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

Annotations already set readOnlyHint=true, and the description adds meaningful context: data source, 7-day lookback, 21-day baseline, update frequency (daily), and the specific return fields (score, per-hazard drivers, confidence, methodology_version). This goes beyond annotation basics, though it omits the Gold-tier requirement for history, which is covered in the schema.

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 sentences, front-loaded with the return value, then targeted use cases, then update frequency. Every phrase serves a purpose; no redundant or filler content. Highly scannable for an agent.

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 low-complexity tool with one optional parameter, high schema coverage, and no output schema, the description covers what the tool returns, when to use it, and freshness. The only gap is that the daily history option (via 'days') isn't mentioned in the tool description, but the schema fully documents it, so overall it's complete enough.

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?

The only parameter 'days' is fully described in the schema (100% coverage), including range and behavior (history series vs snapshot, Gold tier requirement). The description adds no additional parameter-specific details, so it meets the baseline but doesn't elevate it.

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 and resource: 'Returns a 0-100 US severe storm activity index' and explains the data source (NOAA SPC reports) and scope (tornado, hail, damaging wind, versus 21-day baseline). This clearly distinguishes the tool from generic weather tools and aligns with the title.

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?

Explicit guidance is provided: 'Call when the user asks about recent tornado, hail, or wind activity versus the norm, or when timing claims staffing, catastrophe logistics, or storm-repair inventory decisions.' This names concrete trigger scenarios, though it doesn't explicitly exclude alternative tools or mention siblings for contrast.

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