get_departures

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

No annotations are provided, so the description carries the burden. It usefully discloses defaults (today, now, 15) and a max cap (50), which are behavioral constraints beyond the schema. However, it says nothing about whether results include realtime vs scheduled data, error behavior for invalid stops, or pagination.

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 one-line purpose is front-loaded and the Args block is compact and scannable. No filler sentences, though the format is slightly mechanical rather than prose-efficient.

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 4-parameter query tool with no annotations but an existing output schema, the description covers all parameters with formats and defaults, and points to search_stops for ID discovery. Missing only edge-case behavior (invalid IDs, realtime vs scheduled), which is a minor gap.

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 must compensate, and it does: it gives the GTFS stop ID format with an example ('1:4173'), the date format YYYY-MM-DD, the time format HH:MM, and the limit bounds (default 15, max 50). This is meaningfully richer than the bare schema titles.

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?

Clear verb+resource: 'Get upcoming departures from a specific stop.' An agent can distinguish it from plan_trip or get_trip_stops. It does not explicitly name which sibling to use instead, but the purpose is unambiguous.

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?

Explicitly routes the agent to search_stops to obtain the required stop_id, which is a real usage prerequisite. It lacks when-not guidance (e.g. use plan_trip for door-to-door itineraries), so it stops short of a full 5.

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