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

Goes well past the readOnlyHint/openWorldHint annotations by disclosing the commercial model: $0.002 USDC per successful call via x402 (Base, Solana, Arc), with failed calls uncharged. It also flags deliberate data gaps (no runway/frequency) so the agent won't over-trust the record. This is exactly the behavioral context annotations cannot carry.

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?

Two sentences, zero filler: the resource and key formats come first, then scope exclusions and pricing. The field enumeration is dense but each item is decision-relevant for an agent checking coverage.

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 a single fully documented required param, an output schema covering the return shape, and safety hints already in annotations, the description closes the remaining gaps (coverage limits, cost/failure billing). Nothing an agent needs before calling is 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 coverage is 100% and the parameter already documents "IATA code like HEL or ICAO code like EFHK," so the schema carries the load. The description's "3-letter / 4-letter" restatement adds marginal disambiguation value but no new syntax, format, or validation detail.

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?

Names a specific verb+resource ("Airport record") with the two lookup keys (IATA 3-letter / ICAO 4-letter), the data source (OurAirports), and an explicit field inventory (name, type, coordinates, elevation, country, municipality, scheduled-service flag). An agent can distinguish this from logistics_seaport_unlocode or logistics_air_waybill_awb purely from the text.

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?

Usage is implied by the code-based lookup framing, and there is a useful scope exclusion ("No runway or frequency data"), but the description never names an alternative or states when to prefer a sibling like logistics_seaport_unlocode. The agent must infer routing from sibling names alone.

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