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

Annotations already declare readOnly, idempotent, open-world, non-destructive, so the safety bar is low. The description still adds real behavioral detail beyond them: results ordered by earliest arrival, prices in EUR, local times per airport, 10-per-page paging, rail links only under 1,200 km, and the explicit 'Nothing is booked' reassurance.

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?

Front-loaded with the verb and resource, then two short sentences for paging/timezone and the no-booking guarantee. Every clause carries information an agent needs; there is no filler.

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?

An output schema exists, so return values need not be explained, and the description covers scope, ordering, units, paging, geography and safety. Only the missing explicit usage trigger keeps it from being fully complete.

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 all six parameters are already documented (date window, limit range and default, cursor, IATA patterns, nearby-airport default). The description only echoes a few of these (300 km radius, 10 per page) and adds no new syntax or format meaning, so the baseline 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?

States a precise verb and resource (searches live one-way flights) plus scope: origin, nearby airports within 300 km, a single date. The ordering rule and output fields are named, so an agent can distinguish this from the case/message siblings without opening any 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?

Usage is implied through the scenario framing ('from the traveller's airport', 'one date', one-way), which tells the agent the context in which the tool applies. However, there is no explicit when-to-use statement, no prerequisites, and no named alternative or when-not condition.

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