E.164-normalize and classify a phone number using libphonenumber. Returns format variants (E.164, international, national, RFC3966) plus type (mobile, fixed_line, voip, premium_rate, toll_free, etc.) and region.
AI agents call phone.normalize to retrieve information from Mcp without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool retrieves and transforms metadata about a phone number using libphonenumber library—it parses, formats, and classifies input to return standardized representations and attributes. No data is created, modified, deleted, or executed. The tool has no side effects and produces only informational output. It is a pure read/analysis operation with minimal security risk if misused.
From the tool's definition Tool description states it 'E.164-normalize and classify a phone number' and 'Returns format variants...plus type...and region.' The verb is 'normalize and classify' which are read operations that analyze and format input without modifying stored data or…
Attacks that exploit this kind of access
E.164-normalize and classify a phone number using libphonenumber. Returns format variants (E.164, international, national, RFC3966) plus type (mobile, fixed_line, voip, premium_rate, toll_free, etc.) and region. It is categorised as a Read tool in the Mcp MCP Server, which means it retrieves data without modifying state.
Register the MCP server in PolicyLayer and add a rule for phone.normalize: allow, deny, rate-limit, or require approval. Point your MCP client at the PolicyLayer proxy URL and the rule is enforced on every call, before it reaches Mcp. Nothing to install.
phone.normalize is a Read tool with low risk. Read-only tools are generally safe to allow by default.
Yes. Add a rate_limit block to the phone.normalize rule in your PolicyLayer policy. For example, setting max: 10 and window: 60 limits the tool to 10 calls per minute. Rate limits are tracked per agent session and reset automatically.
Set action: deny in the PolicyLayer policy for phone.normalize. The AI agent will receive a policy violation error and cannot call the tool. You can also include a reason field to explain why the tool is blocked.
phone.normalize is provided by the MCP server (@2sio/mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Every MCP server has a record like this.
Type a name, get the same breakdown: verified identity, auth posture, risk grade, capabilities, recommended policy.
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