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

Beyond the readOnly and openWorld annotations, the description discloses important behavioral details: the data comes from a public route page, results are recent rather than live, and each successful call costs $0.002 in USDC via x402 with failed calls not charged. This adds substantial cost, payment, and recency context.

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 dense and front-loads the core purpose before listing returned data and pricing. It is mostly efficient, though the long parenthetical list and multi-part sentence make it somewhat run-on.

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, complete parameter schema, and read-only annotations, the description supplies the remaining critical context: data recency, return categories, code examples, and payment model. An agent has enough information to decide when to call it and what to expect.

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 input schema already documents both parameters thoroughly, including airport and city code formats. The description reinforces the use of Skyscanner codes with examples such as 'lond to pari' and 'ist to lond,' but does not add much beyond what the schema already provides.

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 states a specific resource and verb: Skyscanner flight prices from its public route page. It further specifies the returned data, including recent fares, up to 16 one-way deals, monthly cheapest fares, route facts, and FAQ answers, and explicitly says it is not a live date search, which helps distinguish it from live flight-search siblings.

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 description gives clear usage context by stating it is 'Not a live date search,' implying it is for route-level recent-price research rather than date-specific fare searches. However, it does not explicitly name alternative tools such as live flight search siblings, so it falls short of full alternative routing.

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