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

Annotations already declare readOnlyHint=true, openWorldHint=true, and destructiveHint=false, so the description adds value by disclosing that no auth is required and that the scope is limited to European zones. These traits go beyond what the annotations provide and are consistent with them.

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?

Two sentences totaling roughly twenty words, with zero waste. The verb and subject are front-loaded, the output contents are specified in the first sentence, and the auth note in the second sentence removes a potential access barrier. Every word earns its place.

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?

For a zero-argument, read-only enumeration tool with no output schema, the description is complete: it states scope (European), return contents (codes, names, capabilities), and access requirements (none). An agent can call it safely with no further information and knows what to expect back.

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?

With zero parameters and 100% schema coverage, the baseline is 4. The description reinforces the no-filter semantics with 'all supported', and the empty input schema carries the rest of the burden. No parameter documentation is needed here.

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 ('List'), a specific resource ('all supported European bidding zones'), and the output contents ('codes, names, and capabilities'). It is clearly distinguishable from siblings like get_prices, get_carbon, and get_forecast, which retrieve time-series data rather than a zone reference catalog.

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 usage context is implied — this is evidently the discovery tool an agent would call first to learn valid zone codes before using price/forecast siblings — but it is never stated explicitly. There is no when-to-use guidance connecting this tool to the siblings that likely require a zone parameter, and no exclusions are given.

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