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

Annotations already declare this a safe, idempotent, closed-world read, so the bar is low, yet the description still adds valuable behavioral context: it discloses the shape of results (transfer times, terminals, Safer Parking status, compulsory charges on the day, full price including known fees, tracked booking link). The one gap is that it does not address result count/pagination despite a `limit` parameter.

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 tool's capabilities are front-loaded in a dense but information-rich opening sentence, followed by a short, high-value caveat about pricing scope. The first sentence is long and list-heavy, but no clause is filler.

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 carries the return-value burden well by enumerating the fields an agent should expect. It also clarifies the pricing precondition for from/to, which is the key nuance for a 5-parameter tool. Only the optional-date and limit behavior remain unaddressed.

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 is 80%, so the schema already documents most parameters (including the London-local-time format for from/to and the IATA/name hint for airport). The description only reinforces that from/to define the priced stay and lists the `type` categories, adding marginal meaning over the schema; it says nothing about `limit`.

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 names a specific domain and resource (UK airport car parks from multiple providers) and enumerates the car-park categories returned, so an agent knows exactly what this tool aggregates. It does not need to differentiate from siblings, which are unrelated product/deal tools, but it also never states a crisp verb like 'compare prices' beyond the title.

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 is only implied: 'for given drop-off and pick-up times, the full price' and 'Prices are only for a stay given by `from` and `to`' suggest when to supply dates, but the tool can be called with only `airport` required and the description never says what happens (or is returned) in that case. There is no explicit when-to-use/when-not guidance and no named alternative tool.

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