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

Annotations already establish read-only, idempotent, non-destructive behavior, and the description adds useful domain context: prices are monthly in PLN per mileage package, VAT differs for business versus individual customers, and each package includes an inquiry link. It does not discuss pagination or rate behavior, but with annotations covering safety this is a strong addition.

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 compact and front-loaded, opening with the core use case before giving exclusions and examples. Every sentence carries useful routing or filtering information, and the examples are efficiently placed at the end.

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 14 optional parameters and an output schema, the description is largely sufficient: it explains the main scope, the key VAT and facet semantics, and gives examples. The remaining gap is that it does not fully explain all filter parameters or clarify where facet values come from, but the output schema and enum constraints reduce the burden.

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 only 50% across 14 parameters, so the description must compensate. It adds key semantics for facets-based filters, customer_type VAT treatment, rent_length values, and examples, but many parameters such as market, ordering, transmission, production-year bounds, limit, and offset are not meaningfully explained beyond their names or enums.

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 scope: a car rented for months or years, from 1 month renewed monthly up to 3 years, with monthly PLN prices, VAT treatment, and inquiry links per package. It clearly distinguishes this from dated trip search by naming search_offers as the wrong tool for date-based trips.

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 an explicit when-to-use condition and a when-not-to-use condition, directing date-based trips to search_offers. It also explains that filters take facet values, which tells the agent how to populate the filter parameters.

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