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

Annotations already mark this as read-only, idempotent, and non-destructive, so no safety contradiction exists. The description adds meaningful behavioral context beyond annotations by listing what the response covers (origin, magnitude details, focal mechanism with an 'if available' caveat, shake-map link, felt reports, tsunami flag, and impact estimates), which is especially useful because no output schema is provided.

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?

Both sentences are dense and useful: the first states the action and key input, the second lists return contents. There is no filler, repetition, or buried context.

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 single-parameter read-only lookup, this description is complete: it explains what the tool does, what input identifies the target, and what the response will contain, with an explicit conditional for focal mechanism. The lack of an output schema is compensated by the return-field enumeration.

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 input schema fully documents event_id with a type and a concrete example, so the schema carries the semantic weight. The tool description adds only that lookup is by USGS event ID, not enough to raise the score above the baseline 3.

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 uses a specific verb ('Get'), names the exact resource ('full detail for a specific earthquake event'), and identifies the key identifier ('USGS event ID'). It also enumerates the returned data categories, making it easy to distinguish this detail tool from sibling list/search tools like usgs_earthquake_feed and usgs_earthquake_search.

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 clearly implies this tool is for a single known event rather than discovery, and the parameter schema reinforces that by instructing the agent to obtain the event_id from feed or search results. It does not explicitly name alternatives or state when not to use the tool, so it stops just short of full routing guidance.

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