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

With no annotations provided, the description carries the behavioral disclosure burden. It reveals useful behaviors beyond a generic search: prices are in EUR, purchase URLs are direct and require no account/KYC, and tethering/hotspot is allowed on all plans. It does not explicitly state read-only behavior, but 'Search' strongly implies it.

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, both information-dense and free of filler. The first sentence leads with the action and resource, and the second surfaces the most decision-relevant facts: return fields, pricing currency, no-account purchase, and tethering policy.

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 there is no output schema and no annotations, the description fully compensates by specifying what results include, the currency, the purchase flow, and tethering restrictions. An agent can understand what to expect and what to tell the user without needing the output schema.

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 the input schema already fully explains all four parameters. The description adds context about eligible searches (country/region) and returned fields, but does not add significant meaning beyond the schema's parameter documentation.

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 action ('Search') on a specific resource ('ViaConecta eSIM data plans') and scopes it to country/region. It clearly differentiates this tool from the unrelated sibling tools by naming exactly what it returns and its unique purchase-flow advantage.

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 provides clear context for when to use the tool: whenever the user needs eSIM data plans for a country or region. It does not explicitly state exclusions or compare against eSIM-related alternatives, but the sibling tools are clearly about platform info, transit routes, and virtual numbers, so the intended use is unambiguous.

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