line_info

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

With no annotations, the description carries the full burden and does well: it discloses the fuzzy-text fallback behavior for a non-exact line number, the meaning of trips_today=0 (seasonal/weekday-only lines), and the past-midnight time convention like "24:30". It stops short of stating what happens on zero matches or any error condition.

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?

Front-loaded with the resource and return fields, then use cases, then edge-case behavior, then a clean Args block. Every sentence earns its place; the trips_today and midnight-time notes are non-obvious and directly prevent misreading the response.

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 formatting need not be re-explained, and both parameters plus the key behavioral quirks are covered. The remaining gap is failure-mode handling — what an agent should expect when a fuzzy `line` matches nothing at all.

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 0%, so the description must compensate entirely, and it does via a dedicated Args block: `line` is either a 4-digit number or free text matched against line names, and `include_stops` triggers an ordered per-direction stop listing. Both parameters gain meaning well beyond their bare string/boolean types.

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 states a specific resource (Carris Metropolitana line) and enumerates exactly what is returned: name, route ends, directions, municipalities. The three example questions make it instantly distinguishable from siblings like next_arrivals or find_stops, which cover timing and stop lookup rather than line metadata.

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?

Explicit use cases are given ("where does line 4715 go?", "which bus goes from Cacilhas to Almada?", "check whether a line passes a stop"), and the include_stops flag is tied to the third case. However, it never names an alternative sibling or an exclusion — e.g. it doesn't say to use find_stops when you already have a stop id and want lines serving it.

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