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

Annotations already declare readOnlyHint=true and openWorldHint=false, so safety and data scope are partially covered. The description adds a useful privacy assurance ('Er wordt niets van de gebruiker bewaard') and explains what the answer contains, which goes beyond the annotations. It does not discuss rate limits or failure modes, but for a read-only calculation tool that is a minor gap.

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 description is a single, information-dense sentence that front-loads the required inputs before describing the outputs. Every clause contributes useful information, though the semicolon-heavy structure makes it slightly harder to parse quickly.

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 three parameters, full schema coverage, and no output schema, the description does a good job of explaining what the tool returns (annual overspend, own-provider cost, switch link) and includes a privacy note. It could be more complete by clarifying what 'voordeligste vergelijkbare abonnement' means or any assumptions used in the comparison.

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 description coverage is 100%, so all three parameters are already well documented. The description mentions provider, bundle, and monthly price but adds no new parameter-level detail such as format or validation beyond what the schema provides. A baseline of 3 is appropriate when the schema does the heavy lifting.

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 calculates how much a user overpays per year for a SIM-only plan, using provider, bundle, and current monthly price. It names the outputs (annual difference, own-provider cost, switch link) and thus is more than a restatement of the title. However, it does not explicitly differentiate itself from sibling tools like sim_only or mobiele_markt.

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 implies when to use it by listing the inputs needed and the comparison it performs, but it does not state explicit usage conditions, exclusions, or alternatives. An agent must infer that this is the right tool when a user wants to check if their SIM-only subscription is overpriced.

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