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

Annotations already establish read-only, idempotent, non-open-world behavior, so the description focuses on added context: the data provenance (USGS as held by QuakeIndex), the catalogue-span concept, and per-result fields (source, last-confirmed date, links). It also explicitly disclaims predictions/warnings and redirects EEW to ShakeAlert/MyShake, which is useful scoping beyond the annotations.

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?

The lead sentence is well front-loaded with the key scope, but the trailing sentences mix valuable return-field detail with a somewhat tangential disclaimer about ShakeAlert/MyShake as early-warning sources, which costs space without helping tool selection.

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 does the work of describing returned fields (source, last-confirmed, links), and it defines the catalogue-span notion that distinguishes this from recency-based siblings. The main gap is radius_km behavior for town/ZIP queries, left entirely to the schema.

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 coverage is 75%, so the schema carries most of the load. The description adds value by enumerating place formats with concrete examples ('Kern County, CA', 'Ridgecrest, CA', ZIP), but says nothing about limit, state disambiguation, or the radius_km constraint for towns/ZIPs.

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 resource and scope: the largest earthquakes in QuakeIndex's USGS catalogue, resolved by state/county/town/ZIP, over the full catalogue span. 'On record' plus the catalogue-span framing implicitly separates it from latest_earquakes and earthquakes_near, though no sibling is named explicitly.

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?

Usage context is implied rather than stated: it is clearly a place-scoped historical-ranking tool, and the accepted place formats are given. There is no explicit when-to-use-this-vs-X guidance against earthquake_details, place_activity, or latest_earquakes, and no exclusion conditions beyond 'no predictions/warnings'.

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