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

Annotations already establish readOnlyHint=true and openWorldHint=false, so the agent knows this is a safe, self-contained calculation. The description adds that the result is an estimate and that it carries source and page URL, but says nothing about rate structure, tiered-pricing behavior, or what happens at the amperes/kWh boundaries — modest added value over annotations.

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?

Short, front-loaded with the resource identity, and efficient overall. The inline Japanese source citation is dense but arguably earns its place by documenting provenance for a regulated-tariff estimate.

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 no output schema, the description does briefly cover the return shape (an estimate plus source/page URL), which is appropriate. But with only a third of parameters documented anywhere and no usage context, it is thin for a tool whose correctness depends on picking the right kWh and ampere tier.

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 only 33% (just fuel_adjustment), so the description carries the burden for kwh and amperes — and it provides nothing. No hint that kwh is monthly consumption or that amperes selects the contract breaker tier, and no explanation of how the default fuel adjustment is derived beyond the schema's brief note.

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 states a specific verb/resource combination — computing a Japanese (TEPCO Juryo Dento B) electricity bill — and the country/utility qualifier implicitly separates it from siblings like kr_electricity, tw_electricity, and ph_meralco. However, the first sentence merely restates the title verbatim, and it never explicitly contrasts itself with the other electricity tools, so full differentiation is left to inference.

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 tool, when not to, or which alternative to pick (e.g., kr_electricity vs tw_electricity for other markets). The only directional content is a reference URL, which points at documentation rather than at tool-selection context.

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