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

Annotations already declare read-only, idempotent, and non-destructive behavior. The description adds valuable operational context beyond that: the calendar is cached, nights are actually on sale, and total_count/has_more warn that the response may be a capped subset, so the agent must not present it as the full calendar. This is meaningful behavioral guidance.

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 three dense sentences with no filler. The primary purpose is front-loaded, the cap/pagination caveat and filter guidance follow, and the alternative tool is named last. Every sentence earns its place.

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?

Even though there is no output schema, the description names the key result contents (nights_available, booking-search link, total_count/has_more) and the critical pagination caveat. Combined with the fully described schema and read-only annotations, an agent has enough information to call the tool correctly and interpret the response.

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 input schema already describes all 8 parameters with 100% coverage, so the baseline is 3. The description mostly restates filtering options and references an output field (nights_available) rather than adding new parameter semantics, but it does not need to compensate for missing schema documentation.

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 exactly what the tool provides: real upcoming charter departure dates from Tirana for a destination, including trip lengths actually on sale and a booking-search link. It also distinguishes itself from charter_flexible_dates by explicitly naming that alternative for cheapest-date 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?

It gives concrete filter guidance (date_from/date_to or month) and an explicit routing rule: use charter_flexible_dates when the user wants the cheapest date. This clearly tells an agent when to choose this tool over the most relevant sibling.

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