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

Annotations already signal read-only, idempotent, and non-destructive behavior, and the description does not contradict them. It adds behavioral context the annotations do not provide: what data the comparison includes and that starting price appears only when a press kit is on file.

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, compact sentence that front-loads the comparison concept and lists decisive factors without padding. The lack of an explicit verb is a minor structural issue.

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?

For a two-parameter read-only comparison tool, the description tells the agent what will be compared and the press-kit caveat, and no output schema is expected, so the return-value burden is low. It covers the main facts needed to invoke the tool correctly.

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 for both parameters is 100% with examples and a required difference between a and b, so the structured data carries the semantic load. The description's content is about the output attributes, not the parameters, so it adds no value beyond the schema.

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 that the tool lays two model years/vehicles side by side and enumerates the comparison dimensions (fuel economy/EV range, Safety Signal grade, recalls, complaints, crash rating, starting price). This makes the resource and intended output clear and distinguishes it from single-vehicle tools like get_vehicle, though it never uses an explicit verb like 'compares.'

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 phrase 'figures that decide most purchases' implies a purchase-comparison use case, and the press-kit caveat adds a boundary. However, there is no explicit statement of when to choose this over get_vehicle or search_vehicles, and no exclusions.

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