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

Despite readOnlyHint=true, the description adds valuable behavioral context: it explains that the 'source_lineage' fields exist to 'separate real signal from small-area estimation noise' and notes 'Updates: annually.' These details go beyond the annotations and inform the user about data quality and freshness.

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, front-loaded with the core return value and composition. It then provides usage triggers and update frequency with no wasted words. Every sentence 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?

With no output schema, the description names the return fields (value, confidence, source_lineage) and explains the score's derivation and purpose. It covers the main aspects needed to invoke the tool, but does not detail the exact types or structure of those fields, and the 'days' parameter is only documented in the schema.

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 description does not mention the 'days' parameter, but the input schema already provides a thorough description (returning a daily history series, up to 5 years, Gold tier requirement). With 100% schema coverage, the baseline is 3, and the description adds no additional parameter meaning.

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 clearly states it 'Returns a 0-100 US behavioral-health stress score' with details on composition (CDC PLACES mental-distress and depression prevalence) and scope (US, history to 1951). It is specific about the resource and what it provides, making it distinguishable even though sibling tools are not explicitly compared.

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: 'Call when the user asks about mental-health strain, depression rates, psychological distress, or EAP demand...' This provides clear context for use. However, it does not mention when not to use or name alternative tools, so it falls short of the 5-level.

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