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

With no annotations, the description carries the full behavioral burden and does disclose that it returns full event history, current status, and delivered status. It does not mention authentication behavior, rate limits, error handling for invalid codes, or whether partial results are possible.

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 two front-loaded sentences with no wasted text. It states the action first and then what is returned, making it easy for an agent to parse.

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?

Given the simple two-parameter read-only nature of the tool, full schema coverage, and the existence of an output schema, the description is nearly complete. It omits only secondary behavioral details such as auth context and error/rate-limit behavior.

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 coverage is 100%, so both parameters are already documented in the input schema, including example format and the 50-code limit. The description repeats the tracking-code example but adds no meaning beyond the schema for the codes or instanceId parameters.

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 gives a specific verb and resource: 'Track Brazilian Correios objects by tracking code,' with an example code. This clearly distinguishes it from sibling tools such as generate_label, get_shipping_rates, and diagnose_* 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?

The intended use is clear from 'Track ... by tracking code,' and no alternative tracking tool exists among the siblings. However, it does not explicitly state when not to use it or whether there are prerequisites such as having generated a label first.

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