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

Annotations already declare readOnly/openWorld/idempotent/destructive=false, so the safety profile is covered. The description adds genuinely new context: the backing API (USGS fdsnws), the 100-event result cap, and time-sorted ordering. No mention of rate limits or failure behavior, but the additions go 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?

Three tight sentences: purpose, filter scope, return shape, then the routing rule. The alternative-to-feed guidance is placed last where it matters, and nothing is redundant.

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 usefully discloses the return shape (up to 100 time-sorted events). Filters, scope, and the sibling alternative are all covered. Minor gaps remain around pagination/offset behavior and the default limit of 25, but an agent has enough to call it correctly.

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 100%, so the schema already documents ISO formats, defaults, and the limit bounds. The description only restates the filter categories (magnitude, time range, bbox) at the same abstraction level, adding no syntax or interaction detail.

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+resource (earthquake search) and immediately scopes it: filtering by magnitude, time range, and bounding box. It explicitly distinguishes itself from the feed sibling, so an agent can route without opening either 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?

Explicitly says to use this 'instead of the feed when you need historical or geographic filtering,' naming the alternative and the selecting condition. It does not mention the usgs_earthquake_detail sibling, so routing against that tool is left to inference.

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