Bulk Lookup

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

Annotations already indicate readOnlyHint, idempotentHint, and destructiveHint=false, so safety is covered. The description adds meaningful behavioral context beyond annotations: each number is 'a fresh paid read' and 'spend scope required', disclosing cost and entitlement requirements that an agent would not otherwise know.

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 with no fluff. The core operation and size limit are front-loaded, and the paid-read spend warning is placed second where it is easy to notice. Every phrase 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?

Given the output schema exists and annotations cover read-only/idempotent behavior, the description covers function scope, optionality, limits, cost, and entitlement. It stops just short of complete guidance because it doesn't explicitly contrast with sibling tools or explain what 'spend scope' entails, but an agent can invoke it correctly with available information.

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%, giving baseline 3. The description adds value by mapping product enums to concrete output categories (carrier, line type, routing, cnam/spam/messaging) and reinforcing the 'up to 100' limit and North American scope, which helps the agent reason about parameter values.

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 clearly states the verb 'lookup', the resource 'North American phone numbers', and the scope 'up to 100 in one call'. It also lists the data dimensions (carrier, line type, routing, optional cnam/spam/messaging), which distinguishes it from siblings like vri_spam_check or vri_number_lookup.

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 bulk nature is implied by 'up to 100 in one call', and the optional product list hints at use cases, but the description never explicitly says when to use this tool over vri_number_lookup for single lookups or vri_spam_check for spam-only checks. No exclusions or alternative routing are provided.

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