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

With no annotations, the description states 'Read only', which fully discloses the behavioral trait of no side effects. It also lists the returned data fields (price, supply left, sale status), giving good context for a read operation. It doesn't cover edge cases or output format details, but for a simple read tool this is adequate.

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 sentence that packs all necessary information, front-loading the core purpose. It could be slightly more structured (e.g., separate sentences for vehicle types and purchase guidance), but it remains concise and every sentence earns its place.

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 simplicity (no parameters, no output schema, read-only), the description provides enough context to understand what it returns and how to proceed with buying. It doesn't explain the output format in detail (e.g., list vs object), but it enumerates the key fields, which is sufficient for this use case.

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 tool has zero parameters, so there is no parameter semantics to explain. The baseline score of 4 applies, as the description correctly focuses on output and usage guidance instead.

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 explicitly states what the tool returns: vehicles for sale with price, supply left, and public sale status. It differentiates ground vehicles (Sentinel, Hauler, Courier, priced in ZENI) from aircraft (Helicopter, Private jet, priced in ETH), making the scope unambiguous and distinguishable from sibling tools like prepare_vehicle_buy.

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 clearly directs the agent to use prepare_vehicle_buy for ground vehicles and prepare_vehicle_buy_eth for aircraft, implying this tool is for browsing before purchase. While it doesn't explicitly say when not to use this tool, the guidance is sufficient for correct invocation.

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