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

No annotations are supplied, so the description carries the full behavioral burden. It usefully discloses the return contents (all unlimited terms plus dedicated-service offers with their terms), implying a read-only lookup, but says nothing about auth, currency, freshness, or whether pricing is live.

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 that leads with the resource and scope. The parenthetical term list (12h, 1d, 7d, 30d, 180d, 365d) is bulky but genuinely informative, so it earns its place.

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, the description must convey the return shape, and it does so partially by naming the pricing categories. It omits currency, pricing freshness, and whether all services are covered, leaving a moderate gap for a pricing lookup.

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% and the single 'country' parameter is documented as an ISO country code with an example, so the schema does the heavy lifting. The description only echoes the one-country scoping and adds no extra semantics.

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?

States a specific resource (virtual numbers) constrained to one country and enumerates the pricing categories returned. It is distinguishable from sibling get_pricing only implicitly; there is no explicit statement of how it differs from get_pricing or get_number_renewal_options.

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 phrase 'in one country' implies this is the per-country pricing lookup, hinting at a contrast with the generic get_pricing sibling, but no when-to-use condition or alternative is ever named. Usage must be inferred from scope wording alone.

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