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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description adds useful operational context beyond annotations: cost per call (5 points), free carrier-list endpoint, real-time tracking behavior, and fallback to the auto tool. It does not cover auth, rate limits, or error behavior.

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?

The purpose and required inputs are front-loaded in the first sentence, followed by carrier examples, list endpoint, alternative tool, and cost. It is dense but every element aids invocation. Minor repetition of carrier examples already present in the schema keeps it from a 5.

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?

The description covers invocation essentials: purpose, required parameters, carrier examples, fallback tool, cost, and carrier list source. Because no output schema exists, it would ideally describe returned fields or error cases; that gap keeps it from 5 for this two-parameter tool.

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%, setting a baseline of 3. The description adds meaning by listing several carrier code examples and pointing to a free endpoint for the full carrier list, which helps correct carrier selection. trackingNumber remains generic, so it does not reach 5.

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?

Uses a specific verb ('Track') and resource ('Korean parcel in real time') and identifies required inputs. It distinguishes itself from the sibling parcel_tracking_auto by noting the automatic lookup is for when the carrier is unknown. Carrier examples and the list endpoint further sharpen scope.

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?

Explicitly names the alternative ('parcel_tracking_auto') and the condition that selects it: when the carrier is unknown. It also directs the agent to /rest/parcel_tracking_carriers for the full carrier list, giving clear when-to-use guidance.

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