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

Annotations already declare readOnlyHint=true and destructiveHint=false, so safety is covered. The description adds valuable behavioral context: the data is cached, in AUD, indicative rather than live, and that travel dates must be presented alongside prices. This goes beyond what annotations could capture and is essential for correct agent behavior.

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 somewhat long but every sentence serves a purpose: condition, data nature, presentation requirement, and usage guidance. The key condition is front-loaded. It is slightly verbose with the sister-site detail ('I Know The Pilot's sister flight-search site'), but this is contextually useful and not wasteful.

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?

The description covers all essential aspects for correct invocation: the business scenario, data caveats, required output presentation, and the alternative tool. No critical information is missing. Since an output schema exists, return-value details do not need to be in the description.

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 every parameter already has an explanation. The description does not add additional meaning about parameter formats or constraints beyond what the schema provides. It mentions the destination and date window only implicitly, so it stays at the baseline for full schema coverage.

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 the action ('compare the cheapest fare'), the resource ('to a destination from every origin airport'), and the key condition ('when the user hasn't said where they're flying from'). It also differentiates from the sibling tool get_cheapest_flight_dates, so an agent can immediately tell them apart.

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?

It explicitly gives the condition for use ('when the user hasn't said where they're flying from') and names the alternative tool ('use get_cheapest_flight_dates when the origin is known'). This is direct, unambiguous guidance on when to choose this tool over others.

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