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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint and destructiveHint=false, so the safety profile is covered by structured data. The description adds genuinely new behavioral context the annotations do not carry: the free daily allowance and the $0.001 USDC per-call x402 pricing, which materially affects invocation strategy.

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?

Two short sentences with zero filler; the substantive scope (magnitude, worldwide, past day) is front-loaded and the cost sentence follows. 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?

An output schema exists, so return-value explanation is not required, and the annotations cover the safety profile. The description supplies scope and cost, which is sufficient for a no-parameter, read-only tool; only the lack of sibling routing keeps it from a 5.

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 tool takes zero parameters and schema description coverage is effectively 100%, so there is nothing for the description to clarify about inputs. Baseline 4 applies for a parameterless tool.

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 names a specific resource (earthquakes), a numeric threshold (magnitude 2.5+), a geographic scope (worldwide) and a time window (past day), so an agent can distinguish it from siblings like earthquakes__m45-week or earthquakes__near. It stops short of naming those siblings explicitly, which keeps it at 4 rather than 5.

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?

There is no explicit when-to-use or when-not-to-use guidance, and no alternative tool is named. The magnitude and timeframe constraints imply a use case, but an agent choosing between this and earthquakes__m45-week, earthquakes__significant-week, or earthquakes__count gets no routing help from the description.

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