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

Annotations already declare the safe, read-only, idempotent, open-world profile. The description adds the return payload—time, line, destination, platform, live delay, cancellations—which is valuable given there is no output schema. It omits auth, rate limits, and cancellation semantics, but annotations lower the burden.

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?

Two crisp sentences plus a useful example; every element is front-loaded and relevant. No redundant text.

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 simple two-parameter read tool with annotations covering safety and no output schema, the description is nearly complete: it lists return fields, usage context, and an example. The only omission is any guidance on the results count, which is minor.

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 50%: the station parameter is documented in the schema, but results (count) is not described anywhere. The description supplies a concrete example for station and clarifies 'one station or stop', but it never mentions the results parameter or its default/maximum. It adds some value but does not compensate for the coverage gap.

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 'Next departures' and resource 'Norwegian station or stop', lists transport modes, and makes clear it returns departures from a single stop. It does not explicitly contrast with siblings no_connections or no_find_station, so an agent must infer the distinction from scope wording ('one station or stop').

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 line 'Use when: someone is at (or going to) a stop in Norway' gives clear context for when to call. No when-not condition or alternative tool is named, but the usage context is explicit.

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