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

Annotations already declare readOnlyHint=true, openWorldHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is fully covered. The description adds valuable behavioral context beyond annotations: it specifies the waypoint fields (Unix timestamp, latitude, longitude, barometric altitude, true track angle, on-ground flag), explains the time=0 or omit behavior for current active flight, and states the 'actively tracked' requirement. It also notes no auth is required. This goes beyond what annotations provide.

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 well-structured and appropriately sized. It front-loads the core purpose, then details the output fields, usage notes, use cases, and source attribution. Every sentence earns its place, and the most important information (what it does, key parameter behavior) comes first. No fluff or redundancy.

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?

The description is complete for a read-only lookup tool. It covers the input (icao24, time), the output structure (waypoint fields), the precondition (actively tracked), use cases, source attribution, and auth requirements. The output schema exists, so return values don't need further explanation. An agent has everything needed to select and invoke this tool 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%, so the schema already documents both parameters (time and icao24) with descriptions. The description adds a bit of context by explaining the waypoint fields and the time=0 behavior, but it doesn't add significant meaning beyond the schema's parameter descriptions. Baseline 3 is appropriate since the schema does the heavy lifting.

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 clearly states the tool retrieves a flight trajectory (sequence of GPS waypoints) for a specific aircraft identified by ICAO24 hex address. It specifies the exact resource (aircraft track) and the verb (retrieve), and distinguishes it from sibling tools like opensky.traffic.aircraft_state and opensky.traffic.states_bbox by focusing on trajectory/waypoints rather than current state or bounding-box queries.

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 explicitly states when to use this tool: for reconstructing a flight path, computing distance flown, or detecting airport arrivals/departures. It also gives a clear precondition: the aircraft must be actively tracked by the OpenSky network. It does not explicitly name alternative sibling tools, but the use cases and the 'actively tracked' constraint provide clear context for when this tool is appropriate versus other OpenSky traffic tools.

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