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

Annotations already establish readOnlyHint, idempotentHint, and non-destructive behavior, so the safety profile is covered. The description adds useful context about global scope and returned fields, but it does not mention pagination, rate limits, or any limits on the number of events returned.

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 with the core purpose front-loaded. It lists the key parameters, allowed values, and return fields without any wasted words.

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 simple two-parameter read-only feed with complete schema annotations, the description is sufficient: it defines input choices, scope ('all events worldwide above the threshold'), and output contents ('magnitude, location, depth, and event detail URL'). No important invocation information is missing.

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?

Input schema coverage is 100% and each parameter already has an enum and description. The description repeats the allowed values (hour|day|week|month and 1.0|2.5|4.5|significant) but adds no new meaning beyond what the schema provides.

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 'USGS official earthquake summary feed by period and minimum magnitude' and specifies that it returns all events worldwide above a threshold. This is a specific verb-resource pairing, though it does not explicitly contrast itself with sibling tools like usgs_earthquake_search or usgs_earthquake_detail.

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 use case is implied: select a period and minimum magnitude to get a worldwide summary feed. However, there is no explicit guidance on when to prefer this tool over the sibling earthquake_recent, usgs_earthquake_search, or usgs_earthquake_detail tools, and no mention of when not to use it.

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