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

Annotations already declare readOnlyHint, openWorldHint, idempotentHint, and non-destructive behavior. The description adds the important context "current public state", indicating a transient, openly accessible snapshot. This complements the annotations without contradicting them.

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?

A single, focused sentence that immediately states the tool's action and scope. Every word earns its place, and the key identifying information (ICAO 24-bit hex address) is front-loaded.

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 simple one-parameter, read-only lookup tool, the description is largely complete: it states the target identifier and the type of data returned. It could mention what happens when no aircraft exists for the given hex or what fields the returned state contains, but the lack of an output schema and the simplicity of the operation keep this gap minor.

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?

With schema description coverage at 0%, the description compensates by explaining that the hex parameter is an ICAO 24-bit hex address. This gives the parameter meaning beyond its name and regex pattern, although it does not elaborate further on expected formats beyond the pattern.

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 uses a specific verb, "Return", names the resource ("current public state for one ICAO 24-bit hex address"), and clearly differentiates from siblings by focusing on a single aircraft identified by hex. The distinction from nearby_aircraft and network_stats is immediately apparent.

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?

The description clearly implies the use case: when you have a specific ICAO 24-bit hex address and need the public state for that aircraft. It does not explicitly state when to use alternatives, but the contrast with nearby_aircraft and network_stats makes the appropriate usage evident.

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