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

Annotations already indicate a mutating, destructive operation, so the description does not need to restate that. It adds useful context about required prerequisites and where parameters originate, but it does not disclose side effects like charges or confirmation behavior, which would strengthen transparency.

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?

Three short sentences, front-loaded with the core action and immediately followed by the most critical prerequisites. Every sentence adds useful information with no fluff.

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 output schema, full parameter descriptions, and annotations, the description is sufficient for correct invocation. It covers prerequisites and parameter provenance; only minor extras like confirmation or charge behavior are left out.

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?

The schema already describes all parameters with 100% coverage, so the baseline is 3. The description adds cross-reference value by explaining that vendor_code, rate_code, acriss_code, and search_id all come from search_vehicles results, and that payment_id comes from get_payment_methods.

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 verb and resource: 'Book a rental vehicle from a search result.' It clearly differentiates from sibling tools like book_hotel and cancel_vehicle_booking by focusing on rental vehicles and the booking action.

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 preconditions: a Gondola account and a saved payment method, and points to get_payment_methods for finding the payment ID. It also tells the agent that key identifiers come from search_vehicles results, which is strong usage guidance, though it does not mention when to avoid this tool.

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