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

No annotations are provided, so the description carries the disclosure burden. It is transparent about what the response contains (fuel grades, unit, week-over-week change), which is valuable given there is no output schema, but it says nothing about data source cadence, staleness, or the read-only nature of the call.

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?

A single front-loaded sentence with a bracketed category tag, then the resource and its full scope. No filler, nothing repeated.

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 parameters, no annotations and no output schema, the description is the sole carrier of information, and it does cover the returned fields, unit and comparison basis. The only omission is refresh timing/source for the weekly figures.

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?

The tool takes zero parameters, so the baseline is 4. The description still adds worth by enumerating the fuel grades and currency the caller will receive, information the empty input schema cannot convey.

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 (get), resource (Taiwan CPC weekly fuel prices) and enumerates exactly which products are covered (92/95/98 unleaded, ethanol gasoline, super diesel) with units (NTD per litre). No sibling in the catalog covers fuel prices, so an agent can identify this immediately.

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 phrase 『本週油價』and 『比上週漲跌』implicitly scope the tool to the current week's published prices plus week-over-week delta, which tells an agent not to use it for historical lookups. However, there is no explicit when-to-use statement, no freshness caveat (e.g. when the weekly update lands), and no named alternative.

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