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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so the safety profile is fully covered. The description adds useful freshness context ('the date checked') and source URL, but says nothing about rate limits, caching, or behavior for unknown airlines. With annotations doing the heavy lifting, this is adequate but not rich.

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?

A single front-loaded sentence that leads with the resource and scope before listing return fields and the optional filter. Slightly run-on, but every clause carries information and nothing is wasted.

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 lookup with an output schema, the description need not explain return values, and the 'one airline's' scoping plus filter note is a reasonable minimum. However, it omits the currency parameter's meaning and gives no signal about how this relates to true_cost, so the picture is not fully complete.

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 only 33%, so the description should compensate for undocumented parameters. It clarifies that 'category' is an optional filter but never explains the 'currency' parameter (EUR/GBP) or the format of the airline input, leaving a gap the schema also leaves open.

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 names a specific resource ('one airline's published extra fees') and enumerates its scope (bags, seats, priority, check-in, changes, payment), so an agent knows exactly what is returned. It does not differentiate itself from siblings like true_cost or list_airlines, leaving the agent to infer the boundary.

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?

'Optionally filter by category' implies the filter is optional and the airline is the primary key, but there is no explicit when-to-use guidance, no conditions for choosing this over true_cost, and no exclusions. Usage is only implied.

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