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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the safety profile is known. The description adds that the data is live SP-API tracking and that the result contains milestones and estimates, which is useful behavioral context beyond the annotations. It does not cover failure modes or rate limits, but that is a minor gap for a read-only tracker.

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 description is a single front-loaded sentence: purpose first, then scope, then identifier constraint. There is no filler, and the parenthetical identifier list is dense but necessary.

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 purpose, scope, and identifier choices well, but the schema has 8 optional parameters and no output schema. It does not clarify seller_connection_id, the shape of the returned milestones/estimates, or behavior when no identifier is supplied, so an agent still has some ambiguity before calling.

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 0%, so the description carries the burden. It names seven of the eight parameters and clarifies the critical usage rule that only one identifier should be passed. However, seller_connection_id is not explained in the description, and 'id' remains ambiguous, so it is strong but not complete.

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 names the exact operation (live shipment tracking), the source system (SP-API Tracking), the regional scope (US store only), and the output type (milestones and estimates). It clearly stands apart from the many inventory, account, and PPC sibling tools as the shipment-tracking tool.

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 clear usage context: for a shipment moving through Amazon in the US store, and it explicitly instructs the caller to pass ONE identifier. It also lists valid identifier combinations, including the carrier_tracking_number + carrier_code pairing. It does not name a sibling alternative, but the scope and constraints are specific enough for most invocation decisions.

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