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

Annotations already establish readOnly, idempotent, non-destructive, non-open-world, so the safety profile is covered. The description adds genuinely non-obvious behavior: a short cache, the fact that a cache miss triggers a metered vehicle_data read (cost implication), and that it will not wake a sleeping car. It stops short of stating cache TTL or staleness bounds.

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 dense sentences with the returned fields front-loaded and the cost/no-wake caveats following. No filler, no restatement of the name or title.

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 enumerates the returned fields and flags the metered-read cost, which is the key operational detail. The main gap is the unexplained `vin` parameter and the absence of required/optional clarity.

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 0% for the single `vin` parameter, and the description never mentions it, let alone its format or whether it is optional (required count is 0, which is itself surprising and unexplained). The description provides no parameter meaning beyond the bare 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 opens with a specific verb and resource ("Returns a vehicle snapshot") and enumerates the exact fields returned (online/asleep, battery, range, lock, climate, sentry, last location), so an agent knows precisely what comes back. It does not explicitly contrast itself with close siblings like get_vehicle_state, get_battery_and_range, or get_location, which keeps it from a 5.

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?

Usage context is only implied: the cache note and "does not wake the car" suggest this is the cheap, non-intrusive read versus wake_vehicle, and the broad field list suggests it supersedes narrower reads like get_battery_and_range. However, there is no explicit statement of when to prefer it over get_vehicle_state or get_location, and no exclusion guidance beyond the wake hint.

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