact resource and scope.

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?

The tool's purpose is clear enough that an agent can infer when to use it, but the description gives no explicit guidance about when to prefer it over alternatives such as get_credit_note for single records or list_invoices for invoices. It also does not mention any exclusions or conditions that would route the agent to a different tool.

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