get_train_departures

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

Annotations already cover the safety profile (readOnlyHint, idempotentHint, openWorldHint, destructiveHint=false), and the description adds genuinely non-obvious behaviors on top: ambiguous station names are returned as a list rather than guessed, results carry an attribution line, and hard caps of 15 departures / 120-minute window are stated in prose. There is no contradiction with the annotations.

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?

Four sentences, every one earning its place: purpose and payload fields, when-to-use triggers, exclusions with named alternative tools, then hard limits plus attribution. The core action is front-loaded in the first clauseheb about and the exclusions arrive before any parameter or schema detail.

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 departure-board tool, the description covers selection triggers, exclusions, naming and ambiguity rules, limits)Skipick and attribution, while annotations and rich in-schema docs handle the safety profile and all 6 optional params. The one gap: there is no output schema and the description gives only a flat field list ('time, line, destination, platform, delay and cancellations') without stating edge-case behavior such as an empty result set or an unknown station name.

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% and the in-schema parameter descriptions are already rich (eva_no for follow-ups, language-set-on-every-call rationale, 'do not guess' for station). The tool description adds little new parameter meaning: 'At most 15 departures, window 120 min' merely restates the schema maximums)Skip and the station-naming rule paraphrases the station parameter's schema text. The baseline 3 for high coverage applies.

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?

Opens with a specific verb and resource: 'Return the next departures from a German railway station', and itemizes the payload (time, line, destination, platform, delay and cancellations). It also carves out what it is not — not buses/trams and not motorway traffic — so an agent can tell it apart from check_transit_disruption and check_autobahn_traffic without opening their schemas.

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?

Gives explicit triggers ('when their train, S-Bahn or ICE leaves, whether it is late, or what is leaving a station now') followed by a hard Do-NOT list with named alternatives (check_transit_disruption for buses/trams, check_autobahn_traffic for motorway) and exclusions (tickets, fares, journey planning). It even states the station-input convention (pass the name as the person said it; ambiguous names come back as a list). Nothing is left to inference.

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