Hae polttoaineen hinnat

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

Annotations already declare readOnlyHint=true and idempotentHint=true, covering safety and re-call behavior. The description adds the source (Statistics Finland monthly average) and the exact metrics returned, which is context beyond the annotations. It does not disclose output format or potential delays in data release, but for a read-only retrieval tool this is adequate.

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 Finnish sentence that states the resource, the fuel types, the timeframe, and the source without redundancy. Every clause contributes concrete information; no filler or vague phrasing. Easily skimmable for an AI agent.

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?

Without an output schema, the description bears the responsibility of explaining return values. It clearly states the returned metrics (average prices, changes vs previous month and year), so the agent knows the data shape. It does not specify units (e.g., euros per litre) or exact statistical period lags, but for a query tool the core semantics are complete. A 4 is fair because the description omits currency/unit confirmation.

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 has zero parameters, so the input schema is trivially complete. The description therefore carries all the semantic meaning about what data is returned. It adds value by defining the specific fuel types and the comparison periods, going beyond the empty schema. Baseline 4 for no parameters is appropriate, and the description does not need to explain parameters that do not exist.

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 a specific verb (Hakee), a concrete resource (fuel average prices), specific fuel types (95 E10, 98 E5, diesel, light fuel oil), and a temporal scope (latest statistical month plus changes vs previous month and year). It clearly distinguishes itself from siblings like hae_asuntojen_hinnat (housing prices) and hae_saa (weather) by naming its exact content and source.

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 are no explicit exclusions or alternative recommendations, but the description clearly implies when to use this tool: any time the agent needs fuel price statistics from Statistics Finland. Since the sibling names are all distinct resources, a reader can infer the appropriate selection without confusion. Lacks explicit 'when-not-to-use' guidance, but the resource name is unambiguous.

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