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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false, and a closed-world scope, so the safety profile is fully covered without the description. The description adds only that results are 'slugs' (useful for chaining), and says nothing about pagination behavior despite limit/offset params.

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?

A single front-loaded sentence that earns its place by carrying both purpose and usage context with zero filler. It is efficient, though extremely terse given the tool has four parameters and no output schema.

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?

With annotations covering all safety traits and the schema fully documenting every parameter, the remaining burden on the description is light. It conveys purpose, trigger context, and the return type (slugs), which is adequate, though it omits any note on result shape or paging.

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%, with lang, limit, query, and offset each documented in the schema itself. The description adds no syntax or format guidance beyond what the schema already provides, so the baseline of 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 clear verb+resource ('Find destination city slugs'), which is enough to separate it from search_airports, search_aircraft, and search_articles by domain. It does not explicitly name a sibling or contrast scope, so it stops short of a 5.

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 clause 'before estimating a route' gives concrete workflow context, effectively naming estimate_route as the downstream consumer and implying this is a prerequisite lookup step. No when-not conditions or alternative search tools are mentioned, so it is not fully prescriptive.

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