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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the safety profile and closed-data nature are covered structurally. The description adds the useful freshness signal ('laatste meetdag'), but says nothing about update cadence, currency, units, or whether the snapshot can be stale, which matters for a daily price feed.

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?

A single densely packed sentence that front-loads the core resource (lowest price per contract type) before listing the supplementary outputs. No filler, no repetition of the title.

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 and no parameters, the description carries the burden of describing return values and does so adequately: lowest price per contract type, the supplier, and the lowest combined annual price. Minor gaps remain around units/currency and result shape, but an agent knows what it will get.

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 tool takes zero parameters, so the baseline is 4. The description correctly implies no input is needed and instead spends its words on what the fixed output contains.

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 names the specific resource (lowest electricity and gas price) and enumerates the contract types covered (fixed 1/3/5 years, variable, dynamic), plus the extra fields returned (supplier, lowest combined annual price). It is clearly distinguishable from price siblings like prijsdalers or zorgpremies by domain, though it never explicitly contrasts itself with them.

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?

There is no guidance on when to use this tool versus alternatives, no stated prerequisites, and no exclusions. The only implicit usage signal is 'van de laatste meetdag', which suggests a current-snapshot use case but does not route the agent between siblings.

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