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

Beyond the annotations, the description discloses the data source (the operator's connected calendar), freshness (synced every 15 minutes), output granularity (free or taken per day, never what is scheduled), and an error path when the owner does not publish availability. This gives the agent rich behavioral context for a read-only tool without contradicting any annotation.

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 a single dense sentence with no filler, and the availability-checking purpose is front-loaded. The phrasing is slightly convoluted — 'read from the operator's calendar its owner connected' — but every clause carries useful information.

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 read-only availability check with no output schema, the description covers the return semantics, data freshness, date-span limit, and the case where availability is unpublished. Combined with annotations that already confirm safety and idempotency, nothing material is missing.

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?

The schema already describes all three parameters, so the baseline is 3. The description adds meaningful context not in the schema: the 14-day maximum span for end_date and the typical departure/return interpretation for date and end_date.

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 states a specific verb-plus-resource: checking whether one aircraft has anything scheduled on a date or across a date span. It clearly separates this from sibling operations such as searching aircraft or requesting a trip by focusing on calendar availability, not aircraft attributes or booking actions.

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 explicitly says to call the tool when the user asks whether an aircraft is available, including departure and return dates for round trips. It also states what the tool is not — 'Not a hold and not a confirmation' — but does not name a specific sibling tool to use for holds or confirmations, keeping it just 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.