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

Annotations already declare the safe read profile (readOnlyHint, idempotentHint, non-destructive), so the bar is lower, yet the description still adds real behavioral value: decade-level precision on network data, the meaning of servedCountries, and the networkKnown=false case. It does not discuss pagination behavior beyond the limit cap or response envelope, keeping it short of a 5.

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?

Five sentences, but each carries non-redundant information and the core purpose is front-loaded in the first clause. Density is high with no filler, though the data-precision caveats could be tightened slightly.

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 values need not be explained, and the description still helpfully clarifies output semantics (servedCountries, networkKnown, sort order by airline size). Combined with the 100% schema coverage, an agent has what it needs to call and interpret the tool; only a brief note on result volume/pagination is absent.

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%, so the schema already documents all five parameters including enums and ISO pattern, setting the baseline at 3. The description reinforces the year bounds but adds no syntax or interpretive detail for kind/region/country/limit beyond what the schema states.

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 specifies exactly what is returned — real airlines operating in a year, with fields (name, IATA, country/region, type, years of operation, served countries) — so an agent can instantly tell this apart from aircraft_catalog or get_world. It never names an alternative sibling, but the resource is unambiguous, so no sibling differentiation is needed.

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?

Usage is implied by the year range (1950-2030) and the filtering parameters, but there is no explicit when-to-use or when-not guidance and no alternative named among the siblings. The caveats about decade-precision network data and networkKnown=false function as usage guidance for interpreting results, which lifts it above a bare minimum.

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