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

The readOnlyHint annotation already signals a safe read operation. The description adds useful behavioral context: daily update cadence, the index's component breakdown, 10.5-year history, and the output fields (score, percentile, trend, top_drivers, source_lineage). This goes beyond the annotations without contradicting them.

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 concise sentences: the first states what is returned and its key properties, the second gives usage context and update frequency. No wasted words; front-loaded with the core purpose.

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 adequately lists the return fields (score, percentile, trend, top_drivers, source_lineage) and explains the data source and update frequency. Combined with the schema's description of the optional parameter, an agent has enough context 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?

The only parameter (days) is fully described in the schema (optional, history length, tier requirement). The description does not add parameter-specific semantics beyond what the schema already provides, so the high schema coverage baseline of 3 applies.

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 identifies the tool as returning a 0-100 global seismic-activity index with specific composition (z-score of USGS M4.5+ earthquake energy, event count, shallow-focus share) and history length. This distinguishes it from sibling tools in other domains (e.g., health_risk, air_quality_risk).

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 earthquake activity, seismic risk, tremors, or geophysical hazards worldwide, or when timing disruption alerts...' This provides clear context, though it does not mention when not to use it or suggest alternatives.

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