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

Annotations already declare this as a safe, idempotent read, so the bar is low, yet the description goes well beyond them: it enumerates the full status state machine, explains the payment_held compliance hold (money held, nothing issued), and describes what fields appear once ready. That is the kind of operational context an agent cannot get from annotations or schema.

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?

Dense but economical: statuses, the held-payment edge case, the ready-state fields, and polling cadence each earn their sentence. The opening fragment and the mid-sentence field dump make the structure slightly less scannable than it could be.

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?

Given an output schema exists, return fields need no explanation, yet the description still covers the full status lifecycle, the exception path, QR rendering of esim.activation_code, and polling behavior — everything an agent needs to interpret results and act. Only the invalid/unknown-token case is unaddressed.

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?

With schema coverage at 0% and one required parameter, the description only implicitly documents the token as the order identifier ('An order by its token'). It does not state where the token comes from (e.g., supplied by create_checkout/purchase_esim) or that it must be the exact order token, so it only partially compensates for the schema gap.

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 identifies the resource and lookup key ('An order by its token'), making it distinguishable from siblings like get_deposit, get_wallet, and list_topups. It lacks an explicit verb ('retrieve/fetch an order'), but the intent is unambiguous in context.

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 gives concrete usage guidance — poll every ~10 s after payment, delivery usually under a minute — and a clear action rule for the payment_held branch (do not pay again, contact support). It does not compare against sibling lookup tools, but no exclusions are needed here.

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