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

With no annotations, the description carries the disclosure burden and does add two useful facts: the data is free and only the newest 5 records are returned. It omits auth requirements, rate limits, empty-result behavior, and response structure, which leaves meaningful gaps for a zero-parameter read tool.

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?

Two terse, front-loaded fragments with no filler, and the 'FREE' cost note and record cap are placed prominently. The telegraphic style is efficient if slightly informal for a tool description.

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, zero-parameter, no-output-schema tool, the description covers what it returns (tsunami forecasts/warnings) and the volume (newest 5). Only finer details such as region coverage or output shape are missing, which is minor at this complexity.

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 tool takes no parameters, so the baseline is 4; there is nothing for the description to clarify, and it does not misleadingly imply any inputs.

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 concrete resource (JMA tsunami forecasts/warnings) and a specific scope (latest, newest 5), so an agent knows exactly what it retrieves. It does not explicitly contrast with siblings tsunami_search or active_only, keeping it short of a 5.

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?

There is no statement of when to use this versus tsunami_search (query-based) or active_only (filtered set), nor any prerequisites or exclusions. An agent must infer that 'latest' means the default recent-forecast tool.

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