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

Annotations already declare readOnlyHint=true and openWorldHint=true, so safety is covered; the description contributes value by disclosing the return payload (status, ETA, full scan history) in the absence of an output schema. It does not mention latency, per-carrier rate limits, or failure behavior for unknown numbers.

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 15-word sentence with the return content front-loaded and zero filler. It is a noun phrase without an action verb, but nothing is redundant or buried.

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?

Covering the three return categories compensates somewhat for the missing output schema, and the schema handles parameters fully. However, for an open-world external-call tool with a clear sibling, the absence of any guidance on track_packages vs track_package, or on invalid/unknown tracking numbers, leaves real gaps.

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 100% and the schema itself explains both parameters, including the carrier auto-detection behavior and the list_carriers pointer. The description adds no parameter meaning beyond that, so baseline 3 applies.

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?

Names a specific resource (one tracking number) and enumerates exactly what is returned: current status, estimated delivery and scan history. Clear enough to select without opening the schema, though it never contrasts with the sibling track_packages (bulk), leaving single-vs-many as an inference from the name.

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?

No explicit when/when-not statement or named alternative. The phrase 'one tracking number' implicitly signals the per-package counterpart to track_packages, and the carrier parameter points at list_carriers, but neither is stated in the description itself.

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