nearby_stations

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

Annotations already declare readOnlyHint, idempotentHint and openWorldHint, so the safety and idempotency profile is covered. The description adds the return-content hint (CRS codes) but says nothing about result ordering, how many stations are returned by default, or how proximity is ranked.

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 tight sentence that front-loads the resource and the radius constraint, then names the downstream consumer. Zero filler.

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?

An output schema exists, so return values need not be explained, and the read-only nature is covered by annotations. The only shortfall is that `limit`/ordering behavior is never surfaced, a minor gap for a simple proximity lookup.

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 schema titles alone must carry the load. The description clarifies `radius` (metres) and that lat/lon define a point, but `limit` is never mentioned, leaving one of four parameters undocumented.

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?

States a concrete verb+resource (rail stations within a radius of a point) and names the value returned (CRS codes). The word 'Rail' implicitly separates it from nearby_stops, but it never explicitly contrasts the two, so an agent must infer the split.

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 phrase 'with their CRS codes for rail_departures' hints at the workflow where this tool feeds rail_departures, which is useful context. However, there is no explicit when-to-use or when-not-to-use statement and no comparison against nearby_stops or search_places.

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