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

Annotations already declare this as read-only, idempotent, and non-destructive. The description adds useful behavioral context beyond that: it enumerates the full returned payload, mentions a fresh PDF link, and states that the operation is free, though it does not cover error behavior or permissions.

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?

Two dense but efficient sentences front-load the resource, returned contents, and lookup logic. The final “Free.” is terse and earns its place by disclosing cost behavior.

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?

With no output schema, the description compensates by enumerating the returned data: lines, totals, taxes, payments, credit notes, history, public page, and PDF link. Combined with annotations covering safety and schema descriptions covering parameters, an agent has enough to invoke it correctly.

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 75%, and the description adds meaning by explaining that lookup can be by invoice_id or by number, with kind needed when two document kinds share a number. The link_hours parameter is left to its schema description, which is acceptable given the coverage level.

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 names the exact resource (one quote, invoice, or credit note) and lists the full contents returned, so it is clearly distinguishable from list/search siblings. It also states the two lookup paths, making the tool's purpose concrete.

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 clearly explains when to use this tool for a single document and how to identify it by invoice_id or number, including the need for kind when numbers collide. It does not explicitly name alternatives such as invoices_list, but the single-document scope gives clear usage context.

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