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

Annotations already declare readOnlyHint=true, openWorldHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is clear. The description adds value by noting that the result is read at request time ('Read at request time, so an empty list means nothing is active') and describing the limit mechanism with page.total for completeness. However, it could mention that NWS data may have latency or that the tool depends on upstream availability, which is minor.

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 a single well-structured paragraph that front-loads the core purpose and input types, then provides usage guidance, alternatives, and pricing. Every sentence adds distinct value, and the text is streamlined with no redundancy.

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 tool's complexity (6 parameters, no required ones, an output schema exists, and full annotation support), the description is complete. It covers purpose, input options, alternative tools, behavioral guarantees, and even pricing cost context. The output schema likely handles return value descriptions, so the description need not cover that.

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 all parameters well. The description adds significant meaning beyond the schema: it explains the purpose of limit ('keeps the answer compact...page.total always reports how many are active'), detail's difference ('compact returns the fields an agent decides on; full adds NWS narrative members'), and offset behavior ('the whole active set is read in one upstream request...a window over it is consistent'). This enriches parameter understanding.

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 uses specific verbs ('Get active...weather alerts') and identifies the resource ('National Weather Service watches, warnings and advisories') and location inputs ('US coordinate or a two-letter state or marine area code'). It clearly distinguishes from siblings like weather_us_forecast and weather_us_observation listed in the sibling-tools.

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 explicit when-to-use guidance ('Decide whether an active US weather warning affects a location before dispatching or travelling'), explicit when-not-to-use ('Not for: You need the forecast rather than alerts'), and names specific alternative tools ('use weather.us.forecast', 'Related: weather_us_forecast; weather_us_observation'). It also mentions pricing to inform cost-aware decisions.

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