Trip details (all stops, live)

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

Annotations already mark the tool as read-only, idempotent, and open-world. The description adds valuable behavioral context by emphasizing the live/real-time nature of the data and listing what the response covers, including platform, load, notes, amenities, and running days. This goes beyond the annotations without contradicting them.

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 front-loaded with the core object and packs the resource, data scope, practical examples, and additional return fields into one efficient sentence. Every clause 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?

For a read-only detail tool with an output schema and annotations already covering safety and idempotence, the description is sufficiently complete. It explains what the tool returns, the live aspect, and the practical questions it answers, leaving no critical gap for an agent to select and call it correctly.

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 schema already documents journey_id as coming from a db_journeys leg or board row and format as an enum. The description reinforces that the tool targets one specific train run, but it adds little new parameter-level detail. With 50% schema coverage, this is adequate though not exceptional.

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 identifies the resource ('one specific train run') and the exact data returned: scheduled and real-time times, platform, load, notes, amenities, and running days. This distinguishes it from station-level tools like db_departures and db_arrivals without requiring the agent to open the 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?

The illustrative use cases ('where is this train now, is my stop still served, which platform at my stop') give strong contextual guidance for when to call this tool. It does not explicitly name excluded alternatives, but the 'all stops of one train run' framing makes the intended usage clear.

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