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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the safety profile is covered. The description does add genuinely useful context the annotations don't: the upstream data sources (NWS for the US, BOM for Australia) and the caveat 'where licensed', which signals possible coverage gaps. It says nothing about what happens for regions outside US/AU or how stale the alerts may be.

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 dense sentences with zero filler: scope and ordering come first, then source coverage. Every clause carries information an agent would otherwise have to guess.

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 at least discloses ordering ('severity first') and upstream sources. Remaining gaps (behavior for unsupported regions, alert fields, whether expired alerts are filtered) are minor for a simple read-only lookup with a well-described required parameter.

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 67% and the region parameter already documents accepted formats (US state, NWS zone/county, AU state). The description's only added meaning is implicitly constraining valid geography to the US and Australia, which is a real but modest gain. Severity and limit meanings are left entirely to the schema.

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 ('Active weather alerts for a region') and adds an ordering trait ('severity first'), which cleanly separates it from the forecast/current siblings without naming them. It stops short of explicitly contrasting with weather_current or weather_forecast.

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 word 'Active' implies the use case (current alerts rather than historical or forecast), but there is no explicit when-to-use guidance, no statement of when to prefer weather_forecast, and no prerequisites spelled out. Usage is inferable rather than stated.

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