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

Annotations already declare readOnly/idempotent/non-destructive/open-world, so the safety profile is covered. The description adds genuinely non-structured behavior: an airfield with no fixed-wing runways (e.g. heliports) returns an empty runways array with found:true rather than an error, while an unrecognized code is refused with a clear error — resolving the classic ambiguity between 'empty' and 'not found'.

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?

Four tight sentences: resource+payload, then input contract, then the two edge-case outcomes. Front-loaded and every sentence carries distinct information; nothing is redundant with the title or 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 one-parameter read-only tool with no output schema, the description covers provenance, per-runway field list, accepted input formats, and both empty-result and error behavior. An agent can call this correctly and interpret the response without further documentation.

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% on a single `code` parameter, so the baseline is 3. The description goes slightly beyond the schema by tying accepted formats back to ourairports_lookup, giving the agent an operational definition of what counts as a valid code rather than just restating ICAO/IATA/GPS/local.

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+resource: 'Runway details for one airfield from the OurAirports dataset,' then enumerates exactly what each runway record contains (length/width in feet, surface, lighted, closed, both ends' ident/coords/elevation/heading/threshold). This makes it trivially separable from siblings like airport_frequencies, airport_navaids, and get_airport 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?

It gives clear context for invocation by delegating code semantics to a named sibling ('Pass any code ourairports_lookup accepts (ICAO, IATA, GPS or local ident)'), which tells the agent where to get a valid input. It does not explicitly exclude cases where get_airport or airport_frequencies would be preferred, so it stops short of a full when/when-not statement.

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