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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false and openWorldHint=true. The description adds value beyond that by disclosing 'no auth required' and the Public Data License v1.0 terms (attribution required, commercial reuse permitted), which an agent cannot infer from structured fields.

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?

Front-loads the core action before prerequisites, example, and licensing details. Every sentence contributes, though the licensing/auth tail makes it slightly longer than strictly needed for tool selection.

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?

With an output schema present, return values need not be described. The description covers purpose, prerequisites for code discovery, auth, and licensing, leaving little an agent needs for a correct call.

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 schema already documents all six parameters; baseline is 3. The description modestly adds value by tying parameters together in a concrete example (indicator_code, region_code, time_from, time_to) and confirming comma-separated multi-code usage.

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 specific verb (Fetch) and resource (time-series values for e-Stat Statistics Dashboard indicator codes), and clarifies optional region/time filtering. The scope (Japanese official statistics plus comparable world figures) distinguishes it clearly from the sibling reference tools indicator_info and region_info.

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?

Explicitly directs the agent to call indicator_info first for units and cycle, and region_info for region codes, then provides a worked example of a real call. It gives clear usage context but stops short of stating when-not-to-use or contrasting with alternative data-fetch tools.

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