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

Annotations already declare readOnlyHint=true, destructiveHint=false, and openWorldHint=false, so the agent knows this is a safe, closed-domain read. The description adds the dual-mode behavior (name lookup vs near-code/coordinates), which is useful, but says nothing about result volume, ranking, or limits on the proximity list.

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 tight sentences, zero filler. The lookup-vs-list distinction is front-loaded and the downstream-purpose sentence is the key routing 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?

An output schema exists, so return-value documentation is unnecessary. Both input modes and the practical purpose are covered, which is everything an agent needs to select and call this tool against its two-parameter, zero-required schema.

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 both 'query' and 'near' including their either/or relationship. The description adds only the framing of turning a city name into an IATA code, which clarifies intent but no syntax or format detail 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?

States specific verbs (look up, list) over a specific resource (airports and city codes) and covers both operating modes: name lookup and proximity listing. It also positions the tool relative to its siblings by naming the downstream purpose (producing the IATA code other tools take).

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?

Gives a clear context of use: resolving a city name into the IATA code that the sibling tools consume, plus the two query modes. It stops short of explicitly naming cheapest_routes or route_fares as the consumers or stating when to prefer one mode, so it's clear context without explicit alternatives.

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