station_departures

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

Annotations already declare readOnlyHint, idempotentHint, and openWorldHint, so the safety profile is covered. The description adds useful behavioral context by saying it is a live board with delays and track numbers, but it does not mention freshness, rate limits, or whether station matching is exact.

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 front-loaded with the core purpose and then spends its remaining space on the parameter most likely to be misunderstood. Every sentence is relevant, and the direction explanation is appropriately compact.

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 simple read-only tool with no output schema, the description gives enough about what the live board returns: upcoming trains, destinations, delays, and track numbers. It is nearly complete, though it could mention count behavior or station naming expectations to remove remaining ambiguity.

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%, so the description carries the burden for parameter meaning. It does a good job explaining the non-obvious direction parameter, including N/S semantics and omission behavior, but it does not explain count or clarify the expected station identifier format.

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 verb/resource: a live departure board for a Regional Rail station, listing upcoming trains, destinations, delays, and track numbers. It is clearer than a vague 'get departures' definition, but it does not differentiate itself from the sibling tool next_trains, which may cover similar ground.

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 explains how to use the direction parameter but gives no guidance on when to choose station_departures over siblings like next_trains, train_schedule, or train_status. Usage for live departures is implied, but there is no explicit when-to-use or when-not-to-use guidance.

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