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

The annotations already declare readOnlyHint, idempotentHint, non-destructive and closed-world. The description nonetheless adds a genuinely useful trait beyond them: 'Cache-only ... never triggers an external fetch', which tells the agent results may be stale and that a cache miss will not be refreshed. It stops short of saying what is returned on a miss.

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 sentences, front-loaded with what is returned, then the cache-only constraint. Every clause carries information and nothing is padded.

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 no output schema, the description usefully enumerates the returned fields, and the annotations cover the safety profile. The remaining gap is the zero-required-parameter case: it never says what happens when no argument is supplied, or what a cold cache returns.

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%, so all three parameters are already documented in the schema, including route_to's role and flight_segment_id returning both departure and arrival. The description restates these relationships without adding new syntax, precedence, or combination rules (e.g. what happens if both iata_code and route_to are supplied).

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 (get) and resource (cached airport conditions) and enumerates the payload: delay indices, weather, flight rules. The airport/segment scope is clear enough to separate it from siblings like get_trip_weather or flight_status_for_segment, but no sibling is named explicitly, so the differentiation is inferred rather than asserted.

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 two accepted lookup shapes (an IATA code, or a route via route_to, or a flight_segment_id) are described, which implies usage contexts. However there is no explicit when-to-use guidance, no statement of when to prefer this over get_trip_weather / flight_status_for_segment, and no exclusion rules.

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