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

Annotations already declare readOnlyHint=true, so no extra safety disclosure is needed. The description adds valuable context beyond annotations: the index is an annual series since 1958, updates annually, and returns vintage dates and methodology_version. This tells the agent about data freshness and versioning, which is useful for invoking the tool correctly. No contradiction with annotations.

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 two sentences plus a short update note. It front-loads the core return value, then gives usage scenarios and update frequency. Every sentence earns its place with no redundant or vague wording.

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?

The tool is simple (no required parameters, one optional parameter with schema coverage). The description covers the return values (index, vintage dates, methodology_version) and usage context. It does not explicitly mention the `days` parameter's history behavior, but that is fully covered in the schema. With no output schema, the return components are still described, making this sufficiently complete for selection and invocation.

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 (coverage 100%), including its optional nature, meaning (daily history series vs current snapshot), and the Gold tier requirement. The main description does not add any additional parameter semantics, but the schema already carries the full burden, so the baseline score of 3 is appropriate.

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 clearly defines the resource: a 0-100 US Community Health Index based on CDC PLACES chronic-disease composite z-score. It lists the exact output elements (index values, vintage dates, methodology_version) and is distinct from sibling tools like health_risk or obesity_risk by focusing on a composite community health index.

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 explicitly states when to call the tool ('Call when the user asks about population health, chronic disease burden, community wellness, or how healthy the US is, or when timing payer market entry, actuarial risk loading, or underwriting decisions'). This provides clear context but does not mention when not to use it or name alternative tools, so it lacks explicit exclusions.

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