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

The description goes well beyond the annotations by explaining the unusual annotation profile: readOnlyHint/idempotentHint are false solely because each successful call costs $0.001 in USDC via x402, repeats are billed again, and failed calls are never charged. It also states no side effects on any outside system. This is exactly the kind of context annotations cannot convey.

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?

Purpose and return fields are front-loaded, followed by usage and then the billing caveat. The billing sentences are slightly verbose but each carries non-redundant information (price, network, retry charging, failure charging) that justifies its length.

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 compensates by listing the returned fields. It covers scope, filters, defaults, cost behavior, and annotation rationale, leaving nothing an agent needs before invoking the tool.

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?

Schema description coverage is 100%, so both parameters (period: day/week; minMagnitude: 2.5/4.5/significant) are already fully documented in the schema, including defaults. The description restates the same values and adds no format or semantic detail beyond them; baseline 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 names a specific verb and resource (recent earthquakes worldwide from USGS) and enumerates the returned fields (magnitude, place, time, depth, coordinates, tsunami flag, USGS link). Combined with the scope (past day or week) and filter (minimum magnitude), an agent can distinguish this from every sibling (weather, moon, sun, holidays) without opening a schema.

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?

It gives concrete usage contexts ('Use for alerts, news and travel checks') and states the two filtering axes with defaults. It does not name an alternative tool or an explicit when-not-to-use condition, but no sibling tool overlaps this domain, so the guidance is effectively complete for routing.

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