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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, openWorld), so the description goes further with genuinely additive context: result ordering ('biggest first') and the pricing model (free within a daily allowance, then $0.001 USDC per call via x402). It does not describe pagination or behavior past the result limit, keeping it out of the top score.

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: core search behavior first, then optional filters, ordering, and pricing. Every clause carries information; nothing is redundant.

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?

An output schema exists, so return values need not be explained, and annotations carry the safety profile. The description still supplies criteria, ordering, and cost, making it largely self-sufficient for a 5-param search tool; only pagination/limit-exhaustion behavior is left unaddressed.

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%, so the schema already documents all five parameters and the baseline is 3. The description echoes the facets and clarifies their and/or combination logic, but adds no syntax, format, or default detail beyond the schema.

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 verb (Find) plus resource (airports) and enumerates the search facets: name/town, country, type, scheduled service. The 'biggest first' ordering and text-based matching implicitly distinguish it from sibling airports__near (proximity) and airports__airport (single lookup).

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 'and/or' phrasing and 'optionally by type or scheduled service only' clarify which filters combine, which implies how to use it. However, it never states when to choose this over airports__near or airports__airport, nor any exclusions, leaving the when-to-use decision to inference.

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