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

Annotations already declare readOnly, idempotent and non-destructive, so the safety profile is covered; the description goes beyond that by disclosing cache-backed reads, a metered vehicle_data fallback on miss (a cost/latency implication), and the no-wake guarantee. It leaves cache TTL, staleness of returned values, and failure behavior when the vehicle is offline unspecified.

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?

One dense sentence with the core behavior front-loaded (returns state, from cache, metered on miss) and the key constraint ('does not wake the car') placed last for emphasis. No filler or repetition.

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 no output schema, the description usefully sketches the return categories, but it omits the optional-vin semantics, cache freshness, and what happens when the vehicle is asleep or unreachable — the cases most likely to confuse an agent. Adequate but with clear gaps for a single-parameter read tool.

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 single parameter 'vin' has 0% schema description coverage and is never mentioned in the description, so an agent gets no explanation of its format or, more importantly, what happens when it is omitted given that required count is 0. The description does not compensate for the schema gap at all.

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?

States a specific verb and resource ('Returns vehicle state') and enumerates the data categories returned (charge, climate, lock, location), which lets an agent distinguish it from narrower siblings like get_battery_and_range or get_location. It stops short of explicitly naming those siblings as alternatives, so differentiation is inferential rather than stated.

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?

'Does not wake the car' implicitly routes the agent toward wake_vehicle when the car is asleep, and the cache/metered distinction implies a cheap-first-read strategy. However, no sibling is named and there is no explicit guidance on when to prefer get_vehicle_summary, get_location, or get_charging_status over this broader call.

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