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

Annotations already declare readOnly, idempotent, non-destructive, so the safety profile is covered. The description adds genuinely non-structured behavioral context: which ETA field to quote, that public_tracking_url is null when public pages are off / shipment archived / not yet live, and that URLs must never be invented.

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?

Front-loads the payload summary, then routes to alternatives, then handles the two URL fields. Dense and purposeful, though the URL/ETA caveats make it longer than strictly minimal; every sentence still does work.

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?

No output schema exists, so the description carries the return-value burden — and it does so by listing the returned categories plus the ETA-field and nullability semantics. An agent can call this and interpret the response without further documentation.

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, fully documented in the schema (100% coverage, including the shp_123 format and its source search_shipments). The description adds no further parameter-level detail, so the baseline 3 for schema-carried params 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?

Opens with a specific verb and resource ('Everything about one shipment') and then enumerates the exact payload surface (status, route, ETA, carrier, parties, cargo, containers, labels, check counts, notes, free_time). It is immediately distinguishable from siblings like get_tracking_timeline and list_documents.

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?

Gives explicit trigger phrases ('when does it arrive', 'how many free days are left') and names alternatives with their selecting conditions: get_tracking_timeline for current position/route, list_documents for paperwork. Nothing is left to inference.

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