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

Annotations already declare readOnly, idempotent, openWorld and non-destructive, so the safety profile is covered. The description adds value beyond that by disclosing the data's nature: these are planned/static schedules rather than live vehicle positions, which is a behavioral trait the annotations cannot express. It does not describe response shape, timezone handling, or behavior for dates with no service.

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, front-loaded with the core action, then the dependency, then the scope boundary. No filler or restatement of the title, and each sentence carries distinct information.

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 two-parameter read tool with rich annotations and no output schema, the definition covers purpose, prerequisite and data semantics well. The remaining gap is that it never indicates what the returned departures look like (per stop? all stops on the route?), which matters for a timetable tool with no output schema to fall back on.

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 carry parameter meaning. It does add one genuinely useful point — that routeId is not free-form but must be resolved via get_jsp_routes — yet it adds nothing about the date parameter (format, timezone, past/future limits) beyond what the regex in the schema already shows.

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?

"Fetch planned departure times for a public Skopje bus route and date" gives a specific verb (fetch), a specific resource (scheduled departure times) and the two scoping dimensions (route, date). It further distinguishes this from real-time arrival data and from the route-resolution sibling get_jsp_routes, so an agent can place it precisely among unrelated siblings.

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 description supplies an explicit prerequisite ("Call get_jsp_routes first to resolve the route ID") and a clear negative scope (scheduled timetable, not real-time location or prediction). It lacks only an explicit statement of when to prefer this over any alternative timetable source, but no such sibling exists in the list.

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