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

With no annotations, the description carries the full burden and does well: it discloses the live private-API source, the unofficial status, that failures can occur from rotation or throttling, an implicit cache (via no_cache), and the local-currency return shape. It omits any guidance on retry behavior or rate limits, which keeps it short of a 5.

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?

One tight paragraph, front-loaded with the core definition, then output shape, then the reliability caveat, then sibling routing. Every sentence carries information an agent needs; nothing is redundant with the schema.

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 9-parameter tool with no output schema, the description compensates by explaining the return value (one price per day, local currency, fare-finder link, return legs) and the upstream volatility. Nothing needed to call it correctly 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?

Schema coverage is 100%, so the baseline is 3, but the description adds consequence-level meaning the schema lacks: day_interval defines an up-to-19-day window and return_date causes extra return-leg days in the output. wdc, no_cache, and passenger counts are left to the schema, which already documents them well.

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 resource and verb: cheapest Wizzair fare per day around a date, with an explicit ±day_interval window cap. It also names the sibling tools it is not (timetable, flight_dates), so an agent can discriminate it without opening any schema.

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?

Explicitly routes the agent: use wizzair_search_timetable for departure times and wizzair_search_flight_dates for operating days, which covers the two most likely confusions. It does not address wizzair_search_flights (presumably the booking path), so the routing is strong but not exhaustive.

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