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

Annotations already mark it read-only, idempotent, open-world, and non-destructive. Beyond that, the description discloses that the source is a rolling feed (typically weeks, newest first), includes locality details, and explains the intensity scale. It doesn't fully specify output shape/pagination, but it adds meaningful behavioral context.

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 dense but every sentence earns its place: return fields, source and freshness, then filtering rationale. It front-loads the core result and puts the noise-reduction guidance last without redundancy.

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 simple read-only list tool with 3 optional parameters, the description covers what is returned, the data source URL, the freshness/ordering behavior, the non-obvious intensity scale, and how to use filters. No output schema exists, but the field list is sufficient for an agent to invoke and interpret results 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%: limit, min_intensity, and min_magnitude each have clear descriptions including defaults and the intensity notation. The description's filter sentence repeats the schema's purpose without adding new parameter semantics, matching the baseline for high schema coverage.

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 identifies the tool as retrieving recent JMA earthquake bulletins with specific fields (magnitude, intensity, epicenter, report time) and cites the exact source URL. This differentiates it from sibling JMA tools like jma_forecast and jma_warnings.

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?

It provides clear usage context: use for recent earthquake data from the JMA rolling feed, and use min_magnitude/min_intensity filters to reduce noise from small frequent events. It stops short of explicitly naming alternatives or giving when-not-to-use conditions, so it doesn't earn a 5.

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