Find invoice by order id

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

The annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description adds essentially nothing beyond 'look up': it does not say what happens when no invoice exists (error vs empty result), whether it returns the most recent invoice, or whether the caller's own orders are the only ones accessible — all of which matter for a lookup by an externally supplied id.

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?

A single tight sentence with the resource and the key discriminator (order id) front-loaded. There is no filler, though it stops short of the length that would let it cover usage or 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?

For a one-parameter read tool with an output schema absent and safety hints already present, the description is minimally viable. It is still missing the return shape (what fields a found invoice carries) and the not-found behavior, which are the main things an agent needs to call and interpret this 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 description coverage is 0% for the single order_id parameter, so the schema gives no semantics beyond type and length bounds. The description partially compensates by clarifying that the id is an order id belonging to the caller ('one of your order ids'), which is genuinely useful. However, it does not state format, whether invoice ids are accepted, or what an invalid id does.

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 states a specific verb and resource: 'Look up the invoice' scoped to 'one of your order ids'. That distinguishes it from get_invoice (which presumably looks up by invoice id) and list_invoices, though the sibling differentiation is implicit rather than stated outright.

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 phrase 'for one of your order ids' implies the use case, but there is no explicit when-to-use guidance. Nothing tells the agent when to prefer this tool over get_invoice or list_invoices, or what to do when multiple invoices might exist for an order. No exclusions or prerequisites are mentioned.

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