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

Since no annotations are provided, the description carries the burden of behavioral disclosure. It does disclose that results include realtime delays, cancellations, and a defined set of fields. However, it does not mention whether cancelled departures are still included in the count, whether results are sorted chronologically, or any data freshness/availability caveats. For a read-only tool this is acceptable but not richly transparent.

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 sentences with no filler. The primary purpose is front-loaded, and the second sentence compactly enumerates the returned fields. Every sentence earns its place.

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 must convey what the tool returns. It does this well by listing line, destination, scheduled and expected times, delay, platform, and cancellation status. Minor gaps remain, such as ordering and whether cancelled departures are filtered, but the core information an agent needs is 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?

Schema description coverage is 100%, so both parameters are already well documented with types, defaults, ranges, and an example. The tool description adds no new parameter-specific meaning beyond what the schema provides. The baseline score of 3 is appropriate because the schema does the heavy lifting.

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 clearly states a specific action (get next departures), a specific resource (a stop place), and the Entur data source. It is immediately distinguishable from sibling tools like find_stops_near or get_realtime_status because it focuses on departure data with realtime delay and cancellation information.

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 establishes the clear context for when to use this tool: when upcoming departures from a stop are needed, including realtime updates. The stop_place_id parameter description explicitly directs the agent to resolve IDs via resolve_stop_place, providing a concrete workflow hint. No explicit exclusions or alternative tool mentions are given, but none of the siblings covers departures, so the usage context is clear.

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