AI agents use update_assistant 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.
Although the tool description is empty, the name 'update_assistant' combined with context from the server's stated capability to 'create AI assistants' and the presence of create_assistant as a related tool strongly indicates this modifies assistant configurations. This is reversible (Write) rather than destructive.
From the tool's definition Tool name is 'update_assistant' which modifies AI assistant configuration. The Telnyx MCP Server description confirms it enables 'create AI assistants' and the presence of 'create_assistant' as a sibling tool indicates this server manages assistant lifecycle…
Documented attack patterns abuse exactly the kind of access update_assistant 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 update_assistant:
{
"version": "1",
"default": "deny",
"tools": {
"update_assistant": {
"limits": [
{
"counter": "update_assistant_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}update_assistant 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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update_assistant. 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 update_assistant: 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.
update_assistant 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 update_assistant 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 update_assistant. 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.
update_assistant 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.
Free to start. No card required.
46 Telnyx MCP Server tools catalogued and risk-classified — across an index of 43,000+ MCP servers.