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

Annotations already declare readOnlyHint, openWorldHint, idempotentHint, and non-destructive. The description adds value by specifying the return structure ({unix_seconds, price, unit}), that the array is timestamp-aligned, and the unit (EUR/MWh). This provides context beyond annotations without contradiction.

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, no filler. The first sentence states purpose and scope; the second explains the return format. Every part 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?

The tool is simple and read-only. Parameters are fully described in the schema. The description explains the output structure despite no output schema, covering the essential return fields. No gaps are evident for this use case.

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 coverage is 100%, so baseline 3 applies. The description does not add detail beyond the schema's parameter descriptions (e.g., bzn as bidding-zone code, dates optional). It mentions 'over a date range' which loosely connects to start/end, but doesn't enhance semantic understanding of the parameters.

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 clearly states the tool retrieves day-ahead spot electricity prices for a bidding zone over a date range. It specifies the resource (electricity prices), verb (returns), and scope (bidding zone, date range). This distinguishes it from sibling tools like installed_power or renewable_share, which deal with capacity or generation.

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?

No explicit when-to-use or when-not-to-use guidance is provided. The context is implied by the name and description, but unlike the calibration example with get_calls, no alternative tool is named. The tool is clearly for price data, but agents might benefit from knowing that other power tools exist for different purposes.

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