Find trains between two stations

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

No annotations are provided, so the description carries the behavioral transparency burden. It does well by disclosing that only direct trains are listed, what output fields are included, and that station names are resolved automatically. It does not cover error/no-result behavior or limits, but for a read-only query tool this is adequate.

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 two short, front-loaded sentences with no filler. Every sentence contributes meaningful information: the first defines the primary behavior and output, the second clarifies station input handling.

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, so the description compensates by listing key return fields: departure, arrival, duration, and available classes. It also clarifies station input behavior. An explicit pointer to plan_journey for multi-leg trips would improve completeness, but the core details are present.

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 describes all six parameters with 100% coverage, including formats, defaults, and enums. The description only adds the station-name resolution behavior, which is already reflected in the schema. Baseline 3 is appropriate.

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 states a specific action and resource: 'List direct trains connecting two stations on a given date, with departure, arrival, duration and available classes.' The phrase 'direct trains' helps distinguish it from sibling tools like plan_journey, which likely covers multi-leg routes.

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?

The description implies when to use the tool: when a user wants direct trains between two stations on a specific date. However, it does not explicitly mention alternatives or explain when to prefer plan_journey, get_train_schedule, or check_seat_availability instead.

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