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

Annotations already mark the tool read-only, open-world, idempotent, and non-destructive. The description adds meaningful context beyond that: links are regionalized to the traveler's country, results include affiliate AirHelp, Vueling, and airline-specific links depending on route, and no live fares or schedules are returned. It also discloses the affiliate commission, which is behavior an agent must know to present results appropriately.

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 description is longer than average but every sentence carries load: core action, parameter semantics, additional returned link types, exclusions, sibling reference, and affiliate disclosure. It is front-loaded with the main purpose and keeps details in a logical order. A slight tightening of the airline-specific listing could improve it, but nothing is redundant.

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?

Given the output schema exists and the annotations cover safety, the description is complete for an agent deciding whether and how to call this tool. It explains what is returned, what is not returned, how regionalization works, when certain extra links appear, and the affiliate disclosure requirement. No critical behavioral gap remains.

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 the baseline is 3. The description adds joint parameter semantics not fully captured by the schema: origin and destination are needed together for a prefilled route search, while omitting both opens the general search page. This clarifies how the parameters interact, going beyond individual field definitions.

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 and resource: 'Build a flight search link on Booking.com Flights for a route and optional dates' and adds the secondary return of VoyageHacks guides. It explicitly distinguishes itself from get_airport_transfer_links, so an agent can tell this tool apart from its nearest sibling without opening the schema.

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?

Provides explicit when-to-use guidance: 'Useful when a trip involves air travel and the user wants somewhere to compare fares.' It also states what the tool is not for — no live fares, no booking — and names the alternative for airport transfers. This gives clear selection criteria relative to siblings.

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