Ryanair Low Fare Finder: Cheapest Days, Anywhere & Alerts

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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered structurally. The description adds genuinely useful non-obvious context: the pay-per-result cost model with per-call and per-result prices, which affects how an agent should budget and invoke the tool. It stops short of any rate-limit or reliability notes.

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 sentences, front-loaded with the functional scope before the pricing detail. Every clause carries information. The pricing sentence is dense with three price points but is relevant to invocation cost, not filler.

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, no-required-parameter tool with no output schema, the description covers both modes and the cost model, which is what an agent needs to decide and budget. It does not describe the returned structure or any caps on result volume, leaving a minor gap that the schema partially fills via maxDestinationsPerAirport.

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 the schema itself explains modes, defaults, formats, and even the per-leg pricing note. The description adds no parameter-level detail beyond what the schema already provides, so the baseline of 3 applies.

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 (Ryanair fares) and cleanly separates two operating modes: the per-day fare calendar for a route, and every destination under a price cap from an airport. An agent can tell what it does without opening the schema. It does not, however, differentiate itself from the sibling search_flights tool, which is the nearest overlap.

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 two modes are implied by which parameters are supplied (routes vs airports), so usage is inferable rather than stated. There is no explicit 'use this instead of X' guidance and no exclusion relative to search_flights, so the agent must reason about selection. Adequate but with a clear gap.

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