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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so safety and determinism are covered. The description adds genuine behavioral value with 'age where known', signaling that fields can be legitimately absent rather than an error, but it says nothing about coverage, lookup failures, or auth.

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 sentences, front-loaded with the resource and key, followed by the argument format. No filler, no redundancy with the schema or annotations.

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 no explanation, and the annotation set covers the safety profile; for a one-parameter lookup the description is nearly sufficient. The only gap is that it never characterizes the sibling alternatives or failure/not-found behavior.

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 0%, so the description must carry the single parameter's meaning, and it does: 'registration = tail number' plus two concrete format examples (N12216, F-GSQA) that clarify expected syntax. It stops short of stating whether hyphens are required or accepted, so it is good but not exhaustive.

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 lookup keyed on registration and enumerates the attributes returned (type, manufacturer, operator, age, in-flight Wi-Fi), which is far more than a restatement of the name. It does not explicitly contrast itself with siblings like flight_wifi or airline_wifi, so an agent must infer the boundary.

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 only implied: the argument description ('tail number such as N12216 or F-GSQA') hints that this is a lookup by registration. There is no statement of when to prefer this over flight_wifi, airline_wifi, or flight_status, and no exclusions or prerequisites are given.

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