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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is covered. The description adds concrete behavioral details: the exact fields returned (tail numbers, aircraft types, operators, install dates) and the default/max limit, as well as ordering (most recent). No contradictions 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?

Two sentences, zero fluff. The first sentence immediately states purpose and gives example queries; the second covers return fields, defaults, limits, and the exclusion. Everything earns its place.

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 tool with only two optional parameters and no output schema, the description covers all essential information: what it returns, default behavior, maximum limit, and when to choose an alternative. No gaps remain for an agent to call it correctly.

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% with clear descriptions for both fleet ('Filter to only express (regional) or mainline aircraft') and limit ('Maximum number of aircraft to return (default 50)'). The description only reiterates the limit (up to 500) without adding new semantics, so per the baseline rule for high coverage, a 3 is appropriate.

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 opens with a precise use case ('when the user asks about the planes themselves') and gives concrete example queries ('which tail numbers have Starlink?'). It clearly names the resource (United Airlines aircraft) and the action (list with details), and explicitly differentiates from the sibling search_starlink_flights.

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?

It explicitly states when to use the tool and when not to, pointing to the exact alternative ('Not for finding flights — use search_starlink_flights for that'). It also explains the default behavior (50 most recent) and the upper limit (500), leaving no ambiguity about invocation context.

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