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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint, so the safety profile is covered. The description adds information the annotations do not carry: the cost model (free within a daily allowance, then $0.001 USDC per call via x402), which is meaningful for an agent deciding whether to invoke. It stops short of describing what 'full detail' includes or any failure behavior for invalid ids.

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 waste: purpose first, operational cost second. Nothing is padded or repeated from the title.

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 values need not be explained, and the safety profile is covered by annotations. The one real gap is that the description never tells the agent where a valid USGS event id comes from, which is the only prerequisite for calling this tool successfully.

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% with a single 'eventid' parameter documented as 'USGS event id'. The description restates the same fact ('by USGS event id') without adding format, syntax, or sourcing guidance, so the baseline 3 applies when the schema does the heavy lifting.

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 states a specific verb+resource ('Full detail for one earthquake') and names the lookup key ('by USGS event id'), which cleanly separates it from the collection-oriented siblings (count, near, m25-day, significant-week). It does not explicitly name an alternative tool, so it falls short of the top tier despite being 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?

There is no guidance on when to pick this over the sibling list tools, nor any statement that a valid event id must first come from a listing endpoint (e.g. earthquakes__near or earthquakes__m25-day). The only context offered is a billing/pricing statement, which is not usage routing.

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