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

No annotations exist, so the description carries the full burden. It usefully discloses the return shape (fuel grades, NTD-per-liter units, weekly delta) in the absence of an output schema, but says nothing about data freshness/caching, update cadence, or that the call is a non-mutating read.

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?

One densely packed sentence that front-loads the source and resource, then lists returned fields and units. No filler, no restatement of the tool name.

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 and no annotations, the description does the heavy lifting well by enumerating returned fields and units. It stops short of stating data currency mechanics (when 'this week' refreshes) or that the result is a read-only snapshot.

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 there is nothing for the description to disambiguate beyond confirming it is argument-free; baseline 4 applies. The schema is an empty object, consistent with the description's 'this week' framing.

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+resource ('取得台灣中油本週油價') and enumerates exactly what is returned: 92/95/98 unleaded, alcohol gasoline, super diesel, per-liter NTD, plus week-over-week change. The sibling set (lottery, invoice, holiday tools) covers entirely different domains, so cross-tool confusion is essentially impossible.

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?

Usage is implied rather than stated: '本週油價' signals a current-week lookup with no parameters, so an agent can infer when it applies. However, there is no explicit when-to-use framing, and no note on whether historical weeks are obtainable elsewhere or whether this is the only fuel-price source.

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