get_fare

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

With no annotations provided, the description carries the full behavioral burden, and it discloses almost nothing: it doesn't say whether the fare is a single value or a set (peak/off-peak, adult/child), what currency or units apply, whether a travel time or date affects the result, or whether it fails for unconnected locations. For a lookup tool with zero annotation coverage this is a notable gap.

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?

A single front-loaded sentence with no filler or redundancy. It is efficient, though its brevity is partly under-specification rather than disciplined concision.

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?

There is no output schema and no annotations, so the description is the only place an agent could learn what a fare result looks like or when the call is valid. It omits response shape, currency, and any fare-type variance, leaving the tool under-explained for a domain where fares vary by time and passenger type.

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%, so 'from' and 'to' are already documented as starting location and destination. The description's phrase 'between two locations' reinforces the schema but adds no format details (station IDs vs names, disambiguation) beyond it, making the baseline 3 correct.

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 uses a specific verb ('Get') and resource ('the fare') and scopes it to 'a journey between two locations', which is unambiguous on its own. It does not, however, name or contrast itself with any sibling (e.g. plan_journey, which may also surface cost information), so an agent must infer the boundary.

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?

There is no when-to-use guidance, no statement of prerequisites (such as requiring a valid station pair or a travel date), and no mention of alternatives. The only usage signal is the implicit requirement that both locations be supplied.

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