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

Annotations only cover readOnlyHint and openWorldHint. The description adds substantive traits the agent could not otherwise know: data provenance (own version record rather than upstream history), that reasons are neither published nor inferred, that history begins at tracking_since, and that only the last 30 days are free.

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?

It is front-loaded with the question the tool answers, then layers provenance, payload shape, and constraints. Every clause carries information, though the field enumeration and caveats in the tail make it denser than strictly necessary.

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?

Output schema exists, so return values need not be explained; the description nevertheless summarizes the payload and adds the limits an agent needs (tracking_since floor, 30-day free window, no inferred reasons). Nothing needed to call it correctly is missing.

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 baseline is 3. The description nonetheless adds meaning beyond the schema by paraphrasing the change_type space ('added to, dropped from, changed in or returned to') and by disclosing that personal names are withheld and each change carries before/after fields, an observed_at and a list as-of date.

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 opening question names a specific verb set (added/dropped/changed/relisted) and a concrete resource (Japan FSA registers and warning lists), scoped by a date. Nothing among the siblings is a delta feed, so an agent can distinguish it from jp_fsa_registry_lookup or the customs tools without opening any 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?

It states the governing context clearly: 'From this service's own record of list versions (the FSA publishes only current lists)', which tells the agent this is the way to obtain historical deltas the FSA itself doesn't publish. It also names the free window (last 30 days). It stops short of naming an alternative tool or an explicit 'do not use for current-state lookups' exclusion.

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