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

The readOnlyHint annotation already signals a safe read operation, lowering the bar. The description adds useful behavioral context: it covers all US counties, is a composite of federal storm-event data, and mentions update cadence ('Updates: on source cadence'). It does not disclose response size or pagination, but for a single-score tool this is acceptable, and the output fields are listed.

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 efficient and well-structured. It front-loads the core purpose in the first sentence, lists output fields succinctly, then provides usage guidance and a brief update note. No redundant or filler sentences exist; every part earns its place.

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?

Despite having no output schema, the description enumerates all output fields, explains the geographic coverage, outlines the composite factors, and presents clear usage triggers. The optional 'days' parameter is covered by the schema, so its absence from the description is acceptable. This is sufficient for an agent to select and invoke the tool correctly.

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 for the single parameter 'days' is 100%, with a clear description in the schema itself. The description does not repeat or expand on the parameter, which is fine given the schema already handles semantics. The description's mention of 'severity_score' and other fields indirectly implies the default snapshot behavior, but no additional parameter insight is provided beyond 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?

The description opens with a specific verb ('Returns') and a precise resource ('any of 3,222 US counties'), then details the output fields and composite basis. This leaves no ambiguity about what the tool does and clearly distinguishes it from the sibling tools, none of which appear to offer county-level weather severity.

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?

Explicitly states when to invoke the tool: 'Call when the user asks about local weather risk, storm/hail/tornado exposure, or comparing county-level hazard severity, or when timing property, siting, insurance, or hardening decisions with weather exposure.' This gives clear context and covers primary use cases, though it doesn't name alternative tools, none are obvious from the sibling list.

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