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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, openWorld), and the description adds genuinely new behavior: it returns free/taken per day and never the actual schedule, it is not a hold or confirmation, and it returns a reason instead when the owner does not publish availability. These return-content and failure-mode disclosures are exactly what annotations cannot convey.

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?

Front-loaded and every sentence carries information (scope, trigger, return format, exclusions, error case). However, phrasing is awkward and indirect ('read from the live schedule its owner connected', 'answer with its sentence'), which costs clarity for an agent parsing it quickly.

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?

With no output schema, the description carries the return-value burden and does so: per-day free/taken, never the schedule detail, plus an error-path result. Parameters and scope are covered. Only minor polish is missing, so it is effectively complete for this tool.

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 coverage is 100%, so the baseline is 3. The description adds meaning beyond the schema by tying date to the departure date, end_date to a return trip, and imposing a 14-day span limit that the schema itself does not state. That extra constraint lifts it above baseline.

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?

States a specific verb and resource: checks whether one aircraft has anything scheduled on a date or a span of up to 14 days, reading the owner's live schedule. The scope (single tail, 14-day max, live data) is precise. It doesn't explicitly name a sibling it replaces, but the purpose is unmistakable against estimate_charter or request_trip.

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?

Gives an explicit trigger ('Call it when the person you are helping asks whether the aircraft is available') and the arguments to supply for one-way vs return trips. It also draws boundaries ('Not a hold and not a confirmation'). No named alternative tool is offered, so it falls short of a 5.

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