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

Annotations already declare readOnlyHint=true and destructiveHint=false, covering the safety profile. The description adds value by disclosing the specific content returned (registration, VIN, due dates), which helps the agent set expectations. No contradictions with annotations.

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?

Two concise sentences with zero waste. The main action and resource are front-loaded, followed by the field list, and the second sentence provides a concrete real-world use case. Every word 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?

With zero parameters, an output schema available, annotations covering safety, and sibling tools clearly differentiated, the description is fully adequate. It states the object, the fields, and a representative question it answers, leaving no critical gaps for an agent to call it 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?

There are zero parameters and 100% schema description coverage, so the baseline is 4. The description correctly implies no inputs are needed and focuses entirely on output content.

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 a specific verb and resource: 'List the household's vehicles' and enumerates the exact data fields returned (make, model, year, registration, VIN, MOT/tax/service due dates). This distinguishes it from sibling tools like create_vehicle, update_vehicle, and delete_vehicle, and from other list_* tools for different entities.

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 clear context for when to use the tool: to retrieve vehicle information and specifically to answer questions like when the MOT is due. It does not explicitly name alternatives or exclusions, but the read-only list purpose is evident and unambiguous.

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