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

With no annotations, the description carries the full burden and does reasonably well: it discloses the drivers of the score (wind gusts, convective potential, winter/precipitation, heavy cloud cover), the 6-hour bucketing, the 48-hour horizon, that the transport is GET, and that it costs $0.02 via x402. It stops short of stating auth requirements, rate limits, or whether scores are probabilistic.

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?

Front-loaded and compact, with the metadata line (HTTP method, price, docs URL) earning its place. The opening sentence ('PHX weather delay risk for the next 48 hours') is a near-restatement of the following sentence, which is minor waste.

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 no-arg, no-output-schema read endpoint, the description conveys enough: what the return roughly contains (6-hour risk scores) and that it mirrors the generic delay-risk shape. Enough for correct invocation, though output field details remain unspecified since no output schema exists.

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?

Zero parameters and 100% schema coverage, so there is nothing for the description to document; baseline for an argument-less tool. No parameter confusion is possible since the resource is fully encoded in the tool name.

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+scope: weather-driven delay risk for Phoenix Sky Harbor (PHX) over the next 48 hours. It even distinguishes itself from the sibling generic endpoint ('Same shape as the generic delay-risk endpoint, bound to PHX'), so an agent can tell it apart from weather_aviation-delay-risk without opening a 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?

Usage is implied rather than stated: the field name and 'bound to PHX' signal this is the PHX-specific variant of the generic delay-risk endpoint. But it never says explicitly when to choose this over weather_aviation-delay-risk or weather_forecast_phoenix, nor any exclusions.

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