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

Annotations already declare readOnlyHint and openWorldHint. The description adds genuinely new behavioral context beyond those: the $0.002 USDC x402 payment requirement and the 10-airport batch cap. It omits rate limits and response format, but the cost/payment disclosure is substantive added value.

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 dense sentence that front-loads purpose and return contents, then closes with the batch limit and pricing. Every clause earns its place with no filler, though the sentence is long enough that a cleaner split could improve scannability.

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 carries the return-value burden well by enumerating the decoded fields, and it covers cost and batch limits. The one meaningful omission is any explanation of the 'hours' input parameter, leaving the definition slightly incomplete for a 2-parameter tool.

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 only 50%: 'airport' is documented in the schema (ICAO, comma separated) and the description restates the ICAO/up-to-10 detail, but the 'hours' parameter is explained nowhere. With a full half of the parameters undocumented and the description failing to compensate, this is a clear gap.

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 names a specific resource (aviation weather for airports) and enumerates exactly what it returns: latest METAR decoded plus the TAF forecast. It is clearly distinguished from the generic 'weather' sibling by the METAR/TAF framing, though it never names an alternative tool explicitly, so it falls short of a 5.

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 content (aviation weather for ICAO codes), and the description notes it accepts up to 10 codes and costs $0.002 USDC per call (x402). However, it gives no explicit when-to-use vs the 'weather' sibling, no when-not conditions, and no prerequisites, leaving usage to inference.

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