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

Annotations already declare readOnly, idempotent and non-destructive, so the safety profile is covered. The description adds context the annotations cannot: no authentication is required and the call has no purchasing side effect, which is genuinely useful behavioral framing for a pricing tool.

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?

Three short, front-loaded sentences with no filler; the core output (monthly price, call inclusion) leads and the caveats follow.

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?

It does convey the return shape conceptually, which matters since there is no output schema, and the exclusion of purchasing is stated. However, with two of three parameters undocumented anywhere, the definition is not complete enough to call the tool correctly without guesswork.

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 only 33% (only currency is documented in the schema), and the description mentions no parameters at all. It does not explain what country or number_type accept or how they change the quoted price, so it fails to compensate for the coverage gap.

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 verb and resource: returns the rate-checker monthly price for a number plus whether calls are included. It is clearly distinct from the other quote_* siblings (quote_call, quote_esim, quote_port) by resource, though it never names them explicitly.

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?

'No sign-in' and 'Does not purchase a number' give clear conditions for use and a hard exclusion that prevents the agent from treating this as a purchase step. It stops short of naming a purchase/ordering alternative, so the negative guidance is implied rather than explicitly routed.

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