line_typeReturn only the deterministic fields for a number — validity, line type (mobile / fixed line / VoIP / …), range carrier, country, and formatting. No paid dip; a free, fast classification a voice agent can call before deciding to enrich.
| Name | Required | Description | Default |
|---|---|---|---|
| number | Yes | Phone number in E.164, e.g. +14155552671 (loose input is normalized). |
Changes observed during successful MCP inspections. Dates show when Glama detected each change.
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint, openWorldHint, and idempotentHint, so the description adds useful context: it is free, deterministic (returns specific fields), and intended for pre-enrichment. No contradictions exist, and the description enhances understanding beyond the annotations.
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?
The description is two concise sentences that front-load the core functionality. Every word is meaningful, with no redundancy or filler. The structure efficiently communicates purpose, output, and use case.
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 tool has one input, no output schema, and a simple operation, the description covers the returned fields and usage context. It lacks explicit details on return format or error handling, but the listed fields and deterministic nature provide sufficient completeness for a voice agent.
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?
The input schema has 100% coverage with a detailed description for the 'number' parameter. The tool description does not add new information about the parameter; it only restates the context. Therefore, the description provides no additional semantic value beyond the schema.
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 tool returns deterministic fields for a phone number, including validity, line type, carrier, country, and formatting. It explicitly distinguishes itself from paid enrichment tools by noting it is a free, fast classification a voice agent can call before enriching, which differentiates it from sibling tools like phone_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 description provides context by stating it is a 'free, fast classification a voice agent can call before deciding to enrich,' implying it should be used for preliminary checks. However, it does not explicitly mention when not to use it or name specific sibling alternatives, though the use case is clear.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
Add one secure layer between your agents and this server.
Tools overlap significantly: phone_lookup includes spam signals and DNC check, while caller_risk and dnc_check provide more specific or constrained functionality. Descriptions help differentiate use cases, but an agent might struggle to choose between them.
All tool names use snake_case and are descriptive (e.g., caller_risk, dnc_check, line_type, phone_lookup). The pattern is mostly consistent, though verbs and noun combinations vary slightly.
Four tools cover the core needs of phone intelligence (quick classification, risk assessment, DNC check, comprehensive lookup) without redundancy. The scope is well-matched to the domain.
The set covers essential operations for phone intelligence: basic line info, risk, DNC, and a full lookup. Minor gaps exist (e.g., no tool for updating DNC preferences), but given the server's advisory role, these are acceptable.