Get a train timetable

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

With no annotations provided, the description must carry the burden of behavioral disclosure. It does add value by detailing the output content (arrival, departure, halt, etc.) and implying a read-only operation. However, it does not disclose error handling for invalid train numbers, response format, or any rate/access limitations, leaving gaps for an agent.

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 a single, front-loaded sentence that leads with the primary purpose and then lists the specific return fields. There is no fluff or redundant wording, and every phrase contributes to understanding the tool's output.

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?

For a tool with only one parameter, no annotations, and no output schema, the description covers the essential return details (schedule fields and running days) sufficiently for a basic schedule lookup. It is not fully complete because it omits error behavior and edge cases, but the low complexity means the description is mostly adequate.

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 input schema already provides full coverage for trainNumber with type, length constraints, and an example ('12951'). The description merely refers to 'a train number' and adds no deeper meaning about parameter format, allowed values, or how the parameter affects the result, so it stays at the schema-coverage baseline of 3.

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 returns a 'Full stop-by-step schedule for a train number' and lists the specific fields (arrival, departure, halt, distance, day, platform, days of week). This makes the purpose obvious and implicitly distinguishes it from siblings like find_trains_between_stations, but it does not explicitly name an alternative or specify what it is not.

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?

No guidance is given about when to use this tool versus siblings such as plan_journey, find_trains_between_stations, or check_seat_availability. The description only states what the tool returns, without any context on preferred use cases, prerequisites, or exclusions.

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