AI agents use send_message to create or update resources in Telnyx MCP Server — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Telnyx MCP Server environment.
Sending a message creates new data (message records) and transmits communications, making it a Write operation. The severity is high rather than medium because message sending can be abused at scale (spam, harassment, unauthorized notifications) and involves reaching external parties.
From the tool's definition Tool name is 'send_message' and server handles 'messaging' APIs. The Telnyx server description explicitly states it enables users to 'send messages', which is a write operation that creates new message records in the system and transmits them to recipients.
Documented attack patterns abuse exactly the kind of access send_message 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 send_message:
{
"version": "1",
"default": "deny",
"tools": {
"send_message": {
"limits": [
{
"counter": "send_message_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}send_message stays usable, but capped — an agent stuck in a loop can't make hundreds of changes a minute. Everything else on the server is denied unless you say otherwise.
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send_message. It is categorised as a Write tool in the Telnyx MCP Server MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Telnyx MCP Server MCP server in PolicyLayer and add a rule for send_message: 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.
send_message is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.
Yes. Add a rate_limit block to the send_message 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 send_message. 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.
send_message 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.