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

Annotations already declare readOnlyHint=true and openWorldHint=false, so safety and offline-determinism are covered. The description adds useful behavioral context – it is an estimate, pinned to the 2025-10-01 rate schedule and the 2026 freeze, and it returns the source and page URL – but says nothing about rounding, currency/units, or error handling for out-of-range input.

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?

Three short sentences, front-loaded with the purpose, with the reference line and return-value note after. No redundancy, though the Chinese-language citation is dead weight for an agent that cannot use it to select or invoke the tool.

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 correctly covers the return shape ('an estimate with the source and page URL'). Combined with annotations covering the read-only profile, an agent has enough to invoke it; the main residual gap is that units (NT$) and the estimate's precision are never stated.

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 67%: summer and bimonthly are documented in the schema, while kwh carries only default/min/max with no prose. The description's mention of 'progressive rates' implicitly explains why kwh drives the bracket computation and why bimonthly doubles brackets, but it adds no parameter-level detail beyond the schema.

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 names the resource (Taiwan electricity bill) and the specific pricing model (Taipower residential progressive rates), which clearly separates it from sibling calculators like jp_electricity, kr_electricity, and ph_meralco. It is a calculator, so the verb is implicit rather than stated, but the scope is unambiguous.

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 explicit when-to-use or when-not-to-use guidance, and no sibling is named as an alternative for adjacent cases (e.g. time-of-use vs progressive rates). The only contextual cue is the source URL, which the agent must infer is a companion web calculator.

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