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 that matching is language-agnostic and that results are exact station names, but says nothing about result count, ranking, or empty-match behavior.

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 lines: purpose, trigger condition, and a concrete example, with the core function front-loaded. Every element earns its place and there is no filler.

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 one-parameter, read-only lookup with no output schema, the description covers what the tool does and when to use it, and annotations carry the safety profile. Only the shape of the returned result (list format, ordering) is left unstated, which is a minor gap.

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 coverage is 100% and the single parameter is already documented as 'Part of the station name', which is essentially what the description conveys. The 'Bruxelles' example slightly illustrates the partial-name usage, but adds no format or matching rules beyond the schema.

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 gives a specific verb and resource ('Finds the exact Belgian station names matching a word') and scopes it to any language, which is enough to distinguish it from the departure/connection/details siblings by function. It stops short of explicitly naming or contrasting those 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?

It states a concrete trigger condition: 'Use when: a station name is ambiguous or misspelled.' That tells the agent when to reach for this lookup rather than a schedule tool, but there is no explicit when-not or named alternative.

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