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

Annotations already declare readOnlyHint, openWorldHint, idempotentHint, and non-destructive behavior, so the bar is lower. The description adds useful behavioral context beyond annotations: the data source is a 'community-operated JMA relay,' it is 'open data, no auth required,' and it clarifies which filters and return fields are supported. This goes beyond the structured hints without contradicting them.

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 compact and information-dense: a clear opening statement, a summary of filters and output fields, concrete use cases, practical examples, and data-source/auth context. Every sentence earns its place, and the most important purpose statement is front-loaded.

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?

Given that all 8 parameters are optional and the schema covers them fully, the description covers everything an agent needs to decide to call and invoke the tool: what it returns, why to use it, how to filter, and that no auth is required. It also notes pagination support, and the presence of an output schema reduces the need to document return shapes in prose.

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 description coverage is 100%, so the baseline is 3. The description adds value by giving concrete filter examples (min_scale=60 for Shindo 6+, min_magnitude=7.0, prefecture=13 for Tokyo) and summarizing the available filters, which helps an agent pick the right parameters quickly even though the schema already documents them.

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 opens with a specific verb and resource: 'Search historical JMA earthquake records via the P2PQuake history endpoint.' It enumerates the exact return fields (epicenter name, coordinates, depth, magnitude, etc.) and explicitly frames itself as the tool for older events 'not in the recent feed,' which separates it from the p2pquake.seismic.recent_quakes sibling.

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?

The description gives clear use cases: 'Use this for trend analysis, seismic risk assessment, or retrieving older events not in the recent feed.' This implies a when/where distinction from the recent-feed sibling, but it does not name p2pquake.seismic.recent_quakes explicitly as the alternative, so it falls just short of the most explicit guidance.

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