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

With no annotations, the description carries the full disclosure burden, and it does well on cost ('20 credits'), coverage ('US airspace, FAA SWIM') and temporal bounds. It says nothing about the response shape, latency, or what happens when a flight number has no data in the window, which are the remaining behavioural gaps for a paid query.

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?

Three short sentences, front-loaded with what the tool returns and followed by the input constraint and the cost. Every clause adds information; nothing is repeated from the schema or the title.

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 4-parameter tool with no annotations, no output schema and 0% schema description coverage, the definition supplies the constraints, cost, source and coverage an agent needs to call it correctly. It notably repairs the misleading 'required: 0' in the schema by stating that exactly one subject must be given. Only the return contents remain undescribed.

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 define all four parameters, and it largely does: the days range, route syntax with both ICAO and IATA examples, 'departure airport' rather than any airport, and the mutual-exclusivity rule that the schema's zero required fields do not express. It omits the expected format for the flight and airport string values, leaving some ambiguity.

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 definition names a concrete metric (on-time performance), the three accepted query subjects (flight number, route, departure airport), the historical window (7-90 days) and the data source (FAA SWIM, US airspace). That is far more specific than the title alone and implicitly separates it from point-in-time siblings like flight_status or flight_on_date, though it never names an alternative explicitly.

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 supplies the critical selection rule 'give exactly one of flight, route, airport', which prevents the most likely misuse of the tool. It also states the valid historical window and the covered airspace, implicitly telling the agent when the tool does not apply. It stops short of saying when to prefer this over flight_history or flight_status.

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