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

With no annotations, the description carries the full burden; it does earn credit for disclosing a real behavioral trait absent from structured fields — a 0.005 USD/call x402 charge. However, it is silent on defaults (is `date` optional? does it default to today?), timezone/day-boundary handling, whether a window may span midnight, and whether prices include tariffs or VAT. For a paid tool with zero annotation coverage, these omissions are meaningful.

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, front-loaded with the capability and followed by the cost disclosure. Nothing is padded or redundant.

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 purpose is complete, but for a tool with no output schema the description never hints at the return shape (window start/end, average price, savings) or what happens on an invalid window. An agent knows what to ask for but not what it will get 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?

The description supplies the area domain (DK1/DK2) that the placeholder schema ('description: area') entirely lacks. But for the other two params it mostly restates the schema, and the accepted `date` format (ISO vs. other, plus default behavior) is left undefined despite the schema allowing string/number/boolean unions. Marginal added value over the nominal 100% coverage.

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?

States a specific operation (find the cheapest contiguous N-hour window), the resource (day-ahead spot prices in DK1/DK2), and the intended consumer (a shiftable load). A reader can immediately separate it from the sibling dk_power_price, which returns raw prices rather than an optimized window. It loses a point only because it never names that sibling explicitly.

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 parenthetical examples (EV charging, heat pump, batch job) give concrete, recognizable when-to-use context, and the 'N hours / given day' framing tells the agent what inputs drive selection. There are no stated exclusions or named alternatives for the case where the agent wants the raw price curve instead of an optimum.

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