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

No annotations exist, so the description carries the full burden, and it does well: it discloses the upstream source (Energinet, CC BY 4.0), the granularity, the currency units, and notably the per-call cost of 0.005 USD via x402 — a billing constraint the agent would otherwise not know. It stops short of describing response shape, failure modes, or historical date limits.

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: the capability first, provenance and pricing second. Every clause carries information — zones, granularity, aggregates, currencies, source, license, cost — with no filler.

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, the description still conveys what comes back (15-minute prices plus cheapest/average/most expensive quarter) and in what units, which is most of what an agent needs. Gaps are minor: response format, historical range, and payment/auth mechanics for the x402 fee are mentioned but not explained.

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 both parameters are already documented with the zone list and the YYYY-MM-DD/CET default. The description restates the zone codes and adds the DKK/EUR per MWh unit context, but adds no syntax or constraint detail beyond the schema. Baseline 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?

A specific verb-and-resource statement: day-ahead 15-minute spot prices for DK1/DK2 plus named neighbouring zones, with the derived aggregates (average, cheapest, most expensive quarter) spelled out. An agent can immediately tell this is a price-data retrieval tool, distinct from the sibling dk_power_cheapest_window which finds a window rather than a day's curve.

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 makes the use case obvious (fetch day-ahead prices for a zone and date) but never states when to prefer it over dk_power_cheapest_window, which overlaps on the 'cheapest quarter' output, nor any prerequisites such as x402 payment setup. Usage is implied rather than routed.

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