Get departures from a stop

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

No annotations are provided, so the description carries the full behavioral burden. It usefully discloses that results mix scheduled and real-time data, but says nothing about rate limits, authentication, pagination, or how stale the real-time feed may be.

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?

Two sentences, zero filler, with the core action front-loaded and the dependency on find_nearby_stops placed second where it belongs.

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 no output schema and no annotations, the description should do more: it never explains the shape of a departure result, the limit/duration window behavior, or the language enum. It is enough to call the tool, but not enough to use its output confidently.

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 only 33% (date and time are documented in the schema, not in the description). The description adds genuinely useful provenance for the required stopId, but leaves limit, language, and the durationMinutes departure window entirely unexplained in both places.

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 specific verb and resource ('Get scheduled and real-time public transport departures') scoped to a named provider and id type. It explicitly names the sibling find_nearby_stops as the source of the id, so an agent can tell the two tools apart without opening either 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?

Gives a clear prerequisite/entry point: use the id returned by find_nearby_stops, which tells the agent how to obtain the required parameter. It does not state any when-not condition or alternative for retrieving departures, but with only one sibling, the routing guidance is adequate.

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