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

Annotations already cover read-only, idempotent, and non-destructive behavior, so the safety profile is established. The description adds meaningful behavioral context by specifying the data is 'current/last-known,' limited to in-air flights, and names the output fields. There is no contradiction 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?

The description is two sentences long, front-loads the primary behavior and output fields, and then immediately gives the key prerequisite and a concrete call example. Every sentence earns its place and there is no filler.

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 two-parameter read-only endpoint with no output schema, the description is complete: it names all returned values, gives the required id format, provides a valid example, and the schema handles authentication parameters. An agent can correctly invoke this tool with the information provided.

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?

Input schema covers both parameters at 100%, with the id description already stating it must be an AeroAPI fa_flight_id and _apiKey describing the API key. The description's example adds a concrete example and restates the id requirement, but does not need to add significant extra meaning beyond an already complete schema.

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 and resource: 'Get the current/last-known position of an in-air flight,' and enumerates exactly which fields are returned. The tool name alone could be ambiguous against siblings like flightaware_flight_track, but the description fully resolves what this tool specifically does.

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 strongly implies usage context by requiring an AeroAPI fa_flight_id from flightaware_flight_status and warns that bare flight/tail numbers won't work. However, it does not explicitly contrast this tool against alternatives like flightaware_flight_track or flightaware_airport_flights, leaving the when-to-use decision partially implicit.

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