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

Annotations already cover safety (readOnly/idempotent/non-destructive), and the description adds substantial extra context: a missing code yields 404 airport_not_found and is not charged, answers come from a bundled copy with no upstream call, latency (~2 s first call, then <0.1 s), price, and a shared 5-call free pool per IP per UTC day.

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?

Information-dense and largely front-loaded with purpose, inputs, returns and caveats in order. The opening 'skypeek: an airport by ICAO...' is grammatically truncated, and the parenthetical-heavy single block is long, but almost every clause (data source, caching, price, error behavior) earns its place.

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?

With no output schema, the description compensates by enumerating return fields (runway ends, length, width, surface, lighting, headings; radio frequencies; match fields such as codes, type, position, elevation, country). Error behavior, latency and pricing are also covered, leaving nothing essential for a correct call missing.

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 code, query, limit and country with ranges and defaults. The description only restates those semantics (including the 'send code or query' choice), adding little that isn't already in the schema; baseline 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 verb+resource and both lookup modes ('an airport by ICAO, IATA or ident code ... or up to 20 matches of a name or city search'), listing exactly what it returns. Clearly separable from siblings like airport_distance, geocode and get_metar.

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?

Gives clear context for each input mode (code for a single airport, query for name/city matching, country to narrow) and a domain exclusion ('Informational only: not for flight planning or navigation'). It does not, however, route the agent to a sibling tool for adjacent needs, so no explicit alternatives.

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