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

Beyond the annotations (readOnlyHint=true, openWorldHint=true), the description adds useful behavioral context: results are sorted by price and include vendor, class, and rate details. This goes beyond the annotations and clarifies what the agent can expect from the tool. No contradiction with annotations is present.

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, efficient sentence with no filler. It front-loads the action ('Search for rental vehicles') and then provides essential output details. Every word contributes meaning, and it is appropriately sized for a search tool.

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 that the tool has an output schema, the description does not need to detail return formats. Annotations cover read-only and open-world behavior. The description covers sorting and result fields. The only notable gap is the airport/city ambiguity discussed under parameter semantics, but overall the description is fairly complete for this tool's complexity.

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 the schema provides full parameter documentation, setting a baseline of 3. However, the description says 'airport or city,' while the schema's pickup_location property explicitly restricts values to airport IATA codes. This potential discrepancy could lead an agent to pass a city name (e.g., 'Los Angeles') instead of an airport code, making the description more misleading than helpful.

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 clearly states the tool's function: 'Search for rental vehicles at an airport or city.' This is a specific verb-resource pair with an explicit output description: 'Returns available cars sorted by price with vendor, class, and rate details.' It distinguishes the tool from siblings like get_vehicle_details or get_vehicle_booking, which are about specific vehicles or bookings, not search.

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 provides no guidance on when to use this tool versus alternatives. There is no mention of using get_vehicle_details for a specific car or compare_rates for rate comparisons. The context is only that it searches rental vehicles, which is essentially the purpose, not usage guidance.

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