post_estimate_costWhat a verification SMS to this phone number would cost, in credits, and the number's country (region_code, ISO 3166-1 alpha-2; null when the number belongs to no assigned range). Nothing is sent. The price is for this number's carrier, so it can differ from the country's price in the price list. Group: Pricing. Billing per call: 0 Credits, Requests: metered (~0.36 avg).
| Name | Required | Description | Default |
|---|---|---|---|
| body | No | JSON request body. |
Changes observed during successful MCP inspections.
Input schema / properties / body / descriptionPrevious value: -"JSON request body. Example: {\"target\":\"+44 7459 034784\"}"New value: +"JSON request body."Input schema / properties / body / propertiesAdded value: +{
+ "target": {
+ "description": "The phone number in international format, with its country calling code, for example `+1 201 555 0123`. Spaces and dashes are allowed; a missing `+` is added.",
+ "example": "+1 201 555 0123",
+ "type": "string"
+ }
+}Input schema / properties / body / requiredAdded value: +[
+ "target"
+]Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full burden and does well: it declares no side effects ('Nothing is sent'), explains that cost varies by carrier and may diverge from the price list, and quantifies the billing profile ('0 Credits', 'metered ~0.36 avg'). It also explains the `null` region_code edge case.
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?
Front-loads the tool's output (cost in credits) before qualifiers, and every clause adds information. The trailing parentheticals are dense but not wasteful.
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 annotations and no output schema, the description must cover both behavior and return shape; it does — return values (credits, region_code with null semantics), safety (nothing sent), and billing. Nothing needed to invoke it correctly is missing.
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 `target` parameter's format is fully documented in the schema, so baseline 3 applies. The description adds meaning about the *result* (credits, region_code) rather than the input, which is useful but not parameter 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 precise outcome: the credit cost of a verification SMS to a given number, plus the number's country as `region_code`. It implicitly separates itself from `get_pricing` by noting the price is carrier-specific rather than the country-list price, so an agent can route correctly.
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 'Nothing is sent' clearly signals this is the dry-run counterpart to `post_send_numeric_verify`, which is the key usage decision. It stops short of naming the sibling or stating an explicit when-not rule, but the context is unambiguous.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
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