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

Annotations already declare this is a safe, idempotent, closed-world read, so the safety burden is lifted. The description adds genuine behavioral scope: it only compares nonstop, per-carrier odds and explicitly redirects multi-stop UA routings elsewhere, which prevents misuse. The accuracy-window detail is already carried by the schema, so it earns no extra credit.

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?

Two compact sentences, front-loaded with the user-facing trigger, then scope, then the redirect. No filler and nothing repeated from structured fields unnecessarily.

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 tool with no output schema and fully documented parameters, the description covers purpose, trigger, scope limitation, and an alternative route for the uncovered case. It could note the shape of the comparison result (ranked itineraries vs odds), but nothing required to call it correctly is missing.

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% — origin, destination, date window behavior, max_stops, and max_results are all fully documented in the schema. The description adds no parameter-level meaning beyond that, so the baseline of 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 specific verb+resource (plan a Starlink itinerary by comparing Starlink odds across every tracked airline, nonstop, per-carrier), which is concrete enough to separate it from prediction siblings. However, it never names the nearest siblings (predict_route_starlink, search_starlink_flights), so an agent must infer the boundary from scope wording alone.

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?

Gives an explicit trigger ('Use when the user asks "what's the best way to fly X to Y with Starlink?"') and a routing condition for multi-stop UA itineraries to a different endpoint. It stops short of stating when to prefer sibling tools like predict_route_starlink or search_starlink_flights instead.

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