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

Annotations already declare readOnly/idempotent/non-destructive, yet the description adds genuinely non-obvious behavior: tracking events capped at the latest 50, missing carrier evidence returned as null, and the warning that processing state or a tracking number alone does not prove mailing or delivery. That is semantic context no annotation or schema could convey.

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?

Three sentences, front-loaded with the return payload before the caveats and the negative scope statement. Every clause carries distinct information: field list, bulk-vs-individual routing, null semantics, and the non-action guarantee.

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?

Despite a rich output schema (which alone would absolve it of explaining return values), the description still pre-summarizes the payload shape and flags the bulk-order variation and null semantics. For a single-required-param read tool, nothing an agent needs to invoke it correctly is missing.

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?

Only one parameter (order_id) and schema description coverage is 100%, with format/pattern fully specified in the schema. The description adds nothing about the identifier's syntax or sourcing, so the schema does all the work — the expected baseline of 3.

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?

Specific verb (read/get) plus a precise enumeration of what is returned: payment, processing, mailing/carrier status, latest 50 tracking events, return-receipt availability, plus bulk-order campaign fields. The closing clause 'does not pay, mail, or acquire receipts' cleanly separates it from siblings like pay_order and the create_* tools.

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 routes the agent for a real alternative case ('use the campaign dashboard for individual recipients') and implicitly tells the agent this is the status-check path rather than the pay/mail path. It stops short of an explicit when-to-use/when-not statement with named sibling tools, so it is clear but not exhaustive.

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