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

Annotations already declare readOnlyHint=true and openWorldHint=false, so safety is covered; the description adds real value by disclosing that the result is an estimate, that it carries a source and page URL, and that the same code powers kwhmate.com. It omits whether taxes/levies are included in the estimate, which keeps it from a 5.

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-loaded with the resource and tariff, then provenance and return shape in two short sentences. The Korean reference line and URL are somewhat noisy but do carry sourcing information, so nothing is plainly wasted.

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 covers the essentials: it is an estimate, it cites source and page URL, and the tariff vintage (2026 Q4). Currency, whether VAT and environmental charges are included, and the exact shape of the returned estimate remain unspecified, leaving a minor gap.

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 kwh and season are already fully documented with defaults, bounds and enum semantics. The description's mention of 'progressive tiers' hints at why usage matters but adds no format or edge-case detail beyond the schema, so the baseline 3 applies.

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 resource (Korea household electricity bill) and narrows it with the exact tariff (KEPCO residential low-voltage, progressive tiers), which implicitly separates it from jp_electricity, tw_electricity and ph_meralco. It never names a sibling or explicitly contrasts, so it stops 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?

The scope (household, low-voltage, Korea) implies when the tool applies, but there is no explicit when-to-use statement, no exclusions (e.g. commercial/industrial tariffs or other countries unsupported), and no routing to alternatives. Usage must be inferred from the title.

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