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

With no annotations, the description carries the full burden and does disclose the two behaviors an agent most needs: the FLIGHTAWARE_API_KEY secret requirement and that each call bills AeroAPI usage. It omits any mention of rate limits, error behavior, or whether the server cache affects billing (the no_cache/max_pages schema notes hint at this but the description doesn't connect it).

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 core identification in the first clause, then usage, then operational constraints. Three sentences, each earning its place, with no restatement of the name or title.

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 6-parameter tool with no output schema, the description usefully compensates by listing returned fields and by covering auth and cost, while date-exclusivity and pagination live in the schema. Minor gap: it doesn't tie max_pages/no_cache to the billing warning, so the cost-per-page implication is only discoverable in the schema.

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%, including the non-obvious exclusive-end-date semantics and per-page billing for max_pages, so the schema does the heavy lifting. The description adds only the phrase "date window," no syntax, format, or constraint detail beyond the schema. 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 specific verb+resource+scope: scheduled (future) flights between two airports in a date window, via the AeroAPI /schedules endpoint. It also enumerates the returned fields (ident, operator, scheduled out/in times, aircraft type), which pins down exactly what the tool yields. The scope is clearly disjoint from the sibling flightaware_flight_status, which is about a specific flight rather than a route timetable.

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?

"Use it to see what actually flies a route on given days; it returns no prices" gives a concrete use case and an explicit exclusion, steering agents away from fare lookups. However, it never names flightaware_flight_status or states the condition that selects it over this tool, so the sibling routing is left to inference.

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