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 beyond annotations by noting it is a 'Paid feature' and that it searches Google Flights, implying external data usage. No contradiction with annotations.

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?

Three sentences with no fluff. It front-loads the core purpose, then explains mechanics, then gives usage context. Every sentence earns its place, making it efficient and easy to scan.

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?

For a read-only search tool with no output schema, the description provides enough context: it explains what it does, what inputs are needed (implicitly via schema), and the best-use scenario. It does not mention return format or limitations, but given the tool's simplicity and the annotations covering safety, this is adequate. Slight gap on expected output, hence 4.

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 40% (only cabin and points_value_cents have descriptions). The description adds meaning for these two: 'premium cabins' maps to the cabin enum, and 'award redemptions' implies points_value_cents is used to value points. However, it does not explain origin, destination, or date beyond their obvious purpose, so it only partially compensates for the low 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 tool finds the cheapest way to fly by combining cash and award tickets into a split-ticket journey, with specific verbs and resources (searches cash fares and award availability, combines via hubs). It distinguishes itself from siblings like search_cash_flights and search_availability by explicitly naming the hybrid nature.

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 provides a clear best-use scenario: 'Best for premium cabins (business/first) on long-haul routes.' It implies this is not for economy or short-haul, but does not explicitly name alternatives or exclusions. Since it gives a concrete context, it earns a 4 rather than 3.

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