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

Annotations already establish read-only, idempotent, and open-world behavior. The description adds valuable context beyond those: day-ahead granularity, dual currency output, default-to-recent behavior, data source (Energinet), and no-auth requirement. Nothing contradicts the annotations.

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 tight sentences with the core action front-loaded first. Every sentence contributes: what data is returned, in which units, how to scope it, and access requirements. No filler or redundancy.

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?

Given an output schema, full annotation coverage, and 100% schema parameter coverage, the description supplies the missing context: data source, authentication, units, default time behavior, and supported zones. An agent has everything needed to select and correctly invoke this tool.

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 100%, so the schema already documents limit, start/end dates, and price_area thoroughly. The description reinforces date-range behavior and zone examples but adds little meaning beyond what the schema provides, so the baseline of 3 applies.

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 opens with a specific verb and resource: 'Get hourly day-ahead electricity spot prices for a Nordic/European bidding zone.' It includes concrete zone examples and clear units, making the tool's resource unmistakable and distinguishing it from sibling tools like co2_emissions and production_consumption.

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 description gives clear context for use: optional date range, defaulting to most recent hours when omitted, and supported price zones. It does not explicitly name alternatives or state when-not-to-use, but the focused subject matter makes the intended usage obvious.

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