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

With no annotations, the description carries the disclosure burden and does a solid job: it reveals the tool uses observed median prices, produces a ranked month list, and avoids speculative folklore. It does not mention data period, currency, or error behavior, but the core behavior is transparent for a simple read-only tool.

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?

Two concise sentences that front-load the ranking behavior and the median output. Every sentence adds value, with no redundant or filler language.

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?

Despite having no output schema, the description conveys the return shape: ranked departure months with each month's median price. Combined with fully documented schema parameters, this is sufficient for an agent to call the tool correctly, though minor details like the historical window or currency are not stated.

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%, and both required parameters already have clear descriptions including the city-name requirement and airport-code rejection. The tool description adds no parameter-level detail, so the baseline of 3 is appropriate.

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 action and resource: departure months ranked by observed median price for a route, with the median of each. It answers a concrete question ('when is it cheapest to go') and explicitly distinguishes itself from folklore-based guessing.

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 gives a clear use context: answering when it is cheapest to travel based on measured data. It implies this tool is for month-selection rather than booking timing or per-fare verdicts, but it does not explicitly name when to prefer it over the sibling tools.

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