Scheduled Departures

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

With no annotations, the description carries the burden and discloses the key behavioral traits: this is a scheduled/timetable view, not real-time, the time parameter defaults to now, and past-midnight previous-day trips are included. Auth, rate limits, and pagination behavior for limit are not covered, which keeps it from a 5.

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 purpose and the schedule-vs-real-time distinction front-loaded before the edge case.

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 no explanation, and the description covers the nontrivial traps (real-time confusion, past-midnight trips, default time). The undocumented limit and route parameters are the remaining 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 for all four parameters. It explains stop and adds meaning beyond the schema for at ("default now" versus the schema's null), but route and limit are never mentioned even though both affect results.

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+resource (timetable departures at a stop) with scope (from a given time, default now) and an edge case (previous-service-day trips running past midnight). The contrast with arrivals makes it unmistakable among siblings such as next_trains or connections.

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?

"Schedule only; use arrivals for real time" gives an explicit when-not and names the alternative, which is exactly the confusion an agent would have in this sibling set. It stops short of routing among the other boarding-related siblings (next_trains, connections, service_hours).

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