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

While readOnlyHint is already true, the description adds significant behavioral context beyond annotations: the underlying data source (USGS ComCat), the calculation method (z-scored vs trailing 30-day norm), the update frequency ('Updates: hourly'), and the list of returned fields. This provides a transparent understanding of what the tool does and how it behaves, especially for a read-only data tool.

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 concise and information-dense: one long sentence for the core function and return fields, one for usage, one for the critical caveat, and a short update note. Every sentence earns its place, with no filler. The structure front-loads the purpose and then gives usage and distinctions, making it easy to scan.

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?

Given the tool's complexity and lack of an output schema, the description is remarkably complete. It explains the meaning of the score, the calculation methodology, the returned fields (activity_level, trend, z_score_count, etc.), the update cadence, and when to use it. It also clarifies the relationship to hazard (not hazard) and points to a sibling for further context. The only omitted detail is the 'days' parameter, but that is fully documented in the schema, making the overall context complete.

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 input schema (including the optional history behavior and Gold tier requirement), so schema coverage is 100%. The description does not add extra parameter details, but it doesn't need to because the schema already carries that burden. The score is a solid 3 per the baseline for full schema coverage.

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 a specific verb ('Returns') and the exact resource ('global earthquake activity momentum score'), describing the 0-100 scale and what 50 means. It also distinguishes from siblings with the caveat 'Momentum, not hazard (see ADW-525)', making the tool's unique purpose unambiguous.

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 provides explicit usage guidance: 'Call when the user asks if global seismic activity is accelerating or quieter than usual, or when timing catastrophe-monitoring escalation and seismic-exposure reviews.' It also specifies what the tool is NOT for ('Momentum, not hazard') and points to an alternative (ADW-525), giving clear when-to-use and when-not-to-use context.

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