nearest_airport

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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint. The description adds significant behavioral context: coordinate inputs are not stored or logged, the sort is deterministic, confidence semantics are explained, rate limiting is disclosed with retry_after_seconds and Retry-After header, and the tool is reference-only, not for navigation. This goes well beyond the annotations.

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?

The description is detailed but every sentence carries operational value: scope, dataset size, required and optional parameters, exclusionary behavior, rate-limit details, output format, limitations, and related tools. The key purpose is front-loaded, and there is no 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?

The description covers required inputs, optional parameters, output response envelope, error behavior, limitations, data source, and sibling tools. There is an output schema present, so return values are contextualized. The definition is more than complete for an agent to select and invoke it correctly.

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?

The input schema already defines all parameters with ranges, examples, and defaults; the description mostly restates this. It adds no truly new parameter semantics beyond what is in the schema, so a 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 opens with a specific verb and resource: 'Find the airports nearest to a caller-provided latitude/longitude, sorted by great-circle (haversine) distance.' It clearly differentiates itself from siblings like airport_lookup and unlocode_lookup by stating it does not geocode place names and does not compute routes.

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 explicitly states when to use this tool ('pass coordinates you already hold') and what it does NOT do ('does NOT geocode place names and does NOT compute routes'). It also names related alternatives (airport_lookup, unlocode_lookup) with their different purposes.

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