AI agents call get_phone_number to retrieve information from Telnyx MCP Server without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool retrieves data about a phone number identified by its ID. It performs a query/fetch operation that does not create, modify, delete, execute, or commit financial actions. The verb 'Get' and lack of any mutating language confirm this is a Read category tool with low severity, as it only exposes existing phone number metadata.
From the tool's definition Tool name 'get_phone_number' and description 'Get a phone number by ID' indicate a retrieval operation with no side effects.
Documented attack patterns abuse exactly the kind of access get_phone_number gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Telnyx MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for get_phone_number:
{
"version": "1",
"default": "deny",
"tools": {
"get_phone_number": {}
}
}get_phone_number is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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Get a phone number by ID. It is categorised as a Read tool in the Telnyx MCP Server MCP Server, which means it retrieves data without modifying state.
Register the Telnyx MCP Server MCP server in PolicyLayer and add a rule for get_phone_number: 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 Telnyx MCP Server. Nothing to install.
get_phone_number 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 get_phone_number 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 get_phone_number. 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.
get_phone_number is provided by the Telnyx MCP Server MCP server (team-telnyx/telnyx-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Telnyx MCP Server, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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46 Telnyx MCP Server tools catalogued and risk-classified — across an index of 43,000+ MCP servers.