Train price calendar

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

Annotations already declare readOnly/idempotent/non-destructive, so safety is covered. The description adds genuine behavioral context beyond them: rows are omitted on days without enough free seats, and the window is truncated because sales open only ~18 days ahead, so later days will be missing. The one gap is currency/price units and whether results are cached.

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?

Three short sentences, all front-loaded: what it returns, how to use it, and the availability caveat. Every sentence earns its place with no repetition of schema or annotation content.

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 structure need not be explained, and the description supplies the important domain caveats (free-seat filtering, ~18-day sales horizon). What is missing is minor: price currency/units and whether the calendar is cached or live.

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%, so the schema already documents days, quota, seats, start_date, origin and destination, including the mb_find_place(mode='train') id hint. The description only adds '(one adult)', which is marginal and slightly at odds with the seats parameter allowing up to 10. Baseline 3 is correct.

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+scope: the cheapest train ticket per day for a route, one adult, filtered to days with free seats. It is immediately distinguishable from mb_train_price (single price) and mb_search_trains (actual bookings) by the per-day calendar framing.

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: 'Use to find the cheapest or the next bookable day, then mb_search_trains for that day.' That names the follow-up tool and the condition that triggers it. It stops short of stating when NOT to use it (e.g. versus mb_train_price for a single departure), so it is strong but not fully closed.

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