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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint false, covering the safety profile. The description adds valuable context beyond annotations by noting the data source (NOAA Aviation Weather Center), public domain status, and no-auth requirement, plus the decoded field content. It also indicates the data is 'real-time,' which is behaviorally relevant. There is no contradiction with 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 compact and front-loaded with the core action, followed by data elaborations, use cases, and source attribution. Every sentence contributes value without redundancy, and the total length is appropriate for the tool's complexity.

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?

Given the annotations, a full input schema, and an existing output schema, the description is complete. It covers the domain, the type of data returned, the use case, and the source/auth requirements. Nothing an agent needs to invoke it correctly 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 description coverage is 100%, with detailed descriptions for id, age, and distance already provided. The description's mention of 'configurable radius and time window' maps to these parameters but adds no new meaning beyond what the schema states. Baseline of 3 applies because the schema carries the parameter semantics.

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 clearly states the action ('Retrieve Pilot Reports'), the resource ('PIREPs'), and the geographic/temporal scoping ('near a given ICAO station within a configurable radius and time window'). It distinguishes this from sibling METAR/TAF tools by expressly mentioning PIREP-specific content (icing severity, turbulence, cloud bases, flight level). The verb and resource are specific, and the scope is unambiguous.

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 provides clear context on when to use the tool: 'Useful for pre-flight planning, route analysis, and verifying forecast accuracy.' It does not explicitly name alternatives or state when not to use it, but the use cases are well-defined. Since alternatives like aviationweather.observation.metar or avwx.pireps.list are not referenced, it falls short of a perfect 5 for explicit routing.

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