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

With no annotations provided, the description carries the full behavioral burden and does so well: it discloses daily data freshness, that travel date does not affect price, how active coupons are tested and returned, and which output fields appear under each parameter mode. It also instructs the agent to cite page_url, which is useful operational context.

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 front-loaded with the core purpose and then layers the parameter-specific behavior efficiently. It is somewhat long and dense, mixes Portuguese with a redundant English summary sentence, and would be easier to scan if structured, but most sentences add useful information.

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 there is no output schema and no annotations, the description is complete enough for correct invocation: it explains the main response shapes, coupon structure, page_url citation, and age/days behaviors. The remaining schema-covered details, such as region values and the limit default, are already in the schema.

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?

Although schema description coverage is 100%, the description adds substantial meaning beyond the schema: no-days returns the minimum price per duration, days returns plans from cheapest to most expensive with coverages and comparison fields, and age filters to plans that accept that age. It explains the practical semantics of the main optional parameters rather than merely restating them.

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 states a specific resource and dimensions: travel insurance prices per person in BRL by destination region and trip length. It clearly distinguishes this tool from the flight/route/history siblings by domain, so an agent can identify it without opening the schema.

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 explicit conditional usage for the optional parameters: without days it returns the cheapest price per duration from 1 to 90 days; with days it returns plans sorted by price; with age it filters to plans accepting that age. It also tells the agent to answer coupon questions with the returned coupon. It does not explicitly name alternatives or when-not-to-use cases, but the relevant sibling alternatives are in a different domain.

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