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

Annotations already cover readOnly, idempotent, openWorld, and non-destructive, so the safety profile is handled. The description adds genuinely new behavioral context: the cost model (free within the daily allowance, then $0.001 USDC per call via x402), which an agent needs for budgeting and auth decisions. It omits any note on result limits or how an unbounded magnitude window affects output size.

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 tight sentences, front-loaded with the operation and its scope, followed by cost. Neither sentence is filler and nothing is repeated from the schema or annotations.

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 an output schema present, return values need no explanation, and annotations cover the safety profile, so the description only needs to convey scope and cost, which it does. The remaining gap is behavior when minmagnitude is omitted (does it count everything?) and any cap on returned counts.

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% and both parameters carry descriptions, so the schema does the heavy lifting. The phrase 'time and magnitude window' confirms the two dimensions but adds no format, default, or range detail beyond the schema. 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?

States a specific verb (count) and resource (earthquakes) plus the filter dimensions (time and magnitude window), which cleanly separates it from siblings like earthquakes__event, earthquakes__near, and the fixed m25-day/m45-week endpoints. It stops short of naming a sibling or stating distinguishing scope (e.g. whether it counts globally or takes a location filter).

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 says what it does but never says when to use it instead of earthquakes__near, m25-day, m45-week, or significant-week. There is no guidance on required vs optional filters or on choosing a count over a listing. The only context offered is pricing, which is not usage guidance.

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