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

Annotations already indicate readOnlyHint, openWorldHint, idempotentHint, and destructiveHint false. The description adds operational details: returned fields (time, magnitude, depth, epicenter region, coordinates, felt intensity), date coverage (last 30 days), and filtering behavior (excludes events without computed magnitude when min_magnitude set). This goes beyond 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 description is a single substantial sentence with an example appended. It is concise and front-loaded with the core purpose. Could be structured as two sentences for improved readability, but no redundant text.

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 tool with no output schema, the description adequately covers return fields, time coverage, geographic scope, and filtering examples. It also explains behavior when min_magnitude is set. Given the parameter count and simplicity, it is complete.

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% with descriptions for all three parameters. The description adds an example that demonstrates parameter combinations and default values (area defaults to 'mainland', days defaults to 7). This provides practical meaning beyond the schema alone.

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 clearly states 'Portugal earthquakes — recent seismic events recorded by IPMA for mainland Portugal + Madeira or for the Azores archipelago.' It specifies the resource (seismic events), verb (returns), geographic scope, and distinguishes itself from sibling tools like ipma_forecast and ipma_locations which cover different data types.

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?

Provides context on usage with an example call and specifies time range ('roughly the last 30 days') and scope. While it doesn't explicitly state when not to use, the sibling tool set covers distinct domains (forecast, locations, sea, UV), so ambiguity is low. A more explicit alternative could improve it.

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