get_next_departures

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

With no annotations, the description carries the full burden of behavioral disclosure. It usefully reveals that results reflect the static timetable rather than real-time positions, and clarifies that all routes serving the stop are included. It does not cover edge cases like multiple partial matches or sorting, but the core behavior is 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 plus a compact Args list. It is front-loaded with the purpose, uses a separate note for an important caveat, and has no unnecessary words.

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 two-parameter read tool with an output schema, the description covers the essential context: what it returns (scheduled departures), scope (all routes), and static nature. It could add sorting order or why one might first use search_stops, but the core information is sufficient.

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?

The Args section adds meaningful semantics beyond the schema: stop_name is a name or partial name, and limit is the maximum number of departures. Since schema description coverage is 0%, this compensation is important; it could additionally mention default behavior or allowed range.

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 opens with a specific verb ('Get upcoming scheduled departures') and clearly identifies the resource (a given stop across all routes serving it). This distinguishes it from sibling tools like search_stops and list_routes, which target stops and routes rather than departures.

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?

It states a clear use case—upcoming scheduled departures for a stop—and adds a contextual note that it reads static GTFS, not live GPS, which implies it should not be used when real-time delays matter. However, it does not explicitly name alternative tools or provide comprehensive when-to-use/when-not-to-use guidance.

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