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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false, so the safety profile is covered. The description adds substantial behavioral context beyond annotations: null price_day is normal and common, total_eur:null with price_note is not a failure, instant:true vs owner-confirmed booking flow, and the golden link rule. It also discloses data limitations (no phone/address/licence plate, approximate coordinates). This is rich, non-obvious behavior that an agent must know.

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 longer than average but every section earns its place: the first sentence is a clear summary, then sections cover business logic (private owners), price semantics, the golden link rule, and data privacy limitations. It is front-loaded with the core purpose and then organized into labeled paragraphs. Slightly verbose in places (e.g., repeated emphasis on null being normal), but the repetition serves to prevent a costly misinterpretation.

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 tool's complexity (business rules, null semantics, booking link requirement, privacy constraints) and the presence of an output schema, the description is complete. It covers what the agent needs to correctly interpret results and present them to the traveller. The output schema exists, so return values don't need to be re-explained in detail, but the description adds the crucial interpretation layer (null is normal, not a failure).

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 67%: pickup_date and return_date are described as YYYY-MM-DD, but vehicle_ids has no description beyond type/maxItems. The description compensates by explaining the meaning of key outputs (available, days, price_day, total_eur, price_note) and the max 10 cars constraint, which maps to vehicle_ids maxItems. It doesn't add detail about the vehicle_ids format, but the schema already defines it as an array of integers. Slight gap: no explicit statement that vehicle_ids must come from a prior search, but the overall context is strong.

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 opens with a specific verb and resource: 'Check availability and total price of up to 10 cars for given pickup/return dates.' It clearly distinguishes this from siblings like search_vehicles (searching) and get_vehicle (single vehicle details) by focusing on availability and price for a date range. The scope (up to 10 cars) and key outputs are named.

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 description gives explicit when-to-use context: checking availability and total price for given dates. It also provides strong usage guardrails: never call a car with price_day:null unavailable, always include booking_link verbatim, never invent phone/address/licence plate, and treat coordinates as approximate. These are clear behavioral instructions that an agent can follow without ambiguity.

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