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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false and openWorldHint=false, so the safety profile is covered. The description adds genuinely useful data-freshness context ('cheapest Aviasales travellers found in the last 48 hours', 'live price is on the booking page'), but does not explain return shape or how the code is normally used downstream.

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?

The core purpose is front-loaded, but two of the four sentences are fare-marketing copy ('Cheap flights from any city, to one place or anywhere...') that does little to help an agent invoke a place-lookup. Moderate waste for a one-parameter tool.

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?

There is no output schema, so the description carries some burden for explaining returns; it partially does so via the fare-freshness and booking-page notes, but never clarifies what a lookup actually returns (a resolved code, a list of matches). Adequate but with a clear gap for a param-only tool.

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?

With a single parameter and 100% schema description coverage, the schema already documents the `q` argument with an example ('Lisbon or LIS'). The description adds no meaning beyond that, 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?

The description clearly states a specific verb and resource: 'Look up a city or airport code,' matching the title. However, the following sentence pivots to flight-deal marketing ('Cheap flights from any city... cheapest days to fly'), which blurs whether this tool resolves a place or returns deals, and it never distinguishes itself from siblings faredeals_find_deals or faredeals_cheapest_dates.

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?

There is no guidance on when to use this tool versus the sibling faredeals_find_deals or faredeals_cheapest_dates, even though a place lookup is the obvious prerequisite for those. No prerequisites, sequencing, or exclusions are stated.

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