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

Annotations indicate this is a write operation (readOnlyHint false) but not destructive. The description adds useful behavioral context beyond annotations by noting 'All fields are optional' and specifying the scope of data tracked. This is meaningful but does not go into side effects or prerequisites, which is acceptable given the 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?

The description is two short sentences with no redundancy. The first sentence front-loads the action and resource, and the second adds a key constraint (all fields optional). Every word contributes to clarity, making it an ideal length.

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?

The description plus the complete schema and output schema provide sufficient context for an agent to select and invoke the tool correctly. It lacks explicit guidance on prerequisites, such as whether the household must already exist or if the insurance document ID must reference an existing document, but given the richness of structured data, this is a minor gap.

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 description coverage is 100% for all 11 parameters, so the description bears little burden for explaining parameters. It mentions categories like registration/VIN and due dates, but this does not add significant semantic value beyond the schema's own detailed descriptions. The optionality note is helpful but not parameter-specific.

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: 'Create a vehicle record for the household' with a specific verb and resource. It also lists what the record tracks (details, registration/VIN, insurance document, MOT/tax/service due dates), distinguishing it from sibling tools like update_vehicle, delete_vehicle, and list_vehicles.

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 implies use for adding a new vehicle to a household but does not explicitly state when to use this tool versus update_vehicle or other create tools. It lacks exclusions or explicit alternative guidance, though the context of 'create a vehicle record' makes the primary use case evident.

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