Service days of a line

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

Annotations already declare readOnlyHint=true and openWorldHint=true. The description adds genuinely useful non-annotation behavior: the codes are seasonal (the current set is the winter one) and must be read, not assumed, plus a hard geographic coverage limit. It stops short of describing return volume, ordering, or labeling, so it is strong but not exhaustive.

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 tight sentences, front-loaded with what is returned, then the downstream usage rule, then the coverage constraint. Every sentence carries information an agent needs; nothing is redundant with the name or title.

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?

No output schema exists, so the description must explain returns — it does so by naming the output concept and its field (schedule_day_code) and giving example values. The seasonal-caveat and coverage limits are covered. Minor gaps remain around the exact shape of each returned variant (labels, holiday variants), but the essentials for correct invocation are present.

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% for both parameters, so the schema already carries the semantics (line accepts number/code/name; language enum controls Greek/English pairing). The description adds no parameter-level syntax or format guidance beyond mentioning schedule_day_code, which belongs to line_schedule's input, not this tool's. Baseline 3 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?

States a specific verb+resource: returns the timetable variants (service days) published for one OASA line, with concrete examples (weekday, Saturday, Sunday). It is clearly distinguishable from sibling line_schedule, which consumes its output rather than producing it.

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: feed a schedule_day_code from here into line_schedule for an exact timetable. It also warns that codes are seasonal and must be read rather than assumed, and states the scope (Attica only: OASA buses, trolleys, metro, tram) so an agent knows when this tool does not apply.

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