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

Annotations already declare this a safe, idempotent, read-only, closed-world operation, so the safety profile is covered. The description still adds real behavioral context beyond the annotations: the sort order (average monthly price across the term) and the per-result contents (price, data, minutes, contract duration, link). No pagination or rate-limit detail, which 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?

A single front-loaded sentence packs purpose, provider set, sorting rule, and return fields with no filler. It is efficient, though cramming the result fields into the same sentence slightly weakens scannability.

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 eight optional filters, no required parameters, and no output schema, the description usefully compensates by naming the fields each result contains and the sort order. An agent has enough to call and interpret it, with only sibling routing and result limits unspecified.

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% for all eight filters (esim, fiveG, provider, minDataGb, maxMonthly, unlimitedData, monthlyCancellable, limit), so the schema carries full parameter meaning. The description adds nothing parameter-specific, making the baseline 3 appropriate.

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 verb and resource ('Zoekt sim only abonnementen in Nederland'), names concrete providers, and adds scope details (sorted by average monthly price over the contract term). It does not, however, explicitly differentiate itself from the sibling 'search_phone_deals', so an agent must infer the boundary from the name alone.

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?

Usage is implied by the domain (SIM-only subscriptions vs. device or internet searches), but there is no explicit guidance on when to pick this over search_phone_deals or search_internet, and no stated prerequisites or exclusions. Adequate but leaves routing to inference.

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