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

No annotations are provided, so the description carries the full behavioral burden. It usefully discloses the shape of the result — five offers, coarse cost split, fetch time — but says nothing about read-only status, permissions, error behavior, or freshness guarantees. This is moderate transparency for a read-oriented query, but incomplete without 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?

The definition is two sentences and front-loads what the tool returns before explaining the profile parameter. Every included detail — cost split, fetch time, profile source — earns its place, 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?

Given one optional parameter, no output schema, and no annotations, the description is reasonably complete: it explains the result shape and how to supply a valid profile. It could still clarify default behavior and whether the profile list is exhaustive, but an agent has enough to invoke it correctly.

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 input schema has 0% description coverage for the single profile parameter, so the description must compensate. It does so by explaining that profile must come from methodology()’s standard profiles and by giving examples such as 'median', 'solar', 'heatpump', and 'ev'. It does not state the default, but the added meaning is substantial.

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 states a specific resource and scope: the five cheapest energy offers in the Netherlands for a standard household profile on the most recent day with data. It also lists the returned cost split and fetch time, so an agent can distinguish it from the historical sibling cheapest_history without opening either schema.

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 no explicit when-to-use guidance or alternatives. It only points to methodology() as the source for valid profile values, which is parameter guidance rather than usage guidance. There is no mention of when to choose this over cheapest_history or market_summary.

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