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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false. The description reinforces the read-only nature and adds useful trust context: predictions are unofficial and may be wrong, while station screens are the official source. It does not describe return format or ordering, but the added reliability caveat is meaningful beyond the annotations.

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 short, front-loaded with the core action and returned fields, and contains no filler. The 'Read only' sentence repeats the annotation, and the predictions caveat is somewhat tangential to listing stations, but both are brief enough not to undermine conciseness.

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 zero parameters, rich annotations, and no output schema, the description provides enough context to call the tool correctly. It states what is returned and includes an important data-accuracy caveat, though it could more explicitly relate to sibling tools for routing purposes.

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 tool has zero parameters, so there is no parameter semantics to explain. The baseline for a parameterless tool is 4, and the description correctly does not invent input details.

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 gives a specific verb and resource ('List stations') and previews the returned fields (enabled status, platform range). It does not explicitly distinguish the tool from siblings like find_train or get_departures, but the purpose is clear without opening the schema.

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 explicit guidance on when to use this tool versus alternatives such as find_train or get_departures. Usage is only implied by the verb 'List stations', leaving the agent to infer its place among sibling tools.

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